<?php
/**
 * Plugin Name: WordPress Activity Stats
 * Description: Wtyczka do śledzenia statystyk sportowych (Rower, Bieganie, itp.).
 * Version: 1.0
 * Author: Jacek Fefliński
 */

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

// --- 1. INSTALACJA BAZY DANYCH (AKTYWACJA) ---
register_activation_hook( __FILE__, 'mystat_activate' );

function mystat_activate() {
    global $wpdb;
    $charset_collate = $wpdb->get_charset_collate();

    $table_categories = $wpdb->prefix . 'mystat_categories';
    $table_activities = $wpdb->prefix . 'mystat_activities';
    $table_event_types = $wpdb->prefix . 'mystat_event_types';
    $table_equipment = $wpdb->prefix . 'mystat_equipment';

    // SQL dla Kategorii
    $sql_cat = "CREATE TABLE $table_categories (
        id mediumint(9) NOT NULL AUTO_INCREMENT,
        name varchar(50) NOT NULL,
        icon varchar(50) NOT NULL,
        color varchar(20) NOT NULL,
        PRIMARY KEY  (id)
    ) $charset_collate;";

    // SQL dla Typów Wydarzeń
    $sql_event_types = "CREATE TABLE $table_event_types (
        id mediumint(9) NOT NULL AUTO_INCREMENT,
        name varchar(100) NOT NULL,
        PRIMARY KEY  (id)
    ) $charset_collate;";

    // SQL dla Sprzętu
    $sql_equipment = "CREATE TABLE $table_equipment (
        id mediumint(9) NOT NULL AUTO_INCREMENT,
        name varchar(100) NOT NULL,
        PRIMARY KEY  (id)
    ) $charset_collate;";

    // SQL dla Aktywności
    $sql_act = "CREATE TABLE $table_activities (
        id bigint(20) NOT NULL AUTO_INCREMENT,
        category_id mediumint(9) NOT NULL,
        date date NOT NULL,
        title varchar(255) DEFAULT '' NOT NULL,
        distance decimal(10,2) DEFAULT 0.00,
        duration time DEFAULT '00:00:00',
        calories int(11) DEFAULT 0,
        comment text,
        strava_url varchar(255) DEFAULT NULL,
        avg_heart_rate smallint(5) UNSIGNED DEFAULT NULL,
        max_heart_rate smallint(5) UNSIGNED DEFAULT NULL,
        avg_speed decimal(5,2) DEFAULT NULL,
        max_speed decimal(5,2) DEFAULT NULL,
        avg_cadence smallint(5) UNSIGNED DEFAULT NULL,
        max_cadence smallint(5) UNSIGNED DEFAULT NULL,
        total_elevation_gain int(11) DEFAULT NULL,
        total_elevation_loss int(11) DEFAULT NULL,
        min_altitude int(11) DEFAULT NULL,
        max_altitude int(11) DEFAULT NULL,
        equipment_id mediumint(9) DEFAULT NULL,
        gpx_url varchar(255) DEFAULT NULL,
        event_type_id mediumint(9) DEFAULT NULL,
        PRIMARY KEY  (id)
    ) $charset_collate;";

    require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
    dbDelta( $sql_equipment );
    dbDelta( $sql_cat );
    dbDelta( $sql_event_types );
    dbDelta( $sql_act );

    // Dodanie domyślnych kategorii, jeśli tabela jest pusta
    if ( $wpdb->get_var( "SELECT COUNT(*) FROM $table_categories" ) == 0 ) {
        $wpdb->insert( $table_categories, array( 'name' => 'Rower', 'icon' => 'dashicons-buddicons-groups', 'color' => '#3498db' ) );
        $wpdb->insert( $table_categories, array( 'name' => 'Bieganie', 'icon' => 'dashicons-businessman', 'color' => '#e74c3c' ) );
    }

    // Dodanie domyślnych typów wydarzeń, jeśli tabela jest pusta
    if ( $wpdb->get_var( "SELECT COUNT(*) FROM $table_event_types" ) == 0 ) {
        $default_event_types = ['Bez kategorii', 'Fitness', 'Geocaching', 'Podróżowanie', 'Rekreacyjny', 'Specjalne zdarzenie', 'Transport', 'Trening', 'Wyścig'];
        foreach ($default_event_types as $type_name) {
            $wpdb->insert( $table_event_types, array( 'name' => $type_name ) );
        }
        // Ustawienie domyślnego typu "Trening" dla istniejących aktywności, które go nie mają
        $training_id = $wpdb->get_var( $wpdb->prepare( "SELECT id FROM $table_event_types WHERE name = %s", 'Trening' ) );
        if ($training_id) {
            $wpdb->query( $wpdb->prepare( "UPDATE $table_activities SET event_type_id = %d WHERE event_type_id IS NULL OR event_type_id = 0", $training_id ) );
        }
    }

