<?php

if (!defined('ABSPATH')) {
    exit;
}

class KGV_Termine_Plugin {
    private static $instance = null;
    private $table_name;

    public static function instance() {
        if (self::$instance === null) {
            self::$instance = new self();
        }
        return self::$instance;
    }

    private function __construct() {
        global $wpdb;
        $this->table_name = $wpdb->prefix . KGV_TERMINE_TABLE;

        register_activation_hook(KGV_TERMINE_FILE, array($this, 'activate'));

        add_action('admin_menu', array($this, 'register_admin_menu'));
        add_action('admin_enqueue_scripts', array($this, 'enqueue_admin_assets'));
        add_action('wp_enqueue_scripts', array($this, 'enqueue_front_assets'));
        add_action('init', array($this, 'register_shortcodes'));
        add_action('init', array($this, 'maybe_upgrade_table'));
        add_action('admin_post_kgv_save_termin', array($this, 'handle_save_termin'));
        add_action('admin_post_kgv_delete_termin', array($this, 'handle_delete_termin'));
        add_filter('query_vars', array($this, 'register_query_vars'));
    }

    public function activate() {
        $this->create_table();
    }

    private function create_table() {
        global $wpdb;

        require_once ABSPATH . 'wp-admin/includes/upgrade.php';

        $charset_collate = $wpdb->get_charset_collate();
        $sql = "CREATE TABLE {$this->table_name} (
            id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
            title VARCHAR(255) NOT NULL,
            event_date DATETIME NOT NULL,
            owner VARCHAR(255) NULL,
            location VARCHAR(255) NULL,
            summary TEXT NULL,
            description LONGTEXT NULL,
            is_published TINYINT(1) NOT NULL DEFAULT 1,
            created_at DATETIME NOT NULL,
            updated_at DATETIME NOT NULL,
            post_id BIGINT UNSIGNED NULL DEFAULT NULL,
            PRIMARY KEY (id),
            KEY event_date (event_date),
            KEY is_published (is_published)
        ) {$charset_collate};";

        dbDelta($sql);
    }

    public function maybe_upgrade_table() {
        global $wpdb;

        $col = $wpdb->get_results(
            $wpdb->prepare(
                "SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA = %s AND TABLE_NAME = %s AND COLUMN_NAME = 'post_id'",
                DB_NAME,
                $this->table_name
            )
        );

        if ( empty( $col ) ) {
            require_once ABSPATH . 'wp-admin/includes/upgrade.php';
            $charset_collate = $wpdb->get_charset_collate();
            $sql = "CREATE TABLE {$this->table_name} (
                id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
                title VARCHAR(255) NOT NULL,
                event_date DATETIME NOT NULL,
                owner VARCHAR(255) NULL,
                location VARCHAR(255) NULL,
                summary TEXT NULL,
                description LONGTEXT NULL,
                is_published TINYINT(1) NOT NULL DEFAULT 1,
                created_at DATETIME NOT NULL,
                updated_at DATETIME NOT NULL,
                post_id BIGINT UNSIGNED NULL DEFAULT NULL,
                PRIMARY KEY (id),
                KEY event_date (event_date),
                KEY is_published (is_published)
            ) {$charset_collate};";
            dbDelta($sql);
        }
    }

    public function enqueue_admin_assets($hook) {
        if (strpos((string) $hook, 'kgv-termine') === false) {
            return;
        }

        wp_enqueue_style(
            'kgv-termine-admin-style',
            KGV_TERMINE_URL . 'assets/css/admin.css',
            array(),
            '1.0.2'
        );
    }

    public function enqueue_front_assets() {
        wp_enqueue_style(
            'kgv-termine-front-style',
            KGV_TERMINE_URL . 'assets/css/front.css',
            array(),
            '1.0.2'
        );
    }

    public function register_query_vars($vars) {
        $vars[] = 'kgv_termin';
        return $vars;
    }

