function lcs(a,b){
    var l = new Array();
    for(var i = -1; i < a.length; i++)
	l[i] = new Array();

    for(var i = -1; i < a.length; i++)
	l[i][-1] = 0;
    for(var j = -1; j < b.length; j++)
	l[-1][j] = 0;

    for(var i = 0; i < a.length; i++)
	for(var j = 0; j < b.length; j++)
	    if (a[i] == b[j])
		l[i][j] = l[i-1][j-1] + 1;
	    else
		l[i][j] = Math.max(l[i-1][j], l[i][j-1]);

    var r = [];
    var i = a.length, j = b.length;
    while (i > 0 && j > 0) {
	i--;
	j--;
	if (a[i] == b[j])
	    r.unshift(a[i]);
	else if (l[i][j-1] > l[i-1][j])
	    i++;
	else
	    j++;
    }

    return r;
}

function parseFile(fileName, parser) {
    var req = new XMLHttpRequest();
    req.onreadystatechange = function() {
	if(req.readyState == 4)
	    parser(req.responseText);
    }

    req.open("GET", fileName);
    req.send(null);
}

function getFile(fileName) {
    var req = new XMLHttpRequest();
    req.open("GET", fileName, false);
    req.send(null);
    return req.responseText;
}

function parsePublic(target) {
    var mainLines = getFile(target).split('/* DIFFTABLE */')[1].split('\n');

    var fileNames = new Array();

    var privateFilesRE = new RegExp('#include "simpleops/(.*\.h)"');
    for(var i = 0; i < mainLines.length; i++)
	if(privateFilesRE.test(mainLines[i]))
	    fileNames.push(privateFilesRE.exec(mainLines[i])[1]);

    return fileNames;
}

function addRow(table, row) {
    var tr = table.insertRow(-1);

    for(var j = 0; j < row.length; j++) {
	var cell = tr.insertCell(-1);
	cell.setAttribute("class", row[j].getAttribute("class"));
	cell.appendChild(row[j]);
    }
}

function createPre(x, cls) {
    var node = document.createElement('pre');
    node.setAttribute("class", cls);
    node.appendChild(document.createTextNode(x));
    return node;
}

function diffNode(x) {
    return createPre(x, "diff");
}

function emptyNode() {
    return createPre("", "empty");
}

function equalNode(x) {
    return createPre(x, "equal");
}

function multidiff(diffTable, target) {
    var sourceNames = parsePublic(target);

    var sourceLines = new Array();
    var idx = new Array();
    var ref;
    for(var i = 0; i < sourceNames.length; i++) {
	var data = getFile(sourceNames[i]);
	var lines = data.split('\n');
	sourceLines.push(lines);
	idx.push(0);

	if(i == 0)
	    ref = lines;
	else
	    ref = lcs(ref, lines);
    }

    for(var refidx = 0; refidx < ref.length; refidx++) {
	while (true) {
	    var matching = true;
	    var line = new Array();

	    for(var j = 0; j < sourceLines.length; j++)
		if (ref[refidx] != sourceLines[j][idx[j]]) {
		    matching = false;
		    line.push(diffNode(sourceLines[j][idx[j]++]));
		} else {
		    line.push(emptyNode());
		}

	    if (matching)
		break;
	    else
		addRow(diffTable, line);
	}

	var line = new Array();
	for(var j = 0; j < sourceLines.length; j++)
	    line.push(equalNode(sourceLines[j][idx[j]++]));
	addRow(diffTable, line);
    }

    while (true) {
	var complete = true;
	var line = new Array();

	for(var j = 0; j < sourceLines.length; j++)
	    if (idx[j] < sourceLines[j].length) {
		complete = false;
		line.push(diffNode(sourceLines[j][idx[j]++]));
	    } else {
		line.push(emptyNode());
	    }

	if (complete)
	    break;
	else
	    addRow(diffTable, line);
    }

    var tr = diffTable.createTHead().insertRow(0);
    for(var j = 0; j < sourceNames.length; j++) {
	var td = tr.insertCell(j);
	var text = document.createTextNode(sourceNames[j]);
	td.appendChild(text);
    }
}