    // Dodanie domyślnego sprzętu, jeśli tabela jest pusta
    if ( $wpdb->get_var( "SELECT COUNT(*) FROM $table_equipment" ) == 0 ) {
        $default_equipment = ['Giant Revolt', 'Cube LTD', 'Author Agang', 'Liv Tempt 4', 'Cube Acid 24', 'Mongoose BMX', 'Nextbike - Miejski'];
        foreach ($default_equipment as $eq_name) {
            $wpdb->insert( $table_equipment, array( 'name' => $eq_name ) );
        }
    }
}

// --- 2. MENU ADMINA I DASHBOARD ---
add_action( 'admin_menu', 'mystat_add_admin_menu' );

/**
 * Set up admin-specific hooks.
 */
function mystat_admin_init_setup() {
    add_filter( 'upload_mimes', 'mystat_add_gpx_mime_type' );
    add_filter( 'wp_check_filetype_and_ext', 'mystat_fix_gpx_upload_permission', 10, 4 );
}
add_action( 'admin_init', 'mystat_admin_init_setup' );

/**
 * Add GPX support to WordPress Media Library.
 *
 * @param array $mimes Allowed mime types.
 * @return array Modified mime types.
 */
function mystat_add_gpx_mime_type( $mimes ) {
    $mimes['gpx'] = 'application/gpx+xml';
    return $mimes;
}

/**
 * Bypasses WordPress's strict file type check for GPX files.
 * This is needed because WordPress can be overly cautious with XML-based files.
 *
 * @param array  $data     File data.
 * @param string $file     Full path to the file.
 * @param string $filename The filename.
 * @param array  $mimes    Mime types.
 * @return array Modified file data.
 */
function mystat_fix_gpx_upload_permission( $data, $file, $filename, $mimes ) {
    if ( strtolower( pathinfo( $filename, PATHINFO_EXTENSION ) ) === 'gpx' ) {
        $data['ext']  = 'gpx';
        $data['type'] = 'application/gpx+xml';
    }
    return $data;
}

function mystat_add_admin_menu() {
    add_menu_page( 
        'Moje Statystyki',          // Tytuł strony
        'Statystyki',               // Tytuł w menu
        'manage_options',           // Wymagane uprawnienia
        'moje-statystyki',          // Slug menu
        'mystat_dashboard_page',    // Funkcja renderująca stronę główną (dashboard)
        'dashicons-chart-line',     // Ikona
        6                           // Pozycja
    );

    add_submenu_page(
        'moje-statystyki',          // Slug rodzica
        'Dodaj Nowy Trening',       // Tytuł strony
        'Nowy trening',             // Tytuł w podmenu
        'manage_options',           // Wymagane uprawnienia
        'mystat-nowy-trening',      // Slug podmenu
        'mystat_add_new_page'       // Funkcja renderująca stronę dodawania
    );

    add_submenu_page(
        'moje-statystyki',
        'Typy Wydarzeń',
        'Typy wydarzeń',
        'manage_options',
        'mystat-event-types',
        'mystat_event_types_page'
    );

    add_submenu_page(
        'moje-statystyki',
        'Sprzęt',
        'Sprzęt',
        'manage_options',
        'mystat-equipment',
        'mystat_equipment_page'
    );

    add_submenu_page(
        null,                       // Ukryta strona, nie pojawia się w menu
        'Szczegóły Treningu',       // Tytuł strony
        'Szczegóły Treningu',       // Tytuł w menu (nieistotny)
        'manage_options',           // Wymagane uprawnienia
        'mystat-view-activity',     // Slug podmenu
        'mystat_view_activity_page' // Funkcja renderująca
    );

    add_submenu_page(
        null,                       // Ukryta strona
        'Edytuj Trening',           // Tytuł strony
        'Edytuj Trening',           // Tytuł w menu (nieistotny)
        'manage_options',           // Wymagane uprawnienia
        'mystat-edit-activity',     // Slug podmenu
        'mystat_edit_activity_page' // Funkcja renderująca
    );

    add_submenu_page(
        'moje-statystyki',          // Slug rodzica
        'Podsumowanie Roczne',      // Tytuł strony
        'Podsumowanie Roczne',      // Tytuł w podmenu
        'manage_options',           // Wymagane uprawnienia
        'mystat-yearly-summary',    // Slug podmenu
        'mystat_yearly_summary_page'// Funkcja renderująca
    );
}

