var Lib = module.exports;

// http://codereview.stackexchange.com/questions/37028/grouping-elements-in-array-by-multiple-properties
Lib.groupBy = function(array, f)
{
    var groups = {};
    array.forEach(function(o) {
        var group = JSON.stringify(f(o));
        groups[group] = groups[group] || [];
        groups[group].push(o);
    });

    return Object.keys(groups).map(function(group) {
        return groups[group];
    });
};

function letterToInt(letter) {
    switch (letter) {
        case 'B': return 0;
        case 'V': return 1;
        case 'A': return 2;
        default:  return null;
    }
}

Lib.compareRecommendationStyle = function(style1, style2) {

    return letterToInt(style1.recommendation_style[4]) - letterToInt(style2.recommendation_style[4]);

};

Lib.experimentDuration = function(exp) {

    if (exp === undefined) {

        return;

    }

    var lastCoin = null;

    for (var i = exp.elements.events.length - 1; i >= 0; i--) {
        if (exp.elements.events[i].type === 'coin') {
            lastCoin = exp.elements.events[i];
            break;
        }
    }

    return Lib.timeDifference(exp.elements.events[0].time, lastCoin.time);

};

Lib.max = function(elt1, elt2) {

    if (elt1 === undefined)
        return elt2;

    if (elt2 === undefined)
        return elt1;

    return Math.max(elt1,elt2);

};

Lib.min = function(elt1, elt2) {

    if (elt1 === undefined)
        return elt2;

    if (elt2 === undefined)
        return elt1;

    return Math.min(elt1,elt2);

};

Lib.timeDifference = function(time1, time2) {

    return new Date(time2).getTime() - new Date(time1).getTime();

};

Lib.timeToString = function(_time) {

    var time = _time / 1000;

    return Math.floor(time / 3600) + 'h' + Math.floor((time % 3600) / 60) + 'm' + Math.floor(time % 60);

};

Lib.makeGroups = function(db) {

    var elements = [];

    for (var i = 0; i < db.experiments.length; i++) {

        if (db.experiments[i].coinCombination.scene_id !== 1 && db.experiments[i].elements.events.length !== 0) {

            elements.push(db.experiments[i]);

        }

    }

    return Lib.groupBy(elements, function(item) {
        return item.coin_combination_id;//, item.user.rating];
    });

};

Lib.loadFromFile = function(path) {

    return JSON.parse(require('fs').readFileSync(path, 'utf8'));

};

Lib.toMatlabArray = function(name, array) {

    var str = name + ' = [ ';

    array.forEach(function(elt) { str += ' ' + elt + ' '; });

    str += '];\n';

    return str;

};

// http://stackoverflow.com/questions/3895478/
Lib.range = function(start, stop, step, computation) {

    if (typeof step === 'function') {

        computation = step;
        step = 1;

    }

    if (computation === undefined) {

        computation = function(i) { return i; };

    }

    if (step === undefined) {

        step = 1;

    }

    var a = [];
    while (start < stop) {
        a.push(computation(start));
        start += step;
    }
    return a;
};

// Simplified version
Lib.numberOfInteraction = function(exp) {

    if (exp === undefined) {

        return;

    }


    for (var i = exp.elements.events.length - 1; i >= 0; i--) {
        if (exp.elements.events[i].type === 'coin') {
            // lastCoin = exp.elements.events[i];
            break;
        }
    }




    return i;

};