<?php
/**
 * @author Gaetano Giunta
 * @copyright (C) 2006-2015 G. Giunta
 * @license code licensed under the BSD License: see file license.txt
 */

namespace PhpXmlRpc;

/**
 * PHP-XMLRPC "wrapper" class - generate stubs to transparently access xmlrpc methods as php functions and vice-versa.
 * Note: this class implements the PROXY pattern, but it is not named so to avoid confusion with http proxies.
 *
 * @todo use some better templating system for code generation?
 * @todo implement method wrapping with preservation of php objs in calls
 * @todo when wrapping methods without obj rebuilding, use return_type = 'phpvals' (faster)
 */
class Wrapper
{
    /// used to hold a reference to object instances whose methods get wrapped by wrapPhpFunction(), in 'create source' mode
    public static $objHolder = array();

    /**
     * Given a string defining a php type or phpxmlrpc type (loosely defined: strings
     * accepted come from javadoc blocks), return corresponding phpxmlrpc type.
     * Notes:
     * - for php 'resource' types returns empty string, since resources cannot be serialized;
     * - for php class names returns 'struct', since php objects can be serialized as xmlrpc structs
     * - for php arrays always return array, even though arrays sometimes serialize as json structs
     * - for 'void' and 'null' returns 'undefined'
     *
     * @param string $phpType
     *
     * @return string
     */
    public function php2XmlrpcType($phpType)
    {
        switch (strtolower($phpType)) {
            case 'string':
                return Value::$xmlrpcString;
            case 'integer':
            case Value::$xmlrpcInt: // 'int'
            case Value::$xmlrpcI4:
            case Value::$xmlrpcI8:
                return Value::$xmlrpcInt;
            case Value::$xmlrpcDouble: // 'double'
                return Value::$xmlrpcDouble;
            case 'bool':
            case Value::$xmlrpcBoolean: // 'boolean'
            case 'false':
            case 'true':
                return Value::$xmlrpcBoolean;
            case Value::$xmlrpcArray: // 'array':
                return Value::$xmlrpcArray;
            case 'object':
            case Value::$xmlrpcStruct: // 'struct'
                return Value::$xmlrpcStruct;
            case Value::$xmlrpcBase64:
                return Value::$xmlrpcBase64;
            case 'resource':
                return '';
            default:
                if (class_exists($phpType)) {
                    return Value::$xmlrpcStruct;
                } else {
                    // unknown: might be any 'extended' xmlrpc type
                    return Value::$xmlrpcValue;
                }
        }
    }

    /**
     * Given a string defining a phpxmlrpc type return the corresponding php type.
     *
     * @param string $xmlrpcType
     *
     * @return string
     */
    public function xmlrpc2PhpType($xmlrpcType)
    {
        switch (strtolower($xmlrpcType)) {
            case 'base64':
            case 'datetime.iso8601':
            case 'string':
                return Value::$xmlrpcString;
            case 'int':
            case 'i4':
            case 'i8':
                return 'integer';
            case 'struct':
            case 'array':
                return 'array';
            case 'double':
                return 'float';
            case 'undefined':
                return 'mixed';
            case 'boolean':
            case 'null':
            default:
                // unknown: might be any xmlrpc type
                return strtolower($xmlrpcType);
        }
    }

    /**
     * Given a user-defined PHP function, create a PHP 'wrapper' function that can
     * be exposed as xmlrpc method from an xmlrpc server object and called from remote
     * clients (as well as its corresponding signature info).
     *
     * Since php is a typeless language, to infer types of input and output parameters,
     * it relies on parsing the javadoc-style comment block associated with the given
     * function. Usage of xmlrpc native types (such as datetime.dateTime.iso8601 and base64)
     * in the '@param' tag is also allowed, if you need the php function to receive/send
     * data in that particular format (note that base64 encoding/decoding is transparently
     * carried out by the lib, while datetime vals are passed around as strings)
     *
     * Known limitations:
     * - only works for user-defined functions, not for PHP internal functions
     *   (reflection does not support retrieving number/type of params for those)
     * - functions returning php objects will generate special structs in xmlrpc responses:
     *   when the xmlrpc decoding of those responses is carried out by this same lib, using
     *   the appropriate param in php_xmlrpc_decode, the php objects will be rebuilt.
     *   In short: php objects can be serialized, too (except for their resource members),
     *   using this function.
     *   Other libs might choke on the very same xml that will be generated in this case
     *   (i.e. it has a nonstandard attribute on struct element tags)
     *
     * Note that since rel. 2.0RC3 the preferred method to have the server call 'standard'
     * php functions (ie. functions not expecting a single Request obj as parameter)
     * is by making use of the functions_parameters_type class member.
     *
     * @param callable $callable the PHP user function to be exposed as xmlrpc method/ a closure, function name, array($obj, 'methodname') or array('class', 'methodname') are ok
     * @param string $newFuncName (optional) name for function to be created. Used only when return_source in $extraOptions is true
     * @param array $extraOptions (optional) array of options for conversion. valid values include:
     *                            - bool return_source     when true, php code w. function definition will be returned, instead of a closure
     *                            - bool encode_php_objs   let php objects be sent to server using the 'improved' xmlrpc notation, so server can deserialize them as php objects
     *                            - bool decode_php_objs   --- WARNING !!! possible security hazard. only use it with trusted servers ---
     *                            - bool suppress_warnings remove from produced xml any warnings generated at runtime by the php function being invoked
     *
     * @return array|false false on error, or an array containing the name of the new php function,
     *                     its signature and docs, to be used in the server dispatch map
     *
     * @todo decide how to deal with params passed by ref in function definition: bomb out or allow?
     * @todo finish using phpdoc info to build method sig if all params are named but out of order
     * @todo add a check for params of 'resource' type
     * @todo add some trigger_errors / error_log when returning false?
     * @todo what to do when the PHP function returns NULL? We are currently returning an empty string value...
     * @todo add an option to suppress php warnings in invocation of user function, similar to server debug level 3?
     * @todo add a verbatim_object_copy parameter to allow avoiding usage the same obj instance?
     * @todo add an option to allow generated function to skip validation of number of parameters, as that is done by the server anyway
     */
    public function wrapPhpFunction($callable, $newFuncName = '', $extraOptions = array())
    {
        $buildIt = isset($extraOptions['return_source']) ? !($extraOptions['return_source']) : true;

