import { makeGetSet } from '../moment/get-set';
import { addFormatToken } from '../format/format';
import { addUnitAlias } from './aliases';
import { addUnitPriority } from './priorities';
import {
    addRegexToken,
    match1to2,
    match2,
    match3to4,
    match5to6,
} from '../parse/regex';
import { addParseToken } from '../parse/token';
import { HOUR, MINUTE, SECOND } from './constants';
import toInt from '../utils/to-int';
import zeroFill from '../utils/zero-fill';
import getParsingFlags from '../create/parsing-flags';

// FORMATTING

function hFormat() {
    return this.hours() % 12 || 12;
}

function kFormat() {
    return this.hours() || 24;
}

addFormatToken('H', ['HH', 2], 0, 'hour');
addFormatToken('h', ['hh', 2], 0, hFormat);
addFormatToken('k', ['kk', 2], 0, kFormat);

addFormatToken('hmm', 0, 0, function () {
    return '' + hFormat.apply(this) + zeroFill(this.minutes(), 2);
});

addFormatToken('hmmss', 0, 0, function () {
    return (
        '' +
        hFormat.apply(this) +
        zeroFill(this.minutes(), 2) +
        zeroFill(this.seconds(), 2)
    );
});

addFormatToken('Hmm', 0, 0, function () {
    return '' + this.hours() + zeroFill(this.minutes(), 2);
});

addFormatToken('Hmmss', 0, 0, function () {
    return (
        '' +
        this.hours() +
        zeroFill(this.minutes(), 2) +
        zeroFill(this.seconds(), 2)
    );
});

function meridiem(token, lowercase) {
    addFormatToken(token, 0, 0, function () {
        return this.localeData().meridiem(
            this.hours(),
            this.minutes(),
            lowercase
        );
    });
}

meridiem('a', true);
meridiem('A', false);

// ALIASES

addUnitAlias('hour', 'h');

// PRIORITY
addUnitPriority('hour', 13);

// PARSING

function matchMeridiem(isStrict, locale) {
    return locale._meridiemParse;
}

addRegexToken('a', matchMeridiem);
addRegexToken('A', matchMeridiem);
addRegexToken('H', match1to2);
addRegexToken('h', match1to2);
addRegexToken('k', match1to2);
addRegexToken('HH', match1to2, match2);
addRegexToken('hh', match1to2, match2);
addRegexToken('kk', match1to2, match2);

addRegexToken('hmm', match3to4);
addRegexToken('hmmss', match5to6);
addRegexToken('Hmm', match3to4);
addRegexToken('Hmmss', match5to6);

addParseToken(['H', 'HH'], HOUR);
addParseToken(['k', 'kk'], function (input, array, config) {
    var kInput = toInt(input);
    array[HOUR] = kInput === 24 ? 0 : kInput;
});
addParseToken(['a', 'A'], function (input, array, config) {
    config._isPm = config._locale.isPM(input);
    config._meridiem = input;
});
addParseToken(['h', 'hh'], function (input, array, config) {
    array[HOUR] = toInt(input);
    getParsingFlags(config).bigHour = true;
});
addParseToken('hmm', function (input, array, config) {
    var pos = input.length - 2;
    array[HOUR] = toInt(input.substr(0, pos));
    array[MINUTE] = toInt(input.substr(pos));
    getParsingFlags(config).bigHour = true;
});
addParseToken('hmmss', function (input, array, config) {
    var pos1 = input.length - 4,
        pos2 = input.length - 2;
    array[HOUR] = toInt(input.substr(0, pos1));
    array[MINUTE] = toInt(input.substr(pos1, 2));
    array[SECOND] = toInt(input.substr(pos2));
    getParsingFlags(config).bigHour = true;
});
addParseToken('Hmm', function (input, array, config) {
    var pos = input.length - 2;
    array[HOUR] = toInt(input.substr(0, pos));
    array[MINUTE] = toInt(input.substr(pos));
});
addParseToken('Hmmss', function (input, array, config) {
    var pos1 = input.length - 4,
        pos2 = input.length - 2;
    array[HOUR] = toInt(input.substr(0, pos1));
    array[MINUTE] = toInt(input.substr(pos1, 2));
    array[SECOND] = toInt(input.substr(pos2));
});

// LOCALES

export function localeIsPM(input) {
    // IE8 Quirks Mode & IE7 Standards Mode do not allow accessing strings like arrays
    // Using charAt should be more compatible.
    return (input + '').toLowerCase().charAt(0) === 'p';
}

export var defaultLocaleMeridiemParse = /[ap]\.?m?\.?/i,
    // Setting the hour should keep the time, because the user explicitly
    // specified which hour they want. So trying to maintain the same hour (in
    // a new timezone) makes sense. Adding/subtracting hours does not follow
    // this rule.
    getSetHour = makeGetSet('Hours', true);

export function localeMeridiem(hours, minutes, isLower) {
    if (hours > 11) {
        return isLower ? 'pm' : 'PM';
    } else {
        return isLower ? 'am' : 'AM';
    }
}