/*

    File: PVRTexture.m

Abstract: The PVRTexture class is responsible for loading .pvr files.

 Version: 1.6

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*/

#import "PVRTexture.h"

#define PVR_TEXTURE_FLAG_TYPE_MASK  0xff

static char gPVRTexIdentifier[4] = "PVR!";

enum

{

    kPVRTextureFlagTypePVRTC_2 = 24,

    kPVRTextureFlagTypePVRTC_4

};

typedef struct _PVRTexHeader

{

    uint32_t headerLength;

    uint32_t height;

    uint32_t width;

    uint32_t numMipmaps;

    uint32_t flags;

    uint32_t dataLength;

    uint32_t bpp;

    uint32_t bitmaskRed;

    uint32_t bitmaskGreen;

    uint32_t bitmaskBlue;

    uint32_t bitmaskAlpha;

    uint32_t pvrTag;

    uint32_t numSurfs;

} PVRTexHeader;

@implementation PVRTexture

@synthesize name = _name;

@synthesize width = _width;

@synthesize height = _height;

@synthesize internalFormat = _internalFormat;

@synthesize hasAlpha = _hasAlpha;

- (BOOL)unpackPVRData:(NSData *)data

{

    BOOL success = FALSE;

    PVRTexHeader *header = NULL;

    uint32_t flags, pvrTag;

    uint32_t dataLength = 0, dataOffset = 0, dataSize = 0;

    uint32_t blockSize = 0, widthBlocks = 0, heightBlocks = 0;

    uint32_t width = 0, height = 0, bpp = 4;

    uint8_t *bytes = NULL;

    uint32_t formatFlags;

    header = (PVRTexHeader *)[data bytes];

    pvrTag = CFSwapInt32LittleToHost(header->pvrTag);

    if (gPVRTexIdentifier[0] != ((pvrTag >>  0) & 0xff) ||

        gPVRTexIdentifier[1] != ((pvrTag >>  8) & 0xff) ||

        gPVRTexIdentifier[2] != ((pvrTag >> 16) & 0xff) ||

        gPVRTexIdentifier[3] != ((pvrTag >> 24) & 0xff))

    {

        return FALSE;

    }

    flags = CFSwapInt32LittleToHost(header->flags);

    formatFlags = flags & PVR_TEXTURE_FLAG_TYPE_MASK;

    if (formatFlags == kPVRTextureFlagTypePVRTC_4 || formatFlags == kPVRTextureFlagTypePVRTC_2)

    {

        [_imageData removeAllObjects];

        if (formatFlags == kPVRTextureFlagTypePVRTC_4)

            _internalFormat = GL_COMPRESSED_RGBA_PVRTC_4BPPV1_IMG;

        else if (formatFlags == kPVRTextureFlagTypePVRTC_2)

            _internalFormat = GL_COMPRESSED_RGBA_PVRTC_2BPPV1_IMG;

        _width = width = CFSwapInt32LittleToHost(header->width);

        _height = height = CFSwapInt32LittleToHost(header->height);

        if (CFSwapInt32LittleToHost(header->bitmaskAlpha))

            _hasAlpha = TRUE;

        else

            _hasAlpha = FALSE;

        dataLength = CFSwapInt32LittleToHost(header->dataLength);

        bytes = ((uint8_t *)[data bytes]) + sizeof(PVRTexHeader);

        // Calculate the data size for each texture level and respect the minimum number of blocks

        while (dataOffset < dataLength)

        {

            if (formatFlags == kPVRTextureFlagTypePVRTC_4)

            {

                blockSize = 4 * 4; // Pixel by pixel block size for 4bpp

                widthBlocks = width / 4;

                heightBlocks = height / 4;

                bpp = 4;

            }

            else

            {

                blockSize = 8 * 4; // Pixel by pixel block size for 2bpp

                widthBlocks = width / 8;

                heightBlocks = height / 4;

                bpp = 2;

            }

            // Clamp to minimum number of blocks

            if (widthBlocks < 2)

                widthBlocks = 2;

            if (heightBlocks < 2)

                heightBlocks = 2;

            dataSize = widthBlocks * heightBlocks * ((blockSize  * bpp) / 8);

            [_imageData addObject:[NSData dataWithBytes:bytes+dataOffset length:dataSize]];

            dataOffset += dataSize;

            width = MAX(width >> 1, 1);

            height = MAX(height >> 1, 1);

        }

        success = TRUE;

    }

    return success;

}

- (BOOL)createGLTexture

{

    int width = _width;

    int height = _height;

    NSData *data;

    GLenum err;

    if ([_imageData count] > 0)

    {

        if (_name != 0)

            glDeleteTextures(1, &_name);

        glGenTextures(1, &_name);

        glBindTexture(GL_TEXTURE_2D, _name);

    }

    if ([_imageData count] > 1)

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

    else

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

    for (int i=0; i < [_imageData count]; i++)

    {

        data = [_imageData objectAtIndex:i];

        glCompressedTexImage2D(GL_TEXTURE_2D, i, _internalFormat, width, height, 0, (int)[data length], [data bytes]);

        err = glGetError();

        if (err != GL_NO_ERROR)

        {

            NSLog(@"Error uploading compressed texture level: %d. glError: 0x%04X", i, err);

            return FALSE;

        }

        width = MAX(width >> 1, 1);

        height = MAX(height >> 1, 1);

    }

    [_imageData removeAllObjects];

    return TRUE;

}

- (id)initWithContentsOfFile:(NSString *)path

{

    if (self = [super init])

    {

        NSData *data = [NSData dataWithContentsOfFile:path];

        _imageData = [[NSMutableArray alloc] initWithCapacity:10];

        _name = 0;

        _width = _height = 0;

        _internalFormat = GL_COMPRESSED_RGBA_PVRTC_4BPPV1_IMG;

        _hasAlpha = FALSE;

        if (!data || ![self unpackPVRData:data] || ![self createGLTexture])

        {

            [self release];

            self = nil;

        }

    }

    return self;

}

- (id)initWithContentsOfURL:(NSURL *)url

{

    if (![url isFileURL])

    {

        [self release];

        return nil;

    }

    return [self initWithContentsOfFile:[url path]];

}

+ (id)pvrTextureWithContentsOfFile:(NSString *)path

{

    return [[[self alloc] initWithContentsOfFile:path] autorelease];

}

+ (id)pvrTextureWithContentsOfURL:(NSURL *)url

{

    if (![url isFileURL])

        return nil;

    return [PVRTexture pvrTextureWithContentsOfFile:[url path]];

}

- (void)dealloc

{

    [_imageData release];

    if (_name != 0)

        glDeleteTextures(1, &_name);

    [super dealloc];

}

@end