function mystat_dashboard_page() {
    echo '<div class="wrap"><h1>Moje Statystyki Sportowe</h1>';
    mystat_render_history_table();
    echo '</div>';
}

function mystat_add_new_page() {
    echo '<div class="wrap"><h1>Dodaj Nowy Trening</h1>';
    // Obsługa zapisu formularza (musi być przed renderowaniem, aby wyświetlić komunikat)
    mystat_handle_activity_form_submission();
    // Formularz dodawania
    mystat_render_add_form();
    echo '</div>';
}

function mystat_event_types_page() {
    global $wpdb;
    $table_event_types = $wpdb->prefix . 'mystat_event_types';
    $message = '';
    $notice_class = '';

    // Handle POST requests (add/update)
    if ( isset( $_POST['submit'] ) && check_admin_referer( 'mystat_manage_event_type' ) ) {
        $name = sanitize_text_field( $_POST['event_type_name'] );
        $type_id = isset( $_POST['event_type_id'] ) ? intval( $_POST['event_type_id'] ) : 0;

        if ( ! empty( $name ) ) {
            if ( $type_id > 0 ) { // Update
                $wpdb->update( $table_event_types, [ 'name' => $name ], [ 'id' => $type_id ] );
                $message = 'Typ wydarzenia zaktualizowany.';
                $notice_class = 'notice-success';
            } else { // Insert
                $wpdb->insert( $table_event_types, [ 'name' => $name ] );
                $message = 'Typ wydarzenia dodany.';
                $notice_class = 'notice-success';
            }
        } else {
            $message = 'Nazwa typu wydarzenia nie może być pusta.';
            $notice_class = 'notice-error';
        }
    }

    // Handle GET requests (delete)
    if ( isset( $_GET['action'], $_GET['id'], $_GET['_wpnonce'] ) && $_GET['action'] === 'delete' ) {
        if ( wp_verify_nonce( $_GET['_wpnonce'], 'mystat_delete_event_type_' . $_GET['id'] ) ) {
            $wpdb->delete( $table_event_types, [ 'id' => intval( $_GET['id'] ) ] );
            $message = 'Typ wydarzenia usunięty.';
            $notice_class = 'notice-success';
        }
    }

    // Prepare for form (for editing)
    $item_to_edit = null;
    if ( isset( $_GET['action'], $_GET['id'] ) && $_GET['action'] === 'edit' ) {
        $item_to_edit = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $table_event_types WHERE id = %d", intval( $_GET['id'] ) ) );
    }

    $event_types = $wpdb->get_results( "SELECT * FROM $table_event_types ORDER BY name ASC" );
    ?>
    <div class="wrap">
        <h1>Typy Wydarzeń</h1>
        <?php if ( ! empty( $message ) ) : ?>
            <div class="notice <?php echo esc_attr( $notice_class ); ?> is-dismissible"><p><?php echo esc_html( $message ); ?></p></div>
        <?php endif; ?>

        <div id="col-container" class="wp-clearfix">
            <div id="col-left">
                <div class="col-wrap">
                    <div class="form-wrap">
                        <h2><?php echo $item_to_edit ? 'Edytuj typ wydarzenia' : 'Dodaj nowy typ wydarzenia'; ?></h2>
                        <form method="post">
                            <input type="hidden" name="event_type_id" value="<?php echo $item_to_edit ? esc_attr( $item_to_edit->id ) : '0'; ?>">
                            <?php wp_nonce_field( 'mystat_manage_event_type' ); ?>
                            <div class="form-field">
                                <label for="event_type_name">Nazwa</label>
                                <input type="text" name="event_type_name" id="event_type_name" value="<?php echo $item_to_edit ? esc_attr( $item_to_edit->name ) : ''; ?>" required>
                            </div>
                            <?php submit_button( $item_to_edit ? 'Zaktualizuj' : 'Dodaj' ); ?>
                        </form>
                    </div>
                </div>
            </div>
            <div id="col-right">
                <div class="col-wrap">
                    <table class="wp-list-table widefat fixed striped">
                        <thead><tr><th>Nazwa</th><th style="width: 100px;">Akcje</th></tr></thead>
                        <tbody>
                            <?php foreach ( $event_types as $type ) : ?>
                                <tr><td><?php echo esc_html( $type->name ); ?></td><td><a href="<?php echo esc_url( add_query_arg( [ 'action' => 'edit', 'id' => $type->id ] ) ); ?>">Edytuj</a> | <a href="<?php echo esc_url( wp_nonce_url( add_query_arg( [ 'action' => 'delete', 'id' => $type->id ] ), 'mystat_delete_event_type_' . $type->id ) ); ?>" onclick="return confirm('Czy na pewno chcesz usunąć ten typ?')" style="color: #a00;">Usuń</a></td></tr>
                            <?php endforeach; ?>
                        </tbody>
                    </table>
                </div>
            </div>
        </div>
    </div>
    <?php
}

function mystat_equipment_page() {
    global $wpdb;
    $table_equipment = $wpdb->prefix . 'mystat_equipment';
    $message = '';
    $notice_class = '';

