<?php

/**
 * This file is part of the Nette Framework (http://nette.org)
 * Copyright (c) 2004 David Grudl (http://davidgrudl.com)
 */

namespace Nette\Utils;

use Nette;


/**
 * String tools library.
 *
 * @author     David Grudl
 */
class Strings
{

	/**
	 * Static class - cannot be instantiated.
	 */
	final public function __construct()
	{
		throw new Nette\StaticClassException;
	}


	/**
	 * Checks if the string is valid for the specified encoding.
	 * @param  string  byte stream to check
	 * @param  string  expected encoding
	 * @return bool
	 */
	public static function checkEncoding($s, $encoding = 'UTF-8')
	{
		return $s === self::fixEncoding($s, $encoding);
	}


	/**
	 * Returns correctly encoded string.
	 * @param  string  byte stream to fix
	 * @param  string  encoding
	 * @return string
	 */
	public static function fixEncoding($s, $encoding = 'UTF-8')
	{
		// removes xD800-xDFFF, x110000 and higher
		if (PHP_VERSION_ID >= 50400) {
			ini_set('mbstring.substitute_character', 'none');
			return mb_convert_encoding($s, $encoding, $encoding);
		} else {
			return @iconv('UTF-16', 'UTF-8//IGNORE', iconv($encoding, 'UTF-16//IGNORE', $s)); // intentionally @
		}
	}


	/**
	 * Returns a specific character.
	 * @param  int     codepoint
	 * @param  string  encoding
	 * @return string
	 */
	public static function chr($code, $encoding = 'UTF-8')
	{
		return iconv('UTF-32BE', $encoding . '//IGNORE', pack('N', $code));
	}


	/**
	 * Starts the $haystack string with the prefix $needle?
	 * @param  string
	 * @param  string
	 * @return bool
	 */
	public static function startsWith($haystack, $needle)
	{
		return strncmp($haystack, $needle, strlen($needle)) === 0;
	}


	/**
	 * Ends the $haystack string with the suffix $needle?
	 * @param  string
	 * @param  string
	 * @return bool
	 */
	public static function endsWith($haystack, $needle)
	{
		return strlen($needle) === 0 || substr($haystack, -strlen($needle)) === $needle;
	}


	/**
	 * Does $haystack contain $needle?
	 * @param  string
	 * @param  string
	 * @return bool
	 */
	public static function contains($haystack, $needle)
	{
		return strpos($haystack, $needle) !== FALSE;
	}


	/**
	 * Returns a part of UTF-8 string.
	 * @param  string
	 * @param  int
	 * @param  int
	 * @return string
	 */
	public static function substring($s, $start, $length = NULL)
	{
		if ($length === NULL) {
			$length = self::length($s);
		}
		if (function_exists('mb_substr')) {
			return mb_substr($s, $start, $length, 'UTF-8'); // MB is much faster
		}
		return iconv_substr($s, $start, $length, 'UTF-8');
	}


	/**
	 * Removes special controls characters and normalizes line endings and spaces.
	 * @param  string  UTF-8 encoding or 8-bit
	 * @return string
	 */
	public static function normalize($s)
	{
		$s = self::normalizeNewLines($s);

		// remove control characters; leave \t + \n
		$s = preg_replace('#[\x00-\x08\x0B-\x1F\x7F]+#', '', $s);

		// right trim
		$s = preg_replace('#[\t ]+$#m', '', $s);

		// leading and trailing blank lines
		$s = trim($s, "\n");

		return $s;
	}


	/**
	 * Standardize line endings to unix-like.
	 * @param  string  UTF-8 encoding or 8-bit
	 * @return string
	 */
	public static function normalizeNewLines($s)
	{
		return str_replace(array("\r\n", "\r"), "\n", $s);
	}


