var BinaryReader = function(buffer) {
    this.position = 0;
    this.length = buffer.length;
    this.data = buffer;
}

BinaryReader.prototype.readInt8 = function() {
    var ret = this.data.charCodeAt(this.position);
    ++this.position;
    return ret & 0xFF;
}

BinaryReader.prototype.readInt16 = function() {
    var b1 = this.readInt8();
    var b2 = this.readInt8();

    return b1 | (b2 << 8);
}

BinaryReader.prototype.readInt32 = function() {
    var s1 = this.readInt16();
    var s2 = this.readInt16();

    return s1 | (s2 << 16);
}

BinaryReader.prototype.readInt64 = function() {
    var i1 = this.readInt32();
    var i2 = this.readInt32();

    return i1 | (i2 << 32);
}

BinaryReader.prototype.readFloat = function() {
    var bits = this.readInt32();

    var sign     = ((bits & 0x80000000) == 0) ? 1 : -1;
    var exponent = ((bits & 0x7f800000) >> 23);
    var mantissa =  (bits & 0x007fffff);

    mantissa |= 0x00800000;
    return (sign * mantissa * Math.pow(2, exponent - 150));
}

BinaryReader.prototype.readString = function(length) {
    if(typeof length !== "undefined") {
        var ret = "";
        var cur = this.readInt8();
        while(cur !== 0) {
            ret += String.fromCharCode(cur);
            cur = this.readInt8();
        }

        return ret;
    } else {
       var content = [];
       for(var i = 0; i < length; ++i) {
           content.push(this.readInt8());
       }

       return String.fromCharCode.apply(String, content);
    }
}

BinaryReader.prototype.readArray = function(length, typeDesc) {
    if(typeDesc === Float32Array) {
        var ret = new Float32Array(length);
        for(var i = 0; i < length; ++i) {
            ret[i] = this.readFloat();
        }

        return ret;
    }

    if(typeDesc === Int32Array) {
        var ret = new Int32Array(length);
        for(var i = 0; i < length; ++i) {
            ret[i] = this.readInt32();
        }

        return ret;
    }

    if(typeDesc === Int16Array) {
        var ret = new Int16Array(length);
        for(var i = 0; i < length; ++i) {
            ret[i] = this.readInt16();
        }

        return ret;
    }

    if(typeDesc === Int8Array) {
        var ret = new Int8Array(length);
        for(var i = 0; i < length; ++i) {
            ret[i] = this.readInt8();
        }

        return ret;
    }

    if(typeDesc === Uint8Array) {
        var ret = new Uint8Array(length);
        for(var i = 0; i < length; ++i) {
            ret[i] = this.readInt8() & 0xFF;
        }

        return ret;
    }

    var ret = [];
    for(var i = 0; i < length; ++i) {
        ret.push(this.readType(typeDesc));
    }

    return ret;
}

BinaryReader.prototype.readType = function(typeDesc) {
    var ret = { };

    for(var i = 0; i < typeDesc.length; ++i) {
        var valName = typeDesc[i].name;
        var value = undefined;

        switch(typeDesc[i].type) {
            case "i64":
                value = this.readInt64();
                break;

            case "i32":
                value = this.readInt32();
                break;

            case "i16":
                value = this.readInt16();
                break;

            case "i8":
                value = this.readInt8();
                break;

            case "f32":
                value = this.readFloat();
                break;

            case "s":
                value = this.readString(typeDesc[i].strLen);
                break;

            case "v3":
                value = {
                    x: this.readFloat(),
                    y: this.readFloat(),
                    z: this.readFloat()
                }
                break;

            case "v2":
                value = {
                    x: this.readFloat(),
                    y: this.readFloat()
                }
                break;
        }

        ret[valName] = value;
    }

    return ret;
}