/*

Copyright 2008-2011 Clipperz Srl

This file is part of Clipperz's Javascript Crypto Library.
Javascript Crypto Library provides web developers with an extensive
and efficient set of cryptographic functions. The library aims to
obtain maximum execution speed while preserving modularity and
reusability.
For further information about its features and functionalities please
refer to http://www.clipperz.com

* Javascript Crypto Library is free software: you can redistribute
  it and/or modify it under the terms of the GNU Affero General Public
  License as published by the Free Software Foundation, either version
  3 of the License, or (at your option) any later version.

* Javascript Crypto Library is distributed in the hope that it will
  be useful, but WITHOUT ANY WARRANTY; without even the implied
  warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  See the GNU Affero General Public License for more details.

* You should have received a copy of the GNU Affero General Public
  License along with Javascript Crypto Library.  If not, see
  <http://www.gnu.org/licenses/>.

*/

try { if (typeof(Clipperz.ByteArray) == 'undefined') { throw ""; }} catch (e) {
	throw "Clipperz.Crypto.ECC depends on Clipperz.ByteArray!";
}  
if (typeof(Clipperz.Crypto.ECC) == 'undefined') { Clipperz.Crypto.ECC = {}; }
if (typeof(Clipperz.Crypto.ECC.BinaryField) == 'undefined') { Clipperz.Crypto.ECC.BinaryField = {}; }

Clipperz.Crypto.ECC.BinaryField.Value = function(aValue, aBase) {
	if (aValue.constructor == String) {
		var	value;
		var	stringLength;
		var numberOfWords;
		var	i,c;
	
		if (aBase != 16) {
			throw Clipperz.Crypto.ECC.BinaryField.Value.exception.UnsupportedBase;
		}

		value = aValue.replace(/ /g, '');
		stringLength = value.length;
		numberOfWords = Math.ceil(stringLength / 8);
		this._value = new Array(numberOfWords);
	
		c = numberOfWords;
		for (i=0; i<c; i++) {
			var	word;
		
			if (i < (c-1)) {
				word = parseInt(value.substr(stringLength-((i+1)*8), 8), 16);
			} else {
				word = parseInt(value.substr(0, stringLength-(i*8)), 16);
			}
			
			this._value[i] = word;
		}
	} else if (aValue.constructor == Array) {
		var itemsToCopy;

		itemsToCopy = aValue.length;
		while (aValue[itemsToCopy - 1] == 0) {
			itemsToCopy --;
		}

		this._value = aValue.slice(0, itemsToCopy);
	} else if (aValue.constructor == Number) {
		this._value = [aValue];
	} else {
//		throw Clipperz.Crypto.ECC.BinaryField.Value.exception.UnsupportedConstructorValueType;
	}
	
	return this;
}

Clipperz.Crypto.ECC.BinaryField.Value.prototype = MochiKit.Base.update(null, {

	'value': function() {
		return this._value;
	},

	//-----------------------------------------------------------------------------
	
	'wordSize': function() {
		return this._value.length
	},

	//-----------------------------------------------------------------------------

	'clone': function() {
		return new Clipperz.Crypto.ECC.BinaryField.Value(this._value.slice(0));
	},
	
	//-----------------------------------------------------------------------------

	'isZero': function() {
		return (this.compare(Clipperz.Crypto.ECC.BinaryField.Value.O) == 0);
	},

	//-----------------------------------------------------------------------------

	'asString': function(aBase) {
		var	result;
		var i,c;
		
		if (aBase != 16) {
			throw Clipperz.Crypto.ECC.BinaryField.Value.exception.UnsupportedBase;
		}
		
		result = "";
		c = this.wordSize();
		for (i=0; i<c; i++) {
			var	wordAsString;
			
//			wordAsString = ("00000000" + this.value()[i].toString(16));
			wordAsString = ("00000000" + this._value[i].toString(16));
			wordAsString = wordAsString.substring(wordAsString.length - 8);
			result = wordAsString + result;
		}
		
		result = result.replace(/^(00)*/, "");
		
		if (result == "") {
			result = "0";
		}
		
		return result;
	},
	
	//-----------------------------------------------------------------------------

	'shiftLeft': function(aNumberOfBitsToShift) {
		return new Clipperz.Crypto.ECC.BinaryField.Value(Clipperz.Crypto.ECC.BinaryField.Value._shiftLeft(this._value, aNumberOfBitsToShift));
	},