	/**
	 * Converts to ASCII.
	 * @param  string  UTF-8 encoding
	 * @return string  ASCII
	 */
	public static function toAscii($s)
	{
		$s = preg_replace('#[^\x09\x0A\x0D\x20-\x7E\xA0-\x{2FF}\x{370}-\x{10FFFF}]#u', '', $s);
		$s = strtr($s, '`\'"^~', "\x01\x02\x03\x04\x05");
		if (ICONV_IMPL === 'glibc') {
			$s = @iconv('UTF-8', 'WINDOWS-1250//TRANSLIT', $s); // intentionally @
			$s = strtr($s, "\xa5\xa3\xbc\x8c\xa7\x8a\xaa\x8d\x8f\x8e\xaf\xb9\xb3\xbe\x9c\x9a\xba\x9d\x9f\x9e"
				. "\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3"
				. "\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8"
				. "\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf8\xf9\xfa\xfb\xfc\xfd\xfe\x96",
				"ALLSSSSTZZZallssstzzzRAAAALCCCEEEEIIDDNNOOOOxRUUUUYTsraaaalccceeeeiiddnnooooruuuuyt-");
		} else {
			$s = @iconv('UTF-8', 'ASCII//TRANSLIT', $s); // intentionally @
		}
		$s = str_replace(array('`', "'", '"', '^', '~'), '', $s);
		return strtr($s, "\x01\x02\x03\x04\x05", '`\'"^~');
	}


	/**
	 * Converts to web safe characters [a-z0-9-] text.
	 * @param  string  UTF-8 encoding
	 * @param  string  allowed characters
	 * @param  bool
	 * @return string
	 */
	public static function webalize($s, $charlist = NULL, $lower = TRUE)
	{
		$s = self::toAscii($s);
		if ($lower) {
			$s = strtolower($s);
		}
		$s = preg_replace('#[^a-z0-9' . preg_quote($charlist, '#') . ']+#i', '-', $s);
		$s = trim($s, '-');
		return $s;
	}


	/**
	 * Truncates string to maximal length.
	 * @param  string  UTF-8 encoding
	 * @param  int
	 * @param  string  UTF-8 encoding
	 * @return string
	 */
	public static function truncate($s, $maxLen, $append = "\xE2\x80\xA6")
	{
		if (self::length($s) > $maxLen) {
			$maxLen = $maxLen - self::length($append);
			if ($maxLen < 1) {
				return $append;

			} elseif ($matches = self::match($s, '#^.{1,'.$maxLen.'}(?=[\s\x00-/:-@\[-`{-~])#us')) {
				return $matches[0] . $append;

			} else {
				return self::substring($s, 0, $maxLen) . $append;
			}
		}
		return $s;
	}


	/**
	 * Indents the content from the left.
	 * @param  string  UTF-8 encoding or 8-bit
	 * @param  int
	 * @param  string
	 * @return string
	 */
	public static function indent($s, $level = 1, $chars = "\t")
	{
		if ($level > 0) {
			$s = self::replace($s, '#(?:^|[\r\n]+)(?=[^\r\n])#', '$0' . str_repeat($chars, $level));
		}
		return $s;
	}


	/**
	 * Convert to lower case.
	 * @param  string  UTF-8 encoding
	 * @return string
	 */
	public static function lower($s)
	{
		return mb_strtolower($s, 'UTF-8');
	}


	/**
	 * Convert to upper case.
	 * @param  string  UTF-8 encoding
	 * @return string
	 */
	public static function upper($s)
	{
		return mb_strtoupper($s, 'UTF-8');
	}


	/**
	 * Convert first character to upper case.
	 * @param  string  UTF-8 encoding
	 * @return string
	 */
	public static function firstUpper($s)
	{
		return self::upper(self::substring($s, 0, 1)) . self::substring($s, 1);
	}


	/**
	 * Capitalize string.
	 * @param  string  UTF-8 encoding
	 * @return string
	 */
	public static function capitalize($s)
	{
		return mb_convert_case($s, MB_CASE_TITLE, 'UTF-8');
	}


	/**
	 * Case-insensitive compares UTF-8 strings.
	 * @param  string
	 * @param  string
	 * @param  int
	 * @return bool
	 */
	public static function compare($left, $right, $len = NULL)
	{
		if ($len < 0) {
			$left = self::substring($left, $len, -$len);
			$right = self::substring($right, $len, -$len);
		} elseif ($len !== NULL) {
			$left = self::substring($left, 0, $len);
			$right = self::substring($right, 0, $len);
		}
		return self::lower($left) === self::lower($right);
	}


	/**
	 * Finds the length of common prefix of strings.
	 * @param  string|array
	 * @param  string
	 * @return string
	 */
	public static function findPrefix($strings, $second = NULL)
	{
		if (!is_array($strings)) {
			$strings = func_get_args();
		}
		$first = array_shift($strings);
		for ($i = 0; $i < strlen($first); $i++) {
			foreach ($strings as $s) {
				if (!isset($s[$i]) || $first[$i] !== $s[$i]) {
					while ($i && $first[$i-1] >= "\x80" && $first[$i] >= "\x80" && $first[$i] < "\xC0") {
						$i--;
					}
					return substr($first, 0, $i);
				}
			}
		}
		return $first;
	}


