ResourceManager.m

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/*
 
ResourceManager.m
 
Oolite
Copyright (C) 2004-2013 Giles C Williams and contributors
 
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
 
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA.
 
*/
 
#import "ResourceManager.h"
#import "NSScannerOOExtensions.h"
#import "NSMutableDictionaryOOExtensions.h"
#import "NSStringOOExtensions.h"
#import "OOSound.h"
#import "OOCacheManager.h"
#import "Universe.h"
#import "OOStringParsing.h"
#import "OOPListParsing.h"
#import "MyOpenGLView.h"
#import "OOCollectionExtractors.h"
#import "OOLogOutputHandler.h"
#import "NSFileManagerOOExtensions.h"
#import "OldSchoolPropertyListWriting.h"
#import "OOOXZManager.h"
#import "unzip.h"
#import "HeadUpDisplay.h"
#import "OODebugStandards.h"
#import "OOSystemDescriptionManager.h"
 
#import "OOJSScript.h"
#import "OOPListScript.h"
 
#import "OOManifestProperties.h"
 
static NSString * const kOOLogCacheUpToDate             = @"dataCache.upToDate";
static NSString * const kOOLogCacheExplicitFlush        = @"dataCache.rebuild.explicitFlush";
static NSString * const kOOLogCacheStalePaths           = @"dataCache.rebuild.pathsChanged";
static NSString * const kOOLogCacheStaleDates           = @"dataCache.rebuild.datesChanged";
static NSString * const kOOCacheSearchPathModDates      = @"search path modification dates";
static NSString * const kOOCacheKeySearchPaths          = @"search paths";
static NSString * const kOOCacheKeyModificationDates    = @"modification dates";
 
 
 
extern NSDictionary* ParseOOSScripts(NSString* script);
 
 
@interface ResourceManager (OOPrivate)
 
+ (void) checkOXPMessagesInPath:(NSString *)path;
+ (void) checkPotentialPath:(NSString *)path :(NSMutableArray *)searchPaths;
+ (BOOL) validateManifest:(NSDictionary*)manifest forOXP:(NSString *)path;
+ (BOOL) areRequirementsFulfilled:(NSDictionary*)requirements forOXP:(NSString *)path andFile:(NSString *)file;
+ (void) filterSearchPathsForConflicts:(NSMutableArray *)searchPaths;
+ (BOOL) filterSearchPathsForRequirements:(NSMutableArray *)searchPaths;
+ (void) filterSearchPathsToExcludeScenarioOnlyPaths:(NSMutableArray *)searchPaths;
+ (void) filterSearchPathsByScenario:(NSMutableArray *)searchPaths;
+ (BOOL) manifestAllowedByScenario:(NSDictionary *)manifest;
+ (BOOL) manifestAllowedByScenario:(NSDictionary *)manifest withIdentifier:(NSString *)identifier;
+ (BOOL) manifestAllowedByScenario:(NSDictionary *)manifest withTag:(NSString *)tag;
 
+ (void) addErrorWithKey:(NSString *)descriptionKey param1:(id)param1 param2:(id)param2;
+ (BOOL) checkCacheUpToDateForPaths:(NSArray *)searchPaths;
+ (void) logPaths;
+ (void) mergeRoleCategories:(NSDictionary *)catData intoDictionary:(NSMutableDictionary *)category;
+ (void) preloadFileLists;
+ (void) preloadFileListFromOXZ:(NSString *)path forFolders:(NSArray *)folders;
+ (void) preloadFileListFromFolder:(NSString *)path forFolders:(NSArray *)folders;
+ (void) preloadFilePathFor:(NSString *)fileName inFolder:(NSString *)subFolder atPath:(NSString *)path;
 
@end
 
 
static NSMutableArray   *sSearchPaths;
static NSString         *sUseAddOns;
static NSArray          *sUseAddOnsParts;
static BOOL             sFirstRun = YES;
static BOOL             sAllMet = NO;
static NSMutableArray   *sOXPsWithMessagesFound;
static NSMutableArray   *sExternalPaths;
static NSMutableArray   *sErrors;
static NSMutableDictionary *sOXPManifests;
 
 
 
// caches allow us to load any given file once only
//
static NSMutableDictionary *sSoundCache;
static NSMutableDictionary *sStringCache;
 
 
 
@implementation ResourceManager
 
+ (void) reset
{
    sFirstRun = YES;
    DESTROY(sUseAddOns);
    DESTROY(sUseAddOnsParts);
    DESTROY(sSearchPaths);
    DESTROY(sOXPsWithMessagesFound);
    DESTROY(sExternalPaths);
    DESTROY(sErrors);
    DESTROY(sOXPManifests);
}
 
 
+ (void) resetManifestKnowledgeForOXZManager
{
    DESTROY(sUseAddOns);
    DESTROY(sUseAddOnsParts);
    DESTROY(sSearchPaths);
    DESTROY(sOXPManifests);
    [ResourceManager pathsWithAddOns];
}
 
 
+ (NSString *) errors
{
    NSArray                 *error = nil;
    NSUInteger              i, count;
    NSMutableArray          *result = nil;
    NSString                *errStr = nil;
    
    count = [sErrors count];
    if (count == 0)  return nil;
    
    // Expand error messages. This is deferred for localizability.
    result = [NSMutableArray arrayWithCapacity:count];
    for (i = 0; i != count; ++i)
    {
        error = [sErrors objectAtIndex:i];
        errStr = [UNIVERSE descriptionForKey:[error oo_stringAtIndex:0]];
        if (errStr != nil)
        {
            errStr = [NSString stringWithFormat:errStr, [error objectAtIndex:1], [error objectAtIndex:2]];
            [result addObject:errStr];
        }
    }
    
    [sErrors release];
    sErrors = nil;
    
    return [result componentsJoinedByString:@"\n"];
}
 
 
+ (NSArray *)rootPaths
{
    static NSArray *sRootPaths = nil;
    if (sRootPaths == nil) {
        /* Built-in data, then managed OXZs, then manually installed ones,
         * which may be useful for debugging/testing purposes. */
        sRootPaths = [NSArray arrayWithObjects:[self builtInPath], [[OOOXZManager sharedManager] installPath], nil];
        sRootPaths = [[sRootPaths arrayByAddingObjectsFromArray:[self userRootPaths]] retain];
    }
    return sRootPaths;
}
 
 
+ (NSArray *)userRootPaths
{
    static NSArray          *sUserRootPaths = nil;
    
    if (sUserRootPaths == nil)
    {
        // the paths are now in order of preference as per yesterday's talk. -- Kaks 2010-05-05
        
        sUserRootPaths = [[NSArray alloc] initWithObjects:
 
#if OOLITE_MAC_OS_X
                      [[[[NSHomeDirectory() stringByAppendingPathComponent:@"Library"]
                         stringByAppendingPathComponent:@"Application Support"]
                         stringByAppendingPathComponent:@"Oolite"]
                        stringByAppendingPathComponent:@"AddOns"],
                      [[[[NSBundle mainBundle] bundlePath]
                         stringByDeletingLastPathComponent]
                        stringByAppendingPathComponent:@"AddOns"],
 
#elif OOLITE_WINDOWS
                      @"../AddOns",
#else   
                      @"AddOns",
#endif
 
#if !OOLITE_WINDOWS
                      [[NSHomeDirectory()
                        stringByAppendingPathComponent:@".Oolite"]
                       stringByAppendingPathComponent:@"AddOns"],
#endif
        
                        nil];
    }
    OOLog(@"searchPaths.debug",@"%@",sUserRootPaths);
    return sUserRootPaths;
}
 
 
+ (NSString *)builtInPath
{
#if OOLITE_WINDOWS
    /*  [[NSBundle mainBundle] resourcePath] causes complaints under Windows,
        because we don't have a properly-built bundle.
    */
    return @"Resources";
#else
    return [[NSBundle mainBundle] resourcePath];
#endif
}
 
 
+ (NSArray *)pathsWithAddOns
{
    if ([sSearchPaths count] > 0)  return sSearchPaths;
 
    if (sUseAddOns == nil)
    {
        sUseAddOns = [[NSString alloc] initWithString:SCENARIO_OXP_DEFINITION_ALL];
        sUseAddOnsParts = [[sUseAddOns componentsSeparatedByString:@";"] retain];
    }
    
    /* Handle special case of 'strict mode' efficiently */
    // testing actual string
    if ([sUseAddOns isEqualToString:SCENARIO_OXP_DEFINITION_NONE])
    {
        return (NSArray *)[NSArray arrayWithObject:[self builtInPath]];
    }
 
    [sErrors release];
    sErrors = nil;
    
    NSFileManager           *fmgr = [NSFileManager defaultManager];
    NSArray                 *rootPaths = nil;
    NSMutableArray          *existingRootPaths = nil;
    NSEnumerator            *pathEnum = nil;
    NSString                *root = nil;
    NSDirectoryEnumerator   *dirEnum = nil;
    NSString                *subPath = nil;
    NSString                *path = nil;
    BOOL                    isDirectory;
    
    // Copy those root paths that actually exist to search paths.
    rootPaths = [self rootPaths];
    existingRootPaths = [NSMutableArray arrayWithCapacity:[rootPaths count]];
    for (pathEnum = [rootPaths objectEnumerator]; (root = [pathEnum nextObject]); )
    {
        if ([fmgr fileExistsAtPath:root isDirectory:&isDirectory] && isDirectory)
        {
            [existingRootPaths addObject:root];
        }
    }
    
    // validate default search paths
    DESTROY(sSearchPaths);
    sSearchPaths = [NSMutableArray new];
    foreach(path, existingRootPaths)
    {
        [self checkPotentialPath:path :sSearchPaths];
    }
    