    // Handle POST requests (add/update)
    if ( isset( $_POST['submit'] ) && check_admin_referer( 'mystat_manage_equipment' ) ) {
        $name = sanitize_text_field( $_POST['equipment_name'] );
        $item_id = isset( $_POST['equipment_id'] ) ? intval( $_POST['equipment_id'] ) : 0;

        if ( ! empty( $name ) ) {
            if ( $item_id > 0 ) { // Update
                $wpdb->update( $table_equipment, [ 'name' => $name ], [ 'id' => $item_id ] );
                $message = 'Sprzęt zaktualizowany.';
                $notice_class = 'notice-success';
            } else { // Insert
                $wpdb->insert( $table_equipment, [ 'name' => $name ] );
                $message = 'Sprzęt dodany.';
                $notice_class = 'notice-success';
            }
        } else {
            $message = 'Nazwa sprzętu nie może być pusta.';
            $notice_class = 'notice-error';
        }
    }

    // Handle GET requests (delete)
    if ( isset( $_GET['action'], $_GET['id'], $_GET['_wpnonce'] ) && $_GET['action'] === 'delete' ) {
        if ( wp_verify_nonce( $_GET['_wpnonce'], 'mystat_delete_equipment_' . $_GET['id'] ) ) {
            $wpdb->delete( $table_equipment, [ 'id' => intval( $_GET['id'] ) ] );
            $message = 'Sprzęt usunięty.';
            $notice_class = 'notice-success';
        }
    }

    // Prepare for form (for editing)
    $item_to_edit = null;
    if ( isset( $_GET['action'], $_GET['id'] ) && $_GET['action'] === 'edit' ) {
        $item_to_edit = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $table_equipment WHERE id = %d", intval( $_GET['id'] ) ) );
    }

    $equipment_list = $wpdb->get_results( "SELECT * FROM $table_equipment ORDER BY name ASC" );
    ?>
    <div class="wrap">
        <h1>Zarządzaj Sprzętem</h1>
        <?php if ( ! empty( $message ) ) : ?>
            <div class="notice <?php echo esc_attr( $notice_class ); ?> is-dismissible"><p><?php echo esc_html( $message ); ?></p></div>
        <?php endif; ?>

        <div id="col-container" class="wp-clearfix">
            <div id="col-left">
                <div class="col-wrap">
                    <div class="form-wrap">
                        <h2><?php echo $item_to_edit ? 'Edytuj sprzęt' : 'Dodaj nowy sprzęt'; ?></h2>
                        <form method="post">
                            <input type="hidden" name="equipment_id" value="<?php echo $item_to_edit ? esc_attr( $item_to_edit->id ) : '0'; ?>">
                            <?php wp_nonce_field( 'mystat_manage_equipment' ); ?>
                            <div class="form-field">
                                <label for="equipment_name">Nazwa</label>
                                <input type="text" name="equipment_name" id="equipment_name" value="<?php echo $item_to_edit ? esc_attr( $item_to_edit->name ) : ''; ?>" required>
                            </div>
                            <?php submit_button( $item_to_edit ? 'Zaktualizuj' : 'Dodaj' ); ?>
                        </form>
                    </div>
                </div>
            </div>
            <div id="col-right">
                <div class="col-wrap">
                    <table class="wp-list-table widefat fixed striped">
                        <thead><tr><th>Nazwa</th><th style="width: 100px;">Akcje</th></tr></thead>
                        <tbody>
                            <?php foreach ( $equipment_list as $item ) : ?>
                                <tr><td><?php echo esc_html( $item->name ); ?></td><td><a href="<?php echo esc_url( add_query_arg( [ 'action' => 'edit', 'id' => $item->id ] ) ); ?>">Edytuj</a> | <a href="<?php echo esc_url( wp_nonce_url( add_query_arg( [ 'action' => 'delete', 'id' => $item->id ] ), 'mystat_delete_equipment_' . $item->id ) ); ?>" onclick="return confirm('Czy na pewno chcesz usunąć ten sprzęt?')" style="color: #a00;">Usuń</a></td></tr>
                            <?php endforeach; ?>
                        </tbody>
                    </table>
                </div>
            </div>
        </div>
    </div>
    <?php
}

function mystat_yearly_summary_page() {
    global $wpdb;
    $table_activities = $wpdb->prefix . 'mystat_activities';

