import zeroFill from '../utils/zero-fill';

export var formattingTokens = /(\[[^\[]*\])|(\\)?(Mo|MM?M?M?|Do|DDDo|DD?D?D?|ddd?d?|do?|w[o|w]?|W[o|W]?|Q|YYYYYY|YYYYY|YYYY|YY|gg(ggg?)?|GG(GGG?)?|e|E|a|A|hh?|HH?|mm?|ss?|S{1,4}|x|X|zz?|ZZ?|.)/g;

var localFormattingTokens = /(\[[^\[]*\])|(\\)?(LTS|LT|LL?L?L?|l{1,4})/g;

var formatFunctions = {};

export var formatTokenFunctions = {};

// token:    'M'
// padded:   ['MM', 2]
// ordinal:  'Mo'
// callback: function () { this.month() + 1 }
export function addFormatToken (token, padded, ordinal, callback) {
    var func = callback;
    if (typeof callback === 'string') {
        func = function () {
            return this[callback]();
        };
    }
    if (token) {
        formatTokenFunctions[token] = func;
    }
    if (padded) {
        formatTokenFunctions[padded[0]] = function () {
            return zeroFill(func.apply(this, arguments), padded[1], padded[2]);
        };
    }
    if (ordinal) {
        formatTokenFunctions[ordinal] = function () {
            return this.localeData().ordinal(func.apply(this, arguments), token);
        };
    }
}

function removeFormattingTokens(input) {
    if (input.match(/\[[\s\S]/)) {
        return input.replace(/^\[|\]$/g, '');
    }
    return input.replace(/\\/g, '');
}

function makeFormatFunction(format) {
    var array = format.match(formattingTokens), i, length;

    for (i = 0, length = array.length; i < length; i++) {
        if (formatTokenFunctions[array[i]]) {
            array[i] = formatTokenFunctions[array[i]];
        } else {
            array[i] = removeFormattingTokens(array[i]);
        }
    }

    return function (mom) {
        var output = '';
        for (i = 0; i < length; i++) {
            output += array[i] instanceof Function ? array[i].call(mom, format) : array[i];
        }
        return output;
    };
}

// format date using native date object
export function formatMoment(m, format) {
    if (!m.isValid()) {
        return m.localeData().invalidDate();
    }

    format = expandFormat(format, m.localeData());

    if (!formatFunctions[format]) {
        formatFunctions[format] = makeFormatFunction(format);
    }

    return formatFunctions[format](m);
}

export function expandFormat(format, locale) {
    var i = 5;

    function replaceLongDateFormatTokens(input) {
        return locale.longDateFormat(input) || input;
    }

    localFormattingTokens.lastIndex = 0;
    while (i >= 0 && localFormattingTokens.test(format)) {
        format = format.replace(localFormattingTokens, replaceLongDateFormatTokens);
        localFormattingTokens.lastIndex = 0;
        i -= 1;
    }

    return format;
}