    // Iterate over root paths.
    for (pathEnum = [existingRootPaths objectEnumerator]; (root = [pathEnum nextObject]); )
    {
        // Iterate over each root path's contents.
        if ([fmgr fileExistsAtPath:root isDirectory:&isDirectory] && isDirectory)
        {
            for (dirEnum = [fmgr enumeratorAtPath:root]; (subPath = [dirEnum nextObject]); )
            {
                // Check if it's a directory.
                path = [root stringByAppendingPathComponent:subPath];
                if ([fmgr fileExistsAtPath:path isDirectory:&isDirectory])
                {
                    if (isDirectory)
                    {
                        // If it is, is it an OXP?.
                        if ([[[path pathExtension] lowercaseString] isEqualToString:@"oxp"])
                        {
                            [self checkPotentialPath:path :sSearchPaths];
                            if ([sSearchPaths containsObject:path])  [self checkOXPMessagesInPath:path];
                        }
                        else
                        {
                            // If not, don't search subdirectories.
                            [dirEnum skipDescendents];
                        }
                    }
                    else
                    {
                        // If not a directory, is it an OXZ?
                        if ([[[path pathExtension] lowercaseString] isEqualToString:@"oxz"])
                        {
                            [self checkPotentialPath:path :sSearchPaths];
                            if ([sSearchPaths containsObject:path])  [self checkOXPMessagesInPath:path];
                        }
                    }
                }
            }
        }
    }
    
    for (pathEnum = [sExternalPaths objectEnumerator]; (path = [pathEnum nextObject]); )
    {
        [self checkPotentialPath:path :sSearchPaths];
        if ([sSearchPaths containsObject:path])  [self checkOXPMessagesInPath:path];
    }
 
    /* If a scenario restriction is *not* in place, remove
     * scenario-only OXPs. */
    // test string
    if ([sUseAddOns isEqualToString:SCENARIO_OXP_DEFINITION_ALL])
    {
        [self filterSearchPathsToExcludeScenarioOnlyPaths:sSearchPaths];
    }
 
    /* This is a conservative filter. It probably gets rid of more
     * OXPs than it technically needs to in certain situations with
     * dependency chains, but really any conflict here needs to be
     * resolved by the user rather than Oolite. The point is to avoid
     * loading OXPs which we shouldn't; if doing so takes out other
     * OXPs which would have been safe, that's not important. */
    [self filterSearchPathsForConflicts:sSearchPaths];
 
    /* This one needs to be run repeatedly to be sure. Take the chain
     * A depends on B depends on C. A and B are installed. A is
     * checked first, and depends on B, which is thought to be
     * okay. So A is kept. Then B is checked and removed. A must then
     * be rechecked. This function therefore is run repeatedly until a
     * run of it removes no further items.
     *
     * There may well be more elegant and efficient ways to do this
     * but this is already fast enough for most purposes.
     */
    while (![self filterSearchPathsForRequirements:sSearchPaths]) {}
 
    /* If a scenario restriction is in place, restrict OXPs to the
     * ones valid for the scenario only. */
    // test string
    if (![sUseAddOns isEqualToString:SCENARIO_OXP_DEFINITION_ALL])
    {
        [self filterSearchPathsByScenario:sSearchPaths];
    }
 
    [self checkCacheUpToDateForPaths:sSearchPaths];
    
    return sSearchPaths;
}
 
 
+ (void) preloadFileLists
{
    NSString         *path = nil;
    NSEnumerator *pathEnum = nil;
 
    // folders which may contain files to be cached
    NSArray *folders = [NSArray arrayWithObjects:@"AIs",@"Images",@"Models",@"Music",@"Scenarios",@"Scripts",@"Shaders",@"Sounds",@"Textures",nil];
 
    for (pathEnum = [[ResourceManager paths] reverseObjectEnumerator]; (path = [pathEnum nextObject]); )
    {
        if ([path hasSuffix:@".oxz"])
        {
            [self preloadFileListFromOXZ:path forFolders:folders];
        }
        else
        {
            [self preloadFileListFromFolder:path forFolders:folders];
        }
    }
}
 
 
+ (void) preloadFileListFromOXZ:(NSString *)path forFolders:(NSArray *)folders
{
    unzFile uf = NULL;
    const char* zipname = [path UTF8String];
    char componentName[512];
 
    if (zipname != NULL)
    {
        uf = unzOpen64(zipname);
    }
    if (uf == NULL)
    {
        OOLog(@"resourceManager.error",@"Could not open .oxz at %@ as zip file",path);
        return;
    }
    if (unzGoToFirstFile(uf) == UNZ_OK)
    {
        do 
        {
            unzGetCurrentFileInfo64(uf, NULL,
                                    componentName, 512,
                                    NULL, 0,
                                    NULL, 0);
            NSString *zipEntry = [NSString stringWithUTF8String:componentName];
            NSArray *pathBits = [zipEntry pathComponents];
            if ([pathBits count] >= 2)
            {
                NSString *folder = [pathBits oo_stringAtIndex:0];
                if ([folders containsObject:folder])
                {
                    NSRange bitRange;
                    bitRange.location = 1;
                    bitRange.length = [pathBits count]-1;
                    NSString *file = [NSString pathWithComponents:[pathBits subarrayWithRange:bitRange]];
                    NSString *fullPath = [[path stringByAppendingPathComponent:folder] stringByAppendingPathComponent:file];
                    
                    [self preloadFilePathFor:file inFolder:folder atPath:fullPath];
                }
            }
 
        } 
        while (unzGoToNextFile(uf) == UNZ_OK);
    }
    unzClose(uf);
 
}
 
 
+ (void) preloadFileListFromFolder:(NSString *)path forFolders:(NSArray *)folders
{
    NSFileManager *fmgr         = [NSFileManager defaultManager];
    NSString *subFolder         = nil;
    NSString *subFolderPath     = nil;
    NSArray *fileList           = nil;
    NSString *fileName          = nil;
 
    // search each subfolder for files
    foreach (subFolder, folders)
    {
        subFolderPath = [path stringByAppendingPathComponent:subFolder];
        fileList = [fmgr oo_directoryContentsAtPath:subFolderPath];
        foreach (fileName, fileList)
        {
            [self preloadFilePathFor:fileName inFolder:subFolder atPath:[subFolderPath stringByAppendingPathComponent:fileName]];
        }
    }
 
}
 
 
+ (void) preloadFilePathFor:(NSString *)fileName inFolder:(NSString *)subFolder atPath:(NSString *)path
{
    OOCacheManager  *cache = [OOCacheManager sharedCache];
    NSString *cacheKey = [NSString stringWithFormat:@"%@/%@", subFolder, fileName];
    NSString *result = [cache objectForKey:cacheKey inCache:@"resolved paths"];
    // if nil, not found in another OXP already
    if (result == nil)
    {
        OOLog(@"resourceManager.foundFile.preLoad", @"Found %@/%@ at %@", subFolder, fileName, path);
        [cache setObject:path forKey:cacheKey inCache:@"resolved paths"];
    }
}
 
 
 
+ (NSArray *)paths
{
    if (EXPECT_NOT(sSearchPaths == nil))
    {
        sSearchPaths = [[NSMutableArray alloc] init];
    }
    return [self pathsWithAddOns];
}
 
 
+ (NSString *)useAddOns
{
    return sUseAddOns;
}
 
 
+ (void)setUseAddOns:(NSString *)useAddOns
{
    if (sFirstRun || ![useAddOns isEqualToString:sUseAddOns])
    {
        [self reset];
        sFirstRun = NO;
        DESTROY(sUseAddOnsParts);
        DESTROY(sUseAddOns);
        sUseAddOns = [useAddOns retain];
        sUseAddOnsParts = [[sUseAddOns componentsSeparatedByString:@";"] retain];
 
        [ResourceManager clearCaches];
        OOHUDResetTextEngine();
 
        OOCacheManager *cmgr = [OOCacheManager sharedCache];
        /* only allow cache writes for the "all OXPs" default
         *
         * cache should be less necessary for restricted sets anyway */
        // testing the actual string here
        if ([sUseAddOns isEqualToString:SCENARIO_OXP_DEFINITION_ALL])
        {
            [cmgr reloadAllCaches];
            [cmgr setAllowCacheWrites:YES];
        }
        else
        {
            [cmgr clearAllCaches];
            [cmgr setAllowCacheWrites:NO];
        }
        
        [self checkCacheUpToDateForPaths:[self paths]];
        [self logPaths];
        /* preloading the file lists at this stage helps efficiency a
         * lot when many OXZs are installed */
        [self preloadFileLists];
 
    }
}
 
 
+ (void) addExternalPath:(NSString *)path
{
    if (sSearchPaths == nil)  sSearchPaths = [[NSMutableArray alloc] init];
    if (![sSearchPaths containsObject:path])
    {
        [sSearchPaths addObject:path];
        
        if (sExternalPaths == nil)  sExternalPaths = [[NSMutableArray alloc] init];
        [sExternalPaths addObject:path];
    }
}
 
 
+ (NSEnumerator *)pathEnumerator
{
    return [[self paths] objectEnumerator];
}
 
 
+ (NSEnumerator *)reversePathEnumerator
{
    return [[self paths] reverseObjectEnumerator];
}
 
 
+ (NSArray *)OXPsWithMessagesFound
{
    return [[sOXPsWithMessagesFound copy] autorelease];
}
 
 
+ (NSDictionary *)manifestForIdentifier:(NSString *)identifier
{
    return [sOXPManifests objectForKey:identifier];
}
 
 
+ (void) checkOXPMessagesInPath:(NSString *)path
{
    NSArray *OXPMessageArray = OOArrayFromFile([path stringByAppendingPathComponent:@"OXPMessages.plist"]);
    
    if ([OXPMessageArray count] > 0)
    {
        unsigned i;
        for (i = 0; i < [OXPMessageArray count]; i++)
        {
            NSString *oxpMessage = [OXPMessageArray oo_stringAtIndex:i];
            if (oxpMessage)
            {
                OOLog(@"oxp.message", @"%@: %@", path, oxpMessage);
            }
        }
        if (sOXPsWithMessagesFound == nil)  sOXPsWithMessagesFound = [[NSMutableArray alloc] init];
        [sOXPsWithMessagesFound addObject:[path lastPathComponent]];
    }
}
 