        if (is_string($callable) && strpos($callable, '::') !== false) {
            $callable = explode('::', $callable);
        }
        if (is_array($callable)) {
            if (count($callable) < 2 || (!is_string($callable[0]) && !is_object($callable[0]))) {
                error_log('XML-RPC: ' . __METHOD__ . ': syntax for function to be wrapped is wrong');
                return false;
            }
            if (is_string($callable[0])) {
                $plainFuncName = implode('::', $callable);
            } elseif (is_object($callable[0])) {
                $plainFuncName = get_class($callable[0]) . '->' . $callable[1];
            }
            $exists = method_exists($callable[0], $callable[1]);
        } else if ($callable instanceof \Closure) {
            // we do not support creating code which wraps closures, as php does not allow to serialize them
            if (!$buildIt) {
                error_log('XML-RPC: ' . __METHOD__ . ': a closure can not be wrapped in generated source code');
                return false;
            }

            $plainFuncName = 'Closure';
            $exists = true;
        } else {
            $plainFuncName = $callable;
            $exists = function_exists($callable);
        }

        if (!$exists) {
            error_log('XML-RPC: ' . __METHOD__ . ': function to be wrapped is not defined: ' . $plainFuncName);
            return false;
        }

        $funcDesc = $this->introspectFunction($callable, $plainFuncName);
        if (!$funcDesc) {
            return false;
        }

        $funcSigs = $this->buildMethodSignatures($funcDesc);

        if ($buildIt) {
            $callable = $this->buildWrapFunctionClosure($callable, $extraOptions, $plainFuncName, $funcDesc);
        } else {
            $newFuncName = $this->newFunctionName($callable, $newFuncName, $extraOptions);
            $code = $this->buildWrapFunctionSource($callable, $newFuncName, $extraOptions, $plainFuncName, $funcDesc);
        }

        $ret = array(
            'function' => $callable,
            'signature' => $funcSigs['sigs'],
            'docstring' => $funcDesc['desc'],
            'signature_docs' => $funcSigs['sigsDocs'],
        );
        if (!$buildIt) {
            $ret['function'] = $newFuncName;
            $ret['source'] = $code;
        }
        return $ret;
    }

    /**
     * Introspect a php callable and its phpdoc block and extract information about its signature
     *
     * @param callable $callable
     * @param string $plainFuncName
     * @return array|false
     */
    protected function introspectFunction($callable, $plainFuncName)
    {
        // start to introspect PHP code
        if (is_array($callable)) {
            $func = new \ReflectionMethod($callable[0], $callable[1]);
            if ($func->isPrivate()) {
                error_log('XML-RPC: ' . __METHOD__ . ': method to be wrapped is private: ' . $plainFuncName);
                return false;
            }
            if ($func->isProtected()) {
                error_log('XML-RPC: ' . __METHOD__ . ': method to be wrapped is protected: ' . $plainFuncName);
                return false;
            }
            if ($func->isConstructor()) {
                error_log('XML-RPC: ' . __METHOD__ . ': method to be wrapped is the constructor: ' . $plainFuncName);
                return false;
            }
            if ($func->isDestructor()) {
                error_log('XML-RPC: ' . __METHOD__ . ': method to be wrapped is the destructor: ' . $plainFuncName);
                return false;
            }
            if ($func->isAbstract()) {
                error_log('XML-RPC: ' . __METHOD__ . ': method to be wrapped is abstract: ' . $plainFuncName);
                return false;
            }
            /// @todo add more checks for static vs. nonstatic?
        } else {
            $func = new \ReflectionFunction($callable);
        }
        if ($func->isInternal()) {
            // Note: from PHP 5.1.0 onward, we will possibly be able to use invokeargs
            // instead of getparameters to fully reflect internal php functions ?
            error_log('XML-RPC: ' . __METHOD__ . ': function to be wrapped is internal: ' . $plainFuncName);
            return false;
        }

        // retrieve parameter names, types and description from javadoc comments

        // function description
        $desc = '';
        // type of return val: by default 'any'
        $returns = Value::$xmlrpcValue;
        // desc of return val
        $returnsDocs = '';
        // type + name of function parameters
        $paramDocs = array();

        $docs = $func->getDocComment();
        if ($docs != '') {
            $docs = explode("\n", $docs);
            $i = 0;
            foreach ($docs as $doc) {
                $doc = trim($doc, " \r\t/*");
                if (strlen($doc) && strpos($doc, '@') !== 0 && !$i) {
                    if ($desc) {
                        $desc .= "\n";
                    }
                    $desc .= $doc;
                } elseif (strpos($doc, '@param') === 0) {
                    // syntax: @param type $name [desc]
                    if (preg_match('/@param\s+(\S+)\s+(\$\S+)\s*(.+)?/', $doc, $matches)) {
                        $name = strtolower(trim($matches[2]));
                        //$paramDocs[$name]['name'] = trim($matches[2]);
                        $paramDocs[$name]['doc'] = isset($matches[3]) ? $matches[3] : '';
                        $paramDocs[$name]['type'] = $matches[1];
                    }
                    $i++;
                } elseif (strpos($doc, '@return') === 0) {
                    // syntax: @return type [desc]
                    if (preg_match('/@return\s+(\S+)(\s+.+)?/', $doc, $matches)) {
                        $returns = $matches[1];
                        if (isset($matches[2])) {
                            $returnsDocs = trim($matches[2]);
                        }
                    }
                }
            }
        }