	/**
	 * Returns UTF-8 string length.
	 * @param  string
	 * @return int
	 */
	public static function length($s)
	{
		return strlen(utf8_decode($s)); // fastest way
	}


	/**
	 * Strips whitespace.
	 * @param  string  UTF-8 encoding
	 * @param  string
	 * @return string
	 */
	public static function trim($s, $charlist = " \t\n\r\0\x0B\xC2\xA0")
	{
		$charlist = preg_quote($charlist, '#');
		return self::replace($s, '#^['.$charlist.']+|['.$charlist.']+\z#u', '');
	}


	/**
	 * Pad a string to a certain length with another string.
	 * @param  string  UTF-8 encoding
	 * @param  int
	 * @param  string
	 * @return string
	 */
	public static function padLeft($s, $length, $pad = ' ')
	{
		$length = max(0, $length - self::length($s));
		$padLen = self::length($pad);
		return str_repeat($pad, $length / $padLen) . self::substring($pad, 0, $length % $padLen) . $s;
	}


	/**
	 * Pad a string to a certain length with another string.
	 * @param  string  UTF-8 encoding
	 * @param  int
	 * @param  string
	 * @return string
	 */
	public static function padRight($s, $length, $pad = ' ')
	{
		$length = max(0, $length - self::length($s));
		$padLen = self::length($pad);
		return $s . str_repeat($pad, $length / $padLen) . self::substring($pad, 0, $length % $padLen);
	}


	/**
	 * Reverse string.
	 * @param  string  UTF-8 encoding
	 * @return string
	 */
	public static function reverse($s)
	{
		return @iconv('UTF-32LE', 'UTF-8', strrev(@iconv('UTF-8', 'UTF-32BE', $s)));
	}


	/**
	 * Generate random string.
	 * @param  int
	 * @param  string
	 * @return string
	 */
	public static function random($length = 10, $charlist = '0-9a-z')
	{
		$charlist = str_shuffle(preg_replace_callback('#.-.#', function($m) {
			return implode('', range($m[0][0], $m[0][2]));
		}, $charlist));
		$chLen = strlen($charlist);

		if (function_exists('openssl_random_pseudo_bytes')
			&& (PHP_VERSION_ID >= 50400 || !defined('PHP_WINDOWS_VERSION_BUILD')) // slow in PHP 5.3 & Windows
		) {
			$rand3 = openssl_random_pseudo_bytes($length);
		}
		if (empty($rand3) && function_exists('mcrypt_create_iv')) {
			$rand3 = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM);
		}
		if (empty($rand3) && @is_readable('/dev/urandom')) {
			$rand3 = file_get_contents('/dev/urandom', FALSE, NULL, -1, $length);
		}
		if (empty($rand3)) {
			static $cache;
			$rand3 = $cache ?: $cache = md5(serialize($_SERVER), TRUE);
		}

		$s = '';
		for ($i = 0; $i < $length; $i++) {
			if ($i % 5 === 0) {
				list($rand, $rand2) = explode(' ', microtime());
				$rand += lcg_value();
			}
			$rand *= $chLen;
			$s .= $charlist[($rand + $rand2 + ord($rand3[$i % strlen($rand3)])) % $chLen];
			$rand -= (int) $rand;
		}
		return $s;
	}


	/**
	 * Splits string by a regular expression.
	 * @param  string
	 * @param  string
	 * @param  int
	 * @return array
	 */
	public static function split($subject, $pattern, $flags = 0)
	{
		set_error_handler(function($severity, $message) use ($pattern) { // preg_last_error does not return compile errors
			restore_error_handler();
			throw new RegexpException("$message in pattern: $pattern");
		});
		$res = preg_split($pattern, $subject, -1, $flags | PREG_SPLIT_DELIM_CAPTURE);
		restore_error_handler();
		if (preg_last_error()) { // run-time error
			throw new RegexpException(NULL, preg_last_error(), $pattern);
		}
		return $res;
	}