	//-----------------------------------------------------------------------------

	'bitSize': function() {
		return Clipperz.Crypto.ECC.BinaryField.Value._bitSize(this._value);
	},
	
	//-----------------------------------------------------------------------------

	'isBitSet': function(aBitPosition) {
		return Clipperz.Crypto.ECC.BinaryField.Value._isBitSet(this._value, aBitPosition);
	},
	
	//-----------------------------------------------------------------------------

	'xor': function(aValue) {
		return new Clipperz.Crypto.ECC.BinaryField.Value(Clipperz.Crypto.ECC.BinaryField.Value._xor(this._value, aValue._value));
	}, 

	//-----------------------------------------------------------------------------

	'compare': function(aValue) {
		return Clipperz.Crypto.ECC.BinaryField.Value._compare(this._value, aValue._value);
	},
	
	//-----------------------------------------------------------------------------
	__syntaxFix__: "syntax fix"
});

Clipperz.Crypto.ECC.BinaryField.Value.O = new Clipperz.Crypto.ECC.BinaryField.Value('0', 16);
Clipperz.Crypto.ECC.BinaryField.Value.I = new Clipperz.Crypto.ECC.BinaryField.Value('1', 16);

Clipperz.Crypto.ECC.BinaryField.Value._xor = function(a, b, aFirstItemOffset) {
	var result;
	var resultSize;
	var i,c;
	var firstItemOffset;
	
	firstItemOffset = aFirstItemOffset || 0;
	resultSize = Math.max((a.length - firstItemOffset), b.length) + firstItemOffset;

	result = new Array(resultSize);
	
	c = firstItemOffset;
	for (i=0; i<c; i++) {
		result[i] = a[i];
	}

	c = resultSize;
	for (i=firstItemOffset; i<c; i++) {
		result[i] = (((a[i] || 0) ^ (b[i - firstItemOffset] || 0)) >>> 0);
	}
	
	return result;
};

Clipperz.Crypto.ECC.BinaryField.Value._overwriteXor = function(a, b, aFirstItemOffset) {
	var i,c;
	var firstItemOffset;
	
	firstItemOffset = aFirstItemOffset || 0;

	c = Math.max((a.length - firstItemOffset), b.length) + firstItemOffset;
	for (i=firstItemOffset; i<c; i++) {
		a[i] = (((a[i] || 0) ^ (b[i - firstItemOffset] || 0)) >>> 0);
	}
};

Clipperz.Crypto.ECC.BinaryField.Value._shiftLeft = function(aWordArray, aNumberOfBitsToShift) {
	var numberOfWordsToShift;
	var	numberOfBitsToShift;
	var result;
	var	overflowValue;
	var	i,c;

	numberOfWordsToShift = Math.floor(aNumberOfBitsToShift / 32);
	numberOfBitsToShift = aNumberOfBitsToShift % 32;

	result = new Array(aWordArray.length + numberOfWordsToShift);
	
	c = numberOfWordsToShift;
	for (i=0; i<c; i++) {
		result[i] = 0;
	}
	
	overflowValue = 0;
	nextOverflowValue = 0;
	
	c = aWordArray.length;
	for (i=0; i<c; i++) {
		var	value;
		var	resultWord;

//		value = this.value()[i];
		value = aWordArray[i];

		if (numberOfBitsToShift > 0) {
			var nextOverflowValue;
		
			nextOverflowValue = (value >>> (32 - numberOfBitsToShift));
			value = value & (0xffffffff >>> numberOfBitsToShift);
			resultWord = (((value << numberOfBitsToShift) | overflowValue) >>> 0);
		} else {
			resultWord = value;
		}
		
		result[i+numberOfWordsToShift] = resultWord;
		overflowValue = nextOverflowValue;
	}

	if (overflowValue != 0) {
		result[aWordArray.length + numberOfWordsToShift] = overflowValue;
	}

	return result;
};

