renderer.php

<?php
// This file is part of 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/>.

/**
 * Renderer for local_helloworld
 *
 *
 * @package    local_helloworld
 * @copyright  2020 Jakub Kleban <jakub.kleban2000@gmail.com>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die;

/**
 * Renderer for displaying local_helloworld as HTML
 *
 * @package    local_helloworld
 * @copyright  2020 Jakub Kleban <jakub.kleban2000@gmail.com>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class local_helloworld_renderer extends plugin_renderer_base {

    /**
     * Generates html to display script
     *
     * @param string $url URL of index.php
     * @return string
     */
    public function display_script($url) {
        $output = '';
        $context = context_system::instance();

        if (has_capability('local/helloworld:postmessages', $context)) {
            $output .= $this->message_input($url);
        }

        if (has_capability('local/helloworld:viewmessages', $context)) {
            $output .= $this->display_messages($url);
        }

        $output .= $this->footer($url);

        return $output;
    }

    /**
     * Generate html to make textarea message form
     *
     * @param string $url URL of index.php
     * @return string Form for message-textarea
     */
    private function message_input($url) {
        $output = '';

        $output .= html_writer::start_tag('form', array(
                'method' => 'post',
                'action' => $url
        ));
            $output .= html_writer::start_div('form-group');
                $output .= html_writer::label(get_string('typemessage', 'local_helloworld'), 'messagetextarea');
                $output .= html_writer::empty_tag('input', array(
                    'type' => 'hidden',
                    'name' => 'sesskey',
                    'value' => sesskey()
                ));
                $output .= html_writer::tag('textarea', '', array(
                        'class' => 'form-control',
                        'id' => 'messagetextarea',
                        'rows' => 5,
                        'name' => 'message'
                ));
            $output .= html_writer::end_div();
            $output .= html_writer::tag('button', get_string('messageselectadd', 'core_moodle') , array(
                    'type' => 'submit',
                    'class' => 'btn btn-primary rounded'
            ));
        $output .= html_writer::end_tag('form');

        return $output;
    }

    /**
     * Generate html to display messages
     *
     * @param string $url URL of index.php
     * @return string html for displaying messages
     */
    private function display_messages(string $url) {
        global $DB;

        $output = '';

        $output .= $this->make_break();

        $output .= html_writer::start_div('card-columns');

        $userfields = get_all_user_name_fields(true, 'u');
        $sql = "SELECT m.id, m.message, m.timecreated, u.id AS userid, $userfields
                FROM {local_helloworld_messages} m
                LEFT JOIN {user} u ON u.id = m.userid
                ORDER BY timemodified DESC";
        $messages = $DB->get_records_sql($sql);

        foreach ($messages as $message) {
            $now = new DateTime('now', core_date::get_server_timezone_object());
            $timediff = $now->getTimestamp() - $message->timecreated;
            $formatedtime = format_time($timediff);
            $lastupdated = get_string('lastupdated', 'local_helloworld', $formatedtime);
            $id = $message->id;

            $output .= $this->display_message($url, $id, fullname($message) , $message->message, $lastupdated);
        }

        $output .= html_writer::end_div();

        return $output;
    }

    /**
     * Generate html to display one message
     *
     * @param string $url URL of index.php
     * @param int $id Id of message
     * @param string $fullname Full name of author
     * @param string $message Content of the message
     * @param string $lastupdated Formated text displaying how long ago was the message created
     * @return string html for displaying one message
     */
    private function display_message(string $url, int $id, string $fullname, string $message, string $lastupdated) {
        $output = '';
        $context = context_system::instance();

        $output .= html_writer::start_div('card');
            $output .= html_writer::start_div('card-body');
                $output .= html_writer::start_tag('h5', array(
                        'class' => 'card-title d-flex justify-content-between'
                ));
                    $output .= $fullname;

        if (has_capability('local/helloworld:deleteanymessage', $context)) {
            $output .= html_writer::start_tag('form', array(
                    'method' => 'post',
                    'action' => $url
            ));
            $output .= html_writer::empty_tag('input', array(
                'type' => 'hidden',
                'name' => 'sesskey',
                'value' => sesskey()
            ));
            $output .= html_writer::start_tag('button', array(
                    'type' => 'submit',
                    'class' => 'btn btn-danger rounded',
                    'name' => 'deleteid',
                    'value' => $id
            ));
                $output .= html_writer::tag('i', '', array(
                        'class' => 'fa fa-trash',
                        'aria-hidden' => 'true'
                ));
            $output .= html_writer::end_tag('button');
            $output .= html_writer::end_tag('form');
        }
                $output .= html_writer::end_tag('h5');
                $output .= html_writer::tag('p', $message, array(
                        'class' => 'card-text'
                ));
                $output .= html_writer::start_tag('p', array(
                        'class' => 'card-text'
                ));
                    $output .= html_writer::tag('small', $lastupdated , array('class' => 'text-muted'));
                $output .= html_writer::end_tag('p');
            $output .= html_writer::end_div();
        $output .= html_writer::end_div();

        return $output;
    }

    /**
     * Generate html for footer that contain links
     *
     * @param string $url URL of index.php
     * @return string html for footer
     */
    private function footer($url) {
        $output = '';

        $output .= $this->make_break();

        $output .= html_writer::start_tag('ul');
            $output .= html_writer::start_tag('li');
                $output .= html_writer::link(new moodle_url('/'), get_string('backtohome', 'core_moodle'));
            $output .= html_writer::end_tag('li');
            $output .= html_writer::start_tag('li');
                $output .= html_writer::link($url, get_string('backtopageyouwereon', 'core_moodle'));
            $output .= html_writer::end_tag('li');
        $output .= html_writer::end_tag('ul');

        return $output;
    }

    /**
     * Generate html to make a brake between two HTML elements
     *
     * @return string html with break-lines and horizontal-line
     */
    private function make_break() {
        $output = '';

        $output .= html_writer::empty_tag('br');
        $output .= html_writer::empty_tag('hr');
        $output .= html_writer::empty_tag('br');

        return $output;
    }
}