<?php
/**
 * MoodleRest
 *
 * MoodleRest is a class to query Moodle REST webservices
 *
 * @package    MoodleRest
 * @version    2.4.0
 * @author     Lawrence Lagerlof <llagerlof@gmail.com>
 * @copyright  2021 Lawrence Lagerlof
 * @link       http://github.com/llagerlof/MoodleRest
 * @license    https://opensource.org/licenses/MIT MIT
 */
class MoodleRest
{
    /**
     * The constant that defines the JSON return format
     * @access public
     */
    const RETURN_JSON = 'json';

    /**
     * The constant that defines the XML return format
     * @access public
     */
    const RETURN_XML = 'xml';

    /**
     * The constant that defines the ARRAY return format
     * @access public
     */
    const RETURN_ARRAY = 'array';

    /**
     * The constant that defines the request method using GET
     * @access public
     */
    const METHOD_GET = 'get';

    /**
     * The constant that defines the request method using POST
     * @access public
     */
    const METHOD_POST = 'post';

    /**
     * The full server address to Moodle REST webservices.
     * @access private
     */
    private $server_address;

    /**
     * The Moodle webservice token
     * @access private
     */
    private $token;

    /**
     * The return format (json, xml, array)
     * @access private
     */
    private $return_format = 'json'; // or xml

    /**
     * The RAW return data (as returned by the request. could be json or xml)
     * @access private
     */
    private $request_return;

    /**
     * The PARSED return data (could be json, xml or array)
     * @access private
     */
    private $parsed_return;

    /**
     * The full encoded URL used to access the webservice
     * @access private
     */
    private $url;

    /**
     * The full URL decoded
     * @access private
     */
    private $url_decoded;

    /**
     * The header string to be used in header() output
     * @access private
     */
    private $output_header;

    /**
     * The header string to be used in header() output
     * @access private
     */
    private $print_on_request = false;

    /**
     * The method to be used on request
     * @access private
     */
    private $method = 'get'; // or post

    /**
     * Print debug information to standard output?
     * @access private
     */
    private $debug = false;

    /**
     * Constructor
     *
     * @param string $server_address The full URL of Moodle rest server script. Eg: http://127.0.0.1/moodle/webservice/rest/server.php
     */
    public function __construct($server_address = null, $token = null, $return_format = self::RETURN_ARRAY)
    {
        $this->server_address = $server_address;
        $this->token = $token;
        if (!is_null($return_format) && $return_format <> 'json' && $return_format <> 'xml' && $return_format <> 'array') {
            throw new Exception("MoodleRest: Invalid return format: '$return_format'.");
        }
        $this->return_format = $return_format;
    }

    /**
     * Set the full server address to Moodle REST webservices
     *
     * @param string $server_address The server address. eg:
     *
     * @return MoodleRest
     */
    public function setServerAddress($server_address)
    {
        $this->server_address = $server_address;
        return $this;
    }

    /**
     * Get the server address to Moodle REST webservices
     *
     * @return string The server address
     */
    public function getServerAddress()
    {
        return $this->server_address;
    }

    /**
     * Set the Moodle token to access Moodle REST webservices
     *
     * @param string $token The oken generated by Moodle admin
     *
     * @return MoodleRest
     */
    public function setToken($token)
    {
        $this->token = $token;

        return $this;
    }

    /**
     * Get the Moodle token
     *
     * @return string The Moodle token
     */
    public function getToken()
    {
        return $this->token;
    }

    /**
     * Set the return format (json, xml or array)
     *
     * @param string $return_format The return format (json, xml or array)
     *
     * @return MoodleRest
     */
    public function setReturnFormat($return_format) // json, xml, array
    {
        if ($return_format <> 'json' && $return_format <> 'xml' && $return_format <> 'array') {
            throw new Exception("MoodleRest: Invalid return format: '$return_format'.");
        }
        $this->return_format = $return_format;

        return $this;
    }

    /**
     * Get the return format
     *
     * @return string The return format (array, json or xml)
     */
    public function getReturnFormat()
    {
        return $this->return_format;
    }

    /**
     * Store the return data
     *
     * @param string $request_return The returned data made by request() method
     */
    private function setRawData($request_return)
    {
        $this->request_return = $request_return;
    }

    /**
     * Get the returned data previously made by request() method
     *
     * @return mixed
     */
    public function getRawData()
    {
        return $this->request_return;
    }

    /**
     * Store the parsed return data
     *
     * @param string $parsed_return The parsed returned data made by request() method
     */
    private function setData($parsed_return)
    {
        $this->parsed_return = $parsed_return;
    }

    /**
     * Get the parsed returned data previously made by request() method
     *
     * @return mixed The returned data in his final form
     */
    public function getData()
    {
        return $this->parsed_return;
    }

    /**
     * Store the full URL when querying the server
     *
     * @param string $url The parsed returned data made by request() method
     */
    private function setUrl($url)
    {
        $this->url = $url;
        $this->url_decoded = urldecode($url);
    }

    /**
     * Get the full URL stored when the query was made
     *
     * @return string The requested URL
     */
    public function getUrl($decoded = true)
    {
        return $decoded ? $this->url_decoded : $this->url;
    }

    /**
     * Store the output header
     *
     * @param string $output_header The header
     */
    private function setHeader($output_header)
    {
        $this->output_header = $output_header;
    }

    /**
     * Get the output header string
     *
     * @return string Get the output header
     */
    public function getHeader()
    {
        return $this->output_header;
    }

    /**
     * Set the request method
     *
     * @param string $method The method to be used on request: MoodleRest::METHOD_GET or METHOD_POST
     */
    public function setMethod($method)
    {
        $this->method = $method;
    }

