<?php
/**
 * @package framework
 * @subpackage dev
 */
class SS_Backtrace {

	/**
	 * @var array Replaces all arguments with a '<filtered>' string,
	 * mostly for security reasons. Use string values for global functions,
	 * and array notation for class methods.
	 * PHP's debug_backtrace() doesn't allow to inspect the argument names,
	 * so all arguments of the provided functions will be filtered out.
	 */
	private static $ignore_function_args = array(
		'mysql_connect',
		'mssql_connect',
		'pg_connect',
		array('PDO', '__construct'),
		array('mysqli', 'mysqli'),
		array('mysqli', 'select_db'),
		array('SilverStripe\\ORM\\DB', 'connect'),
		array('Security', 'check_default_admin'),
		array('Security', 'encrypt_password'),
		array('Security', 'setDefaultAdmin'),
		array('SilverStripe\\ORM\\DB', 'createDatabase'),
		array('Member', 'checkPassword'),
		array('Member', 'changePassword'),
		array('MemberPassword', 'checkPassword'),
		array('PasswordValidator', 'validate'),
		array('PasswordEncryptor_PHPHash', 'encrypt'),
		array('PasswordEncryptor_PHPHash', 'salt'),
		array('PasswordEncryptor_LegacyPHPHash', 'encrypt'),
		array('PasswordEncryptor_LegacyPHPHash', 'salt'),
		array('PasswordEncryptor_MySQLPassword', 'encrypt'),
		array('PasswordEncryptor_MySQLPassword', 'salt'),
		array('PasswordEncryptor_MySQLOldPassword', 'encrypt'),
		array('PasswordEncryptor_MySQLOldPassword', 'salt'),
		array('PasswordEncryptor_Blowfish', 'encrypt'),
		array('PasswordEncryptor_Blowfish', 'salt'),
	);

	/**
	 * Return debug_backtrace() results with functions filtered
	 * specific to the debugging system, and not the trace.
	 *
	 * @param null|array $ignoredFunctions If an array, filter these functions out of the trace
	 * @return array
	 */
	public static function filtered_backtrace($ignoredFunctions = null) {
		return self::filter_backtrace(debug_backtrace(), $ignoredFunctions);
	}

	/**
	 * Filter a backtrace so that it doesn't show the calls to the
	 * debugging system, which is useless information.
	 *
	 * @param array $bt Backtrace to filter
	 * @param null|array $ignoredFunctions List of extra functions to filter out
	 * @return array
	 */
	public static function filter_backtrace($bt, $ignoredFunctions = null) {
		$defaultIgnoredFunctions = array(
			'SS_Log::log',
			'SS_Backtrace::backtrace',
			'SS_Backtrace::filtered_backtrace',
			'Zend_Log_Writer_Abstract->write',
			'Zend_Log->log',
			'Zend_Log->__call',
			'Zend_Log->err',
			'DebugView->writeTrace',
			'CliDebugView->writeTrace',
			'Debug::emailError',
			'Debug::warningHandler',
			'Debug::noticeHandler',
			'Debug::fatalHandler',
			'errorHandler',
			'Debug::showError',
			'Debug::backtrace',
			'exceptionHandler'
		);

		if($ignoredFunctions) foreach($ignoredFunctions as $ignoredFunction) {
			$defaultIgnoredFunctions[] = $ignoredFunction;
		}

		while($bt && in_array(self::full_func_name($bt[0]), $defaultIgnoredFunctions)) {
			array_shift($bt);
		}

		$ignoredArgs = Config::inst()->get('SS_Backtrace', 'ignore_function_args');

		// Filter out arguments
		foreach($bt as $i => $frame) {
			$match = false;
			if(!empty($bt[$i]['class'])) {
				foreach($ignoredArgs as $fnSpec) {
					if(is_array($fnSpec) && $bt[$i]['class'] == $fnSpec[0] && $bt[$i]['function'] == $fnSpec[1]) {
						$match = true;
					}
				}
			} else {
				if(in_array($bt[$i]['function'], $ignoredArgs)) $match = true;
			}
			if($match) {
				foreach($bt[$i]['args'] as $j => $arg) $bt[$i]['args'][$j] = '<filtered>';
			}
		}

		return $bt;
	}

	/**
	 * Render or return a backtrace from the given scope.
	 *
	 * @param unknown_type $returnVal
	 * @param unknown_type $ignoreAjax
	 * @return unknown
	 */
	public static function backtrace($returnVal = false, $ignoreAjax = false, $ignoredFunctions = null) {
		$plainText = Director::is_cli() || (Director::is_ajax() && !$ignoreAjax);
		$result = self::get_rendered_backtrace(debug_backtrace(), $plainText, $ignoredFunctions);
		if($returnVal) {
			return $result;
		} else {
			echo $result;
		}
	}

	/**
	 * Return the full function name.  If showArgs is set to true, a string representation of the arguments will be
	 * shown
	 *
	 * @param Object $item
	 * @param boolean $showArg
	 * @param Int $argCharLimit
	 * @return String
	 */
	public static function full_func_name($item, $showArgs = false, $argCharLimit = 10000) {
		$funcName = '';
		if(isset($item['class'])) $funcName .= $item['class'];
		if(isset($item['type'])) $funcName .= $item['type'];
		if(isset($item['function'])) $funcName .= $item['function'];

		if($showArgs && isset($item['args'])) {
			$args = array();
			foreach($item['args'] as $arg) {
				if(!is_object($arg) || method_exists($arg, '__toString')) {
					$sarg = is_array($arg) ? 'Array' : strval($arg);
					$args[] = (strlen($sarg) > $argCharLimit) ? substr($sarg, 0, $argCharLimit) . '...' : $sarg;
				} else {
					$args[] = get_class($arg);
				}
			}

			$funcName .= "(" . implode(",", $args)  .")";
		}

		return $funcName;
	}

	/**
	 * Render a backtrace array into an appropriate plain-text or HTML string.
	 *
	 * @param array $bt The trace array, as returned by debug_backtrace() or Exception::getTrace()
	 * @param boolean $plainText Set to false for HTML output, or true for plain-text output
	 * @param array List of functions that should be ignored. If not set, a default is provided
	 * @return string The rendered backtrace
	 */
	public static function get_rendered_backtrace($bt, $plainText = false, $ignoredFunctions = null) {
		if(empty($bt)) {
			return '';
		}
		$bt = self::filter_backtrace($bt, $ignoredFunctions);
		$result = ($plainText) ? '' : '<ul>';
		foreach($bt as $item) {
			if($plainText) {
				$result .= self::full_func_name($item,true) . "\n";
				if(isset($item['line']) && isset($item['file'])) $result .= basename($item['file']) . ":$item[line]\n";
				$result .= "\n";
			} else {
				if ($item['function'] == 'user_error') {
					$name = $item['args'][0];
				} else {
					$name = self::full_func_name($item,true);
				}
				$result .= "<li><b>" . htmlentities($name, ENT_COMPAT, 'UTF-8') . "</b>\n<br />\n";
				$result .=  isset($item['file']) ? htmlentities(basename($item['file']), ENT_COMPAT, 'UTF-8') : '';
				$result .= isset($item['line']) ? ":$item[line]" : '';
				$result .= "</li>\n";
			}
		}
		if(!$plainText) $result .= '</ul>';
		return $result;
	}

}