Clipperz.Crypto.ECC.BinaryField.Value._overwriteShiftLeft = function(aWordArray, aNumberOfBitsToShift) {
	var numberOfWordsToShift;
	var	numberOfBitsToShift;
	var result;
	var	overflowValue;
	var	i,c;

	numberOfWordsToShift = Math.floor(aNumberOfBitsToShift / 32);
	numberOfBitsToShift = aNumberOfBitsToShift % 32;

	result = new Array(aWordArray.length + numberOfWordsToShift);
	
	c = numberOfWordsToShift;
	for (i=0; i<c; i++) {
		result[i] = 0;
	}
	
	overflowValue = 0;
	nextOverflowValue = 0;
	
	c = aWordArray.length;
	for (i=0; i<c; i++) {
		var	value;
		var	resultWord;

//		value = this.value()[i];
		value = aWordArray[i];

		if (numberOfBitsToShift > 0) {
			var nextOverflowValue;
		
			nextOverflowValue = (value >>> (32 - numberOfBitsToShift));
			value = value & (0xffffffff >>> numberOfBitsToShift);
			resultWord = (((value << numberOfBitsToShift) | overflowValue) >>> 0);
		} else {
			resultWord = value;
		}
		
		result[i+numberOfWordsToShift] = resultWord;
		overflowValue = nextOverflowValue;
	}

	if (overflowValue != 0) {
		result[aWordArray.length + numberOfWordsToShift] = overflowValue;
	}

	return result;
};

Clipperz.Crypto.ECC.BinaryField.Value._bitSize = function(aWordArray) {
	var	result;
	var	notNullElements;
	var mostValuableWord;
	var matchingBitsInMostImportantWord;
	var mask;
	var i,c;

	notNullElements = aWordArray.length;
	
	if ((aWordArray.length == 1) && (aWordArray[0] == 0)) {
		result = 0;
	} else {
		while((aWordArray[notNullElements - 1] == 0) && (notNullElements > 0)) {
			notNullElements --;
		}
	
		result = (notNullElements - 1) * 32;
		mostValuableWord = aWordArray[notNullElements - 1];

		matchingBits = 32;
		mask = 0x80000000;
	
		while ((matchingBits > 0) && ((mostValuableWord & mask) == 0)) {
			matchingBits --;
			mask >>>= 1;
		}
	
		result += matchingBits;
	}
	
	return result;
};

Clipperz.Crypto.ECC.BinaryField.Value._isBitSet = function(aWordArray, aBitPosition) {
	var result;
	var	byteIndex;
	var bitIndexInSelectedByte;

	byteIndex = Math.floor(aBitPosition / 32);
	bitIndexInSelectedByte = aBitPosition % 32;
	
	if (byteIndex <= aWordArray.length) {
		result = ((aWordArray[byteIndex] & (1 << bitIndexInSelectedByte)) != 0);
	} else {
		result = false;
	}

	return result;
};

Clipperz.Crypto.ECC.BinaryField.Value._compare = function(a,b) {
	var	result;
	var i,c;
	
	result = MochiKit.Base.compare(a.length, b.length);

	c = a.length;
	for (i=0; (i<c) && (result==0); i++) {
//console.log("compare[" + c + " - " + i + " - 1] " + this.value()[c-i-1] + ", " + aValue.value()[c-i-1]);
//		result = MochiKit.Base.compare(this.value()[c-i-1], aValue.value()[c-i-1]);
		result = MochiKit.Base.compare(a[c-i-1], b[c-i-1]);
	}
	
	return result;
};


Clipperz.Crypto.ECC.BinaryField.Value['exception']= {
	'UnsupportedBase':					new MochiKit.Base.NamedError("Clipperz.Crypto.ECC.BinaryField.Value.exception.UnsupportedBase"),
	'UnsupportedConstructorValueType':	new MochiKit.Base.NamedError("Clipperz.Crypto.ECC.BinaryField.Value.exception.UnsupportedConstructorValueType")
};