    $current_year = isset( $_GET['year'] ) ? intval( $_GET['year'] ) : current_time( 'Y' );

    // Pobierz dostępne lata z bazy danych
    $available_years = $wpdb->get_col( "SELECT DISTINCT YEAR(date) FROM $table_activities ORDER BY YEAR(date) DESC" );
    if ( empty( $available_years ) ) {
        $available_years = [current_time('Y')]; // Domyślny rok, jeśli brak danych
    }

    // Zapytanie SQL do grupowania danych miesięcznie
    $sql = $wpdb->prepare("
        SELECT
            MONTH(date) as month_num,
            SUM(distance) as total_distance,
            SUM(calories) as total_calories,
            SEC_TO_TIME(SUM(TIME_TO_SEC(duration))) as total_duration
        FROM $table_activities
        WHERE YEAR(date) = %d
        GROUP BY month_num
        ORDER BY month_num ASC
    ", $current_year);

    $monthly_summary = $wpdb->get_results( $sql, OBJECT_K ); // OBJECT_K zwróci tablicę z kluczami będącymi numerami miesięcy

    // Przygotowanie danych dla wszystkich 12 miesięcy
    $full_year_summary = [];
    $total_year_distance = 0;
    $total_year_calories = 0;
    $total_year_seconds = 0;

    for ( $i = 1; $i <= 12; $i++ ) {
        $month_name = date_i18n( 'F', mktime( 0, 0, 0, $i, 10 ) ); // Nazwa miesiąca
        $data = isset( $monthly_summary[$i] ) ? $monthly_summary[$i] : null;

        $full_year_summary[$i] = (object) [
            'month_name' => $month_name,
            'total_distance' => $data ? $data->total_distance : 0,
            'total_calories' => $data ? $data->total_calories : 0,
            'total_duration' => $data ? $data->total_duration : '00:00:00',
        ];

        $total_year_distance += $full_year_summary[$i]->total_distance;
        $total_year_calories += $full_year_summary[$i]->total_calories;
        if ( $data && ! empty( $data->total_duration ) ) {
            list($h, $m, $s) = explode(':', $data->total_duration);
            $total_year_seconds += $h * 3600 + $m * 60 + $s;
        }
    }

    $total_year_hours = floor($total_year_seconds / 3600);
    $total_year_minutes = floor(($total_year_seconds % 3600) / 60);
    $total_year_duration_formatted = sprintf('%d godz. %d min.', $total_year_hours, $total_year_minutes);

    // Przygotowanie danych dla wykresu
    $chart_labels = [];
    $chart_data_distance = [];
    foreach ($full_year_summary as $month_data) {
        $chart_labels[] = $month_data->month_name;
        $chart_data_distance[] = round((float)$month_data->total_distance, 2);
    }

    // Włączenie skryptów dla Chart.js
    wp_enqueue_script('chart-js', 'https://cdn.jsdelivr.net/npm/chart.js', [], null, true);
    wp_register_script('mystat-chart-loader', false);
    wp_enqueue_script('mystat-chart-loader');
    wp_add_inline_script('mystat-chart-loader', '
        document.addEventListener("DOMContentLoaded", function() {
            const ctx = document.getElementById("mystatYearlyChart");
            if (!ctx) return;
            new Chart(ctx, {
                type: "bar",
                data: {
                    labels: ' . json_encode($chart_labels) . ',
                    datasets: [{
                        label: "Dystans (km)",
                        data: ' . json_encode($chart_data_distance) . ',
                        backgroundColor: "rgba(52, 152, 219, 0.5)",
                        borderColor: "rgba(52, 152, 219, 1)",
                        borderWidth: 1
                    }]
                },
                options: {
                    responsive: true,
                    maintainAspectRatio: false,
                    scales: {
                        y: {
                            beginAtZero: true,
                            title: { display: true, text: "Kilometry" }
                        }
                    }
                }
            });
        });
    ');

