var symbols = [ 'C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#' ];

function playNote(note) {
    var a = document.body.appendChild(document.createElement('audio'));
    a.src = 'resources/' + escape(note) + '.mp3';
    a.autoplay = 'true';
    a.addEventListener("ended", function (e) {
        this.parentNode.removeChild(this);
    });
}

var estart = document.getElementById('start');
var eproduce_and_play = document.getElementById('produce_and_play');
var eproduction = document.getElementById('production');
var eiterations = document.getElementById('iter');
var eoutput = document.getElementById('output');

function produce() {
    var start = estart.value;
    var production = eproduction.value;

    var p_lines = eproduction.value.split('\n').map(function(l) {
        return l.split('-');
    });

    p_rules = {};
    p_lines.forEach(function(x) {
        var n = 0;
        if (n = x[0].match(/\(([\d\.]+)\)/)) {
            var n = parseFloat(n[1]);
            var k = x[0].match(/\w\#?/)[0].trim(),
                v = x[1].trim();
            if (!p_rules[k]) p_rules[k] = [];
            p_rules[k].push([n, v]);
            p_rules[k].sort(function(a, b) { return a[0] - b[0]; });
        } else {
            var k = x[0].trim(),
                v = x[1].trim();
            if (typeof p_rules[k] == 'object') {
                alert('do not mix statochastic (0.5) grammars with deterministic.');
                throw Exception('err');
            }
            p_rules[k] = v;
        }
    });

    var start_notes = start.match(/\w\#?/g);
    for (var i = 0; i < parseInt(eiterations.value, 10); i++) {
        var start_notes = start_notes.join('').match(/\w\#?/g);
        start_notes = start_notes.map(function(s) {
            if (typeof p_rules[s] == 'object') {
                var r = Math.random();
                var sum = 0;
                for (var i = 0; i < p_rules[s].length; i++) {
                    sum += p_rules[s][i][0];
                    if (r <= sum) {
                        return p_rules[s][i][1];
                    }
                }
            } else {
                return (p_rules[s]) || s;
            }
        });
    }

    eoutput.value = start_notes.join('');
}

function play() {
    var start_notes = eoutput.value.match(/\w\#?/g);
    var i = 0;
    function p() {
        if (i < start_notes.length) {
            playNote(start_notes[i]);
            i++;
            window.setTimeout(p, 300);
        }
    }
    p();
}

eproduce_and_play.onclick = function() {
    produce();
    play();
};