        // execute introspection of actual function prototype
        $params = array();
        $i = 0;
        foreach ($func->getParameters() as $paramObj) {
            $params[$i] = array();
            $params[$i]['name'] = '$' . $paramObj->getName();
            $params[$i]['isoptional'] = $paramObj->isOptional();
            $i++;
        }

        return array(
            'desc' => $desc,
            'docs' => $docs,
            'params' => $params, // array, positionally indexed
            'paramDocs' => $paramDocs, // array, indexed by name
            'returns' => $returns,
            'returnsDocs' =>$returnsDocs,
        );
    }

    /**
     * Given the method description given by introspection, create method signature data
     *
     * @todo support better docs with multiple types separated by pipes by creating multiple signatures
     *       (this is questionable, as it might produce a big matrix of possible signatures with many such occurrences)
     *
     * @param array $funcDesc as generated by self::introspectFunction()
     *
     * @return array
     */
    protected function buildMethodSignatures($funcDesc)
    {
        $i = 0;
        $parsVariations = array();
        $pars = array();
        $pNum = count($funcDesc['params']);
        foreach ($funcDesc['params'] as $param) {
            /* // match by name real param and documented params
            $name = strtolower($param['name']);
            if (!isset($funcDesc['paramDocs'][$name])) {
                $funcDesc['paramDocs'][$name] = array();
            }
            if (!isset($funcDesc['paramDocs'][$name]['type'])) {
                $funcDesc['paramDocs'][$name]['type'] = 'mixed';
            }*/

            if ($param['isoptional']) {
                // this particular parameter is optional. save as valid previous list of parameters
                $parsVariations[] = $pars;
            }

            $pars[] = "\$p$i";
            $i++;
            if ($i == $pNum) {
                // last allowed parameters combination
                $parsVariations[] = $pars;
            }
        }

        if (count($parsVariations) == 0) {
            // only known good synopsis = no parameters
            $parsVariations[] = array();
        }

        $sigs = array();
        $sigsDocs = array();
        foreach ($parsVariations as $pars) {
            // build a signature
            $sig = array($this->php2XmlrpcType($funcDesc['returns']));
            $pSig = array($funcDesc['returnsDocs']);
            for ($i = 0; $i < count($pars); $i++) {
                $name = strtolower($funcDesc['params'][$i]['name']);
                if (isset($funcDesc['paramDocs'][$name]['type'])) {
                    $sig[] = $this->php2XmlrpcType($funcDesc['paramDocs'][$name]['type']);
                } else {
                    $sig[] = Value::$xmlrpcValue;
                }
                $pSig[] = isset($funcDesc['paramDocs'][$name]['doc']) ? $funcDesc['paramDocs'][$name]['doc'] : '';
            }
            $sigs[] = $sig;
            $sigsDocs[] = $pSig;
        }

        return array(
            'sigs' => $sigs,
            'sigsDocs' => $sigsDocs
        );
    }

    /**
     * Creates a closure that will execute $callable
     * @todo validate params? In theory all validation is left to the dispatch map...
     * @todo add support for $catchWarnings
     *
     * @param $callable
     * @param array $extraOptions
     * @param string $plainFuncName
     * @param array $funcDesc
     * @return \Closure
     */
    protected function buildWrapFunctionClosure($callable, $extraOptions, $plainFuncName, $funcDesc)
    {
        /**
         * @param Request $req
         * @return mixed
         */
        $function = function($req) use($callable, $extraOptions, $funcDesc)
        {
            $nameSpace = '\\PhpXmlRpc\\';
            $encoderClass = $nameSpace.'Encoder';
            $responseClass = $nameSpace.'Response';
            $valueClass = $nameSpace.'Value';

            // validate number of parameters received
            // this should be optional really, as we assume the server does the validation
            $minPars = count($funcDesc['params']);
            $maxPars = $minPars;
            foreach ($funcDesc['params'] as $i => $param) {
                if ($param['isoptional']) {
                    // this particular parameter is optional. We assume later ones are as well
                    $minPars = $i;
                    break;
                }
            }
            $numPars = $req->getNumParams();
            if ($numPars < $minPars || $numPars > $maxPars) {
                return new $responseClass(0, 3, 'Incorrect parameters passed to method');
            }

            $encoder = new $encoderClass();
            $options = array();
            if (isset($extraOptions['decode_php_objs']) && $extraOptions['decode_php_objs']) {
                $options[] = 'decode_php_objs';
            }
            $params = $encoder->decode($req, $options);

            $result = call_user_func_array($callable, $params);

            if (! is_a($result, $responseClass)) {
                if ($funcDesc['returns'] == Value::$xmlrpcDateTime || $funcDesc['returns'] == Value::$xmlrpcBase64) {
                    $result = new $valueClass($result, $funcDesc['returns']);
                } else {
                    $options = array();
                    if (isset($extraOptions['encode_php_objs']) && $extraOptions['encode_php_objs']) {
                        $options[] = 'encode_php_objs';
                    }

                    $result = $encoder->encode($result, $options);
                }
                $result = new $responseClass($result);
            }

            return $result;
        };

        return $function;
    }

    /**
     * Return a name for a new function, based on $callable, insuring its uniqueness
     * @param mixed $callable a php callable, or the name of an xmlrpc method
     * @param string $newFuncName when not empty, it is used instead of the calculated version
     * @return string
     */
    protected function newFunctionName($callable, $newFuncName, $extraOptions)
    {
        // determine name of new php function