    ?>
    <div class="wrap">
        <h1>Podsumowanie Roczne</h1>

        <div class="tablenav top">
            <div class="alignleft actions">
                <label for="filter-by-year" class="screen-reader-text">Filtruj według roku</label>
                <form method="get" style="display: flex; gap: 5px; align-items: center;">
                    <input type="hidden" name="page" value="mystat-yearly-summary">
                    <select name="year" id="filter-by-year">
                        <?php foreach ( $available_years as $year_option ) : ?>
                            <option value="<?php echo esc_attr( $year_option ); ?>" <?php selected( $current_year, $year_option ); ?>><?php echo esc_html( $year_option ); ?></option>
                        <?php endforeach; ?>
                    </select>
                    <?php submit_button( 'Filtruj', 'secondary', 'filter_action', false ); ?>
                </form>
            </div>
        </div>

        <div class="postbox" style="margin-bottom: 20px;">
            <div class="postbox-header"><h2 class="hndle">Wykres Dystansu w <?php echo esc_html($current_year); ?></h2></div>
            <div class="inside">
                <div style="position: relative; height:40vh; width:100%;">
                    <canvas id="mystatYearlyChart"></canvas>
                </div>
            </div>
        </div>

        <table class="wp-list-table widefat fixed striped">
            <thead>
                <tr><th>Miesiąc</th><th>Dystans (km)</th><th>Kalorie (kcal)</th><th>Czas</th></tr>
            </thead>
            <tbody>
                <?php foreach ( $full_year_summary as $month_data ) : ?>
                    <tr>
                        <td><?php echo esc_html( $month_data->month_name ); ?></td>
                        <td><?php echo number_format( $month_data->total_distance, 2, ',', ' ' ); ?></td>
                        <td><?php echo number_format( $month_data->total_calories, 0, ',', ' ' ); ?></td>
                        <td><?php echo esc_html( $month_data->total_duration ); ?></td>
                    </tr>
                <?php endforeach; ?>
                <tr class="alternate">
                    <th>SUMA ROCZNA</th>
                    <th><?php echo number_format( $total_year_distance, 2, ',', ' ' ); ?></th>
                    <th><?php echo number_format( $total_year_calories, 0, ',', ' ' ); ?></th>
                    <th><?php echo esc_html( $total_year_duration_formatted ); ?></th>
                </tr>
            </tbody>
        </table>
    </div>
    <?php
}

/**
 * Fetches and parses a GPX file from a URL to extract track points.
 *
 * @param string $gpx_url The URL of the GPX file.
 * @return array An array of [lat, lon] coordinates, or an empty array on failure.
 */
function mystat_get_track_from_gpx_url( $gpx_url ) {
    if ( empty( $gpx_url ) ) {
        return [];
    }

    $response = wp_remote_get( $gpx_url, [ 'timeout' => 20 ] );

    if ( is_wp_error( $response ) || wp_remote_retrieve_response_code( $response ) !== 200 ) {
        return [];
    }

    $gpx_content = wp_remote_retrieve_body( $response );
    if ( empty( $gpx_content ) ) {
        return [];
    }

    libxml_use_internal_errors( true );
    $gpx = simplexml_load_string( $gpx_content );
    libxml_clear_errors();

    if ( $gpx === false ) {
        return [];
    }

    $points = [];
    if ( isset( $gpx->trk ) ) {
        foreach ( $gpx->trk->trkseg as $trkseg ) {
            foreach ( $trkseg->trkpt as $trkpt ) {
                if ( isset( $trkpt['lat'] ) && isset( $trkpt['lon'] ) ) {
                    $points[] = [ (float) $trkpt['lat'], (float) $trkpt['lon'] ];
                }
            }
        }
    }

    return $points;
}

function mystat_edit_activity_page() {
    global $wpdb;
    $activity_id = isset( $_GET['id'] ) ? intval( $_GET['id'] ) : 0;

    if ( $activity_id === 0 ) {
        echo '<div class="wrap"><h1>Błąd</h1><p>Nie podano ID aktywności do edycji.</p></div>';
        return;
    }

    // Handle form submission for update
    mystat_handle_activity_form_submission();

    $table_activities = $wpdb->prefix . 'mystat_activities';
    $activity = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $table_activities WHERE id = %d", $activity_id ) );

    if ( ! $activity ) {
        echo '<div class="wrap"><h1>Błąd</h1><p>Nie znaleziono aktywności o podanym ID.</p></div>';
        return;
    }

    echo '<div class="wrap"><h1>Edytuj Trening</h1>';
    mystat_render_add_form( $activity );
    echo '</div>';
}

function mystat_view_activity_page() {
    global $wpdb;

    $activity_id = isset( $_GET['id'] ) ? intval( $_GET['id'] ) : 0;

    if ( $activity_id === 0 ) {
        echo '<div class="wrap"><h1>Błąd</h1><p>Nie podano ID aktywności.</p></div>';
        return;
    }