 
// Given a path to an assumed OXP (or other location where files are permissible), check for a requires.plist or manifest.plist and add to search paths if acceptable.
+ (void)checkPotentialPath:(NSString *)path :(NSMutableArray *)searchPaths
{
    NSDictionary            *requirements = nil;
    NSDictionary            *manifest = nil;
    BOOL                    requirementsMet = YES;
 
    if (![[[path pathExtension] lowercaseString] isEqualToString:@"oxz"])
    {
        // OXZ format ignores requires.plist
        requirements = OODictionaryFromFile([path stringByAppendingPathComponent:@"requires.plist"]);
        requirementsMet = [self areRequirementsFulfilled:requirements forOXP:path andFile:@"requires.plist"];
    }
    if (!requirementsMet)
    {
        NSString *version = [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleVersion"];
        OOLog(@"oxp.versionMismatch", @"OXP %@ is incompatible with version %@ of Oolite.", path, version);
        [self addErrorWithKey:@"oxp-is-incompatible" param1:[path lastPathComponent] param2:version];
        return;
    }
    
    manifest = OODictionaryFromFile([path stringByAppendingPathComponent:@"manifest.plist"]);
    if (manifest == nil)
    {
        if ([[[path pathExtension] lowercaseString] isEqualToString:@"oxz"])
        {
            OOLog(@"oxp.noManifest", @"OXZ %@ has no manifest.plist", path);
            [self addErrorWithKey:@"oxz-lacks-manifest" param1:[path lastPathComponent] param2:nil];
            return;
        }
        else
        {
            if ([[[path pathExtension] lowercaseString] isEqualToString:@"oxp"])
            {
                OOStandardsError([NSString stringWithFormat:@"OXP %@ has no manifest.plist", path]);
                if (OOEnforceStandards())
                {
                    [self addErrorWithKey:@"oxp-lacks-manifest" param1:[path lastPathComponent] param2:nil];
                    return;
                }
            }
            // make up a basic manifest in relaxed mode or for base folders
            manifest = [NSDictionary dictionaryWithObjectsAndKeys:[NSString stringWithFormat:@"__oolite.tmp.%@",path],kOOManifestIdentifier,@"1",kOOManifestVersion,@"OXP without manifest",kOOManifestTitle,@"1",kOOManifestRequiredOoliteVersion,nil];
        }
    }
    
    requirementsMet = [self validateManifest:manifest forOXP:path];
 
 
    if (requirementsMet) 
    {
        [searchPaths addObject:path];
    }
}
 
 
+ (BOOL) validateManifest:(NSDictionary*)manifest forOXP:(NSString *)path
{
    if (EXPECT_NOT(sOXPManifests == nil))
    {
        sOXPManifests = [[NSMutableDictionary alloc] initWithCapacity:32];
    }
    
    BOOL        OK = YES;
    NSString    *identifier = [manifest oo_stringForKey:kOOManifestIdentifier defaultValue:nil];
    NSString    *version = [manifest oo_stringForKey:kOOManifestVersion defaultValue:nil];
    NSString    *required = [manifest oo_stringForKey:kOOManifestRequiredOoliteVersion defaultValue:nil];
    NSString    *title = [manifest oo_stringForKey:kOOManifestTitle defaultValue:nil];
 
    if (identifier == nil)
    {
        OOLog(@"oxp.noManifest", @"OXZ %@ manifest.plist has no '%@' field.", path, kOOManifestIdentifier);
        [self addErrorWithKey:@"oxp-manifest-incomplete" param1:title param2:kOOManifestIdentifier];
        OK = NO;
    }
    if (version == nil)
    {
        OOLog(@"oxp.noManifest", @"OXZ %@ manifest.plist has no '%@' field.", path, kOOManifestVersion);
        [self addErrorWithKey:@"oxp-manifest-incomplete" param1:title param2:kOOManifestVersion];
        OK = NO;
    }
    if (required == nil)
    {
        OOLog(@"oxp.noManifest", @"OXZ %@ manifest.plist has no '%@' field.", path, kOOManifestRequiredOoliteVersion);
        [self addErrorWithKey:@"oxp-manifest-incomplete" param1:title param2:kOOManifestRequiredOoliteVersion];
        OK = NO;
    }
    if (title == nil)
    {
        OOLog(@"oxp.noManifest", @"OXZ %@ manifest.plist has no '%@' field.", path, kOOManifestTitle);
        [self addErrorWithKey:@"oxp-manifest-incomplete" param1:title param2:kOOManifestTitle];
        OK = NO;
    }
    if (!OK)
    {
        return NO;
    }
    OK = [self checkVersionCompatibility:manifest forOXP:title];
 
    if (!OK)
    {
        NSString *version = [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleVersion"];
        OOLog(@"oxp.versionMismatch", @"OXP %@ is incompatible with version %@ of Oolite.", path, version);
        [self addErrorWithKey:@"oxp-is-incompatible" param1:[path lastPathComponent] param2:version];
        return NO;
    }
 
    NSDictionary *duplicate = [sOXPManifests objectForKey:identifier];
    if (duplicate != nil)
    {
        OOLog(@"oxp.duplicate", @"OXP %@ has the same identifier (%@) as %@ which has already been loaded.",path,identifier,[duplicate oo_stringForKey:kOOManifestFilePath]);
        [self addErrorWithKey:@"oxp-manifest-duplicate" param1:path param2:[duplicate oo_stringForKey:kOOManifestFilePath]];
        return NO;
    }
    NSMutableDictionary *mData = [NSMutableDictionary dictionaryWithDictionary:manifest];
    [mData setObject:path forKey:kOOManifestFilePath];
    // add an extra key
    [sOXPManifests setObject:mData forKey:identifier];
    return YES;
}
 
 
+ (BOOL) checkVersionCompatibility:(NSDictionary *)manifest forOXP:(NSString *)title
{
    NSString    *required = [manifest oo_stringForKey:kOOManifestRequiredOoliteVersion defaultValue:nil];
    NSString *maxRequired = [manifest oo_stringForKey:kOOManifestMaximumOoliteVersion defaultValue:nil];
    // ignore empty max version string rather than treating as "version 0"
    if (maxRequired == nil || [maxRequired length] == 0)
    {
        return [self areRequirementsFulfilled:[NSDictionary dictionaryWithObjectsAndKeys:required, @"version", nil] forOXP:title andFile:@"manifest.plist"];
    }
    else
    {
        return [self areRequirementsFulfilled:[NSDictionary dictionaryWithObjectsAndKeys:required, @"version", maxRequired, @"max_version", nil] forOXP:title andFile:@"manifest.plist"];
    }
}
 
 
+ (BOOL) areRequirementsFulfilled:(NSDictionary*)requirements forOXP:(NSString *)path andFile:(NSString *)file
{
    BOOL                OK = YES;
    NSString            *requiredVersion = nil;
    NSString            *maxVersion = nil;
    unsigned            conditionsHandled = 0;
    static NSArray      *ooVersionComponents = nil;
    NSArray             *oxpVersionComponents = nil;
    
    if (requirements == nil)  return YES;
    
    if (ooVersionComponents == nil)
    {
        ooVersionComponents = ComponentsFromVersionString([[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleVersion"]);
        [ooVersionComponents retain];
    }
    
    // Check "version" (minimum version)
    if (OK)
    {
        // Not oo_stringForKey:, because we need to be able to complain about non-strings.
        requiredVersion = [requirements objectForKey:@"version"];
        if (requiredVersion != nil)
        {
            ++conditionsHandled;
            if ([requiredVersion isKindOfClass:[NSString class]])
            {
                oxpVersionComponents = ComponentsFromVersionString(requiredVersion);
                if (NSOrderedAscending == CompareVersions(ooVersionComponents, oxpVersionComponents))  OK = NO;
            }
            else
            {
                OOLog(@"requirements.wrongType", @"Expected %@ entry \"%@\" to be string, but got %@ in OXP %@.", file, @"version", [requirements class], [path lastPathComponent]);
                OK = NO;
            }
        }
    }
    
    // Check "max_version" (minimum max_version)
    if (OK)
    {
        // Not oo_stringForKey:, because we need to be able to complain about non-strings.
        maxVersion = [requirements objectForKey:@"max_version"];
        if (maxVersion != nil)
        {
            ++conditionsHandled;
            if ([maxVersion isKindOfClass:[NSString class]])
            {
                oxpVersionComponents = ComponentsFromVersionString(maxVersion);
                if (NSOrderedDescending == CompareVersions(ooVersionComponents, oxpVersionComponents))  OK = NO;
            }
            else
            {
                OOLog(@"requirements.wrongType", @"Expected %@ entry \"%@\" to be string, but got %@ in OXP %@.", file, @"max_version", [requirements class], [path lastPathComponent]);
                OK = NO;
            }
        }
    }
    
    if (OK && conditionsHandled < [requirements count])
    {
        // There are unknown requirement keys - don't support. NOTE: this check was not made pre 1.69!
        OOLog(@"requirements.unknown", @"requires.plist for OXP %@ contains unknown keys, rejecting.", [path lastPathComponent]);
        OK = NO;
    }
    
    return OK;
}
 
 
+ (BOOL) manifestHasConflicts:(NSDictionary *)manifest logErrors:(BOOL)logErrors
{
    NSDictionary    *conflicting = nil;
    NSDictionary    *conflictManifest = nil;
    NSString        *conflictID = nil;
    NSArray         *conflicts = nil;
    
    conflicts = [manifest oo_arrayForKey:kOOManifestConflictOXPs defaultValue:nil];
    // if it has a non-empty conflict_oxps list 
    if (conflicts != nil && [conflicts count] > 0)
    {
        // iterate over that list
        foreach (conflicting, conflicts)
        {
            conflictID = [conflicting oo_stringForKey:kOOManifestRelationIdentifier];
            conflictManifest = [sOXPManifests objectForKey:conflictID];
            // if the other OXP is in the list
            if (conflictManifest != nil)
            {
                // then check versions
                if ([self matchVersions:conflicting withVersion:[conflictManifest oo_stringForKey:kOOManifestVersion]])
                {
                    if (logErrors)
                    {
                        [self addErrorWithKey:@"oxp-conflict" param1:[manifest oo_stringForKey:kOOManifestTitle] param2:[conflictManifest oo_stringForKey:kOOManifestTitle]];
                        OOLog(@"oxp.conflict",@"OXP %@ conflicts with %@ and was removed from the loading list",[[manifest oo_stringForKey:kOOManifestFilePath] lastPathComponent],[[conflictManifest oo_stringForKey:kOOManifestFilePath] lastPathComponent]);
                    }
                    return YES;
                }
            }
        }
    }
    return NO;
}
 
 
+ (void) filterSearchPathsForConflicts:(NSMutableArray *)searchPaths
{
    NSDictionary    *manifest = nil;
    NSString        *identifier = nil;
    NSArray         *identifiers = [sOXPManifests allKeys];
 
    // take a copy because we'll mutate the original
    // foreach identified add-on
    foreach (identifier, identifiers)
    {
        manifest = [sOXPManifests objectForKey:identifier];
        if (manifest != nil)
        {
            if ([self manifestHasConflicts:manifest logErrors:YES])
            {
                // then we have a conflict, so remove this path
                [searchPaths removeObject:[manifest oo_stringForKey:kOOManifestFilePath]];
                [sOXPManifests removeObjectForKey:identifier];
            }
        }
    }
}
 
