import { makeGetSet } from '../moment/get-set';
import { addFormatToken } from '../format/format';
import { addUnitAlias } from './aliases';
import { addRegexToken, match1to2, match2 } from '../parse/regex';
import { addParseToken } from '../parse/token';
import { HOUR } from './constants';
import toInt from '../utils/to-int';
import getParsingFlags from '../create/parsing-flags';

// FORMATTING

addFormatToken('H', ['HH', 2], 0, 'hour');
addFormatToken('h', ['hh', 2], 0, function () {
    return this.hours() % 12 || 12;
});

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');

// PARSING

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

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

addParseToken(['H', 'HH'], HOUR);
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;
});

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


// MOMENTS

// Setting the hour should keep the time, because the user explicitly
// specified which hour he wants. So trying to maintain the same hour (in
// a new timezone) makes sense. Adding/subtracting hours does not follow
// this rule.
export var getSetHour = makeGetSet('Hours', true);