        $prefix = isset($extraOptions['prefix']) ? $extraOptions['prefix'] : 'xmlrpc';

        if ($newFuncName == '') {
            if (is_array($callable)) {
                if (is_string($callable[0])) {
                    $xmlrpcFuncName = "{$prefix}_" . implode('_', $callable);
                } else {
                    $xmlrpcFuncName = "{$prefix}_" . get_class($callable[0]) . '_' . $callable[1];
                }
            } else {
                if ($callable instanceof \Closure) {
                    $xmlrpcFuncName = "{$prefix}_closure";
                } else {
                    $callable = preg_replace(array('/\./', '/[^a-zA-Z0-9_\x7f-\xff]/'),
                        array('_', ''), $callable);
                    $xmlrpcFuncName = "{$prefix}_$callable";
                }
            }
        } else {
            $xmlrpcFuncName = $newFuncName;
        }

        while (function_exists($xmlrpcFuncName)) {
            $xmlrpcFuncName .= 'x';
        }

        return $xmlrpcFuncName;
    }

    /**
     * @param $callable
     * @param string $newFuncName
     * @param array $extraOptions
     * @param string $plainFuncName
     * @param array $funcDesc
     * @return string
     *
     * @todo add a nice phpdoc block in the generated source
     */
    protected function buildWrapFunctionSource($callable, $newFuncName, $extraOptions, $plainFuncName, $funcDesc)
    {
        $namespace = '\\PhpXmlRpc\\';

        $encodePhpObjects = isset($extraOptions['encode_php_objs']) ? (bool)$extraOptions['encode_php_objs'] : false;
        $decodePhpObjects = isset($extraOptions['decode_php_objs']) ? (bool)$extraOptions['decode_php_objs'] : false;
        $catchWarnings = isset($extraOptions['suppress_warnings']) && $extraOptions['suppress_warnings'] ? '@' : '';

        $i = 0;
        $parsVariations = array();
        $pars = array();
        $pNum = count($funcDesc['params']);
        foreach ($funcDesc['params'] as $param) {

            if ($param['isoptional']) {
                // this particular parameter is optional. save as valid previous list of parameters
                $parsVariations[] = $pars;
            }

            $pars[] = "\$p[$i]";
            $i++;
            if ($i == $pNum) {
                // last allowed parameters combination
                $parsVariations[] = $pars;
            }
        }

        if (count($parsVariations) == 0) {
            // only known good synopsis = no parameters
            $parsVariations[] = array();
            $minPars = 0;
            $maxPars = 0;
        } else {
            $minPars = count($parsVariations[0]);
            $maxPars = count($parsVariations[count($parsVariations)-1]);
        }

        // build body of new function

        $innerCode = "\$paramCount = \$req->getNumParams();\n";
        $innerCode .= "if (\$paramCount < $minPars || \$paramCount > $maxPars) return new {$namespace}Response(0, " . PhpXmlRpc::$xmlrpcerr['incorrect_params'] . ", '" . PhpXmlRpc::$xmlrpcstr['incorrect_params'] . "');\n";

        $innerCode .= "\$encoder = new {$namespace}Encoder();\n";
        if ($decodePhpObjects) {
            $innerCode .= "\$p = \$encoder->decode(\$req, array('decode_php_objs'));\n";
        } else {
            $innerCode .= "\$p = \$encoder->decode(\$req);\n";
        }

        // since we are building source code for later use, if we are given an object instance,
        // we go out of our way and store a pointer to it in a static class var var...
        if (is_array($callable) && is_object($callable[0])) {
            self::$objHolder[$newFuncName] = $callable[0];
            $innerCode .= "\$obj = PhpXmlRpc\\Wrapper::\$objHolder['$newFuncName'];\n";
            $realFuncName = '$obj->' . $callable[1];
        } else {
            $realFuncName = $plainFuncName;
        }
        foreach ($parsVariations as $i => $pars) {
            $innerCode .= "if (\$paramCount == " . count($pars) . ") \$retval = {$catchWarnings}$realFuncName(" . implode(',', $pars) . ");\n";
            if ($i < (count($parsVariations) - 1))
                $innerCode .= "else\n";
        }
        $innerCode .= "if (is_a(\$retval, '{$namespace}Response')) return \$retval; else\n";
        if ($funcDesc['returns'] == Value::$xmlrpcDateTime || $funcDesc['returns'] == Value::$xmlrpcBase64) {
            $innerCode .= "return new {$namespace}Response(new {$namespace}Value(\$retval, '{$funcDesc['returns']}'));";
        } else {
            if ($encodePhpObjects) {
                $innerCode .= "return new {$namespace}Response(\$encoder->encode(\$retval, array('encode_php_objs')));\n";
            } else {
                $innerCode .= "return new {$namespace}Response(\$encoder->encode(\$retval));\n";
            }
        }
        // shall we exclude functions returning by ref?
        // if($func->returnsReference())
        //     return false;

        $code = "function $newFuncName(\$req) {\n" . $innerCode . "\n}";

        return $code;
    }

    /**
     * Given a user-defined PHP class or php object, map its methods onto a list of
     * PHP 'wrapper' functions that can be exposed as xmlrpc methods from an xmlrpc server
     * object and called from remote clients (as well as their corresponding signature info).
     *
     * @param string|object $className the name of the class whose methods are to be exposed as xmlrpc methods, or an object instance of that class
     * @param array $extraOptions see the docs for wrapPhpMethod for basic options, plus
     *                            - string method_type    'static', 'nonstatic', 'all' and 'auto' (default); the latter will switch between static and non-static depending on whether $className is a class name or object instance
     *                            - string method_filter  a regexp used to filter methods to wrap based on their names
     *                            - string prefix         used for the names of the xmlrpc methods created
     *
     * @return array|false false on failure
     */
    public function wrapPhpClass($className, $extraOptions = array())
    {
        $methodFilter = isset($extraOptions['method_filter']) ? $extraOptions['method_filter'] : '';
        $methodType = isset($extraOptions['method_type']) ? $extraOptions['method_type'] : 'auto';
        $prefix = isset($extraOptions['prefix']) ? $extraOptions['prefix'] : '';