 
+ (BOOL) manifestHasMissingDependencies:(NSDictionary *)manifest logErrors:(BOOL)logErrors
{
    NSDictionary    *required = nil;
    NSArray         *requireds = nil;
 
    requireds = [manifest oo_arrayForKey:kOOManifestRequiresOXPs defaultValue:nil];
    // if it has a non-empty required_oxps list 
    if (requireds != nil && [requireds count] > 0)
    {
        // iterate over that list
        foreach (required, requireds)
        {
            if ([ResourceManager manifest:manifest HasUnmetDependency:required logErrors:logErrors])
            {
                return YES;
            }
        }
    }
    return NO;
}
 
 
+ (BOOL) manifest:(NSDictionary *)manifest HasUnmetDependency:(NSDictionary *)required logErrors:(BOOL)logErrors
{
    NSString        *requiredID = [required oo_stringForKey:kOOManifestRelationIdentifier];
    NSMutableDictionary *requiredManifest = [sOXPManifests objectForKey:requiredID];
    // if the other OXP is in the list
    BOOL requirementsMet = NO;
    if (requiredManifest != nil)
    {
        // then check versions
        if ([self matchVersions:required withVersion:[requiredManifest oo_stringForKey:kOOManifestVersion]])
        {
            requirementsMet = YES;
            /* Mark the requiredManifest as a dependency of the
             * requiring manifest */
            NSSet *reqby = [requiredManifest oo_setForKey:kOOManifestRequiredBy defaultValue:[NSSet set]];
            NSUInteger reqbycount = [reqby count];
            /* then add this manifest to its required set. This is
             * done without checking if it's already there, because
             * the list of nested requirements may have changed. */
            reqby = [reqby setByAddingObject:[manifest oo_stringForKey:kOOManifestIdentifier]];
            // *and* anything that requires this OXP to be installed
            reqby = [reqby setByAddingObjectsFromSet:[manifest oo_setForKey:kOOManifestRequiredBy]];
            if (reqbycount < [reqby count])
            {
                /* Then the set has increased in size. To handle
                 * potential cases with nested dependencies, need to
                 * re-run the requirement filter until all the sets
                 * stabilise. */
                sAllMet = NO;
            }
            // and push back into the requiring manifest
            [requiredManifest setObject:reqby forKey:kOOManifestRequiredBy];
        }
    }
    if (!requirementsMet)
    {
        if (logErrors)
        {
            [self addErrorWithKey:@"oxp-required" param1:[manifest oo_stringForKey:kOOManifestTitle] param2:[required oo_stringForKey:kOOManifestRelationDescription defaultValue:[required oo_stringForKey:kOOManifestRelationIdentifier]]];
            OOLog(@"oxp.requirementMissing",@"OXP %@ had unmet requirements and was removed from the loading list",[[manifest oo_stringForKey:kOOManifestFilePath] lastPathComponent]);
        }
        return YES;
    }
    return NO;
}
 
 
+ (BOOL) filterSearchPathsForRequirements:(NSMutableArray *)searchPaths
{
    NSDictionary    *manifest = nil;
    NSString        *identifier = nil;
    NSArray         *identifiers = [sOXPManifests allKeys];
 
    sAllMet = YES;
 
    // take a copy because we'll mutate the original
    // foreach identified add-on
    foreach (identifier, identifiers)
    {
        manifest = [sOXPManifests objectForKey:identifier];
        if (manifest != nil)
        {
            if ([self manifestHasMissingDependencies:manifest logErrors:YES])
            {
                // then we have a missing requirement, so remove this path
                [searchPaths removeObject:[manifest oo_stringForKey:kOOManifestFilePath]];
                [sOXPManifests removeObjectForKey:identifier];
                sAllMet = NO;
            }
        }
    }
 
    return sAllMet;
}
 
 
+ (BOOL) matchVersions:(NSDictionary *)rangeDict withVersion:(NSString *)version
{
    NSString    *minimum = [rangeDict oo_stringForKey:kOOManifestRelationVersion defaultValue:nil];
    NSString    *maximum = [rangeDict oo_stringForKey:kOOManifestRelationMaxVersion defaultValue:nil];
    NSArray     *isVersionComponents = ComponentsFromVersionString(version);
    NSArray     *reqVersionComponents = nil;
    if (minimum != nil)
    {
        reqVersionComponents = ComponentsFromVersionString(minimum);
        if (NSOrderedAscending == CompareVersions(isVersionComponents, reqVersionComponents))
        {
            // earlier than minimum version
            return NO;
        }
    }
    if (maximum != nil)
    {
        reqVersionComponents = ComponentsFromVersionString(maximum);
        if (NSOrderedDescending == CompareVersions(isVersionComponents, reqVersionComponents))
        {
            // later than maximum version
            return NO;
        }
    }
    // either version was okay, or no version info so an unconditional match
    return YES;
}
 
 
+ (void) filterSearchPathsToExcludeScenarioOnlyPaths:(NSMutableArray *)searchPaths
{
    NSDictionary    *manifest = nil;
    NSString        *identifier = nil;
    NSArray         *identifiers = [sOXPManifests allKeys];
 
    // take a copy because we'll mutate the original
    // foreach identified add-on
    foreach (identifier, identifiers)
    {
        manifest = [sOXPManifests objectForKey:identifier];
        if (manifest != nil)
        {
            if ([[manifest oo_arrayForKey:kOOManifestTags] containsObject:kOOManifestTagScenarioOnly])
            {
                [searchPaths removeObject:[manifest oo_stringForKey:kOOManifestFilePath]];
                [sOXPManifests removeObjectForKey:identifier];
            }
        }
    }
}
 
 
 
+ (void) filterSearchPathsByScenario:(NSMutableArray *)searchPaths
{
    NSDictionary    *manifest = nil;
    NSString        *identifier = nil;
    NSArray         *identifiers = [sOXPManifests allKeys];
 
    // take a copy because we'll mutate the original
    // foreach identified add-on
    foreach (identifier, identifiers)
    {
        manifest = [sOXPManifests objectForKey:identifier];
        if (manifest != nil)
        {
            if (![ResourceManager manifestAllowedByScenario:manifest])
            {
                // then we don't need this one
                [searchPaths removeObject:[manifest oo_stringForKey:kOOManifestFilePath]];
                [sOXPManifests removeObjectForKey:identifier];
            }
        }
    }
}
 
 
+ (BOOL) manifestAllowedByScenario:(NSDictionary *)manifest
{
    /* Checks for a couple of "never happens" cases */
#ifndef NDEBUG
    // test string
    if ([sUseAddOns isEqualToString:SCENARIO_OXP_DEFINITION_ALL])
    {
        OOLog(@"scenario.check", @"%@", @"Checked scenario allowances in all state - this is an internal error; please report this");
        return YES;
    }
    if ([sUseAddOns isEqualToString:SCENARIO_OXP_DEFINITION_NONE])
    {
        OOLog(@"scenario.check", @"%@", @"Checked scenario allowances in none state - this is an internal error; please report this");
        return NO;
    }
#endif
    if ([[manifest oo_stringForKey:kOOManifestIdentifier] isEqualToString:@"org.oolite.oolite"])
    {
        // the core data is always allowed!
        return YES;
    }
 
    NSString *uaoBit = nil;
    BOOL result = NO;
    foreach (uaoBit, sUseAddOnsParts)
    {
        if ([uaoBit hasPrefix:SCENARIO_OXP_DEFINITION_BYID])
        {
            result |= [ResourceManager manifestAllowedByScenario:manifest withIdentifier:[uaoBit substringFromIndex:[SCENARIO_OXP_DEFINITION_BYID length]]];
        }
        else if ([uaoBit hasPrefix:SCENARIO_OXP_DEFINITION_BYTAG])
        {
            result |= [ResourceManager manifestAllowedByScenario:manifest withTag:[uaoBit substringFromIndex:[SCENARIO_OXP_DEFINITION_BYTAG length]]];
        }
    }
    return result;
}
 
 
+ (BOOL) manifestAllowedByScenario:(NSDictionary *)manifest withIdentifier:(NSString *)identifier
{
    if ([[manifest oo_stringForKey:kOOManifestIdentifier] isEqualToString:identifier])
    {
        // manifest has the identifier - easy
        return YES;
    }
    // manifest is also allowed if a manifest with that identifier
    // requires it to be installed
    if ([[manifest oo_setForKey:kOOManifestRequiredBy] containsObject:identifier])
    {
        return YES;
    }
    // otherwise, no
    return NO;
}
 
 
+ (BOOL) manifestAllowedByScenario:(NSDictionary *)manifest withTag:(NSString *)tag
{
    if ([[manifest oo_arrayForKey:kOOManifestTags] containsObject:tag])
    {
        // manifest has the tag - easy
        return YES;
    }
    // manifest is also allowed if a manifest with that tag
    // requires it to be installed
    NSSet *reqby = [manifest oo_setForKey:kOOManifestRequiredBy];
    if (reqby != nil)
    {
        NSString *identifier = nil;
        foreach (identifier, reqby)
        {
            NSDictionary *reqManifest = [sOXPManifests oo_dictionaryForKey:identifier defaultValue:nil];
            // need to check for nil as this one may already have been ruled out
            if (reqManifest != nil && [[reqManifest oo_arrayForKey:kOOManifestTags] containsObject:tag])
            {
                return YES;
            }
        }
    }
    // otherwise, no
    return NO;
}
 
 
 
+ (void) addErrorWithKey:(NSString *)descriptionKey param1:(id)param1 param2:(id)param2
{
    if (descriptionKey != nil)
    {
        if (sErrors == nil)  sErrors = [[NSMutableArray alloc] init];
        [sErrors addObject:[NSArray arrayWithObjects:descriptionKey, param1 ?: (id)@"", param2 ?: (id)@"", nil]];
    }
}
 
