<?php
/**
 * 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
 */

/**
 * Return UTF-8 sequence for a given Unicode code point.
 * May die if fed out of range data.
 *
 * @param $codepoint Integer:
 * @return String
 * @public
 */
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 );
	}

	echo "Asked for code outside of range ($codepoint)\n";
	die( -1 );
}

/**
 * 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 $sequence String
 * @return String
 * @private
 */
function hexSequenceToUtf8( $sequence ) {
	$utf = '';
	foreach ( explode( ' ', $sequence ) as $hex ) {
		$n = hexdec( $hex );
		$utf .= 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
 */
function utf8ToHexSequence( $str ) {
	$buf = '';
	foreach ( preg_split( '//u', $str, -1, PREG_SPLIT_NO_EMPTY ) as $cp ) {
		$buf .= sprintf( '%04x ', utf8ToCodepoint( $cp ) );
	}

	return rtrim( $buf );
}

/**
 * Determine the Unicode codepoint of a single-character UTF-8 sequence.
 * Does not check for invalid input data.
 *
 * @param $char String
 * @return Integer
 * @public
 */
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
 */
function escapeSingleString( $string ) {
	return strtr( $string,
		array(
			'\\' => '\\\\',
			'\'' => '\\\''
		) );
}