/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {Inject, LOCALE_ID, Pipe, PipeTransform} from '@angular/core';
import {DateFormatter} from '../facade/intl';
import {NumberWrapper, isBlank, isDate} from '../facade/lang';
import {InvalidPipeArgumentError} from './invalid_pipe_argument_error';


/**
 * @ngModule CommonModule
 * @whatItDoes Formats a date according to locale rules.
 * @howToUse `date_expression | date[:format]`
 * @description
 *
 * Where:
 * - `expression` is a date object or a number (milliseconds since UTC epoch) or an ISO string
 * (https://www.w3.org/TR/NOTE-datetime).
 * - `format` indicates which date/time components to include. The format can be predifined as
 *   shown below or custom as shown in the table.
 *   - `'medium'`: equivalent to `'yMMMdjms'` (e.g. `Sep 3, 2010, 12:05:08 PM` for `en-US`)
 *   - `'short'`: equivalent to `'yMdjm'` (e.g. `9/3/2010, 12:05 PM` for `en-US`)
 *   - `'fullDate'`: equivalent to `'yMMMMEEEEd'` (e.g. `Friday, September 3, 2010` for `en-US`)
 *   - `'longDate'`: equivalent to `'yMMMMd'` (e.g. `September 3, 2010` for `en-US`)
 *   - `'mediumDate'`: equivalent to `'yMMMd'` (e.g. `Sep 3, 2010` for `en-US`)
 *   - `'shortDate'`: equivalent to `'yMd'` (e.g. `9/3/2010` for `en-US`)
 *   - `'mediumTime'`: equivalent to `'jms'` (e.g. `12:05:08 PM` for `en-US`)
 *   - `'shortTime'`: equivalent to `'jm'` (e.g. `12:05 PM` for `en-US`)
 *
 *
 *  | Component | Symbol | Short Form   | Long Form         | Numeric   | 2-digit   |
 *  |-----------|:------:|--------------|-------------------|-----------|-----------|
 *  | era       |   G    | G (AD)       | GGGG (Anno Domini)| -         | -         |
 *  | year      |   y    | -            | -                 | y (2015)  | yy (15)   |
 *  | month     |   M    | MMM (Sep)    | MMMM (September)  | M (9)     | MM (09)   |
 *  | day       |   d    | -            | -                 | d (3)     | dd (03)   |
 *  | weekday   |   E    | EEE (Sun)    | EEEE (Sunday)     | -         | -         |
 *  | hour      |   j    | -            | -                 | j (13)    | jj (13)   |
 *  | hour12    |   h    | -            | -                 | h (1 PM)  | hh (01 PM)|
 *  | hour24    |   H    | -            | -                 | H (13)    | HH (13)   |
 *  | minute    |   m    | -            | -                 | m (5)     | mm (05)   |
 *  | second    |   s    | -            | -                 | s (9)     | ss (09)   |
 *  | timezone  |   z    | -            | z (Pacific Standard Time)| -  | -         |
 *  | timezone  |   Z    | Z (GMT-8:00) | -                 | -         | -         |
 *  | timezone  |   a    | a (PM)       | -                 | -         | -         |
 *
 * In javascript, only the components specified will be respected (not the ordering,
 * punctuations, ...) and details of the formatting will be dependent on the locale.
 *
 * Timezone of the formatted text will be the local system timezone of the end-user's machine.
 *
 * WARNINGS:
 * - this pipe is marked as pure hence it will not be re-evaluated when the input is mutated.
 *   Instead users should treat the date as an immutable object and change the reference when the
 *   pipe needs to re-run (this is to avoid reformatting the date on every change detection run
 *   which would be an expensive operation).
 * - this pipe uses the Internationalization API. Therefore it is only reliable in Chrome and Opera
 *   browsers.
 *
 * ### Examples
 *
 * Assuming `dateObj` is (year: 2015, month: 6, day: 15, hour: 21, minute: 43, second: 11)
 * in the _local_ time and locale is 'en-US':
 *
 * ```
 *     {{ dateObj | date }}               // output is 'Jun 15, 2015'
 *     {{ dateObj | date:'medium' }}      // output is 'Jun 15, 2015, 9:43:11 PM'
 *     {{ dateObj | date:'shortTime' }}   // output is '9:43 PM'
 *     {{ dateObj | date:'mmss' }}        // output is '43:11'
 * ```
 *
 * {@example common/pipes/ts/date_pipe.ts region='DatePipe'}
 *
 * @stable
 */
@Pipe({name: 'date', pure: true})
export class DatePipe implements PipeTransform {
  /** @internal */
  static _ALIASES: {[key: string]: string} = {
    'medium': 'yMMMdjms',
    'short': 'yMdjm',
    'fullDate': 'yMMMMEEEEd',
    'longDate': 'yMMMMd',
    'mediumDate': 'yMMMd',
    'shortDate': 'yMd',
    'mediumTime': 'jms',
    'shortTime': 'jm'
  };

  constructor(@Inject(LOCALE_ID) private _locale: string) {}

  transform(value: any, pattern: string = 'mediumDate'): string {
    if (isBlank(value)) return null;

    if (!this.supports(value)) {
      throw new InvalidPipeArgumentError(DatePipe, value);
    }

    if (NumberWrapper.isNumeric(value)) {
      value = parseFloat(value);
    }

    return DateFormatter.format(
        new Date(value), this._locale, DatePipe._ALIASES[pattern] || pattern);
  }

  private supports(obj: any): boolean {
    return isDate(obj) || NumberWrapper.isNumeric(obj) ||
        (typeof obj === 'string' && isDate(new Date(obj)));
  }
}