var StringUtils = require('./stringutils');

/**
 * @constructor
 */
function BinaryFile(strData, iDataOffset, iDataLength) {
	var data = strData;
	var dataOffset = iDataOffset || 0;
	var dataLength = 0;

	this.getRawData = function() {
		return data;
	};

	if (typeof strData == "string") {
		dataLength = iDataLength || data.length;

		this.getByteAt = function(iOffset) {
			return data.charCodeAt(iOffset + dataOffset) & 0xFF;
		};
	} else if (typeof strData == "unknown") {
		dataLength = iDataLength || IEBinary_getLength(data);

		this.getByteAt = function(iOffset) {
			return IEBinary_getByteAt(data, iOffset + dataOffset);
		};
	}
    // @aadsm
    this.getBytesAt = function(iOffset, iLength) {
        var bytes = new Array(iLength);
        for( var i = 0; i < iLength; i++ ) {
            bytes[i] = this.getByteAt(iOffset+i);
        }
        return bytes;
    };

	this.getLength = function() {
		return dataLength;
	};

    // @aadsm
    this.isBitSetAt = function(iOffset, iBit) {
        var iByte = this.getByteAt(iOffset);
        return (iByte & (1 << iBit)) != 0;
    };

	this.getSByteAt = function(iOffset) {
		var iByte = this.getByteAt(iOffset);
		if (iByte > 127)
			return iByte - 256;
		else
			return iByte;
	};

	this.getShortAt = function(iOffset, bBigEndian) {
		var iShort = bBigEndian ?
			(this.getByteAt(iOffset) << 8) + this.getByteAt(iOffset + 1)
			: (this.getByteAt(iOffset + 1) << 8) + this.getByteAt(iOffset);
		if (iShort < 0) iShort += 65536;
		return iShort;
	};
	this.getSShortAt = function(iOffset, bBigEndian) {
		var iUShort = this.getShortAt(iOffset, bBigEndian);
		if (iUShort > 32767)
			return iUShort - 65536;
		else
			return iUShort;
	};
	this.getLongAt = function(iOffset, bBigEndian) {
		var iByte1 = this.getByteAt(iOffset),
			iByte2 = this.getByteAt(iOffset + 1),
			iByte3 = this.getByteAt(iOffset + 2),
			iByte4 = this.getByteAt(iOffset + 3);

		var iLong = bBigEndian ?
			(((((iByte1 << 8) + iByte2) << 8) + iByte3) << 8) + iByte4
			: (((((iByte4 << 8) + iByte3) << 8) + iByte2) << 8) + iByte1;
		if (iLong < 0) iLong += 4294967296;
		return iLong;
	};
	this.getSLongAt = function(iOffset, bBigEndian) {
		var iULong = this.getLongAt(iOffset, bBigEndian);
		if (iULong > 2147483647)
			return iULong - 4294967296;
		else
			return iULong;
	};
	// @aadsm
	this.getInteger24At = function(iOffset, bBigEndian) {
        var iByte1 = this.getByteAt(iOffset),
			iByte2 = this.getByteAt(iOffset + 1),
			iByte3 = this.getByteAt(iOffset + 2);

		var iInteger = bBigEndian ?
			((((iByte1 << 8) + iByte2) << 8) + iByte3)
			: ((((iByte3 << 8) + iByte2) << 8) + iByte1);
		if (iInteger < 0) iInteger += 16777216;
		return iInteger;
    };
	this.getStringAt = function(iOffset, iLength) {
		var aStr = [];
		for (var i=iOffset,j=0;i<iOffset+iLength;i++,j++) {
			aStr[j] = String.fromCharCode(this.getByteAt(i));
		}
		return aStr.join("");
	};
	// @aadsm
	this.getStringWithCharsetAt = function(iOffset, iLength, iCharset) {
		var bytes = this.getBytesAt(iOffset, iLength);
		var sString;

		switch( iCharset.toLowerCase() ) {
		    case 'utf-16':
		    case 'utf-16le':
		    case 'utf-16be':
		        sString = StringUtils.readUTF16String(bytes, iCharset);
		        break;

		    case 'utf-8':
		        sString = StringUtils.readUTF8String(bytes);
		        break;

		    default:
		        sString = StringUtils.readNullTerminatedString(bytes);
		        break;
		}

		return sString;
	};

	this.getCharAt = function(iOffset) {
		return String.fromCharCode(this.getByteAt(iOffset));
	};
	this.toBase64 = function() {
		return b64utils.btoa(data);
	};
	this.fromBase64 = function(strBase64) {
		data = b64utils.atob(strBase64);
	};

    this.loadRange = function(range, callback) {
        callback();
    };
}

var b64utils = {};

if (typeof document !== 'undefined') {
	var js = document.createElement('script');
	js.type = 'text/vbscript';
	js.textContent = "Function IEBinary_getByteAt(strBinary, iOffset)\r\n" +
	    "	IEBinary_getByteAt = AscB(MidB(strBinary,iOffset+1,1))\r\n" +
	    "End Function\r\n" +
	    "Function IEBinary_getLength(strBinary)\r\n" +
	    "	IEBinary_getLength = LenB(strBinary)\r\n" +
	    "End Function\r\n";
	document.getElementsByTagName('head')[0].appendChild(js);

	b64utils.btoa = window.btoa;
	b64utils.atob = window.atob;
} else {
	b64utils.btoa = require('btoa');
	b64utils.atob = require('atob');
}

module.exports = BinaryFile;