<?php

declare( strict_types = 1 );

namespace Wikimedia\Dodo\Internal;

/**
 * Encodings have a *name*, and one or more *labels*.
 *
 * @see https://encoding.spec.whatwg.org/#name
 */
class Encoding {

	/**
	 * Names and labels.
	 * @see https://encoding.spec.whatwg.org/#ref-for-lable
	 * @param string $label An encoding label
	 * @return ?string An encoding name, or null if the label is not found
	 */
	public static function getEncodingFromLabel( string $label ): ?string {
		$label = Util::toAsciiLowercase( trim( $label, ' ' ) );
		return self::$labelMap[$label] ?? null;
	}

	/**
	 * @param string $name
	 * @return bool True iff the given string is a known encoding name.
	 */
	public static function isKnownEncodingName( string $name ): bool {
		return self::$names[$name] ?? false;
	}

	/**
	 * Developer-only: generated the encoding name and labels table from the
	 * machine-readable data included in the encodings spec.
	 */
	public static function dump(): void {
		// This data is available in machine-readable form as:
		// https://encoding.spec.whatwg.org/encodings.json
		$encodings = json_decode(
			file_get_contents( 'https://encoding.spec.whatwg.org/encodings.json' )
		);
		$names = [];
		$labels = [];
		foreach ( $encodings as $one ) {
			foreach ( $one->encodings as $e ) {
				$names[$e->name] = true;
				foreach ( $e->labels as $l ) {
					$labels[$l] = $e->name;
				}
			}
		}
		echo( 'private static $names = ' );
		var_export( $names );
		echo( ";\n" );
		echo( 'private static $labelMap = ' );
		var_export( $labels );
		echo( ";\n" );
	}

	/** @var array A list of valid encoding names. */
	private static $names = [
		'UTF-8' => true,
		'IBM866' => true,
		'ISO-8859-2' => true,
		'ISO-8859-3' => true,
		'ISO-8859-4' => true,
		'ISO-8859-5' => true,
		'ISO-8859-6' => true,
		'ISO-8859-7' => true,
		'ISO-8859-8' => true,
		'ISO-8859-8-I' => true,
		'ISO-8859-10' => true,
		'ISO-8859-13' => true,
		'ISO-8859-14' => true,
		'ISO-8859-15' => true,
		'ISO-8859-16' => true,
		'KOI8-R' => true,
		'KOI8-U' => true,
		'macintosh' => true,
		'windows-874' => true,
		'windows-1250' => true,
		'windows-1251' => true,
		'windows-1252' => true,
		'windows-1253' => true,
		'windows-1254' => true,
		'windows-1255' => true,
		'windows-1256' => true,
		'windows-1257' => true,
		'windows-1258' => true,
		'x-mac-cyrillic' => true,
		'GBK' => true,
		'gb18030' => true,
		'Big5' => true,
		'EUC-JP' => true,
		'ISO-2022-JP' => true,
		'Shift_JIS' => true,
		'EUC-KR' => true,
		'replacement' => true,
		'UTF-16BE' => true,
		'UTF-16LE' => true,
		'x-user-defined' => true,
	];

