'use strict';

import Q = require('q');
import fs = require('fs');
import path = require('path');
import URL = require('url');
import lang  = require('./meshLanguages');
import u = require('./meshUtil');
import moment  = require('moment');

var TRANSLATE_FILTER_KEY : string = 'translate';
var YOUTUBE_FILTER_KEY : string = 'youtube';
var MOMENT_FILTER_KEY : string = 'moment';

/**
 * Interface for the FilterRegisterFunction. You can pass such a function to register the mesh filters to your
 * template engine.
 */
export interface IFilterRegisterFunction {
    (engine : any, key : string, filterfunction : Function) : void;
}

/**
 * Register default template filters.
 * Out of the box we support registering filters with swig and handlebars. If you have a different template engine
 * please pass a register function to register the filters with your template engine. This function will then be called
 * for each of the mesh filters.
 * @param engine Your template engine.
 * @param registerfunction [optional] register function that will be called for each of the mesh filters.
 **/
export function registerFilters(engine : any, registerfunction? : IFilterRegisterFunction) : void {
    if (u.isDefined(engine) && u.isFunction(engine.setFilter)) {
        engine.setFilter(TRANSLATE_FILTER_KEY, lang.translateFilter);
        engine.setFilter(YOUTUBE_FILTER_KEY, youtubeFilter);
        engine.setFilter(MOMENT_FILTER_KEY, momentFilter);
    } else if (u.isDefined(engine) && u.isFunction(engine.registerHelper)) {
        engine.registerHelper(TRANSLATE_FILTER_KEY, lang.translateFilter);
        engine.registerHelper(YOUTUBE_FILTER_KEY, youtubeFilter);
        engine.registerHelper(MOMENT_FILTER_KEY, momentFilter);
    } else if (u.isDefined(registerfunction) && u.isFunction(registerfunction)) {
        registerfunction(engine, TRANSLATE_FILTER_KEY, lang.translateFilter);
        registerfunction(engine, YOUTUBE_FILTER_KEY, youtubeFilter);
        registerfunction(engine, MOMENT_FILTER_KEY, momentFilter);
    } else {
        throw 'Registering filters failed. Either use a supported engine, or pass a custom register function.';
    }
}

/**
 * Simple youtube filter, that extracts the video id out of a youtube link.
 **/
function youtubeFilter(input : string) : string {
    var regExp = /^.*(youtu\.be\/|v\/|u\/\w\/|embed\/|watch\?v=|\&v=)([^#\&\?]*).*/;
    var match = input.match(regExp);
    if (match && match[2].length == 11) {
        return match[2];
    } else {
        return input;
    }
}

/**
 * Simple moment filter, that can be used to render mesh dates/timestamps with a formatstring.
 * @param input unix timestamp that should be rendered
 * @param format format string (check momentjs website)
 * @returns {string} formated date.
 */
function momentFilter(input : any, format : string) : string {
    if (typeof input === 'number') {
        // In mesh we use unix timestamps
        input = input * 1000;
    }
    return moment(input).format(format);
}