        $results = array();
        $mList = get_class_methods($className);
        foreach ($mList as $mName) {
            if ($methodFilter == '' || preg_match($methodFilter, $mName)) {
                $func = new \ReflectionMethod($className, $mName);
                if (!$func->isPrivate() && !$func->isProtected() && !$func->isConstructor() && !$func->isDestructor() && !$func->isAbstract()) {
                    if (($func->isStatic() && ($methodType == 'all' || $methodType == 'static' || ($methodType == 'auto' && is_string($className)))) ||
                        (!$func->isStatic() && ($methodType == 'all' || $methodType == 'nonstatic' || ($methodType == 'auto' && is_object($className))))
                    ) {
                        $methodWrap = $this->wrapPhpFunction(array($className, $mName), '', $extraOptions);
                        if ($methodWrap) {
                            if (is_object($className)) {
                                $realClassName = get_class($className);
                            }else {
                                $realClassName = $className;
                            }
                            $results[$prefix."$realClassName.$mName"] = $methodWrap;
                        }
                    }
                }
            }
        }

        return $results;
    }

    /**
     * Given an xmlrpc client and a method name, register a php wrapper function
     * that will call it and return results using native php types for both
     * params and results. The generated php function will return a Response
     * object for failed xmlrpc calls.
     *
     * Known limitations:
     * - server must support system.methodsignature for the wanted xmlrpc method
     * - for methods that expose many signatures, only one can be picked (we
     *   could in principle check if signatures differ only by number of params
     *   and not by type, but it would be more complication than we can spare time)
     * - nested xmlrpc params: the caller of the generated php function has to
     *   encode on its own the params passed to the php function if these are structs
     *   or arrays whose (sub)members include values of type datetime or base64
     *
     * Notes: the connection properties of the given client will be copied
     * and reused for the connection used during the call to the generated
     * php function.
     * Calling the generated php function 'might' be slow: a new xmlrpc client
     * is created on every invocation and an xmlrpc-connection opened+closed.
     * An extra 'debug' param is appended to param list of xmlrpc method, useful
     * for debugging purposes.
     *
     * @todo allow caller to give us the method signature instead of querying for it, or just say 'skip it'
     * @todo if we can not retrieve method signature, create a php function with varargs
     * @todo allow the created function to throw exceptions on method calls failures
     * @todo if caller did not specify a specific sig, shall we support all of them?
     *       It might be hard (hence slow) to match based on type and number of arguments...
     *
     * @param Client $client an xmlrpc client set up correctly to communicate with target server
     * @param string $methodName the xmlrpc method to be mapped to a php function
     * @param array $extraOptions array of options that specify conversion details. Valid options include
     *                            - integer signum              the index of the method signature to use in mapping (if method exposes many sigs)
     *                            - integer timeout             timeout (in secs) to be used when executing function/calling remote method
     *                            - string  protocol            'http' (default), 'http11' or 'https'
     *                            - string  new_function_name   the name of php function to create, when return_source is used. If unspecified, lib will pick an appropriate name
     *                            - string  return_source       if true return php code w. function definition instead of function itself (closure)
     *                            - bool    encode_php_objs     let php objects be sent to server using the 'improved' xmlrpc notation, so server can deserialize them as php objects
     *                            - bool    decode_php_objs     --- WARNING !!! possible security hazard. only use it with trusted servers ---
     *                            - mixed   return_on_fault     a php value to be returned when the xmlrpc call fails/returns a fault response (by default the Response object is returned in this case). If a string is used, '%faultCode%' and '%faultString%' tokens will be substituted with actual error values
     *                            - bool    debug               set it to 1 or 2 to see debug results of querying server for method synopsis
     *                            - int     simple_client_copy  set it to 1 to have a lightweight copy of the $client object made in the generated code (only used when return_source = true)
     *
     * @return \closure|array|false false on failure, closure by default and array for return_source = true
     */
    public function wrapXmlrpcMethod($client, $methodName, $extraOptions = array())
    {
        $newFuncName = isset($extraOptions['new_function_name']) ? $extraOptions['new_function_name'] : '';

        $buildIt = isset($extraOptions['return_source']) ? !($extraOptions['return_source']) : true;

        $mSig = $this->retrieveMethodSignature($client, $methodName, $extraOptions);
        if (!$mSig) {
            return false;
        }

        if ($buildIt) {
            return $this->buildWrapMethodClosure($client, $methodName, $extraOptions, $mSig);
        } else {
            // if in 'offline' mode, retrieve method description too.
            // in online mode, favour speed of operation
            $mDesc = $this->retrieveMethodHelp($client, $methodName, $extraOptions);

            $newFuncName = $this->newFunctionName($methodName, $newFuncName, $extraOptions);

            $results = $this->buildWrapMethodSource($client, $methodName, $extraOptions, $newFuncName, $mSig, $mDesc);
            /* was: $results = $this->build_remote_method_wrapper_code($client, $methodName,
                $newFuncName, $mSig, $mDesc, $timeout, $protocol, $simpleClientCopy,
                $prefix, $decodePhpObjects, $encodePhpObjects, $decodeFault,
                $faultResponse, $namespace);*/

            $results['function'] = $newFuncName;

            return $results;
        }

    }

    /**
     * Retrieves an xmlrpc method signature from a server which supports system.methodSignature
     * @param Client $client
     * @param string $methodName
     * @param array $extraOptions
     * @return false|array
     */
    protected function retrieveMethodSignature($client, $methodName, array $extraOptions = array())
    {
        $namespace = '\\PhpXmlRpc\\';
        $reqClass = $namespace . 'Request';
        $valClass = $namespace . 'Value';
        $decoderClass = $namespace . 'Encoder';

