/****************************************************************************
 Copyright (c) 2010-2013 cocos2d-x.org

 http://www.cocos2d-x.org

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 ****************************************************************************/

/**
 * @constant
 * @type Number
 */
cc.TGA_OK = 0;

/**
 * @constant
 * @type Number
 */
cc.TGA_ERROR_FILE_OPEN = 1;

/**
 * @constant
 * @type Number
 */
cc.TGA_ERROR_READING_FILE = 2;

/**
 * @constant
 * @type Number
 */
cc.TGA_ERROR_INDEXED_COLOR = 3;

/**
 * @constant
 * @type Number
 */
cc.TGA_ERROR_MEMORY = 4;

/**
 * @constant
 * @type Number
 */
cc.TGA_ERROR_COMPRESSED_FILE = 5;

/**
 * TGA format
 * @param {Number} status
 * @param {Number} type
 * @param {Number} pixelDepth
 * @param {Number} width map width
 * @param {Number} height map height
 * @param {Array} imageData raw data
 * @param {Number} flipped
 * @constructor
 */
cc.ImageTGA = function (status, type, pixelDepth, width, height, imageData, flipped) {
    this.status = status || 0;
    this.type = type || 0;
    this.pixelDepth = pixelDepth || 0;
    this.width = width || 0;
    this.height = height || 0;
    this.imageData = imageData || [];
    this.flipped = flipped || 0;
};

/**
 *  load the image header field from stream. We only keep those that matter!
 * @param {Array} buffer
 * @param {Number} bufSize
 * @param {cc.ImageTGA} psInfo
 * @return {Boolean}
 */
cc.tgaLoadHeader = function (buffer, bufSize, psInfo) {
    var step = 2;
    if (step + 1 > bufSize)
        return false;

    var binaryReader = new cc.BinaryStreamReader(buffer);

    binaryReader.setOffset(step);
    psInfo.type = binaryReader.readByte();
    step += 10;       // . step += sizeof(unsigned char) * 2; step += sizeof(signed short) * 4;

    if (step + 4 + 1 > bufSize)
        return false;
    binaryReader.setOffset(step);
    psInfo.width = binaryReader.readUnsignedShort();
    psInfo.height = binaryReader.readUnsignedInteger();
    psInfo.pixelDepth = binaryReader.readByte();

    step += 5;      // .  step += sizeof(unsigned char);  step += sizeof(signed short) * 2;
    if (step + 1 > bufSize)
        return false;

    var garbage = binaryReader.readByte();
    psInfo.flipped = 0;
    if (garbage & 0x20)
        psInfo.flipped = 1;
    return true;
};

/**
 * loads the image pixels. You shouldn't call this function directly
 * @param {Array} buffer
 * @param {Number} bufSize
 * @param {cc.ImageTGA} psInfo
 * @return {Boolean}
 */
cc.tgaLoadImageData = function (buffer, bufSize, psInfo) {
    var mode, total, i, aux;
    var step = 18;              // .size_t step = (sizeof(unsigned char) + sizeof(signed short)) * 6;

    // mode equal the number of components for each pixel
    mode = 0 | (psInfo.pixelDepth / 2);
    // total is the number of unsigned chars we'll have to read
    total = psInfo.height * psInfo.width * mode;

    if (step + total > bufSize)
        return false;

    psInfo.imageData = cc.__getSubArray(buffer, step, step + total);

    // mode=3 or 4 implies that the image is RGB(A). However TGA
    // stores it as BGR(A) so we'll have to swap R and B.
    if (mode >= 3) {
        for (i = 0; i < total; i += mode) {
            aux = psInfo.imageData[i];
            psInfo.imageData[i] = psInfo.imageData[i + 2];
            psInfo.imageData[i + 2] = aux;
        }
    }
    return true;
};

/**
 * this is the function to call when we want to load an image
 * @param filename
 * @return {cc.ImageTGA}
 */
cc.tgaLoad = function (filename) {
    var buffer = cc.FileUtils.getInstance().getFileData(filename, "rb");
    var size = buffer.length;

    if (buffer == null)
        return null;

    var info = new cc.ImageTGA();
    // get the file header info
    if (!cc.tgaLoadHeader(buffer, size, info)) {
        info.status = cc.TGA_ERROR_MEMORY;
        return info;
    }

    // check if the image is color indexed
    if (info.type === 1) {
        info.status = cc.TGA_ERROR_INDEXED_COLOR;
        return info;
    }