 
+ (BOOL)checkCacheUpToDateForPaths:(NSArray *)searchPaths
{
    /*  Check if caches are up to date.
        The strategy is to use a two-entry cache. One entry is an array
        containing the search paths, the other an array of modification dates
        (in the same order). If either fails to match the correct settings,
        we delete both.
    */
    OOCacheManager      *cacheMgr = [OOCacheManager sharedCache];
    NSFileManager       *fmgr = [NSFileManager defaultManager];
    BOOL                upToDate = YES;
    id                  oldPaths = nil;
    NSMutableArray      *modDates = nil;
    NSEnumerator        *pathEnum = nil;
    NSString            *path = nil;
    id                  modDate = nil;
    
    if (EXPECT_NOT([[NSUserDefaults standardUserDefaults] boolForKey:@"always-flush-cache"]))
    {
        OOLog(kOOLogCacheExplicitFlush, @"%@", @"Cache explicitly flushed with always-flush-cache preference. Rebuilding from scratch.");
        upToDate = NO;
    }
    else if ([MyOpenGLView pollShiftKey])
    {
        OOLog(kOOLogCacheExplicitFlush, @"%@", @"Cache explicitly flushed with shift key. Rebuilding from scratch.");
        upToDate = NO;
    }
    
    oldPaths = [cacheMgr objectForKey:kOOCacheKeySearchPaths inCache:kOOCacheSearchPathModDates];
    if (upToDate && ![oldPaths isEqual:searchPaths])
    {
        // OXPs added/removed
        if (oldPaths != nil) OOLog(kOOLogCacheStalePaths, @"%@", @"Cache is stale (search paths have changed). Rebuilding from scratch.");
        upToDate = NO;
    }
    
    // Build modification date list. (We need this regardless of whether the search paths matched.)
    
    modDates = [NSMutableArray arrayWithCapacity:[searchPaths count]];
    for (pathEnum = [searchPaths objectEnumerator]; (path = [pathEnum nextObject]); )
    {
        modDate = [[fmgr oo_fileAttributesAtPath:path traverseLink:YES] objectForKey:NSFileModificationDate];
        if (modDate != nil)
        {
            // Converts to double because I'm not sure the cache can deal with dates under GNUstep.
            modDate = [NSNumber numberWithDouble:[modDate timeIntervalSince1970]];
            [modDates addObject:modDate];
        }
    }
        
    if (upToDate && ![[cacheMgr objectForKey:kOOCacheKeyModificationDates inCache:kOOCacheSearchPathModDates] isEqual:modDates])
    {
        OOLog(kOOLogCacheStaleDates, @"%@", @"Cache is stale (modification dates have changed). Rebuilding from scratch.");
        upToDate = NO;
    }
    
    if (!upToDate)
    {
        [cacheMgr clearAllCaches];
        [cacheMgr setObject:searchPaths forKey:kOOCacheKeySearchPaths inCache:kOOCacheSearchPathModDates];
        [cacheMgr setObject:modDates forKey:kOOCacheKeyModificationDates inCache:kOOCacheSearchPathModDates];
    }
    else OOLog(kOOLogCacheUpToDate, @"%@", @"Data cache is up to date.");
 
    return upToDate;
}
 
 
/* This method allows the exclusion of particular files from the plist
 * building when they're in builtInPath. The point of this is to allow
 * scenarios to avoid merging in core files without having to override
 * every individual entry (which may not always be possible
 * anyway). It only works on plists, but of course worldscripts can be
 * excluded by not including the plists which reference them, and
 * everything else can be excluded by not referencing it from a plist.
 */
+ (BOOL) corePlist:(NSString *)fileName excludedAt:(NSString *)path
{
    if (![path isEqualToString:[self builtInPath]])
    {
        // non-core paths always okay
        return NO;
    }
    NSString *uaoBit = nil;
    foreach (uaoBit, sUseAddOnsParts)
    {
        if ([uaoBit hasPrefix:SCENARIO_OXP_DEFINITION_NOPLIST])
        {
            NSString *plist = [uaoBit substringFromIndex:[SCENARIO_OXP_DEFINITION_NOPLIST length]];
            if ([plist isEqualToString:fileName])
            {
                // this core plist file should not be loaded at all
                return YES;
            }
        }
    }
    // then not excluded
    return NO;
}
 
 
+ (NSDictionary *)dictionaryFromFilesNamed:(NSString *)fileName
                                  inFolder:(NSString *)folderName
                                  andMerge:(BOOL) mergeFiles
{
    return [ResourceManager dictionaryFromFilesNamed:fileName inFolder:folderName mergeMode:mergeFiles ? MERGE_BASIC : MERGE_NONE cache:YES];
}
 
 
+ (NSDictionary *)dictionaryFromFilesNamed:(NSString *)fileName
                                  inFolder:(NSString *)folderName
                                 mergeMode:(OOResourceMergeMode)mergeMode
                                     cache:(BOOL)cache
{
    id              result = nil;
    NSMutableArray  *results = nil;
    NSString        *cacheKey = nil;
    NSString        *mergeType = nil;
    OOCacheManager  *cacheMgr = [OOCacheManager sharedCache];
    NSEnumerator    *enumerator = nil;
    NSString        *path = nil;
    NSString        *dictPath = nil;
    NSDictionary    *dict = nil;
    
    if (fileName == nil)  return nil;
    
    switch (mergeMode)
    {
        case MERGE_NONE:
            mergeType = @"none";
            break;
        
        case MERGE_BASIC:
            mergeType = @"basic";
            break;
        
        case MERGE_SMART:
            mergeType = @"smart";
            break;
    }
    if (mergeType == nil)
    {
        OOLog(kOOLogParameterError, @"Unknown dictionary merge mode %u for %@. (This is an internal programming error, please report it.)", mergeMode, fileName);
        return nil;
    }
    
    if (cache)
    {
    
        if (folderName != nil)
        {
            cacheKey = [NSString stringWithFormat:@"%@/%@ merge:%@", folderName, fileName, mergeType];
        }
        else
        {
            cacheKey = [NSString stringWithFormat:@"%@ merge:%@", fileName, mergeType];
        }
        result = [cacheMgr objectForKey:cacheKey inCache:@"dictionaries"];
        if (result != nil)  return result;
    }
    
    if (mergeMode == MERGE_NONE)
    {
        // Find "last" matching dictionary
        for (enumerator = [ResourceManager reversePathEnumerator]; (path = [enumerator nextObject]); )
        {
            if (folderName != nil)
            {
                dictPath = [[path stringByAppendingPathComponent:folderName] stringByAppendingPathComponent:fileName];
                dict = OODictionaryFromFile(dictPath);
                if (dict != nil)  break;
            }
            dictPath = [path stringByAppendingPathComponent:fileName];
            dict = OODictionaryFromFile(dictPath);
            if (dict != nil)  break;
        }
        result = dict;
    }
    else
    {
        // Find all matching dictionaries
        results = [NSMutableArray array];
        for (enumerator = [ResourceManager pathEnumerator]; (path = [enumerator nextObject]); )
        {
            if ([ResourceManager corePlist:fileName excludedAt:path])
            {
                continue;
            }
            dictPath = [path stringByAppendingPathComponent:fileName];
            dict = OODictionaryFromFile(dictPath);
            if (dict != nil)  [results addObject:dict];
            if (folderName != nil)
            {
                dictPath = [[path stringByAppendingPathComponent:folderName] stringByAppendingPathComponent:fileName];
                dict = OODictionaryFromFile(dictPath);
                if (dict != nil)  [results addObject:dict];
            }
        }
        
        if ([results count] == 0)  return nil;
        
        // Merge result
        result = [NSMutableDictionary dictionary];
        
        for (enumerator = [results objectEnumerator]; (dict = [enumerator nextObject]); )
        {
            if (mergeMode == MERGE_SMART)  [result mergeEntriesFromDictionary:dict];
            else  [result addEntriesFromDictionary:dict];
        }
        result = [[result copy] autorelease];   // Make immutable
    }
    
    if (cache && result != nil)  [cacheMgr setObject:result forKey:cacheKey inCache:@"dictionaries"];
    
    return result;
}
 
 
+ (NSArray *) arrayFromFilesNamed:(NSString *)fileName inFolder:(NSString *)folderName andMerge:(BOOL) mergeFiles
{
    return [self arrayFromFilesNamed:fileName inFolder:folderName andMerge:mergeFiles cache:YES];
}
 
 
+ (NSArray *) arrayFromFilesNamed:(NSString *)fileName inFolder:(NSString *)folderName andMerge:(BOOL) mergeFiles cache:(BOOL)useCache
{
    id              result = nil;
    NSMutableArray  *results = nil;
    NSString        *cacheKey = nil;
    OOCacheManager  *cache = [OOCacheManager sharedCache];
    NSEnumerator    *enumerator = nil;
    NSString        *path = nil;
    NSString        *arrayPath = nil;
    NSMutableArray  *array = nil;
    NSArray         *arrayNonEditable = nil;
    
    if (fileName == nil)  return nil;
    
    if (useCache)
    {
        cacheKey = [NSString stringWithFormat:@"%@%@ merge:%@", (folderName != nil) ? [folderName stringByAppendingString:@"/"] : (NSString *)@"", fileName, mergeFiles ? @"yes" : @"no"];
        result = [cache objectForKey:cacheKey inCache:@"arrays"];
        if (result != nil)  return result;
    }
    
    if (!mergeFiles)
    {
        // Find "last" matching array
        for (enumerator = [ResourceManager reversePathEnumerator]; (path = [enumerator nextObject]); )
        {
            if (folderName != nil)
            {
                arrayPath = [[path stringByAppendingPathComponent:folderName] stringByAppendingPathComponent:fileName];
                arrayNonEditable = OOArrayFromFile(arrayPath);
                if (arrayNonEditable != nil)  break;
            }
            arrayPath = [path stringByAppendingPathComponent:fileName];
            arrayNonEditable = OOArrayFromFile(arrayPath);
            if (arrayNonEditable != nil)  break;
        }
        result = arrayNonEditable;
    }
    else
    {
        // Find all matching arrays
        results = [NSMutableArray array];
        for (enumerator = [ResourceManager pathEnumerator]; (path = [enumerator nextObject]); )
        {
            if ([ResourceManager corePlist:fileName excludedAt:path])
            {
                continue;
            }
 
            arrayPath = [path stringByAppendingPathComponent:fileName];
            array = [[OOArrayFromFile(arrayPath) mutableCopy] autorelease];
            if (array != nil) [results addObject:array];
    