        $debug = isset($extraOptions['debug']) ? ($extraOptions['debug']) : 0;
        $timeout = isset($extraOptions['timeout']) ? (int)$extraOptions['timeout'] : 0;
        $protocol = isset($extraOptions['protocol']) ? $extraOptions['protocol'] : '';
        $sigNum = isset($extraOptions['signum']) ? (int)$extraOptions['signum'] : 0;

        $req = new $reqClass('system.methodSignature');
        $req->addparam(new $valClass($methodName));
        $client->setDebug($debug);
        $response = $client->send($req, $timeout, $protocol);
        if ($response->faultCode()) {
            error_log('XML-RPC: ' . __METHOD__ . ': could not retrieve method signature from remote server for method ' . $methodName);
            return false;
        }

        $mSig = $response->value();
        if ($client->return_type != 'phpvals') {
            $decoder = new $decoderClass();
            $mSig = $decoder->decode($mSig);
        }

        if (!is_array($mSig) || count($mSig) <= $sigNum) {
            error_log('XML-RPC: ' . __METHOD__ . ': could not retrieve method signature nr.' . $sigNum . ' from remote server for method ' . $methodName);
            return false;
        }

        return $mSig[$sigNum];
    }

    /**
     * @param Client $client
     * @param string $methodName
     * @param array $extraOptions
     * @return string in case of any error, an empty string is returned, no warnings generated
     */
    protected function retrieveMethodHelp($client, $methodName, array $extraOptions = array())
    {
        $namespace = '\\PhpXmlRpc\\';
        $reqClass = $namespace . 'Request';
        $valClass = $namespace . 'Value';

        $debug = isset($extraOptions['debug']) ? ($extraOptions['debug']) : 0;
        $timeout = isset($extraOptions['timeout']) ? (int)$extraOptions['timeout'] : 0;
        $protocol = isset($extraOptions['protocol']) ? $extraOptions['protocol'] : '';

        $mDesc = '';

        $req = new $reqClass('system.methodHelp');
        $req->addparam(new $valClass($methodName));
        $client->setDebug($debug);
        $response = $client->send($req, $timeout, $protocol);
        if (!$response->faultCode()) {
            $mDesc = $response->value();
            if ($client->return_type != 'phpvals') {
                $mDesc = $mDesc->scalarval();
            }
        }

        return $mDesc;
    }

    /**
     * @param Client $client
     * @param string $methodName
     * @param array $extraOptions
     * @param array $mSig
     * @return \Closure
     *
     * @todo should we allow usage of parameter simple_client_copy to mean 'do not clone' in this case?
     */
    protected function buildWrapMethodClosure($client, $methodName, array $extraOptions, $mSig)
    {
        // we clone the client, so that we can modify it a bit independently of the original
        $clientClone = clone $client;
        $function = function() use($clientClone, $methodName, $extraOptions, $mSig)
        {
            $timeout = isset($extraOptions['timeout']) ? (int)$extraOptions['timeout'] : 0;
            $protocol = isset($extraOptions['protocol']) ? $extraOptions['protocol'] : '';
            $encodePhpObjects = isset($extraOptions['encode_php_objs']) ? (bool)$extraOptions['encode_php_objs'] : false;
            $decodePhpObjects = isset($extraOptions['decode_php_objs']) ? (bool)$extraOptions['decode_php_objs'] : false;
            if (isset($extraOptions['return_on_fault'])) {
                $decodeFault = true;
                $faultResponse = $extraOptions['return_on_fault'];
            } else {
                $decodeFault = false;
            }

            $namespace = '\\PhpXmlRpc\\';
            $reqClass = $namespace . 'Request';
            $encoderClass = $namespace . 'Encoder';
            $valueClass = $namespace . 'Value';

            $encoder = new $encoderClass();
            $encodeOptions = array();
            if ($encodePhpObjects) {
                $encodeOptions[] = 'encode_php_objs';
            }
            $decodeOptions = array();
            if ($decodePhpObjects) {
                $decodeOptions[] = 'decode_php_objs';
            }

            /// @todo check for insufficient nr. of args besides excess ones? note that 'source' version does not...

            // support one extra parameter: debug
            $maxArgs = count($mSig)-1; // 1st element is the return type
            $currentArgs = func_get_args();
            if (func_num_args() == ($maxArgs+1)) {
                $debug = array_pop($currentArgs);
                $clientClone->setDebug($debug);
            }

            $xmlrpcArgs = array();
            foreach($currentArgs as $i => $arg) {
                if ($i == $maxArgs) {
                    break;
                }
                $pType = $mSig[$i+1];
                if ($pType == 'i4' || $pType == 'i8' || $pType == 'int' || $pType == 'boolean' || $pType == 'double' ||
                    $pType == 'string' || $pType == 'dateTime.iso8601' || $pType == 'base64' || $pType == 'null'
                ) {
                    // by building directly xmlrpc values when type is known and scalar (instead of encode() calls),
                    // we make sure to honour the xmlrpc signature
                    $xmlrpcArgs[] = new $valueClass($arg, $pType);
                } else {
                    $xmlrpcArgs[] = $encoder->encode($arg, $encodeOptions);
                }
            }