    // check for other types (compressed images)
    if ((info.type != 2) && (info.type != 3) && (info.type != 10)) {
        info.status = cc.TGA_ERROR_COMPRESSED_FILE;
        return info;
    }

    var bLoadImage = false;
    // finally load the image pixels
    if (info.type == 10)
        bLoadImage = cc.tgaLoadRLEImageData(buffer, size, info);
    else
        bLoadImage = cc.tgaLoadImageData(buffer, size, info);

    // check for errors when reading the pixels
    if (!bLoadImage) {
        info.status = cc.TGA_ERROR_READING_FILE;
        return info;
    }

    info.status = cc.TGA_OK;
    if (info.flipped) {
        cc.tgaFlipImage(info);
        if (info.flipped)
            info.status = cc.TGA_ERROR_MEMORY;
    }
    buffer = null;
    return info;
};

/**
 * converts RGB to grayscale
 * @param {cc.ImageTGA} psInfo
 */
cc.tgaRGBtogreyscale = function (psInfo) {
    var i, j;

    // if the image is already grayscale do nothing
    if (psInfo.pixelDepth === 8)
        return;

    // compute the number of actual components
    var mode = psInfo.pixelDepth / 8;

    // allocate an array for the new image data
    var newImageData = new Uint8Array(psInfo.height * psInfo.width);
    if (newImageData === null)
        return;

    // convert pixels: grayscale = o.30 * R + 0.59 * G + 0.11 * B
    for (i = 0, j = 0; j < psInfo.width * psInfo.height; i += mode, j++)
        newImageData[j] = (0.30 * psInfo.imageData[i] + 0.59 * psInfo.imageData[i + 1] + 0.11 * psInfo.imageData[i + 2]);

    // reassign pixelDepth and type according to the new image type
    psInfo.pixelDepth = 8;
    psInfo.type = 3;
    // reassigning imageData to the new array.
    psInfo.imageData = newImageData;
};

/**
 * releases the memory used for the image
 * @param {cc.ImageTGA} psInfo
 */
cc.tgaDestroy = function (psInfo) {
    if (!psInfo)
        return;

    psInfo.imageData = null;
    psInfo = null;
};

cc.tgaLoadRLEImageData = function (buffer, bufSize, psInfo) {
    var mode, total, i, index = 0 , skip = 0, flag = 0;
    var aux = [], runlength = 0;

    var step = 18;                          // . size_t step = (sizeof(unsigned char) + sizeof(signed short)) * 6;

    // mode equal the number of components for each pixel
    mode = psInfo.pixelDepth / 8;
    // total is the number of unsigned chars we'll have to read
    total = psInfo.height * psInfo.width;

    for (i = 0; i < total; i++) {
        // if we have a run length pending, run it
        if (runlength != 0) {
            // we do, update the run length count
            runlength--;
            skip = (flag != 0);
        } else {
            // otherwise, read in the run length token
            if (step + 1 > bufSize)
                break;
            runlength = buffer[step];
            step += 1;

            // see if it's a RLE encoded sequence
            flag = runlength & 0x80;
            if (flag)
                runlength -= 128;
            skip = 0;
        }

        // do we need to skip reading this pixel?
        if (!skip) {
            // no, read in the pixel data
            if (step + mode > bufSize)
                break;
            aux = cc.__getSubArray(buffer, step, step + mode);
            step += mode;

            // mode=3 or 4 implies that the image is RGB(A). However TGA
            // stores it as BGR(A) so we'll have to swap R and B.
            if (mode >= 3) {
                var tmp = aux[0];
                aux[0] = aux[2];
                aux[2] = tmp;
            }
        }

        // add the pixel to our image
        for (var j = 0; j < mode; j++)
            psInfo.imageData[index + j] = aux[j];

        index += mode;
    }

    return true;
};

cc.tgaFlipImage = function (psInfo) {
    // mode equal the number of components for each pixel
    var mode = psInfo.pixelDepth / 8;
    var rowbytes = psInfo.width * mode;

    for (var y = 0; y < (psInfo.height / 2); y++) {
        var row = cc.__getSubArray(psInfo.imageData, y * rowbytes, y * rowbytes + rowbytes);
        cc.__setDataToArray(cc.__getSubArray(psInfo.imageData, (psInfo.height - (y + 1)) * rowbytes, rowbytes), psInfo.imageData, y * rowbytes);
        cc.__setDataToArray(row, psInfo.imageData, (psInfo.height - (y + 1)) * rowbytes);
    }
    psInfo.flipped = 0;
};

