<?php
namespace UtfNormal;

use InvalidArgumentException;

/**
 * Some of these functions are adapted from places in MediaWiki.
 * Should probably merge them for consistency.
 *
 * Copyright © 2004 Brion Vibber <brion@pobox.com>
 * https://www.mediawiki.org/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup UtfNormal
 */

class Utils {
	/**
	 * Return UTF-8 sequence for a given Unicode code point.
	 *
	 * @param int $codepoint
	 * @return string
	 * @throws InvalidArgumentException if fed out of range data.
	 */
	public static function codepointToUtf8( $codepoint ) {
		if ( $codepoint < 0x80 ) {
			return chr( $codepoint );
		}

		if ( $codepoint < 0x800 ) {
			return chr( $codepoint >> 6 & 0x3f | 0xc0 ) .
			chr( $codepoint & 0x3f | 0x80 );
		}

		if ( $codepoint < 0x10000 ) {
			return chr( $codepoint >> 12 & 0x0f | 0xe0 ) .
			chr( $codepoint >> 6 & 0x3f | 0x80 ) .
			chr( $codepoint & 0x3f | 0x80 );
		}

		if ( $codepoint < 0x110000 ) {
			return chr( $codepoint >> 18 & 0x07 | 0xf0 ) .
			chr( $codepoint >> 12 & 0x3f | 0x80 ) .
			chr( $codepoint >> 6 & 0x3f | 0x80 ) .
			chr( $codepoint & 0x3f | 0x80 );
		}

		throw new InvalidArgumentException( "Asked for code outside of range ($codepoint)" );
	}

	/**
	 * Take a series of space-separated hexadecimal numbers representing
	 * Unicode code points and return a UTF-8 string composed of those
	 * characters. Used by UTF-8 data generation and testing routines.
	 *
	 * @param string $sequence
	 * @return string
	 * @throws InvalidArgumentException if fed out of range data.
	 * @private Used in tests and data table generation
	 */
	public static function hexSequenceToUtf8( $sequence ) {
		$utf = '';
		foreach ( explode( ' ', $sequence ) as $hex ) {
			$n = hexdec( $hex );
			$utf .= self::codepointToUtf8( $n );
		}

		return $utf;
	}

	/**
	 * Take a UTF-8 string and return a space-separated series of hex
	 * numbers representing Unicode code points. For debugging.
	 *
	 * @param string $str UTF-8 string.
	 * @return string
	 * @private
	 */
	private static function utf8ToHexSequence( $str ) {
		$buf = '';
		foreach ( preg_split( '//u', $str, -1, PREG_SPLIT_NO_EMPTY ) as $cp ) {
			$buf .= sprintf( '%04x ', self::utf8ToCodepoint( $cp ) );
		}

		return rtrim( $buf );
	}

	/**
	 * Determine the Unicode codepoint of a single-character UTF-8 sequence.
	 * Does not check for invalid input data.
	 *
	 * @param string $char
	 * @return int
	 */
	public static function utf8ToCodepoint( $char ) {
		# Find the length
		$z = ord( $char[0] );
		if ( $z & 0x80 ) {
			$length = 0;
			while ( $z & 0x80 ) {
				$length++;
				$z <<= 1;
			}
		} else {
			$length = 1;
		}

		if ( $length != strlen( $char ) ) {
			return false;
		}

		if ( $length == 1 ) {
			return ord( $char );
		}

		# Mask off the length-determining bits and shift back to the original location
		$z &= 0xff;
		$z >>= $length;

		# Add in the free bits from subsequent bytes
		for ( $i = 1; $i < $length; $i++ ) {
			$z <<= 6;
			$z |= ord( $char[$i] ) & 0x3f;
		}

		return $z;
	}

	/**
	 * Escape a string for inclusion in a PHP single-quoted string literal.
	 *
	 * @param string $string String to be escaped.
	 * @return string Escaped string.
	 */
	public static function escapeSingleString( $string ) {
		return strtr( $string,
			[
				'\\' => '\\\\',
				'\'' => '\\\''
			] );
	}
}