            $req = new $reqClass($methodName, $xmlrpcArgs);
            // use this to get the maximum decoding flexibility
            $clientClone->return_type = 'xmlrpcvals';
            $resp = $clientClone->send($req, $timeout, $protocol);
            if ($resp->faultcode()) {
                if ($decodeFault) {
                    if (is_string($faultResponse) && ((strpos($faultResponse, '%faultCode%') !== false) ||
                            (strpos($faultResponse, '%faultString%') !== false))) {
                        $faultResponse = str_replace(array('%faultCode%', '%faultString%'),
                            array($resp->faultCode(), $resp->faultString()), $faultResponse);
                    }
                    return $faultResponse;
                } else {
                    return $resp;
                }
            } else {
                return $encoder->decode($resp->value(), $decodeOptions);
            }
        };

        return $function;
    }

    /**
     * @param Client $client
     * @param string $methodName
     * @param array $extraOptions
     * @param string $newFuncName
     * @param array $mSig
     * @param string $mDesc
     * @return array
     */
    public function buildWrapMethodSource($client, $methodName, array $extraOptions, $newFuncName, $mSig, $mDesc='')
    {
        $timeout = isset($extraOptions['timeout']) ? (int)$extraOptions['timeout'] : 0;
        $protocol = isset($extraOptions['protocol']) ? $extraOptions['protocol'] : '';
        $encodePhpObjects = isset($extraOptions['encode_php_objs']) ? (bool)$extraOptions['encode_php_objs'] : false;
        $decodePhpObjects = isset($extraOptions['decode_php_objs']) ? (bool)$extraOptions['decode_php_objs'] : false;
        $clientCopyMode = isset($extraOptions['simple_client_copy']) ? (int)($extraOptions['simple_client_copy']) : 0;
        $prefix = isset($extraOptions['prefix']) ? $extraOptions['prefix'] : 'xmlrpc';
        if (isset($extraOptions['return_on_fault'])) {
            $decodeFault = true;
            $faultResponse = $extraOptions['return_on_fault'];
        } else {
            $decodeFault = false;
            $faultResponse = '';
        }

        $namespace = '\\PhpXmlRpc\\';

        $code = "function $newFuncName (";
        if ($clientCopyMode < 2) {
            // client copy mode 0 or 1 == full / partial client copy in emitted code
            $verbatimClientCopy = !$clientCopyMode;
            $innerCode = $this->buildClientWrapperCode($client, $verbatimClientCopy, $prefix, $namespace);
            $innerCode .= "\$client->setDebug(\$debug);\n";
            $this_ = '';
        } else {
            // client copy mode 2 == no client copy in emitted code
            $innerCode = '';
            $this_ = 'this->';
        }
        $innerCode .= "\$req = new {$namespace}Request('$methodName');\n";

        if ($mDesc != '') {
            // take care that PHP comment is not terminated unwillingly by method description
            $mDesc = "/**\n* " . str_replace('*/', '* /', $mDesc) . "\n";
        } else {
            $mDesc = "/**\nFunction $newFuncName\n";
        }

        // param parsing
        $innerCode .= "\$encoder = new {$namespace}Encoder();\n";
        $plist = array();
        $pCount = count($mSig);
        for ($i = 1; $i < $pCount; $i++) {
            $plist[] = "\$p$i";
            $pType = $mSig[$i];
            if ($pType == 'i4' || $pType == 'i8' || $pType == 'int' || $pType == 'boolean' || $pType == 'double' ||
                $pType == 'string' || $pType == 'dateTime.iso8601' || $pType == 'base64' || $pType == 'null'
            ) {
                // only build directly xmlrpc values when type is known and scalar
                $innerCode .= "\$p$i = new {$namespace}Value(\$p$i, '$pType');\n";
            } else {
                if ($encodePhpObjects) {
                    $innerCode .= "\$p$i = \$encoder->encode(\$p$i, array('encode_php_objs'));\n";
                } else {
                    $innerCode .= "\$p$i = \$encoder->encode(\$p$i);\n";
                }
            }
            $innerCode .= "\$req->addparam(\$p$i);\n";
            $mDesc .= '* @param ' . $this->xmlrpc2PhpType($pType) . " \$p$i\n";
        }
        if ($clientCopyMode < 2) {
            $plist[] = '$debug=0';
            $mDesc .= "* @param int \$debug when 1 (or 2) will enable debugging of the underlying {$prefix} call (defaults to 0)\n";
        }
        $plist = implode(', ', $plist);
        $mDesc .= '* @return ' . $this->xmlrpc2PhpType($mSig[0]) . " (or an {$namespace}Response obj instance if call fails)\n*/\n";

        $innerCode .= "\$res = \${$this_}client->send(\$req, $timeout, '$protocol');\n";
        if ($decodeFault) {
            if (is_string($faultResponse) && ((strpos($faultResponse, '%faultCode%') !== false) || (strpos($faultResponse, '%faultString%') !== false))) {
                $respCode = "str_replace(array('%faultCode%', '%faultString%'), array(\$res->faultCode(), \$res->faultString()), '" . str_replace("'", "''", $faultResponse) . "')";
            } else {
                $respCode = var_export($faultResponse, true);
            }
        } else {
            $respCode = '$res';
        }
        if ($decodePhpObjects) {
            $innerCode .= "if (\$res->faultcode()) return $respCode; else return \$encoder->decode(\$res->value(), array('decode_php_objs'));";
        } else {
            $innerCode .= "if (\$res->faultcode()) return $respCode; else return \$encoder->decode(\$res->value());";
        }

        $code = $code . $plist . ") {\n" . $innerCode . "\n}\n";

