class CTA_Dashboard {

    public function __construct() {
        add_action('admin_menu', [$this, 'menu']);
    }

    /* =====================================================
     * MENU
     * ===================================================== */
    public function menu() {
        add_menu_page(
            'CTA Analytics',
            'CTA Analytics',
            'manage_options',
            'cta-analytics',
            [$this, 'render_router'],
            'dashicons-chart-line',
            26
        );
    }

    /* =====================================================
     * ROUTER (dashboard / detail)
     * ===================================================== */
    public function render_router() {

        if (!empty($_GET['cta_key'])) {
            $this->render_detail();
        } else {
            $this->render_dashboard();
        }
    }

    /* =====================================================
     * DASHBOARD
     * ===================================================== */
    public function render_dashboard() {

        global $wpdb;
        $table = $wpdb->prefix . 'cta_stats';

        $from = $_GET['from'] ?? date('Y-m-07');
        $to   = $_GET['to'] ?? date('Y-m-d');

        $rows = $wpdb->get_results($wpdb->prepare("
            SELECT 
                cta_key,
                SUM(views) as views,
                SUM(clicks) as clicks,
                ROUND(SUM(clicks)/SUM(views)*100,2) as ctr
            FROM $table
            WHERE created_date BETWEEN %s AND %s
            GROUP BY cta_key
            HAVING views > 0
            ORDER BY clicks DESC
            LIMIT 50
        ", $from, $to));

        echo '<div class="wrap">';
        echo '<h1>📊 CTA Analytics</h1>';

        echo '<table class="widefat striped">';
        echo '<thead><tr>
            <th>CTA Key</th>
            <th>Views</th>
            <th>Clicks</th>
            <th>CTR (%)</th>
            <th>URL</th>
        </tr></thead><tbody>';

        if ($rows) {
            foreach ($rows as $r) {

                $link = admin_url('admin.php?page=cta-analytics&cta_key=' . urlencode($r->cta_key));

                echo "<tr>
                    <td><strong>{$r->cta_key}</strong></td>
                    <td>{$r->views}</td>
                    <td>{$r->clicks}</td>
                    <td>{$r->ctr}%</td>
                    <td><a href='{$link}' class='button'>Xem link</a></td>
                </tr>";
            }
        } else {
            echo '<tr><td colspan="5">Không có dữ liệu</td></tr>';
        }

        echo '</tbody></table>';
        echo '</div>';
    }

    /* =====================================================
     * DETAIL PAGE (LIST URL)
     * ===================================================== */
    private function render_detail() {

        global $wpdb;
        $table = $wpdb->prefix . 'cta_stats';

        $cta_key = sanitize_text_field($_GET['cta_key']);

        // ===== PAGINATION =====
        $paged = max(1, intval($_GET['paged'] ?? 1));
        $per_page = 20;
        $offset = ($paged - 1) * $per_page;

        // ===== TOTAL =====
        $total = $wpdb->get_var($wpdb->prepare("
            SELECT COUNT(DISTINCT post_url)
            FROM $table
            WHERE cta_key = %s
        ", $cta_key));

        // ===== DATA =====
        $rows = $wpdb->get_results($wpdb->prepare("
            SELECT 
                post_url,
                MAX(post_title) as post_title,
                SUM(views) as views,
                SUM(clicks) as clicks
            FROM $table
            WHERE cta_key = %s
            GROUP BY post_url
            ORDER BY clicks DESC
            LIMIT %d OFFSET %d
        ", $cta_key, $per_page, $offset));

        echo '<div class="wrap">';
        echo "<h1>🔗 Danh sách URL – {$cta_key}</h1>";

        echo '<a href="'.admin_url('admin.php?page=cta-analytics').'" class="button">← Quay lại</a><br><br>';

        echo '<table class="widefat striped">';
        echo '<thead><tr>
            <th>Tiêu đề</th>
            <th>URL</th>
            <th>Views</th>
            <th>Clicks</th>
        </tr></thead><tbody>';

        if ($rows) {
            foreach ($rows as $r) {
                echo "<tr>
                    <td>{$r->post_title}</td>
                    <td><a href='{$r->post_url}' target='_blank'>{$r->post_url}</a></td>
                    <td>{$r->views}</td>
                    <td>{$r->clicks}</td>
                </tr>";
            }
        } else {
            echo '<tr><td colspan="4">Không có dữ liệu</td></tr>';
        }

        echo '</tbody></table>';

        // ===== PAGINATION =====
        $total_pages = ceil($total / $per_page);

        if ($total_pages > 1) {
            echo '<div style="margin-top:15px;">';

            for ($i = 1; $i <= $total_pages; $i++) {

                $url = admin_url('admin.php?page=cta-analytics&cta_key=' . urlencode($cta_key) . '&paged=' . $i);

                $active = ($i == $paged) ? 'style="font-weight:bold;"' : '';

                echo "<a {$active} href='{$url}' class='button' style='margin-right:5px;'>{$i}</a>";
            }

            echo '</div>';
        }

        echo '</div>';
    }
}