    public function register_admin_menu() {
        add_menu_page(
            'Termine',
            'Termine',
            'manage_options',
            'kgv-termine',
            array($this, 'render_list_page'),
            'dashicons-calendar-alt',
            25
        );

        add_submenu_page(
            'kgv-termine',
            'Alle Termine',
            'Alle Termine',
            'manage_options',
            'kgv-termine',
            array($this, 'render_list_page')
        );

        add_submenu_page(
            'kgv-termine',
            'Neuer Termin',
            'Neuer Termin',
            'manage_options',
            'kgv-termine-new',
            array($this, 'render_form_page')
        );
    }

    public function register_shortcodes() {
        add_shortcode('kgv_termine', array($this, 'render_termine_shortcode'));
        add_shortcode('kgv_termin_detail', array($this, 'render_detail_shortcode'));
        add_shortcode('kgv_termine_sidebar', array($this, 'render_sidebar_shortcode'));
    }

    public function handle_save_termin() {
        if (!current_user_can('manage_options')) {
            wp_die('Keine Berechtigung.');
        }

        check_admin_referer('kgv_save_termin');
        $this->save_termin_from_request();
    }

    public function handle_delete_termin() {
        if (!current_user_can('manage_options')) {
            wp_die('Keine Berechtigung.');
        }

        $id = isset($_GET['termin_id']) ? absint($_GET['termin_id']) : 0;

        if (!$id || !isset($_GET['_wpnonce']) || !wp_verify_nonce(sanitize_text_field(wp_unslash($_GET['_wpnonce'])), 'kgv_delete_termin_' . $id)) {
            wp_safe_redirect(admin_url('admin.php?page=kgv-termine&message=delete_failed'));
            exit;
        }

        global $wpdb;
        $wpdb->delete($this->table_name, array('id' => $id), array('%d'));
        wp_safe_redirect(admin_url('admin.php?page=kgv-termine&message=deleted'));
        exit;
    }

    private function save_termin_from_request() {
        global $wpdb;

        $id = isset($_POST['termin_id']) ? absint($_POST['termin_id']) : 0;
        $title = sanitize_text_field(wp_unslash($_POST['title'] ?? ''));
        $event_date = sanitize_text_field(wp_unslash($_POST['event_date'] ?? ''));
        $owner = sanitize_text_field(wp_unslash($_POST['owner'] ?? ''));
        $location = sanitize_text_field(wp_unslash($_POST['location'] ?? ''));
        $summary = sanitize_textarea_field(wp_unslash($_POST['summary'] ?? ''));
        $description = wp_kses_post(wp_unslash($_POST['description'] ?? ''));
        $is_published = isset($_POST['is_published']) ? (int) wp_unslash($_POST['is_published']) : 1;
        $is_published = $is_published === 1 ? 1 : 0;
        $post_id = isset($_POST['post_id']) ? absint($_POST['post_id']) : 0;
        $post_id = $post_id > 0 ? $post_id : null;

        if ($title === '' || $event_date === '' || strtotime($event_date) === false) {
            $target = $id ? admin_url('admin.php?page=kgv-termine-new&termin_id=' . $id . '&message=missing') : admin_url('admin.php?page=kgv-termine-new&message=missing');
            wp_safe_redirect($target);
            exit;
        }

        $mysql_date = date('Y-m-d H:i:s', strtotime($event_date));
        $now = current_time('mysql');

        $data = array(
            'title' => $title,
            'event_date' => $mysql_date,
            'owner' => $owner,
            'location' => $location,
            'summary' => $summary,
            'description' => $description,
            'is_published' => $is_published,
            'post_id' => $post_id,
            'updated_at' => $now,
        );

        $formats = array('%s', '%s', '%s', '%s', '%s', '%s', '%d', '%d', '%s');

        if ($id) {
            $wpdb->update($this->table_name, $data, array('id' => $id), $formats, array('%d'));
            wp_safe_redirect(admin_url('admin.php?page=kgv-termine&message=updated'));
            exit;
        }