            // Special handling for arrays merging. Currently, only equipment.plist, nebulatextures.plist and 
            // startextures.plist gets their objects merged.
            // A lookup index is required. For the equipment.plist items, this is the index corresponding to the
            // EQ_* string, which describes the role of an equipment item and is unique.
            // For nebula and star textures, this is the texture filename, although it can be overridden with a 
            // "key" property
            if ([array count] != 0 && ([[fileName lowercaseString] isEqualToString:@"nebulatextures.plist"] || 
                [[fileName lowercaseString] isEqualToString:@"startextures.plist"]))
                [self handleStarNebulaListMerging:results];
 
            if ([array count] != 0 && [[array objectAtIndex:0] isKindOfClass:[NSArray class]])
            {
                if ([[fileName lowercaseString] isEqualToString:@"equipment.plist"])
                    [self handleEquipmentListMerging:results forLookupIndex:3]; // Index 3 is the role string (EQ_*).
            }
            if (folderName != nil)
            {
                arrayPath = [[path stringByAppendingPathComponent:folderName] stringByAppendingPathComponent:fileName];
                array = [[OOArrayFromFile(arrayPath) mutableCopy] autorelease];
                if (array != nil)  [results addObject:array];
 
                if ([array count] != 0 && ([[fileName lowercaseString] isEqualToString:@"nebulatextures.plist"] || 
                    [[fileName lowercaseString] isEqualToString:@"startextures.plist"]))
                    [self handleStarNebulaListMerging:results];
 
                if ([array count] != 0 && [[array objectAtIndex:0] isKindOfClass:[NSArray class]])
                {
                    if ([[fileName lowercaseString] isEqualToString:@"equipment.plist"])
                        [self handleEquipmentListMerging:results forLookupIndex:3]; // Index 3 is the role string (EQ_*).
                }
            }
        }
        
        if ([results count] == 0)  return nil;
        
        // Merge result
        result = [NSMutableArray array];
        
        for (enumerator = [results objectEnumerator]; (array = [enumerator nextObject]); )
        {
            [result addObjectsFromArray:array];
        }
        // if we're doing equipment.plist, do equipment overrides now, while the array is still mutable
        if ([[fileName lowercaseString] isEqualToString:@"equipment.plist"]) 
        {
            [self handleEquipmentOverrides:result];
        }
        result = [[result copy] autorelease];   // Make immutable
    }
    
    if (useCache && result != nil)  [cache setObject:result forKey:cacheKey inCache:@"arrays"];
    
    return [NSArray arrayWithArray:result];
}
 
 
// A method for handling merging of arrays. Currently used with the equipment.plist entries.
// The arrayToProcess array is scanned for repetitions of the item at lookup index location and, if found,
// the latest entry replaces the earliest.
+ (void) handleEquipmentListMerging: (NSMutableArray *)arrayToProcess forLookupIndex:(unsigned)lookupIndex
{
    NSUInteger i,j,k;
    NSMutableArray *refArray = [arrayToProcess objectAtIndex:[arrayToProcess count] - 1];
    
    // Any change to refArray will directly modify arrayToProcess.
    
    for (i = 0; i < [refArray count]; i++)
    {
        for (j = 0; j < [arrayToProcess count] - 1; j++)
        {
            NSUInteger count = [[arrayToProcess oo_arrayAtIndex:j] count];
            if (count == 0)  continue;
            
            for (k=0; k < count; k++)
            {
                id processValue = [[[arrayToProcess oo_arrayAtIndex:j] oo_arrayAtIndex:k] oo_objectAtIndex:lookupIndex defaultValue:nil];
                id refValue = [[refArray oo_arrayAtIndex:i] oo_objectAtIndex:lookupIndex defaultValue:nil];
                
                if ([processValue isEqual:refValue])
                {
                    [[arrayToProcess objectAtIndex:j] replaceObjectAtIndex:k withObject:[refArray objectAtIndex:i]];
                    [refArray removeObjectAtIndex:i];
                }
            }
        }
    }
    // arrayToProcess has been processed at this point. Any necessary merging has been done.
}
 
 
// handles processing of equipment-overrides.plist files, updating the source array with values found.
// format of file is slightly different to the standard equipment.plist file, in that it is a 
// dictionary of dictionary objects (rather than an array of arrays). this allows properties like
// techlevel, price, name/short_description and description/long_description to be updated via the overrides file.
+ (void) handleEquipmentOverrides: (NSMutableArray *)arrayToProcess
{
    NSEnumerator            *equipKeyEnum = nil;
    NSString                *equipKey = nil;
    NSDictionary            *overrides = nil;
    NSDictionary            *overridesEntry = nil;
    int                     i;
 
    overrides = [ResourceManager dictionaryFromFilesNamed:@"equipment-overrides.plist"
                                                 inFolder:@"Config"
                                                mergeMode:MERGE_SMART
                                                    cache:NO];
 
    // cycle through all the equipment keys found in override files
    for (equipKeyEnum = [overrides keyEnumerator]; (equipKey = [equipKeyEnum nextObject]); )
    {
        overridesEntry = [overrides objectForKey:equipKey];
        // loop through our data array to find a match
        for (i = 0; i < [arrayToProcess count]; i++)
        {
            NSMutableArray  *equipArray = [[[arrayToProcess objectAtIndex:i] mutableCopy] autorelease];
            id refValue = [equipArray oo_objectAtIndex:EQUIPMENT_KEY_INDEX defaultValue:nil];
            // does the overridden equipment item exist in the equipment array? if so, get working
            if ([equipKey isEqual:refValue])
            {
                NSEnumerator            *infoKeyEnum = nil;
                NSString                *infoKey;
                // cycle through all the properties found for this equipment key in the overrides file
                for (infoKeyEnum = [overridesEntry keyEnumerator]; (infoKey = [infoKeyEnum nextObject]); )
                {
                    // special cases for the array items that don't have a direct keyname
                    if ([infoKey isEqualToString:@"techlevel"]) 
                        [equipArray replaceObjectAtIndex:EQUIPMENT_TECH_LEVEL_INDEX withObject:[overridesEntry objectForKey:infoKey]];
                    else if ([infoKey isEqualToString:@"price"]) 
                        [equipArray replaceObjectAtIndex:EQUIPMENT_PRICE_INDEX withObject:[overridesEntry objectForKey:infoKey]];
                    else if ([infoKey isEqualToString:@"short_description"]) 
                        [equipArray replaceObjectAtIndex:EQUIPMENT_SHORT_DESC_INDEX withObject:[overridesEntry objectForKey:infoKey]];
                    else if ([infoKey isEqualToString:@"name"]) 
                        [equipArray replaceObjectAtIndex:EQUIPMENT_SHORT_DESC_INDEX withObject:[overridesEntry objectForKey:infoKey]];
                    else if ([infoKey isEqualToString:@"long_description"]) 
                        [equipArray replaceObjectAtIndex:EQUIPMENT_LONG_DESC_INDEX withObject:[overridesEntry objectForKey:infoKey]];
                    else if ([infoKey isEqualToString:@"description"]) 
                        [equipArray replaceObjectAtIndex:EQUIPMENT_LONG_DESC_INDEX withObject:[overridesEntry objectForKey:infoKey]];
                    else 
                    {
                        NSMutableDictionary     *extra = nil;
                        // for everything else
                        // do we actually have an extras dictionary?
                        if (![equipArray oo_dictionaryAtIndex:EQUIPMENT_EXTRA_INFO_INDEX]) 
                        {
                            // if not, create a blank one we can add to
                            extra = [NSMutableDictionary dictionary];
                        }
                        else
                        {
                            extra = [[equipArray oo_dictionaryAtIndex:EQUIPMENT_EXTRA_INFO_INDEX] mutableCopy];
                        }
                        // special case for weapon_info && script_info, which are child dictionaries
                        if ([infoKey isEqualToString:@"weapon_info"] || [infoKey isEqualToString:@"script_info"])
                        {
                            NSEnumerator            *subEnum = nil;
                            NSString                *subKey;
                            NSMutableDictionary     *subInfo = nil;
                            NSDictionary            *subOverrides = nil;
                            // do we actually have a weapon_info/script_info dictionary?
                            if (![extra oo_dictionaryForKey:infoKey]) 
                            {
                                // if not, create a blank dictionary we can add to
                                subInfo = [NSMutableDictionary dictionary];
                            } 
                            else 
                            {
                                subInfo = [[extra oo_dictionaryForKey:infoKey] mutableCopy];
                            }
                            subOverrides = [overridesEntry oo_dictionaryForKey:infoKey];
                            // cycle through all the sub keys found in the overrides file for this equipment key item
                            for (subEnum = [subOverrides keyEnumerator]; (subKey = [subEnum nextObject]); )
                            {
                                [subInfo setObject:[subOverrides objectForKey:subKey] forKey:subKey];
                            }
                            [extra setObject:[[subInfo copy] autorelease] forKey:infoKey];
                        }
                        else
                        {
                            // for all other keys in the extras dictionary
                            [extra setObject:[overridesEntry objectForKey:infoKey] forKey:infoKey];
                        }
                        [equipArray replaceObjectAtIndex:EQUIPMENT_EXTRA_INFO_INDEX withObject:[[extra copy] autorelease]];
                    }
                }
                [arrayToProcess replaceObjectAtIndex:i withObject:equipArray];
            }
        }
    }
}
 
 
// A method for handling merging of arrays. Currently used with the nebulatextures.plist and startextures.plist entries.
// uses the "texture" filename as the key value, or "key" if found
+ (void) handleStarNebulaListMerging: (NSMutableArray *)arrayToProcess
{
    NSUInteger i,j,k;
    NSMutableArray *refArray = [arrayToProcess objectAtIndex:[arrayToProcess count] - 1];
 
    // Any change to refArray will directly modify arrayToProcess.  
    for (i = 0; i < [refArray count]; i++)
    {
        for (j = 0; j < [arrayToProcess count] - 1; j++)
        {
            NSUInteger count = [[arrayToProcess oo_arrayAtIndex:j] count];
            if (count == 0)  continue;
 
            for (k = 0; k < count; k++) 
            {
                id processValue = [[arrayToProcess oo_arrayAtIndex:j] oo_objectAtIndex:k defaultValue:nil];
                id refValue = [refArray oo_objectAtIndex:i defaultValue:nil];
                NSString *key1 = nil;
                NSString *key2 = nil;
 
                if ([processValue isKindOfClass:[NSString class]]) 
                {
                    key1 = processValue;
                }
                else if ([processValue isKindOfClass:[NSDictionary class]])
                {
                    if (![processValue objectForKey:@"key"]) 
                    {
                        key1 = [processValue objectForKey:@"texture"];
                    }
                    else
                    {
                        key1 = [processValue objectForKey:@"key"];
                    }
                }
                if (!key1) continue;
 
                if ([refValue isKindOfClass:[NSString class]]) 
                {
                    key2 = refValue;
                }
                else if ([refValue isKindOfClass:[NSDictionary class]])
                {
                    if (![refValue objectForKey:@"key"])
                    {
                        key2 = [refValue objectForKey:@"texture"];
                    }
                    else
                    {
                        key2 = [refValue objectForKey:@"key"];
                    }
                }
                if (!key2) continue;
 
                if ([key1 isEqual:key2])
                {
                    [[arrayToProcess objectAtIndex:j] replaceObjectAtIndex:k withObject:[refArray objectAtIndex:i]];
                    [refArray removeObjectAtIndex:i];
                }
 