cc.__getSubArray = function (array, start, end) {
    if (array instanceof  Array)
        return array.slice(start, end);
    else
        return array.subarray(start, end);
};

cc.__setDataToArray = function (sourceData, destArray, startIndex) {
    for (var i = 0; i < sourceData.length; i++)
        destArray[startIndex + i] = sourceData[i];
};


cc.BinaryStreamReader = cc.Class.extend({
    _binaryData:null,
    _offset:0,

    ctor:function (binaryData) {
        this._binaryData = binaryData;
    },

    setBinaryData:function (binaryData) {
        this._binaryData = binaryData;
        this._offset = 0;
    },

    getBinaryData:function () {
        return this._binaryData;
    },

    _checkSize:function (neededBits) {
        if (!(this._offset + Math.ceil(neededBits / 8) < this._data.length))
            throw new Error("Index out of bound");
    },

    _decodeFloat:function (precisionBits, exponentBits) {
        var length = precisionBits + exponentBits + 1;
        var size = length >> 3;
        this._checkSize(length);

        var bias = Math.pow(2, exponentBits - 1) - 1;
        var signal = this._readBits(precisionBits + exponentBits, 1, size);
        var exponent = this._readBits(precisionBits, exponentBits, size);
        var significand = 0;
        var divisor = 2;
        var curByte = 0; //length + (-precisionBits >> 3) - 1;
        do {
            var byteValue = this._readByte(++curByte, size);
            var startBit = precisionBits % 8 || 8;
            var mask = 1 << startBit;
            while (mask >>= 1) {
                if (byteValue & mask)
                    significand += 1 / divisor;
                divisor *= 2;
            }
        } while (precisionBits -= startBit);

        this._offset += size;

        return exponent == (bias << 1) + 1 ? significand ? NaN : signal ? -Infinity : +Infinity
            : (1 + signal * -2) * (exponent || significand ? !exponent ? Math.pow(2, -bias + 1) * significand
            : Math.pow(2, exponent - bias) * (1 + significand) : 0);
    },

    _readByte:function (i, size) {
        return this._data[this._offset + size - i - 1];
    },

    _decodeInt:function (bits, signed) {
        var x = this._readBits(0, bits, bits / 8), max = Math.pow(2, bits);
        var result = signed && x >= max / 2 ? x - max : x;

        this._offset += bits / 8;
        return result;
    },

    _shl:function (a, b) {
        for (++b; --b; a = ((a %= 0x7fffffff + 1) & 0x40000000) == 0x40000000 ? a * 2 : (a - 0x40000000) * 2 + 0x7fffffff + 1){};
        return a;
    },

    _readBits:function (start, length, size) {
        var offsetLeft = (start + length) % 8;
        var offsetRight = start % 8;
        var curByte = size - (start >> 3) - 1;
        var lastByte = size + (-(start + length) >> 3);
        var diff = curByte - lastByte;

        var sum = (this._readByte(curByte, size) >> offsetRight) & ((1 << (diff ? 8 - offsetRight : length)) - 1);

        if (diff && offsetLeft)
            sum += (this._readByte(lastByte++, size) & ((1 << offsetLeft) - 1)) << (diff-- << 3) - offsetRight;

        while (diff)
            sum += this._shl(this._readByte(lastByte++, size), (diff-- << 3) - offsetRight);

        return sum;
    },

    readInteger:function () {
        return this._decodeInt(32, true);
    },

    readUnsignedInteger:function () {
        return this._decodeInt(32, false);
    },

    readSingle:function () {
        return this._decodeFloat(23, 8);
    },

    readShort:function () {
        return this._decodeInt(16, true);
    },

    readUnsignedShort:function () {
        return this._decodeInt(16, false);
    },

    readByte:function () {
        var readByte = this._data[this._offset];
        this._offset += 1;
        return readByte;
    },

    readData:function (start, end) {
        if (this._binaryData instanceof Array) {
            return this._binaryData.slice(start, end);
        } else {
            //typed array
            return this._binaryData.subarray(start, end);
        }
    },

    setOffset:function (offset) {
        this._offset = offset;
    },

    getOffset:function () {
        return this._offset;
    }
});