        $data['created_at'] = $now;
        $wpdb->insert($this->table_name, $data, array('%s', '%s', '%s', '%s', '%s', '%s', '%d', '%d', '%s', '%s'));

        wp_safe_redirect(admin_url('admin.php?page=kgv-termine&message=created'));
        exit;
    }

    public function render_list_page() {
        global $wpdb;

        $rows = $wpdb->get_results("SELECT * FROM {$this->table_name} ORDER BY event_date ASC, id ASC");
        $message = isset($_GET['message']) ? sanitize_text_field(wp_unslash($_GET['message'])) : '';
        ?>
        <div class="wrap kgv-admin-wrap">
            <div class="kgv-admin-header">
                <h1>Termine</h1>
                <a href="<?php echo esc_url(admin_url('admin.php?page=kgv-termine-new')); ?>" class="page-title-action">Neuen Termin anlegen</a>
            </div>

            <?php $this->render_notice($message); ?>

            <div class="kgv-admin-card">
                <table class="widefat striped kgv-admin-table">
                    <thead>
                        <tr>
                            <th>Titel</th>
                            <th>Datum</th>
                            <th>Verantwortlich</th>
                            <th>Ort</th>
                            <th>Status</th>
                            <th>Aktionen</th>
                        </tr>
                    </thead>
                    <tbody>
                    <?php if (empty($rows)) : ?>
                        <tr>
                            <td colspan="6">Noch keine Termine angelegt.</td>
                        </tr>
                    <?php else : ?>
                        <?php foreach ($rows as $row) : ?>
                            <tr>
                                <td><strong><?php echo esc_html($row->title); ?></strong></td>
                                <td><?php echo esc_html(wp_date('d.m.Y H:i', strtotime($row->event_date))); ?></td>
                                <td><?php echo esc_html($row->owner ?: '—'); ?></td>
                                <td><?php echo esc_html($row->location ?: '—'); ?></td>
                                <td><?php echo (int) $row->is_published === 1 ? 'Veröffentlicht' : 'Entwurf'; ?></td>
                                <td>
                                    <a href="<?php echo esc_url(admin_url('admin.php?page=kgv-termine-new&termin_id=' . (int) $row->id)); ?>">Bearbeiten</a>
                                    |
                                    <a href="<?php echo esc_url(wp_nonce_url(admin_url('admin-post.php?action=kgv_delete_termin&termin_id=' . (int) $row->id), 'kgv_delete_termin_' . (int) $row->id)); ?>" onclick="return confirm('Termin wirklich löschen?');">Löschen</a>
                                </td>
                            </tr>
                        <?php endforeach; ?>
                    <?php endif; ?>
                    </tbody>
                </table>
            </div>
        </div>
        <?php
    }

    public function render_form_page() {
        global $wpdb;

        $id = isset($_GET['termin_id']) ? absint($_GET['termin_id']) : 0;
        $message = isset($_GET['message']) ? sanitize_text_field(wp_unslash($_GET['message'])) : '';
        $row = null;

        if ($id) {
            $row = $wpdb->get_row($wpdb->prepare("SELECT * FROM {$this->table_name} WHERE id = %d", $id));
        }

        $title = $row ? $row->title : '';
        $event_date = $row ? date('Y-m-d\TH:i', strtotime($row->event_date)) : '';
        $owner = $row ? $row->owner : '';
        $location = $row ? $row->location : '';
        $summary = $row ? $row->summary : '';
        $description = $row ? $row->description : '';
        $is_published = $row ? (int) $row->is_published : 1;
        $post_id = $row && !empty($row->post_id) ? (int) $row->post_id : 0;
        $posts = get_posts(array('post_type' => 'post', 'post_status' => 'publish', 'numberposts' => -1, 'orderby' => 'title', 'order' => 'ASC'));
        ?>
        <div class="wrap kgv-admin-wrap">
            <div class="kgv-admin-header">
                <h1><?php echo $id ? 'Termin bearbeiten' : 'Neuen Termin anlegen'; ?></h1>
            </div>