    $table_activities = $wpdb->prefix . 'mystat_activities';
    $table_categories = $wpdb->prefix . 'mystat_categories';
    $table_event_types = $wpdb->prefix . 'mystat_event_types';
    $table_equipment = $wpdb->prefix . 'mystat_equipment';

    $sql = $wpdb->prepare("
        SELECT a.*, c.name as category_name, c.icon, c.color, et.name as event_type_name, eq.name as equipment_name
        FROM $table_activities a
        LEFT JOIN $table_categories c ON a.category_id = c.id
        LEFT JOIN $table_event_types et ON a.event_type_id = et.id
        LEFT JOIN $table_equipment eq ON a.equipment_id = eq.id
        WHERE a.id = %d
    ", $activity_id);

    $activity = $wpdb->get_row( $sql );

    if ( ! $activity ) {
        echo '<div class="wrap"><h1>Błąd</h1><p>Nie znaleziono aktywności o podanym ID.</p></div>';
        return;
    }

    // Funkcja pomocnicza do wyświetlania wiersza, jeśli wartość istnieje
    $render_row = function($label, $value, $unit = '') {
        if ( ! is_null($value) && $value !== '' ) {
            echo '<tr>';
            echo '<th scope="row">' . esc_html($label) . '</th>';
            echo '<td>' . esc_html($value) . ($unit ? ' ' . esc_html($unit) : '') . '</td>';
            echo '</tr>';
        }
    };

    // Prepare map data if GPX exists
    $track_points = [];
    if ( ! empty( $activity->gpx_url ) ) {
        // Note: For performance, you might want to cache the parsed points in post meta
        // rather than parsing the file on every page load.
        $track_points = mystat_get_track_from_gpx_url( $activity->gpx_url );

        if ( ! empty( $track_points ) ) {
            // Enqueue Leaflet assets. For simplicity, this is done here.
            // A better approach is to use the 'admin_enqueue_scripts' hook.
            wp_enqueue_style('leaflet-css', 'https://unpkg.com/leaflet@1.9.4/dist/leaflet.css');
            wp_enqueue_script('leaflet-js', 'https://unpkg.com/leaflet@1.9.4/dist/leaflet.js', [], '1.9.4', true);
            
            // Pass track data to a script
            wp_register_script('mystat-map-loader', false);
            wp_enqueue_script('mystat-map-loader');
            wp_add_inline_script('mystat-map-loader',
                'const mystat_track_points = ' . json_encode($track_points) . ';' .
                'document.addEventListener("DOMContentLoaded", function() {
                    if (typeof L === "undefined" || typeof mystat_track_points === "undefined" || mystat_track_points.length === 0) return;
                    const map = L.map("mystat-activity-map");
                    L.tileLayer("https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png", {
                        attribution: \'&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors\'
                    }).addTo(map);
                    const polyline = L.polyline(mystat_track_points, {color: "#' . esc_js( ltrim($activity->color, '#') ) . '"}).addTo(map);
                    map.fitBounds(polyline.getBounds().pad(0.1));
                    L.marker(mystat_track_points[0]).addTo(map).bindPopup("Start");
                    L.marker(mystat_track_points[mystat_track_points.length - 1]).addTo(map).bindPopup("Koniec");
                });'
            );
        }
    }
    
    ?>
    <div class="wrap">        
        <h1>
            Szczegóły treningu: <?php echo esc_html( $activity->title ); ?>
            <a href="<?php echo esc_url( add_query_arg( ['page' => 'mystat-edit-activity', 'id' => $activity->id], admin_url('admin.php') ) ); ?>" class="page-title-action">
                Edytuj
            </a>
        </h1>

        <p><a href="<?php echo esc_url( admin_url('admin.php?page=moje-statystyki') ); ?>">&larr; Powrót do listy aktywności</a></p>

