<?php
// This file is part of the customcert module for Moodle - http://moodle.org/
//
// Moodle 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 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * This file contains the customcert element QR code's core interaction API.
 *
 * @package    customcertelement_qrcode
 * @copyright  2019 Mark Nelson <markn@moodle.com>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

namespace customcertelement_qrcode;

defined('MOODLE_INTERNAL') || die();

require_once($CFG->libdir . '/tcpdf/tcpdf_barcodes_2d.php');

/**
 * The customcert element QR code's core interaction API.
 *
 * @package    customcertelement_qrcode
 * @copyright  2019 Mark Nelson <markn@moodle.com>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class element extends \mod_customcert\element {
    /**
     * @var string The barcode type.
     */
    const BARCODETYPE = 'QRCODE';

    /**
     * This function renders the form elements when adding a customcert element.
     *
     * @param \MoodleQuickForm $mform the edit_form instance
     */
    public function render_form_elements($mform) {
        \mod_customcert\element_helper::render_form_element_width($mform);

        \mod_customcert\element_helper::render_form_element_height($mform);

        if ($this->showposxy) {
            \mod_customcert\element_helper::render_form_element_position($mform);
        }
    }

    /**
     * Performs validation on the element values.
     *
     * @param array $data the submitted data
     * @param array $files the submitted files
     * @return array the validation errors
     */
    public function validate_form_elements($data, $files) {
        // Array to return the errors.
        $errors = [];

        // Validate the width.
        $errors += \mod_customcert\element_helper::validate_form_element_width($data, false);

        // Validate the height.
        $errors += \mod_customcert\element_helper::validate_form_element_height($data, false);

        if ($this->showposxy) {
            $errors += \mod_customcert\element_helper::validate_form_element_position($data);
        }

        return $errors;
    }

    /**
     * This will handle how form data will be saved into the data column in the
     * customcert_elements table.
     *
     * @param \stdClass $data the form data
     * @return string the json encoded array
     */
    public function save_unique_data($data) {
        $arrtostore = [
            'width' => !empty($data->width) ? (int)$data->width : 0,
            'height' => !empty($data->height) ? (int)$data->height : 0,
        ];

        return json_encode($arrtostore);
    }

    /**
     * Sets the data on the form when editing an element.
     *
     * @param \MoodleQuickForm $mform the edit_form instance
     */
    public function definition_after_data($mform) {
        parent::definition_after_data($mform);

        // Set the image, width, height and alpha channel for this element.
        if (!empty($this->get_data())) {
            $imageinfo = json_decode($this->get_data());

            if (!empty($imageinfo->height)) {
                $element = $mform->getElement('height');
                $element->setValue($imageinfo->height);
            }
        }
    }

    /**
     * Handles rendering the element on the pdf.
     *
     * @param \pdf $pdf the pdf object
     * @param bool $preview true if it is a preview, false otherwise
     * @param \stdClass $user the user we are rendering this for
     */
    public function render($pdf, $preview, $user) {
        global $DB;

        // If there is no element data, we have nothing to display.
        if (empty($this->get_data())) {
            return;
        }

        $imageinfo = json_decode($this->get_data());

        if ($preview) {
            // Generate the URL to verify this.
            $qrcodeurl = new \moodle_url('/');
            $qrcodeurl = $qrcodeurl->out(false);
        } else {
            // Get the information we need.
            $sql = "SELECT c.id, c.verifyany, ct.contextid, ci.code
                      FROM {customcert_issues} ci
                      JOIN {customcert} c
                        ON ci.customcertid = c.id
                      JOIN {customcert_templates} ct
                        ON c.templateid = ct.id
                      JOIN {customcert_pages} cp
                        ON cp.templateid = ct.id
                     WHERE ci.userid = :userid
                       AND cp.id = :pageid";

            // Now we can get the issue for this user.
            $issue = $DB->get_record_sql(
                $sql,
                ['userid' => $user->id, 'pageid' => $this->get_pageid()],
                '*',
                MUST_EXIST
            );
            $code = $issue->code;

            $context = \context::instance_by_id($issue->contextid);

            $urlparams = [
                'code' => $code,
                'qrcode' => 1,
            ];

            // We only add the 'contextid' to the link if the site setting for verifying all certificates is off,
            // or if the individual certificate doesn't allow verification. However, if the user has the
            // mod/customcert:verifyallcertificates then they can verify anything regardless.
            $verifyallcertificatessitesetting = get_config('customcert', 'verifyallcertificates');
            $verifycertificateactivitysettings = $issue->verifyany;
            $canverifyallcertificates = has_capability('mod/customcert:verifyallcertificates', $context);
            if (
                (!$verifyallcertificatessitesetting || !$verifycertificateactivitysettings)
                    && !$canverifyallcertificates
            ) {
                $urlparams['contextid'] = $issue->contextid;
            }

            $qrcodeurl = new \moodle_url('/mod/customcert/verify_certificate.php', $urlparams);
            $qrcodeurl = $qrcodeurl->out(false);
        }

        $barcode = new \TCPDF2DBarcode($qrcodeurl, self::BARCODETYPE);
        $image = $barcode->getBarcodePngData($imageinfo->width, $imageinfo->height);

        $location = make_request_directory() . '/target';
        file_put_contents($location, $image);

        $pdf->Image($location, $this->get_posx(), $this->get_posy(), $imageinfo->width, $imageinfo->height);
    }

    /**
     * Render the element in html.
     *
     * This function is used to render the element when we are using the
     * drag and drop interface to position it.
     *
     * @return string the html
     */
    public function render_html() {
        // If there is no element data, we have nothing to display.
        if (empty($this->get_data())) {
            return;
        }

        $imageinfo = json_decode($this->get_data());

        $qrcodeurl = new \moodle_url('/');
        $qrcodeurl = $qrcodeurl->out(false);

        $barcode = new \TCPDF2DBarcode($qrcodeurl, self::BARCODETYPE);
        return $barcode->getBarcodeHTML($imageinfo->width / 10, $imageinfo->height / 10);
    }
}