            }
        }
    }
    // arrayToProcess has been processed at this point. Any necessary merging has been done.
}
 
 
+ (NSDictionary *) whitelistDictionary
{
    static id whitelistDictionary = nil;
    
    if (whitelistDictionary == nil)
    {
        NSString *path = [[[ResourceManager builtInPath] stringByAppendingPathComponent:@"Config"] stringByAppendingPathComponent:@"whitelist.plist"];
        whitelistDictionary = [NSDictionary dictionaryWithContentsOfFile:path];
        if (whitelistDictionary == nil)  whitelistDictionary = [NSNull null];
        
        [whitelistDictionary retain];
    }
    
    if (whitelistDictionary == [NSNull null])  return nil;
    return whitelistDictionary;
}
 
 
static NSString *LogClassKeyRoot(NSString *key)
{
    NSRange dot = [key rangeOfString:@"."];
    if (dot.location != NSNotFound)
    {
        return [key substringToIndex:dot.location];
    }
    else
    {
        return key;
    }
}
 
 
+ (NSDictionary *) logControlDictionary
{
    // Load built-in copy of logcontrol.plist.
    NSString *path = [[[ResourceManager builtInPath] stringByAppendingPathComponent:@"Config"]
                      stringByAppendingPathComponent:@"logcontrol.plist"];
    NSMutableDictionary *logControl = [NSMutableDictionary dictionaryWithDictionary:OODictionaryFromFile(path)];
    if (logControl == nil)  logControl = [NSMutableDictionary dictionary];
    
    // Build list of root log message classes that appear in the built-in list.
    NSMutableSet *coreRoots = [NSMutableSet set];
    NSString *key = nil;
    foreachkey(key, logControl)
    {
        [coreRoots addObject:LogClassKeyRoot(key)];
    }
    
    NSArray *rootPaths = [self rootPaths];
    NSString *configPath = nil;
    NSDictionary *dict = nil;
    
    // Look for logcontrol.plists inside OXPs (but not in root paths). These are not allowed to define keys in hierarchies used by the build-in one.
    NSEnumerator *pathEnum = [self pathEnumerator];
    while ((path = [pathEnum nextObject]))
    {
        if ([rootPaths containsObject:path])  continue;
        
        configPath = [[path stringByAppendingPathComponent:@"Config"]
                      stringByAppendingPathComponent:@"logcontrol.plist"];
        dict = OODictionaryFromFile(configPath);
        if (dict == nil)
        {
            configPath = [path stringByAppendingPathComponent:@"logcontrol.plist"];
            dict = OODictionaryFromFile(configPath);
        }
        foreachkey (key, dict)
        {
            if (![coreRoots containsObject:LogClassKeyRoot(key)])
            {
                [logControl setObject:[dict objectForKey:key] forKey:key];
            }
        }
    }
    
    // Now, look for logcontrol.plists in root paths, i.e. not within OXPs. These are allowed to override the built-in copy.
    pathEnum = [rootPaths objectEnumerator];
    while ((path = [pathEnum nextObject]))
    {
        configPath = [[path stringByAppendingPathComponent:@"Config"]
                      stringByAppendingPathComponent:@"logcontrol.plist"];
        dict = OODictionaryFromFile(configPath);
        if (dict == nil)
        {
            configPath = [path stringByAppendingPathComponent:@"logcontrol.plist"];
            dict = OODictionaryFromFile(configPath);
        }
        foreachkey (key, dict)
        {
            [logControl setObject:[dict objectForKey:key] forKey:key];
        }
    }
    
    // Finally, look in preferences, which can override all of the above.
    dict = [[NSUserDefaults standardUserDefaults] dictionaryForKey:@"logging-enable"];
    if (dict != nil)  [logControl addEntriesFromDictionary:dict];
    
    return logControl;
}
 
 
+ (NSDictionary *) roleCategoriesDictionary
{
    NSMutableDictionary *roleCategories = [NSMutableDictionary dictionaryWithCapacity:16];
 
    NSString *path = nil;
    NSString *configPath = nil;
    NSDictionary *categories = nil;
    
    NSEnumerator *pathEnum = [self pathEnumerator];
    while ((path = [pathEnum nextObject]))
    {
        if ([ResourceManager corePlist:@"role-categories.plist" excludedAt:path])
        {
            continue;
        }
 
        configPath = [[path stringByAppendingPathComponent:@"Config"]
                      stringByAppendingPathComponent:@"role-categories.plist"];
        categories = OODictionaryFromFile(configPath);
        if (categories != nil)
        {
            [ResourceManager mergeRoleCategories:categories intoDictionary:roleCategories];
        }
    }
    
    /* If the old pirate-victim-roles files exist, merge them in */
    NSArray *pirateVictims = [ResourceManager arrayFromFilesNamed:@"pirate-victim-roles.plist" inFolder:@"Config" andMerge:YES];
    if (OOEnforceStandards() && [pirateVictims count] > 0)
    {
        OOStandardsDeprecated(@"pirate-victim-roles.plist is still being used.");
    }
    [ResourceManager mergeRoleCategories:[NSDictionary dictionaryWithObject:pirateVictims forKey:@"oolite-pirate-victim"] intoDictionary:roleCategories];
 
    return [[roleCategories copy] autorelease];
}
 
 
+ (void) mergeRoleCategories:(NSDictionary *)catData intoDictionary:(NSMutableDictionary *)categories
{
    NSMutableSet *contents = nil;
    NSArray *catDataEntry = nil;
    NSString *key;
    foreachkey(key, catData)
    {
        contents = [categories objectForKey:key];
        if (contents == nil)
        {
            contents = [NSMutableSet setWithCapacity:16];
            [categories setObject:contents forKey:key];
        }
        catDataEntry = [catData oo_arrayForKey:key];
        OOLog(@"shipData.load.roleCategories", @"Adding %ld entries for category %@", (unsigned long)[catDataEntry count], key);
        [contents addObjectsFromArray:catDataEntry];
    }
}
 
 
+ (OOSystemDescriptionManager *) systemDescriptionManager
{
    OOLog(@"resourceManager.planetinfo.load", @"%@", @"Initialising manager");
    OOSystemDescriptionManager *manager = [[OOSystemDescriptionManager alloc] init];
    
    NSString *path = nil;
    NSString *configPath = nil;
    NSDictionary *categories = nil;
    NSString *systemKey = nil;
 
    NSEnumerator *pathEnum = [self pathEnumerator]; 
    while ((path = [pathEnum nextObject]))
    {
        if ([ResourceManager corePlist:@"planetinfo.plist" excludedAt:path])
        {
            continue;
        }
        configPath = [[path stringByAppendingPathComponent:@"Config"]
                      stringByAppendingPathComponent:@"planetinfo.plist"];
        categories = OODictionaryFromFile(configPath);
        if (categories != nil)
        {
            foreachkey(systemKey,categories)
            {
                NSDictionary *values = [categories oo_dictionaryForKey:systemKey defaultValue:nil];
                if (values != nil)
                {
                    if ([systemKey isEqualToString:PLANETINFO_UNIVERSAL_KEY])
                    {
                        [manager setUniversalProperties:values];
                    }
                    else if ([systemKey isEqualToString:PLANETINFO_INTERSTELLAR_KEY])
                    {
                        [manager setInterstellarProperties:values];
                    }
                    else
                    {
                        [manager setProperties:values forSystemKey:systemKey];
                    }
                }
            }
        }
    }
    OOLog(@"resourceManager.planetinfo.load", @"%@", @"Caching routes");
    [manager buildRouteCache];
    OOLog(@"resourceManager.planetinfo.load", @"%@", @"Initialised manager");
    return [manager autorelease];
}
 
 
 
+ (NSDictionary *) shaderBindingTypesDictionary
{
    static id shaderBindingTypesDictionary = nil;
    
    if (shaderBindingTypesDictionary == nil)
    {
        NSAutoreleasePool *pool = [NSAutoreleasePool new];
        
        NSString *path = [[[ResourceManager builtInPath] stringByAppendingPathComponent:@"Config"] stringByAppendingPathComponent:@"shader-uniform-bindings.plist"];
        NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithContentsOfFile:path];
        NSArray *keys = [dict allKeys];
        
        // Resolve all $inherit keys.
        unsigned changeCount = 0;
        do {
            changeCount = 0;
            NSString *key = nil;
            foreach (key, keys)
            {
                NSDictionary *value = [dict oo_dictionaryForKey:key];
                NSString *inheritKey = [value oo_stringForKey:@"$inherit"];
                if (inheritKey != nil)
                {
                    changeCount++;
                    NSMutableDictionary *mutableValue = [[value mutableCopy] autorelease];
                    [mutableValue removeObjectForKey:@"$inherit"];
                    NSDictionary *inherited = [dict oo_dictionaryForKey:inheritKey];
                    if (inherited != nil)
                    {
                        [mutableValue addEntriesFromDictionary:inherited];
                    }
                    
                    [dict setObject:[[mutableValue copy] autorelease] forKey:key];
                }
            }
        } while (changeCount != 0);
        
        shaderBindingTypesDictionary = [dict copy];
        
        [pool release];
    }
    
    return shaderBindingTypesDictionary;
}
 
 
+ (NSString *) pathForFileNamed:(NSString *)fileName inFolder:(NSString *)folderName
{
    return [self pathForFileNamed:fileName inFolder:folderName cache:YES];
}
 
 
/* This is extremely expensive to call with useCache:NO */
+ (NSString *) pathForFileNamed:(NSString *)fileName inFolder:(NSString *)folderName cache:(BOOL)useCache
{
    NSString        *result = nil;
    NSString        *cacheKey = nil;
    OOCacheManager  *cache = [OOCacheManager sharedCache];
    NSEnumerator    *pathEnum = nil;
    NSString        *path = nil;
    NSString        *filePath = nil;
    NSFileManager   *fmgr = nil;
    
    if (fileName == nil)  return nil;
    
    if (cache)
    {
        if (folderName != nil)  cacheKey = [NSString stringWithFormat:@"%@/%@", folderName, fileName];
        else  cacheKey = fileName;
        result = [cache objectForKey:cacheKey inCache:@"resolved paths"];
        if (result != nil)  return result;
    }
    
