// FUSKER.JS
// usage:
// f = new fusker(uri);
// for (var i = 0; i < f.limit(); i++) {
//	document.write(f.getURI(i));
// }
//
// A valid fusker URI must given for the uri parameter.
// The following features are supported:
//
// - Ranges
// A range of numbers. All numbers will be at least the width of the left-hand argument. For example:
//
// http://www.test.com/[001-002]/[1-4]/
//
// will generate:
//
// http://www.test.com/001/1/
// http://www.test.com/001/2/
// http://www.test.com/001/3/
// http://www.test.com/001/4/
// http://www.test.com/002/1/
// http://www.test.com/002/2/
// http://www.test.com/002/3/
// http://www.test.com/002/4/
//
// - Backreferences
// A reference to a previous range. Keep in mind that BACKREFERENCES COUNT TOWARD THE RANGE COUNT. for example:
//
// http://www.test.com/[1-2]/[0]/[3-4]/[2]/
//
// will generate:
//
// http://www.test.com/1/1/3/3/
// http://www.test.com/1/1/4/4/
// http://www.test.com/2/2/3/3/
// http://www.test.com/2/2/4/4/
//
// - TODO
// * add support for lists ([abc,def,ghi,...])
// * add support for backreferences to lists
// * any bug testing whatsoever

function fusker(uri) {
	// split up the uri into ranges and constants
	this.ranges = uri.match(/\[\d+-\d+\]|\[\d\]/g);
	this.constants = uri.split(/\[\d+-\d+\]|\[\d\]/g);
	
	// if there were no range matches, make this an empty
	// array to avoid problems
	if (!this.ranges) {
		this.ranges = new Array();
	}
	

	// make the ranges suitable for use
	for (var i = 0; i < this.ranges.length; i++) {
		// figure out what type of range this is
		
		if (this.ranges[i].search(/\[\d+\]/) > -1) {	// is a backreference
			// eliminate brackets
			this.ranges[i] = { type: 1, ref: parseInt(this.ranges[i].replace(/[\[\]]/g, '')) };
		} else {	// is a range
			// split this range
			var split = this.ranges[i].match(/\d+/g);
			
			// turn the original into an object
			// type: 0 = range, 1 = backref, 2 = list (NI)
			this.ranges[i] = { type: 0, start: parseInt(split[0],10),  end: parseInt(split[1],10), width: split[0].length, pos: 0 };
			
			// make sure the range is sane; if start < end, swap them
			// i may change this in the future to allow reverse iteration
			if (this.ranges[i].start > this.ranges[i].end) {
				var tmp = this.ranges[i].start;
				this.ranges[i].start = this.ranges[i].end;
				this.ranges[i].end = tmp;
			}
		}
	}
}

fusker.prototype.limit = function() {
	// the limit will be at least 1
	var limit = 1;

	// multiply by the size of each range
	for (var i = 0; i < this.ranges.length; i++) {
		// make sure this is a real range, not a backref or list
		if (this.ranges[i].type == 0) {
			limit *= this.ranges[i].end - this.ranges[i].start + 1;
		}
	}

	// return the number of possible values
	return limit;
}

fusker.prototype.getURI = function(pos) {
	var out = new String();
	
	// figure out the proper position for each range
	for (var i = this.ranges.length - 1; i >= 0; i--) {
		// make sure this is a real range, not a backref or list
		if (this.ranges[i].type == 0) {
			// set pos to the right value
			this.ranges[i].pos = (this.ranges[i].start + pos % (this.ranges[i].end - this.ranges[i].start + 1)).toString();
			
			// decrement the counter (TODO: there has to be a simpler way to do this)
			pos = (pos - (pos % (this.ranges[i].end - this.ranges[i].start + 1))) / (this.ranges[i].end - this.ranges[i].start + 1);
			
			// pad the value if necessary
			for (var j = this.ranges[i].pos.toString().length; j < this.ranges[i].width; j++) {
				this.ranges[i].pos = '0' + this.ranges[i].pos;
			}
		}
	}
	
	// assemble the string
	for (var i = 0; i < this.constants.length; i++) {
		// append a constant
		out += this.constants[i];
		
		// if there are more ranges
		if (this.ranges[i] != undefined) {
			if (this.ranges[i].type == 0) {
				// if this range is a constant, append its value
				out += this.ranges[i].pos;
			} else if (this.ranges[i].type == 1) {
				// if this range is a backref, append the value it references
				out += this.ranges[this.ranges[i].ref].pos;
			}
		}
	}
	
	return out;
}