    /**
     * Get the method
     *
     * @return string Get the request method
     */
    public function getMethod()
    {
        return $this->method;
    }

    /**
     * Enable debugging information
     *
     * @param bool $enabled Enable or disable debugging information
     */
    public function setDebug($enabled = true)
    {
        $this->debug = $enabled;
    }

    /**
     * Print debug information
     *
     * @param string $url The full url used to request the Moodle REST server
     * @param string $webservice_function The name of the Moodle function
     * @param string $method The method used to request data (get or post)
     * @param string $returned_data The data returned by Moodle webservice
     */
    private function debug($url, $webservice_function, $method, $returned_data)
    {
        if ($this->debug) {
            $line_break = php_sapi_name() == 'cli' ? "\n" : '<br />';
            $open_html_pre = php_sapi_name() == 'cli' ? '' : '<pre>';
            $close_html_pre = php_sapi_name() == 'cli' ? '' : '</pre>';
            echo $open_html_pre;
            echo $line_break;
            echo '[debug][' . strtoupper($method) . '] ' . get_class($this) . "::request( $webservice_function )$line_break";
            echo "$url $line_break";
            if (is_array($returned_data) || is_object($returned_data)) {
                print_r($returned_data);
            } else {
                if ((strlen(trim($returned_data)) > 0) && in_array($returned_data[0], array('[', '{'))) {
                    print_r(json_decode(trim($returned_data), true));
                } else {
                    echo gettype($returned_data) . " '$returned_data'$line_break";
                }
            }
            echo $line_break;
            echo $close_html_pre;
        }
    }

    /**
     * Set the option to print the requested data to standard output
     *
     * @param bool $print_on_request Set to TRUE if you want to output the result
     */
    public function setPrintOnRequest($print_on_request = true)
    {
        $this->print_on_request = $print_on_request;
    }

    /**
     * Check if the object is configured to print the result to standard output
     *
     * @return bool Print the returned data to the standard output?
     */
    public function getPrintOnRequest()
    {
        return $this->print_on_request;
    }

    /**
     * Output the result if the requested data format is json or xml, or print_r if is an array
     */
    public function printRequest()
    {
        if (($this->getReturnFormat() == 'json') || ($this->getReturnFormat() == 'xml')) {
            if (empty($this->output_header)) {
                if ($this->getReturnFormat() == 'json') {
                    header('Content-Type: application/json');
                } elseif ($this->getReturnFormat() == 'xml') {
                    header('Content-Type: application/xml');
                }
            }
            echo $this->getData();
        } else {
            print_r($this->getData());
        }
    }

    /**
     * Make the request
     *
     * @param string $function A Moodle function
     * @param array $parameters The parameters to be passed to the Moodle function. eg: array('groupids' => array(1,2)) | This translates as "groupids[0]=1&groupids[1]=2" in URL
     *
     * @return mixed The final requested data
     */
    public function request($function, $parameters = null, $method = self::METHOD_GET)
    {
        if (empty($this->server_address)) {
            throw new Exception('MoodleRest: Empty server address. Use setServerAddress() or put the address on constructor.');
        }
        if (empty($this->token)) {
            throw new Exception('MoodleRest: Empty token. Use setToken() or put the token on constructor.');
        }
        if (empty($this->return_format)) {
            throw new Exception('MoodleRest: Empty return format. Use setReturnFormat().');
        }
        if (empty($function)) {
            throw new Exception('MoodleRest: Empty function. Fill the first parameter of request().');
        }
        if (!is_null($parameters)) {
            if (!is_array($parameters)) {
                throw new Exception('MoodleRest: The second parameter of request() should be an array.');
            }
        }

        if ($this->getReturnFormat() == 'array' || $this->getReturnFormat() == 'json') {
            $return_format = 'json';
        } else {
            $return_format = 'xml';
        }

        $this->setMethod($method);

        $query_string = is_array($parameters) ? http_build_query($parameters) : '';

        $this->setUrl(
            $this->getServerAddress() .
            '?wstoken=' . $this->getToken() .
            '&moodlewsrestformat=' . $return_format .
            '&wsfunction=' . $function .
            '&' . $query_string
        );

        $post_url =
            $this->getServerAddress() .
            '?wstoken=' . $this->getToken() .
            '&moodlewsrestformat=' . $return_format .
            '&wsfunction=' . $function;

        if ($this->getMethod() != self::METHOD_POST) {
            // GET
            $moodle_request = file_get_contents($this->getUrl(false));

            if ($moodle_request === false) {
                throw new Exception('MoodleRest: Error trying to connect to Moodle server on GET request. Check PHP warning messages.');
            }

            $this->debug($this->getUrl(), $function, self::METHOD_GET, $moodle_request);
        } else {
            // POST
            $options = array('http' =>
                array(
                    'method'  => 'POST',
                    'header'  => 'Content-type: application/x-www-form-urlencoded',
                    'content' => $query_string
                )
            );
            $context = stream_context_create($options);
            $moodle_request = file_get_contents($post_url, false, $context);

            if ($moodle_request === false) {
                throw new Exception('MoodleRest: Error trying to connect to Moodle server on POST request. Check PHP warning messages.');
            }

            $this->debug($this->getUrl(), $function, self::METHOD_POST, $moodle_request);
        }

        $this->setRawData($moodle_request);

        if ($this->getReturnFormat() == 'array') {
            $this->setData(json_decode($moodle_request, true));
        } else {
            $this->setData($moodle_request);
        }

        if ($this->getPrintOnRequest()) {
            $this->printRequest();
        }

        return $this->getData();
    }
}