    // Search for file
    fmgr = [NSFileManager defaultManager];
    // reverse object enumerator allows OXPs to override core
    for (pathEnum = [[ResourceManager paths] reverseObjectEnumerator]; (path = [pathEnum nextObject]); )
    {
        filePath = [[path stringByAppendingPathComponent:folderName] stringByAppendingPathComponent:fileName];
        if ([fmgr oo_oxzFileExistsAtPath:filePath])
        {
            result = filePath;
            break;
        }
        
        filePath = [path stringByAppendingPathComponent:fileName];
        if ([fmgr oo_oxzFileExistsAtPath:filePath])
        {
            result = filePath;
            break;
        }
    }
    
    if (result != nil)
    {
        OOLog(@"resourceManager.foundFile", @"Found %@/%@ at %@", folderName, fileName, filePath);
        if (useCache)
        {
            [cache setObject:result forKey:cacheKey inCache:@"resolved paths"];
        }
    }
    return result;
}
 
 
/* use extreme caution in calling with usePathCache:NO - this can be
 * an extremely expensive operation */
+ (id) retrieveFileNamed:(NSString *)fileName
                inFolder:(NSString *)folderName
                   cache:(NSMutableDictionary **)ioCache
                     key:(NSString *)key
                   class:(Class)class
            usePathCache:(BOOL)useCache
{
    id              result = nil;
    NSString        *path = nil;
    
    if (ioCache)
    {
        if (key == nil)  key = [NSString stringWithFormat:@"%@:%@", folderName, fileName];
        if (*ioCache != nil)
        {
            // return the cached object, if any
            result = [*ioCache objectForKey:key];
            if (result)  return result;
        }
    }
    
    path = [self pathForFileNamed:fileName inFolder:folderName cache:useCache];
    if (path != nil)  result = [[[class alloc] initWithContentsOfFile:path] autorelease];
    
    if (result != nil && ioCache != NULL)
    {
        if (*ioCache == nil)  *ioCache = [[NSMutableDictionary alloc] init];
        [*ioCache setObject:result forKey:key];
    }
    
    return result;
}
 
 
+ (OOMusic *) ooMusicNamed:(NSString *)fileName inFolder:(NSString *)folderName
{
    return [self retrieveFileNamed:fileName
                          inFolder:folderName
                             cache:NULL // Don't cache music objects; minimizing latency isn't really important.
                               key:[NSString stringWithFormat:@"OOMusic:%@:%@", folderName, fileName]
                             class:[OOMusic class]
                      usePathCache:YES];
}
 
 
+ (OOSound *) ooSoundNamed:(NSString *)fileName inFolder:(NSString *)folderName
{
    return [self retrieveFileNamed:fileName
                          inFolder:folderName
                             cache:&sSoundCache
                               key:[NSString stringWithFormat:@"OOSound:%@:%@", folderName, fileName]
                             class:[OOSound class]
                      usePathCache:YES];
}
 
 
+ (NSString *) stringFromFilesNamed:(NSString *)fileName inFolder:(NSString *)folderName
{
    return [self stringFromFilesNamed:fileName inFolder:folderName cache:YES];
}
 
 
+ (NSString *) stringFromFilesNamed:(NSString *)fileName inFolder:(NSString *)folderName cache:(BOOL)useCache
{
    id              result = nil;
    NSString        *path = nil;
    NSString        *key = nil;
    
    if (useCache)
    {
        key = [NSString stringWithFormat:@"%@:%@", folderName, fileName];
        if (sStringCache != nil)
        {
            // return the cached object, if any
            result = [sStringCache objectForKey:key];
            if (result)  return result;
        }
    }
    
    path = [self pathForFileNamed:fileName inFolder:folderName cache:YES];
    if (path != nil)  result = [NSString stringWithContentsOfUnicodeFile:path];
    
    if (result != nil && useCache)
    {
        if (sStringCache == nil)  sStringCache = [[NSMutableDictionary alloc] init];
        [sStringCache setObject:result forKey:key];
    }
    
    return result;
}
 
 
+ (NSDictionary *)loadScripts
{
    NSMutableDictionary         *loadedScripts = nil;
    NSArray                     *results = nil;
    NSArray                     *paths = nil;
    NSEnumerator                *pathEnum = nil;
    NSString                    *path = nil;
    NSEnumerator                *scriptEnum = nil;
    OOScript                    *script = nil;
    NSString                    *name = nil;
    NSAutoreleasePool           *pool = nil;
    
    OOLog(@"script.load.world.begin", @"%@", @"Loading world scripts...");
    
    loadedScripts = [NSMutableDictionary dictionary];
    paths = [ResourceManager paths];
    for (pathEnum = [paths objectEnumerator]; (path = [pathEnum nextObject]); )
    {
        // excluding world-scripts.plist also excludes script.js / script.plist
        // though as those core files don't and won't exist this is not
        // a problem.
        if (![ResourceManager corePlist:@"world-scripts.plist" excludedAt:path])
        {
            pool = [[NSAutoreleasePool alloc] init];
        
            @try
            {
                results = [OOScript worldScriptsAtPath:[path stringByAppendingPathComponent:@"Config"]];
                if (results == nil) results = [OOScript worldScriptsAtPath:path];
                if (results != nil)
                {
                    for (scriptEnum = [results objectEnumerator]; (script = [scriptEnum nextObject]); )
                    {
                        name = [script name];
                        if (name != nil)  [loadedScripts setObject:script forKey:name];
                        else  OOLog(@"script.load.unnamed", @"Discarding anonymous script %@", script);
                    }
                }
            }
            @catch (NSException *exception)
            {
                OOLog(@"script.load.exception", @"***** %s encountered exception %@ (%@) while trying to load script from %@ -- ignoring this location.", __PRETTY_FUNCTION__, [exception name], [exception reason], path);
                // Ignore exception and keep loading other scripts.
            }
        
            [pool release];
        }
    }
    
    if (OOLogWillDisplayMessagesInClass(@"script.load.world.listAll"))
    {
        NSUInteger count = [loadedScripts count];
        if (count != 0)
        {
            NSMutableArray      *displayNames = nil;
            NSEnumerator        *scriptEnum = nil;
            OOScript            *script = nil;
            NSString            *displayString = nil;
            
            displayNames = [NSMutableArray arrayWithCapacity:count];
            
            for (scriptEnum = [loadedScripts objectEnumerator]; (script = [scriptEnum nextObject]); )
            {
                [displayNames addObject:[script displayName]];
            }
            
            displayString = [[displayNames sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)] componentsJoinedByString:@"\n    "];
            OOLog(@"script.load.world.listAll", @"Loaded %lu world scripts:\n    %@", count, displayString);
        }
        else
        {
            OOLog(@"script.load.world.listAll", @"%@", @"*** No world scripts loaded.");
        }
    }
    
    return loadedScripts;
}
 
 
+ (BOOL) writeDiagnosticData:(NSData *)data toFileNamed:(NSString *)name
{
    if (data == nil || name == nil)  return NO;
    
    NSString *directory = [self diagnosticFileLocation];
    if (directory == nil)  return NO;
    
    NSArray *nameComponents = [name componentsSeparatedByString:@"/"];
    NSUInteger count = [nameComponents count];
    if (count > 1)
    {
        name = [nameComponents lastObject];
        
        for (NSUInteger i = 0; i < count - 1; i++)
        {
            NSString *component = [nameComponents objectAtIndex:i];
            if ([component hasPrefix:@"."])
            {
                component = [@"!" stringByAppendingString:[component substringFromIndex:1]];
            }
            directory = [directory stringByAppendingPathComponent:component];
            [[NSFileManager defaultManager] oo_createDirectoryAtPath:directory attributes:nil];
        }
    }
    
    return [data writeToFile:[directory stringByAppendingPathComponent:name] atomically:YES];
}
 
 
+ (BOOL) writeDiagnosticString:(NSString *)string toFileNamed:(NSString *)name
{
    return [self writeDiagnosticData:[string dataUsingEncoding:NSUTF8StringEncoding] toFileNamed:name];
}
 
 
+ (BOOL) writeDiagnosticPList:(id)plist toFileNamed:(NSString *)name
{
    NSData *data = [plist oldSchoolPListFormatWithErrorDescription:NULL];
    if (data == nil)  [NSPropertyListSerialization dataFromPropertyList:plist format:NSPropertyListXMLFormat_v1_0 errorDescription:NULL];
    if (data == nil)  return NO;
    
    return [self writeDiagnosticData:data toFileNamed:name];
}
 
 
+ (NSDictionary *) materialDefaults
{
    return [self dictionaryFromFilesNamed:@"material-defaults.plist" inFolder:@"Config" andMerge:YES];
}
 
 
+ (BOOL)directoryExists:(NSString *)inPath create:(BOOL)inCreate
{
    BOOL                exists, directory;
    NSFileManager       *fmgr =  [NSFileManager defaultManager];
    
    exists = [fmgr fileExistsAtPath:inPath isDirectory:&directory];
    
    if (exists && !directory)
    {
        OOLog(@"resourceManager.write.buildPath.failed", @"Expected %@ to be a folder, but it is a file.", inPath);
        return NO;
    }
    if (!exists)
    {
        if (!inCreate) return NO;
        if (![fmgr oo_createDirectoryAtPath:inPath attributes:nil])
        {
            OOLog(@"resourceManager.write.buildPath.failed", @"Could not create folder %@.", inPath);
            return NO;
        }
    }
    
    return YES;
}
 
 
+ (NSString *) diagnosticFileLocation
{
    return OOLogHandlerGetLogBasePath();
}
 
 
+ (void) logPaths
{
    NSMutableArray          *displayPaths = nil;
    NSEnumerator            *pathEnum = nil;
    NSString                *path = nil;
 
    // Prettify paths for logging.
    displayPaths = [NSMutableArray arrayWithCapacity:[sSearchPaths count]];
    for (pathEnum = [sSearchPaths objectEnumerator]; (path = [pathEnum nextObject]); )
    {
        [displayPaths addObject:[[path stringByStandardizingPath] stringByAbbreviatingWithTildeInPath]];
    }
    
    OOLog(@"searchPaths.dumpAll", @"Resource paths: %@\n    %@", sUseAddOns, [displayPaths componentsJoinedByString:@"\n    "]);
 
}
 
 
+ (void) clearCaches
{
    [sSoundCache release];
    sSoundCache = nil;
    [sStringCache release];
    sStringCache = nil;
}
 
@end