	/** @var array A map of lowercase encoding labels to encoding names. */
	private static $labelMap = [
		'unicode-1-1-utf-8' => 'UTF-8',
		'unicode11utf8' => 'UTF-8',
		'unicode20utf8' => 'UTF-8',
		'utf-8' => 'UTF-8',
		'utf8' => 'UTF-8',
		'x-unicode20utf8' => 'UTF-8',
		'866' => 'IBM866',
		'cp866' => 'IBM866',
		'csibm866' => 'IBM866',
		'ibm866' => 'IBM866',
		'csisolatin2' => 'ISO-8859-2',
		'iso-8859-2' => 'ISO-8859-2',
		'iso-ir-101' => 'ISO-8859-2',
		'iso8859-2' => 'ISO-8859-2',
		'iso88592' => 'ISO-8859-2',
		'iso_8859-2' => 'ISO-8859-2',
		'iso_8859-2:1987' => 'ISO-8859-2',
		'l2' => 'ISO-8859-2',
		'latin2' => 'ISO-8859-2',
		'csisolatin3' => 'ISO-8859-3',
		'iso-8859-3' => 'ISO-8859-3',
		'iso-ir-109' => 'ISO-8859-3',
		'iso8859-3' => 'ISO-8859-3',
		'iso88593' => 'ISO-8859-3',
		'iso_8859-3' => 'ISO-8859-3',
		'iso_8859-3:1988' => 'ISO-8859-3',
		'l3' => 'ISO-8859-3',
		'latin3' => 'ISO-8859-3',
		'csisolatin4' => 'ISO-8859-4',
		'iso-8859-4' => 'ISO-8859-4',
		'iso-ir-110' => 'ISO-8859-4',
		'iso8859-4' => 'ISO-8859-4',
		'iso88594' => 'ISO-8859-4',
		'iso_8859-4' => 'ISO-8859-4',
		'iso_8859-4:1988' => 'ISO-8859-4',
		'l4' => 'ISO-8859-4',
		'latin4' => 'ISO-8859-4',
		'csisolatincyrillic' => 'ISO-8859-5',
		'cyrillic' => 'ISO-8859-5',
		'iso-8859-5' => 'ISO-8859-5',
		'iso-ir-144' => 'ISO-8859-5',
		'iso8859-5' => 'ISO-8859-5',
		'iso88595' => 'ISO-8859-5',
		'iso_8859-5' => 'ISO-8859-5',
		'iso_8859-5:1988' => 'ISO-8859-5',
		'arabic' => 'ISO-8859-6',
		'asmo-708' => 'ISO-8859-6',
		'csiso88596e' => 'ISO-8859-6',
		'csiso88596i' => 'ISO-8859-6',
		'csisolatinarabic' => 'ISO-8859-6',
		'ecma-114' => 'ISO-8859-6',
		'iso-8859-6' => 'ISO-8859-6',
		'iso-8859-6-e' => 'ISO-8859-6',
		'iso-8859-6-i' => 'ISO-8859-6',
		'iso-ir-127' => 'ISO-8859-6',
		'iso8859-6' => 'ISO-8859-6',
		'iso88596' => 'ISO-8859-6',
		'iso_8859-6' => 'ISO-8859-6',
		'iso_8859-6:1987' => 'ISO-8859-6',
		'csisolatingreek' => 'ISO-8859-7',
		'ecma-118' => 'ISO-8859-7',
		'elot_928' => 'ISO-8859-7',
		'greek' => 'ISO-8859-7',
		'greek8' => 'ISO-8859-7',
		'iso-8859-7' => 'ISO-8859-7',
		'iso-ir-126' => 'ISO-8859-7',
		'iso8859-7' => 'ISO-8859-7',
		'iso88597' => 'ISO-8859-7',
		'iso_8859-7' => 'ISO-8859-7',
		'iso_8859-7:1987' => 'ISO-8859-7',
		'sun_eu_greek' => 'ISO-8859-7',
		'csiso88598e' => 'ISO-8859-8',
		'csisolatinhebrew' => 'ISO-8859-8',
		'hebrew' => 'ISO-8859-8',
		'iso-8859-8' => 'ISO-8859-8',
		'iso-8859-8-e' => 'ISO-8859-8',
		'iso-ir-138' => 'ISO-8859-8',
		'iso8859-8' => 'ISO-8859-8',
		'iso88598' => 'ISO-8859-8',
		'iso_8859-8' => 'ISO-8859-8',
		'iso_8859-8:1988' => 'ISO-8859-8',
		'visual' => 'ISO-8859-8',
		'csiso88598i' => 'ISO-8859-8-I',
		'iso-8859-8-i' => 'ISO-8859-8-I',
		'logical' => 'ISO-8859-8-I',
		'csisolatin6' => 'ISO-8859-10',
		'iso-8859-10' => 'ISO-8859-10',
		'iso-ir-157' => 'ISO-8859-10',
		'iso8859-10' => 'ISO-8859-10',
		'iso885910' => 'ISO-8859-10',
		'l6' => 'ISO-8859-10',
		'latin6' => 'ISO-8859-10',
		'iso-8859-13' => 'ISO-8859-13',
		'iso8859-13' => 'ISO-8859-13',
		'iso885913' => 'ISO-8859-13',
		'iso-8859-14' => 'ISO-8859-14',
		'iso8859-14' => 'ISO-8859-14',
		'iso885914' => 'ISO-8859-14',
		'csisolatin9' => 'ISO-8859-15',
		'iso-8859-15' => 'ISO-8859-15',
		'iso8859-15' => 'ISO-8859-15',
		'iso885915' => 'ISO-8859-15',
		'iso_8859-15' => 'ISO-8859-15',
		'l9' => 'ISO-8859-15',
		'iso-8859-16' => 'ISO-8859-16',
		'cskoi8r' => 'KOI8-R',
		'koi' => 'KOI8-R',
		'koi8' => 'KOI8-R',
		'koi8-r' => 'KOI8-R',
		'koi8_r' => 'KOI8-R',
		'koi8-ru' => 'KOI8-U',
		'koi8-u' => 'KOI8-U',