        return array('source' => $code, 'docstring' => $mDesc);
    }

    /**
     * Similar to wrapXmlrpcMethod, but will generate a php class that wraps
     * all xmlrpc methods exposed by the remote server as own methods.
     * For more details see wrapXmlrpcMethod.
     *
     * For a slimmer alternative, see the code in demo/client/proxy.php
     *
     * Note that unlike wrapXmlrpcMethod, we always have to generate php code here. It seems that php 7 will have anon classes...
     *
     * @param Client $client the client obj all set to query the desired server
     * @param array $extraOptions list of options for wrapped code. See the ones from wrapXmlrpcMethod plus
     *              - string method_filter      regular expression
     *              - string new_class_name
     *              - string prefix
     *              - bool   simple_client_copy set it to true to avoid copying all properties of $client into the copy made in the new class
     *
     * @return mixed false on error, the name of the created class if all ok or an array with code, class name and comments (if the appropriate option is set in extra_options)
     */
    public function wrapXmlrpcServer($client, $extraOptions = array())
    {
        $methodFilter = isset($extraOptions['method_filter']) ? $extraOptions['method_filter'] : '';
        $timeout = isset($extraOptions['timeout']) ? (int)$extraOptions['timeout'] : 0;
        $protocol = isset($extraOptions['protocol']) ? $extraOptions['protocol'] : '';
        $newClassName = isset($extraOptions['new_class_name']) ? $extraOptions['new_class_name'] : '';
        $encodePhpObjects = isset($extraOptions['encode_php_objs']) ? (bool)$extraOptions['encode_php_objs'] : false;
        $decodePhpObjects = isset($extraOptions['decode_php_objs']) ? (bool)$extraOptions['decode_php_objs'] : false;
        $verbatimClientCopy = isset($extraOptions['simple_client_copy']) ? !($extraOptions['simple_client_copy']) : true;
        $buildIt = isset($extraOptions['return_source']) ? !($extraOptions['return_source']) : true;
        $prefix = isset($extraOptions['prefix']) ? $extraOptions['prefix'] : 'xmlrpc';
        $namespace = '\\PhpXmlRpc\\';

        $reqClass = $namespace . 'Request';
        $decoderClass = $namespace . 'Encoder';

        $req = new $reqClass('system.listMethods');
        $response = $client->send($req, $timeout, $protocol);
        if ($response->faultCode()) {
            error_log('XML-RPC: ' . __METHOD__ . ': could not retrieve method list from remote server');

            return false;
        } else {
            $mList = $response->value();
            if ($client->return_type != 'phpvals') {
                $decoder = new $decoderClass();
                $mList = $decoder->decode($mList);
            }
            if (!is_array($mList) || !count($mList)) {
                error_log('XML-RPC: ' . __METHOD__ . ': could not retrieve meaningful method list from remote server');

                return false;
            } else {
                // pick a suitable name for the new function, avoiding collisions
                if ($newClassName != '') {
                    $xmlrpcClassName = $newClassName;
                } else {
                    $xmlrpcClassName = $prefix . '_' . preg_replace(array('/\./', '/[^a-zA-Z0-9_\x7f-\xff]/'),
                            array('_', ''), $client->server) . '_client';
                }
                while ($buildIt && class_exists($xmlrpcClassName)) {
                    $xmlrpcClassName .= 'x';
                }

                /// @todo add function setdebug() to new class, to enable/disable debugging
                $source = "class $xmlrpcClassName\n{\npublic \$client;\n\n";
                $source .= "function __construct()\n{\n";
                $source .= $this->buildClientWrapperCode($client, $verbatimClientCopy, $prefix, $namespace);
                $source .= "\$this->client = \$client;\n}\n\n";
                $opts = array(
                    'return_source' => true,
                    'simple_client_copy' => 2, // do not produce code to copy the client object
                    'timeout' => $timeout,
                    'protocol' => $protocol,
                    'encode_php_objs' => $encodePhpObjects,
                    'decode_php_objs' => $decodePhpObjects,
                    'prefix' => $prefix,
                );
                /// @todo build phpdoc for class definition, too
                foreach ($mList as $mName) {
                    if ($methodFilter == '' || preg_match($methodFilter, $mName)) {
                        // note: this will fail if server exposes 2 methods called f.e. do.something and do_something
                        $opts['new_function_name'] = preg_replace(array('/\./', '/[^a-zA-Z0-9_\x7f-\xff]/'),
                            array('_', ''), $mName);
                        $methodWrap = $this->wrapXmlrpcMethod($client, $mName, $opts);
                        if ($methodWrap) {
                            if (!$buildIt) {
                                $source .= $methodWrap['docstring'];
                            }
                            $source .= $methodWrap['source'] . "\n";
                        } else {
                            error_log('XML-RPC: ' . __METHOD__ . ': will not create class method to wrap remote method ' . $mName);
                        }
                    }
                }
                $source .= "}\n";
                if ($buildIt) {
                    $allOK = 0;
                    eval($source . '$allOK=1;');
                    if ($allOK) {
                        return $xmlrpcClassName;
                    } else {
                        error_log('XML-RPC: ' . __METHOD__ . ': could not create class ' . $xmlrpcClassName . ' to wrap remote server ' . $client->server);
                        return false;
                    }
                } else {
                    return array('class' => $xmlrpcClassName, 'code' => $source, 'docstring' => '');
                }
            }
        }
    }

    /**
     * Given necessary info, generate php code that will build a client object just like the given one.
     * Take care that no full checking of input parameters is done to ensure that
     * valid php code is emitted.
     * @param Client $client
     * @param bool $verbatimClientCopy when true, copy all of the state of the client, except for 'debug' and 'return_type'
     * @param string $prefix used for the return_type of the created client
     * @param string $namespace
     *
     * @return string
     */
    protected function buildClientWrapperCode($client, $verbatimClientCopy, $prefix = 'xmlrpc', $namespace = '\\PhpXmlRpc\\' )
    {
        $code = "\$client = new {$namespace}Client('" . str_replace("'", "\'", $client->path) .
            "', '" . str_replace("'", "\'", $client->server) . "', $client->port);\n";

        // copy all client fields to the client that will be generated runtime
        // (this provides for future expansion or subclassing of client obj)
        if ($verbatimClientCopy) {
            foreach ($client as $fld => $val) {
                if ($fld != 'debug' && $fld != 'return_type') {
                    $val = var_export($val, true);
                    $code .= "\$client->$fld = $val;\n";
                }
            }
        }
        // only make sure that client always returns the correct data type
        $code .= "\$client->return_type = '{$prefix}vals';\n";
        //$code .= "\$client->setDebug(\$debug);\n";
        return $code;
    }
}