            <?php $this->render_notice($message); ?>

            <form method="post" action="<?php echo esc_url(admin_url('admin-post.php')); ?>" class="kgv-admin-form">
                <?php wp_nonce_field('kgv_save_termin'); ?>
                <input type="hidden" name="action" value="kgv_save_termin">
                <input type="hidden" name="termin_id" value="<?php echo esc_attr($id); ?>">

                <div class="kgv-admin-card">
                    <div class="kgv-form-grid">
                        <div class="kgv-form-field kgv-form-field-full">
                            <label for="kgv-title">Titel</label>
                            <input type="text" id="kgv-title" name="title" value="<?php echo esc_attr($title); ?>" required>
                        </div>

                        <div class="kgv-form-field">
                            <label for="kgv-event-date">Datum / Uhrzeit</label>
                            <input type="datetime-local" id="kgv-event-date" name="event_date" value="<?php echo esc_attr($event_date); ?>" required>
                        </div>

                        <div class="kgv-form-field">
                            <label for="kgv-owner">Verantwortlich</label>
                            <input type="text" id="kgv-owner" name="owner" value="<?php echo esc_attr($owner); ?>">
                        </div>

                        <div class="kgv-form-field">
                            <label for="kgv-location">Ort</label>
                            <input type="text" id="kgv-location" name="location" value="<?php echo esc_attr($location); ?>">
                        </div>

                        <div class="kgv-form-field">
                            <label for="kgv-published">Status</label>
                            <select id="kgv-published" name="is_published">
                                <option value="1" <?php selected($is_published, 1); ?>>Veröffentlicht</option>
                                <option value="0" <?php selected($is_published, 0); ?>>Entwurf</option>
                            </select>
                        </div>

                        <div class="kgv-form-field">
                            <label for="kgv-post-id">Verknüpfter Beitrag</label>
                            <select id="kgv-post-id" name="post_id">
                                <option value="0">— kein Beitrag —</option>
                                <?php foreach ($posts as $p) : ?>
                                    <option value="<?php echo esc_attr($p->ID); ?>" <?php selected($post_id, $p->ID); ?>><?php echo esc_html($p->post_title); ?></option>
                                <?php endforeach; ?>
                            </select>
                        </div>

                        <div class="kgv-form-field kgv-form-field-full">
                            <label for="kgv-summary">Kurzbeschreibung</label>
                            <textarea id="kgv-summary" name="summary" rows="3"><?php echo esc_textarea($summary); ?></textarea>
                        </div>

                        <div class="kgv-form-field kgv-form-field-full">
                            <label for="kgv-description">Detailbeschreibung</label>
                            <textarea id="kgv-description" name="description" rows="8"><?php echo esc_textarea($description); ?></textarea>
                        </div>
                    </div>
                </div>

                <div class="kgv-admin-actions">
                    <button type="submit" class="button button-primary">Termin speichern</button>
                    <a href="<?php echo esc_url(admin_url('admin.php?page=kgv-termine')); ?>" class="button">Abbrechen</a>
                </div>
            </form>
        </div>
        <?php
    }

    private function render_notice($message) {
        $map = array(
            'created' => array('success', 'Termin wurde angelegt.'),
            'updated' => array('success', 'Termin wurde aktualisiert.'),
            'deleted' => array('success', 'Termin wurde gelöscht.'),
            'delete_failed' => array('error', 'Termin konnte nicht gelöscht werden.'),
            'missing' => array('error', 'Titel und Datum sind Pflichtfelder.'),
        );

        if (!isset($map[$message])) {
            return;
        }

        list($type, $text) = $map[$message];
        printf('<div class="notice notice-%1$s is-dismissible"><p>%2$s</p></div>', esc_attr($type), esc_html($text));
    }

    private function get_frontend_rows($limit = 0) {
        global $wpdb;

        if ($limit > 0) {
            return $wpdb->get_results($wpdb->prepare(
                "SELECT * FROM {$this->table_name} WHERE is_published = 1 ORDER BY event_date ASC, id ASC LIMIT %d",
                $limit
            ));
        }

        return $wpdb->get_results("SELECT * FROM {$this->table_name} WHERE is_published = 1 ORDER BY event_date ASC, id ASC");
    }

    private function get_row($id) {
        global $wpdb;
        return $wpdb->get_row($wpdb->prepare("SELECT * FROM {$this->table_name} WHERE id = %d", $id));
    }

    public function render_termine_shortcode($atts) {
        $atts = shortcode_atts(array(
            'limit' => 0,
            'detail' => 1,
            'base_url' => '',
        ), $atts, 'kgv_termine');

