/*

File: LSMClassifier.m

Abstract: LSMClassifier encapsulates common Latent Semantic Mapping (LSM) 

          framework functionalities. By studying this class, you will see

          how to use LSM framework in common text classification tasks.

Version: 1.0

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*/ 

#import "LSMClassifier.h"

#import "LSMClassifierResultPrivate.h"

NSString* gIdToNameMap = @"IdToNameMap";

NSString* gNameToIdMap = @"NameToIdMap";

//private methods of LSMClassifier

@interface LSMClassifier(Private)

//

// Update catIdToNameMap and catNameToIdMap to keep them in sync.

//

- (void)mapCategoryId:(LSMCategory)index toName:(NSString*)name;

@end

@implementation LSMClassifier

- (id)init 

{

    self = [super init];

    if (self) {

        //create the LSM map with default allocator and option

        map = LSMMapCreate(kCFAllocatorDefault, 0);

        //set it to training mode, since the map is brandnew.

        currentMode = kLSMCTraining;

        catIdToNameMap = [NSMutableDictionary new];

        catNameToIdMap = [NSMutableDictionary new];

    }

    return self;

}

- (void)dealloc

{

    //dispose everything

    if (catIdToNameMap) [catIdToNameMap release];

    if (catNameToIdMap) [catNameToIdMap release];

    if (map) CFRelease(map);

    [super dealloc];

}

- (void)reset

{

    [catIdToNameMap release];

    [catNameToIdMap release];

    CFRelease(map);

    //create the LSM map with default allocator and option

    map = LSMMapCreate(kCFAllocatorDefault, 0);

    //set it to training mode, since the map is brandnew.

    currentMode = kLSMCTraining;

    catIdToNameMap = [NSMutableDictionary new];

    catNameToIdMap = [NSMutableDictionary new]; 

}

- (OSStatus)setModeTo:(SInt32)mode

{

    if (currentMode != mode)

    {

        switch(mode)

        {

        case kLSMCTraining:

            //set the map to training mode.

            if (LSMMapStartTraining(map) != noErr)

                return kLSMSetModeFailed;

            else

                return noErr;

        case kLSMCEvaluation:

            //compile the map and start evaluation mode

            if (LSMMapCompile(map) != noErr)

                return kLSMSetModeFailed;

            else

                return noErr;

        default:

            return kLSMCNotValidMode;

        }

    }

    return noErr;

}

- (OSStatus)addCategory:(NSString*)name

{

    NSNumber* mapId = [catNameToIdMap objectForKey:name];

    if (mapId)

        return kLSMCDuplicatedCategory;

    [self setModeTo:kLSMCTraining];

    LSMCategory newCategory = LSMMapAddCategory(map);

    [self mapCategoryId:newCategory toName:name];

    return noErr;

}

- (OSStatus)addTrainingText:(NSString*)text toCategory:(NSString*)name with:(UInt32)option

{

    NSNumber* mapId = [catNameToIdMap objectForKey:name];

    if (!mapId)

        return kLSMCNoSuchCategory;

    //convert input text into LSMText text.

    LSMTextRef lsmText = LSMTextCreate(NULL, map);

    if (LSMTextAddWords(lsmText, (CFStringRef)text, CFLocaleGetSystem(), option) != noErr)

    {

        CFRelease(lsmText);

        return kLSMCErr;

    }

    //Store current mode so that we can restore the mode if we fail.

    unsigned preMode = currentMode;

    [self setModeTo:kLSMCTraining];

    LSMCategory category = [mapId unsignedIntValue];

    OSStatus result = LSMMapAddText(map, lsmText, category);

    CFRelease(lsmText);

    if (result != noErr)

    {

        //something bad happened.

        //let's recover to original mode and return error.

        if (preMode != currentMode)

            [self setModeTo:preMode];

        return kLSMCErr;

    }

    else

        return noErr;

}

- (LSMClassifierResult*)createResultFor:(NSString*)text upTo:(SInt32)numOfResults with:(UInt32)textOption

{

    //convert input text into LSMText text.

    LSMTextRef lsmText = LSMTextCreate(NULL, map);

    if (LSMTextAddWords(lsmText, (CFStringRef)text, CFLocaleGetSystem(), textOption) != noErr)

    {

        CFRelease(lsmText);

        return nil;

    }

    //switch to evaluation mode

    [self setModeTo:kLSMCEvaluation];

    LSMResultRef result = LSMResultCreate(NULL, map, lsmText, numOfResults, 0);

    CFRelease(lsmText);

    if (!result) return nil;

    return [[LSMClassifierResult alloc] initWithLSMResult:result withIdToNameMap:catIdToNameMap];

}

- (unsigned)numberOfCategories

{

    return [catNameToIdMap count];

}

- (NSEnumerator*)categoryEnumerator

{

    return [catNameToIdMap keyEnumerator];

}

- (OSStatus)writeToFile:(NSString*) path

{

    //put catNameToIdMap into the map's property list so that

    //we can store them to a file all together.

    //Note, if you plan to store NSDictionary object in the property list, the key

    //has to be NSString.

    NSMutableDictionary* dict = [NSMutableDictionary new];

    [dict setObject:catNameToIdMap forKey:gNameToIdMap];

    LSMMapSetProperties(map, (CFDictionaryRef)dict);

    [dict release];

    NSURL* url = [[NSURL alloc] initFileURLWithPath:path];

    OSStatus status = LSMMapWriteToURL(map, (CFURLRef)url, 0);

    [url release];

    return (status == noErr) ? noErr : kLSMCWriteError;

}

- (OSStatus)readFromFile:(NSString*)path with:(unsigned)mode

{

    CFRelease(map);

    [catIdToNameMap release];

    [catNameToIdMap release];

    BOOL ok = YES;

    NSURL* url = [[NSURL alloc] initFileURLWithPath:path];

    map = LSMMapCreateFromURL(NULL, (CFURLRef)url, kLSMMapLoadMutable);

    [url release];

    if (!map)

        ok = NO;

    else

    {

        NSDictionary* idNameMaps = (NSDictionary*)LSMMapGetProperties(map);

        if (idNameMaps)

        {       

            NSDictionary* dict = [idNameMaps objectForKey:gNameToIdMap];

            if (dict)

            {

                catNameToIdMap = [[NSMutableDictionary alloc] initWithDictionary:dict];

                catIdToNameMap = [NSMutableDictionary new];

                NSEnumerator* keys = [catNameToIdMap keyEnumerator];

                NSString* key;

                while (key = [keys nextObject])

                    [catIdToNameMap setObject:key forKey:[catNameToIdMap objectForKey:key]];

            }

            else

                ok = NO;

        }

        else

            ok = NO;

    }

    if (ok)

        return [self setModeTo:mode];

    else

    {

        //oops, something wrong. Reset the classifier and bail.

        map = LSMMapCreate(NULL, 0);

        catIdToNameMap = [NSMutableDictionary new];

        catNameToIdMap = [NSMutableDictionary new];

        [self setModeTo:kLSMCTraining];

        return kLSMCErr;

    }

}

///// private methods /////

- (void)mapCategoryId:(LSMCategory)index toName:(NSString*)name

{

    NSNumber* idNumber = [[NSNumber alloc] initWithUnsignedInt:index];

    [catIdToNameMap setObject:name forKey:idNumber];

    [catNameToIdMap setObject:idNumber forKey:name];

    [idNumber release];

}

@end