	/**
	 * Performs a regular expression match.
	 * @param  string
	 * @param  string
	 * @param  int  can be PREG_OFFSET_CAPTURE (returned in bytes)
	 * @param  int  offset in bytes
	 * @return mixed
	 */
	public static function match($subject, $pattern, $flags = 0, $offset = 0)
	{
		if ($offset > strlen($subject)) {
			return NULL;
		}
		set_error_handler(function($severity, $message) use ($pattern) { // preg_last_error does not return compile errors
			restore_error_handler();
			throw new RegexpException("$message in pattern: $pattern");
		});
		$res = preg_match($pattern, $subject, $m, $flags, $offset);
		restore_error_handler();
		if (preg_last_error()) { // run-time error
			throw new RegexpException(NULL, preg_last_error(), $pattern);
		}
		if ($res) {
			return $m;
		}
	}


	/**
	 * Performs a global regular expression match.
	 * @param  string
	 * @param  string
	 * @param  int  can be PREG_OFFSET_CAPTURE (returned in bytes); PREG_SET_ORDER is default
	 * @param  int  offset in bytes
	 * @return array
	 */
	public static function matchAll($subject, $pattern, $flags = 0, $offset = 0)
	{
		if ($offset > strlen($subject)) {
			return array();
		}
		set_error_handler(function($severity, $message) use ($pattern) { // preg_last_error does not return compile errors
			restore_error_handler();
			throw new RegexpException("$message in pattern: $pattern");
		});
		preg_match_all(
			$pattern, $subject, $m,
			($flags & PREG_PATTERN_ORDER) ? $flags : ($flags | PREG_SET_ORDER),
			$offset
		);
		restore_error_handler();
		if (preg_last_error()) { // run-time error
			throw new RegexpException(NULL, preg_last_error(), $pattern);
		}
		return $m;
	}


	/**
	 * Perform a regular expression search and replace.
	 * @param  string
	 * @param  string|array
	 * @param  string|callable
	 * @param  int
	 * @return string
	 */
	public static function replace($subject, $pattern, $replacement = NULL, $limit = -1)
	{
		if (is_object($replacement) || is_array($replacement)) {
			if ($replacement instanceof Nette\Callback) {
				$replacement = $replacement->getNative();
			}
			if (!is_callable($replacement, FALSE, $textual)) {
				throw new Nette\InvalidStateException("Callback '$textual' is not callable.");
			}

			set_error_handler(function($severity, $message) use (& $tmp) { // preg_last_error does not return compile errors
				restore_error_handler();
				throw new RegexpException("$message in pattern: $tmp");
			});
			foreach ((array) $pattern as $tmp) {
				preg_match($tmp, '');
			}
			restore_error_handler();

			$res = preg_replace_callback($pattern, $replacement, $subject, $limit);
			if ($res === NULL && preg_last_error()) { // run-time error
				throw new RegexpException(NULL, preg_last_error(), $pattern);
			}
			return $res;

		} elseif ($replacement === NULL && is_array($pattern)) {
			$replacement = array_values($pattern);
			$pattern = array_keys($pattern);
		}

		set_error_handler(function($severity, $message) use ($pattern) { // preg_last_error does not return compile errors
			restore_error_handler();
			throw new RegexpException("$message in pattern: " . implode(' or ', (array) $pattern));
		});
		$res = preg_replace($pattern, $replacement, $subject, $limit);
		restore_error_handler();
		if (preg_last_error()) { // run-time error
			throw new RegexpException(NULL, preg_last_error(), implode(' or ', (array) $pattern));
		}
		return $res;
	}

}


/**
 * The exception that indicates error of the last Regexp execution.
 */
class RegexpException extends \Exception
{
	static public $messages = array(
		PREG_INTERNAL_ERROR => 'Internal error',
		PREG_BACKTRACK_LIMIT_ERROR => 'Backtrack limit was exhausted',
		PREG_RECURSION_LIMIT_ERROR => 'Recursion limit was exhausted',
		PREG_BAD_UTF8_ERROR => 'Malformed UTF-8 data',
		5 => 'Offset didn\'t correspond to the begin of a valid UTF-8 code point', // PREG_BAD_UTF8_OFFSET_ERROR
	);

	public function __construct($message, $code = NULL, $pattern = NULL)
	{
		if (!$message) {
			$message = (isset(self::$messages[$code]) ? self::$messages[$code] : 'Unknown error') . ($pattern ? " (pattern: $pattern)" : '');
		}
		parent::__construct($message, $code);
	}

}
