var Immutable = require('immutable');
var is = require('is');

var timers = {};
var startDate = Date.now();

/**
    Mesure an operation

    @parqm {String} type
    @param {Promise} p
    @return {Promise}
*/
function measure(type, p) {
    timers[type] = timers[type] || {
        type: type,
        count: 0,
        total: 0,
        min: undefined,
        max: 0
    };

    var start = Date.now();

    return p
    .fin(function() {
        var end = Date.now();
        var duration = (end - start);

        timers[type].count ++;
        timers[type].total += duration;

        if (is.undefined(timers[type].min)) {
            timers[type].min = duration;
        } else {
            timers[type].min = Math.min(timers[type].min, duration);
        }

        timers[type].max = Math.max(timers[type].max, duration);
    });
}

/**
    Return a milliseconds number as a second string

    @param {Number} ms
    @return {String}
*/
function time(ms) {
    if (ms < 1000) {
        return (ms.toFixed(0)) + 'ms';
    }

    return (ms/1000).toFixed(2) + 's';
}

/**
    Dump all timers to a logger

    @param {Logger} logger
*/
function dump(logger) {
    var prefix = '    > ';
    var measured = 0;
    var totalDuration = Date.now() - startDate;

    // Enable debug logging
    var logLevel = logger.getLevel();
    logger.setLevel('debug');

    Immutable.Map(timers)
        .valueSeq()
        .sortBy(function(timer) {
            measured += timer.total;
            return timer.total;
        })
        .forEach(function(timer) {
            var percent = (timer.total * 100) / totalDuration;


            logger.debug.ln((percent.toFixed(1)) + '% of time spent in "' + timer.type + '" (' + timer.count + ' times) :');
            logger.debug.ln(prefix + 'Total: ' + time(timer.total)+ ' | Average: ' + time(timer.total / timer.count));
            logger.debug.ln(prefix + 'Min: ' + time(timer.min) + ' | Max: ' + time(timer.max));
            logger.debug.ln('---------------------------');
        });


    logger.debug.ln(time(totalDuration - measured) + ' spent in non-mesured sections');

    // Rollback to previous level
    logger.setLevel(logLevel);
}

module.exports = {
    measure: measure,
    dump: dump
};