        $detail_id = absint(get_query_var('kgv_termin'));
        if (!$detail_id && isset($_GET['kgv_termin'])) {
            $detail_id = absint(wp_unslash($_GET['kgv_termin']));
        }

        $base_url = $this->resolve_termine_base_url($atts['base_url']);

        if ($detail_id && (int) $atts['detail'] === 1) {
            return $this->render_detail_by_id($detail_id, $base_url);
        }

        $rows = $this->get_frontend_rows(absint($atts['limit']));

        if (empty($rows)) {
            return '<div class="kgv-termine-empty">Aktuell sind keine Termine verfügbar.</div>';
        }

        ob_start();
        echo '<div class="kgv-termine-wrap">';
        foreach ($rows as $row) {
            $link = add_query_arg('kgv_termin', (int) $row->id, $base_url);
            echo '<article class="kgv-termin-card">';
            echo '<div class="kgv-termin-card-inner">';
            echo '<div class="kgv-termin-datebox">' . esc_html(wp_date('d.m.Y H:i', strtotime($row->event_date))) . '</div>';
            echo '<h3 class="kgv-termin-title">' . esc_html($row->title) . '</h3>';
            echo '<div class="kgv-termin-meta">';
            if (!empty($row->owner)) {
                echo '<span>Verantwortlich: ' . esc_html($row->owner) . '</span>';
            }
            if (!empty($row->location)) {
                echo '<span>Ort: ' . esc_html($row->location) . '</span>';
            }
            echo '</div>';
            if (!empty($row->summary)) {
                echo '<div class="kgv-termin-excerpt">' . esc_html($row->summary) . '</div>';
            }
            echo '<div class="kgv-termin-actions"><a class="kgv-termin-btn" href="' . esc_url($link) . '">Details ansehen</a>';
            if (!empty($row->post_id)) {
                $post_url = get_permalink((int) $row->post_id);
                if ($post_url) {
                    echo '<a class="kgv-termin-btn kgv-termin-btn-secondary" href="' . esc_url($post_url) . '">Mehr Infos</a>';
                }
            }
            echo '</div>';
            echo '</div>';
            echo '</article>';
        }
        echo '</div>';
        return ob_get_clean();
    }

    public function render_detail_shortcode($atts) {
        $atts = shortcode_atts(array(
            'id' => 0,
        ), $atts, 'kgv_termin_detail');

        $id = absint($atts['id']);
        if (!$id) {
            return '<div class="kgv-termine-notice">Keine Termin-ID übergeben.</div>';
        }

        return $this->render_detail_by_id($id, '');
    }

    private function render_detail_by_id($id, $back_url = '') {
        $row = $this->get_row($id);

        if (!$row || !(int) $row->is_published) {
            return '<div class="kgv-termine-notice">Termin nicht gefunden.</div>';
        }