		'csmacintosh' => 'macintosh',
		'mac' => 'macintosh',
		'macintosh' => 'macintosh',
		'x-mac-roman' => 'macintosh',
		'dos-874' => 'windows-874',
		'iso-8859-11' => 'windows-874',
		'iso8859-11' => 'windows-874',
		'iso885911' => 'windows-874',
		'tis-620' => 'windows-874',
		'windows-874' => 'windows-874',
		'cp1250' => 'windows-1250',
		'windows-1250' => 'windows-1250',
		'x-cp1250' => 'windows-1250',
		'cp1251' => 'windows-1251',
		'windows-1251' => 'windows-1251',
		'x-cp1251' => 'windows-1251',
		'ansi_x3.4-1968' => 'windows-1252',
		'ascii' => 'windows-1252',
		'cp1252' => 'windows-1252',
		'cp819' => 'windows-1252',
		'csisolatin1' => 'windows-1252',
		'ibm819' => 'windows-1252',
		'iso-8859-1' => 'windows-1252',
		'iso-ir-100' => 'windows-1252',
		'iso8859-1' => 'windows-1252',
		'iso88591' => 'windows-1252',
		'iso_8859-1' => 'windows-1252',
		'iso_8859-1:1987' => 'windows-1252',
		'l1' => 'windows-1252',
		'latin1' => 'windows-1252',
		'us-ascii' => 'windows-1252',
		'windows-1252' => 'windows-1252',
		'x-cp1252' => 'windows-1252',
		'cp1253' => 'windows-1253',
		'windows-1253' => 'windows-1253',
		'x-cp1253' => 'windows-1253',
		'cp1254' => 'windows-1254',
		'csisolatin5' => 'windows-1254',
		'iso-8859-9' => 'windows-1254',
		'iso-ir-148' => 'windows-1254',
		'iso8859-9' => 'windows-1254',
		'iso88599' => 'windows-1254',
		'iso_8859-9' => 'windows-1254',
		'iso_8859-9:1989' => 'windows-1254',
		'l5' => 'windows-1254',
		'latin5' => 'windows-1254',
		'windows-1254' => 'windows-1254',
		'x-cp1254' => 'windows-1254',
		'cp1255' => 'windows-1255',
		'windows-1255' => 'windows-1255',
		'x-cp1255' => 'windows-1255',
		'cp1256' => 'windows-1256',
		'windows-1256' => 'windows-1256',
		'x-cp1256' => 'windows-1256',
		'cp1257' => 'windows-1257',
		'windows-1257' => 'windows-1257',
		'x-cp1257' => 'windows-1257',
		'cp1258' => 'windows-1258',
		'windows-1258' => 'windows-1258',
		'x-cp1258' => 'windows-1258',
		'x-mac-cyrillic' => 'x-mac-cyrillic',
		'x-mac-ukrainian' => 'x-mac-cyrillic',
		'chinese' => 'GBK',
		'csgb2312' => 'GBK',
		'csiso58gb231280' => 'GBK',
		'gb2312' => 'GBK',
		'gb_2312' => 'GBK',
		'gb_2312-80' => 'GBK',
		'gbk' => 'GBK',
		'iso-ir-58' => 'GBK',
		'x-gbk' => 'GBK',
		'gb18030' => 'gb18030',
		'big5' => 'Big5',
		'big5-hkscs' => 'Big5',
		'cn-big5' => 'Big5',
		'csbig5' => 'Big5',
		'x-x-big5' => 'Big5',
		'cseucpkdfmtjapanese' => 'EUC-JP',
		'euc-jp' => 'EUC-JP',
		'x-euc-jp' => 'EUC-JP',
		'csiso2022jp' => 'ISO-2022-JP',
		'iso-2022-jp' => 'ISO-2022-JP',
		'csshiftjis' => 'Shift_JIS',
		'ms932' => 'Shift_JIS',
		'ms_kanji' => 'Shift_JIS',
		'shift-jis' => 'Shift_JIS',
		'shift_jis' => 'Shift_JIS',
		'sjis' => 'Shift_JIS',
		'windows-31j' => 'Shift_JIS',
		'x-sjis' => 'Shift_JIS',
		'cseuckr' => 'EUC-KR',
		'csksc56011987' => 'EUC-KR',
		'euc-kr' => 'EUC-KR',
		'iso-ir-149' => 'EUC-KR',
		'korean' => 'EUC-KR',
		'ks_c_5601-1987' => 'EUC-KR',
		'ks_c_5601-1989' => 'EUC-KR',
		'ksc5601' => 'EUC-KR',
		'ksc_5601' => 'EUC-KR',
		'windows-949' => 'EUC-KR',
		'csiso2022kr' => 'replacement',
		'hz-gb-2312' => 'replacement',
		'iso-2022-cn' => 'replacement',
		'iso-2022-cn-ext' => 'replacement',
		'iso-2022-kr' => 'replacement',
		'replacement' => 'replacement',
		'unicodefffe' => 'UTF-16BE',
		'utf-16be' => 'UTF-16BE',
		'csunicode' => 'UTF-16LE',
		'iso-10646-ucs-2' => 'UTF-16LE',
		'ucs-2' => 'UTF-16LE',
		'unicode' => 'UTF-16LE',
		'unicodefeff' => 'UTF-16LE',
		'utf-16' => 'UTF-16LE',
		'utf-16le' => 'UTF-16LE',
		'x-user-defined' => 'x-user-defined',
	];
}