        ob_start();
        echo '<article class="kgv-termin-single">';
        echo '<div class="kgv-termin-single-hero">';
        if ($back_url) {
            echo '<a class="kgv-termin-back" href="' . esc_url($back_url) . '">← Zurück zur Übersicht</a>';
        }
        echo '<div class="kgv-termin-datebox">' . esc_html(wp_date('d.m.Y H:i', strtotime($row->event_date))) . '</div>';
        echo '<h2>' . esc_html($row->title) . '</h2>';
        echo '<div class="kgv-termin-meta">';
        if (!empty($row->owner)) {
            echo '<span>Verantwortlich: ' . esc_html($row->owner) . '</span>';
        }
        if (!empty($row->location)) {
            echo '<span>Ort: ' . esc_html($row->location) . '</span>';
        }
        echo '</div>';
        echo '</div>';
        echo '<div class="kgv-termin-single-inner">';
        if (!empty($row->summary)) {
            echo '<p class="kgv-termin-summary"><strong>' . esc_html($row->summary) . '</strong></p>';
        }
        echo '<div class="kgv-termin-content">' . wpautop(wp_kses_post($row->description)) . '</div>';
        if (!empty($row->post_id)) {
            $post_url = get_permalink((int) $row->post_id);
            if ($post_url) {
                echo '<div class="kgv-termin-more-info"><a class="kgv-termin-btn" href="' . esc_url($post_url) . '">Mehr Infos</a></div>';
            }
        }
        echo '</div>';
        echo '</article>';
        return ob_get_clean();
    }


public function render_sidebar_shortcode($atts) {
    $atts = shortcode_atts(array(
        'limit' => 5,
        'base_url' => '',
    ), $atts, 'kgv_termine_sidebar');

    $rows = $this->get_frontend_rows(max(1, min(20, absint($atts['limit']))));

    if (empty($rows)) {
        return '<div class="kgv-sidebar-box">Keine Termine</div>';
    }

    $base_url = $this->resolve_termine_base_url($atts['base_url']);

    ob_start();
    echo '<div class="kgv-sidebar-box">';
    echo '<h3 class="kgv-sidebar-title">Nächste Termine</h3>';
    echo '<div class="kgv-sidebar-list">';

    foreach ($rows as $row) {
        $link = add_query_arg('kgv_termin', (int) $row->id, $base_url);

        echo '<a class="kgv-sidebar-item" href="' . esc_url($link) . '">';
        echo '<span class="kgv-sidebar-date">' . esc_html(wp_date('d.m.Y', strtotime($row->event_date))) . '</span>';
        echo '<span class="kgv-sidebar-text">' . esc_html($row->title) . '</span>';
        echo '</a>';
    }

    echo '</div>';
    echo '</div>';

    return ob_get_clean();
}

    private function resolve_termine_base_url($base_url = '') {
        if (!empty($base_url)) {
            $clean_url = esc_url_raw((string) $base_url);
            if ($clean_url) {
                return remove_query_arg(array_keys($_GET), $clean_url);
            }
        }

        $shortcode_page_url = $this->find_termine_shortcode_page_url();
        if ($shortcode_page_url) {
            return $shortcode_page_url;
        }

        return $this->get_current_page_url(false);
    }

    private function find_termine_shortcode_page_url() {
        static $cached_url = null;

        if (null !== $cached_url) {
            return $cached_url;
        }

        global $wpdb;

        $like = '%' . $wpdb->esc_like('[kgv_termine') . '%';
        $post_id = (int) $wpdb->get_var(
            $wpdb->prepare(
                "SELECT ID
                FROM {$wpdb->posts}
                WHERE post_status = 'publish'
                    AND post_type IN ('page', 'post')
                    AND post_content LIKE %s
                ORDER BY CASE WHEN post_type = 'page' THEN 0 ELSE 1 END, ID ASC
                LIMIT 1",
                $like
            )
        );

        if ($post_id) {
            $permalink = get_permalink($post_id);
            if ($permalink) {
                $cached_url = remove_query_arg(array_keys($_GET), $permalink);
                return $cached_url;
            }
        }

        $cached_url = '';
        return $cached_url;
    }

    private function get_current_page_url($with_query = true) {
        $page_url = '';

        if (is_singular() && get_queried_object_id()) {
            $page_url = get_permalink(get_queried_object_id());
        }

        if (!$page_url) {
            global $wp;
            $page_url = home_url(add_query_arg(array(), $wp->request ? '/' . ltrim($wp->request, '/') . '/' : '/'));
        }

        if (!$with_query) {
            return remove_query_arg(array_keys($_GET), $page_url);
        }

        return $page_url;
    }
}