        <div class="postbox" style="margin-top: 20px;">
            <div class="postbox-header"><h2 class="hndle">Podsumowanie</h2></div>
            <div class="inside">
                <div id="mystat-details-container" class="wp-clearfix">
                    <div class="mystat-details-col">
                        <h3>Główne dane</h3>
                        <table class="form-table">
                            <?php $render_row('Kategoria', $activity->category_name); ?>
                            <?php $render_row('Data', $activity->date); ?>
                            <?php $render_row('Dystans', number_format($activity->distance, 2, ',', ' '), 'km'); ?>
                            <?php $render_row('Czas trwania', $activity->duration); ?>
                            <?php $render_row('Spalone kalorie', $activity->calories, 'kcal'); ?>
                            <?php $render_row('Typ wydarzenia', $activity->event_type_name); ?>
                            <?php $render_row('Sprzęt', $activity->equipment_name); ?>
                        </table>
                    </div>
                    <div class="mystat-details-col">
                        <h3>Dane szczegółowe</h3>
                        <table class="form-table">
                            <?php $render_row('Średnia prędkość', number_format($activity->avg_speed, 1, ',', ' '), 'km/h'); ?>
                            <?php $render_row('Maksymalna prędkość', number_format($activity->max_speed, 1, ',', ' '), 'km/h'); ?>
                            <?php $render_row('Średnie tętno', $activity->avg_heart_rate, 'bpm'); ?>
                            <?php $render_row('Maksymalne tętno', $activity->max_heart_rate, 'bpm'); ?>
                            <?php $render_row('Średni rytm', $activity->avg_cadence, 'rpm'); ?>
                            <?php $render_row('Maksymalny rytm', $activity->max_cadence, 'rpm'); ?>
                            <?php $render_row('Suma wzniosów', $activity->total_elevation_gain, 'm'); ?>
                            <?php $render_row('Suma spadków', $activity->total_elevation_loss, 'm'); ?>
                            <?php $render_row('Minimalna wysokość', $activity->min_altitude, 'm n.p.m.'); ?>
                            <?php $render_row('Maksymalna wysokość', $activity->max_altitude, 'm n.p.m.'); ?>
                        </table>
                    </div>
                </div>
                <hr>
                <h3>Notatki i linki</h3>
                <table class="form-table">
                    <?php $render_row('Komentarz', nl2br($activity->comment)); ?>
                    <?php if ( ! empty( $activity->strava_url ) ) : ?>
                    <tr><th scope="row">Strava</th><td><a href="<?php echo esc_url( $activity->strava_url ); ?>" target="_blank" rel="noopener noreferrer">Zobacz aktywność na Strava</a></td></tr>
                    <?php endif; ?>
                    <?php if ( ! empty( $activity->gpx_url ) ) : ?>
                    <tr><th scope="row">Plik GPX</th><td><a href="<?php echo esc_url( $activity->gpx_url ); ?>" target="_blank">Pobierz plik GPX</a></td></tr>
                    <?php endif; ?>
                </table>

                <?php if ( ! empty( $track_points ) ) : ?>
                    <hr>
                    <h3>Mapa Trasy</h3>
                    <div id="mystat-activity-map" style="height: 450px; width: 100%; border: 1px solid #ddd;"></div>
                <?php elseif ( ! empty( $activity->gpx_url ) ) : ?>
                    <hr>
                    <h3>Mapa Trasy</h3>
                    <div class="notice notice-warning inline">
                        <p>Nie udało się wczytać danych z pliku GPX lub plik jest uszkodzony/pusty.</p>
                    </div>
                <?php endif; ?>

            </div>
        </div>
    </div>
    <style>
        .mystat-details-col { float: left; width: 49%; }
        .mystat-details-col:first-child { margin-right: 2%; }
        @media screen and (max-width: 782px) { .mystat-details-col { float: none; width: 100%; margin-right: 0; } }
    </style>
    <?php
}

/**
 * Obsługa zapisu nowego lub edytowanego wpisu do bazy danych
 */
function mystat_handle_activity_form_submission() {
    global $wpdb;

    // Sprawdź czy formularz został wysłany
    if ( ! isset( $_POST['mystat_submit_activity'] ) ) {
        return;
    }
    
    $activity_id = isset( $_POST['activity_id'] ) ? intval( $_POST['activity_id'] ) : 0;
    $nonce_action = $activity_id > 0 ? 'mystat_edit_entry_' . $activity_id : 'mystat_add_entry';
    
    // Weryfikacja bezpieczeństwa (Nonce)
    if ( ! isset( $_POST['_wpnonce'] ) || ! wp_verify_nonce( $_POST['_wpnonce'], $nonce_action ) ) {
        echo '<div class="notice notice-error"><p>Błąd weryfikacji bezpieczeństwa formularza.</p></div>';
        return;
    }

    $table_activities = $wpdb->prefix . 'mystat_activities';

    // Przygotowanie danych (zamiana przecinka na kropkę w dystansie)
    $distance = isset($_POST['distance']) ? floatval( str_replace( ',', '.', $_POST['distance'] ) ) : 0;
    
    // Funkcja pomocnicza do zamiany pustych wartości na NULL, aby poprawnie zapisać je w bazie
    $null_if_empty = function($value) {
        return $value !== '' ? $value : null;
    };

    $data = array(
        'category_id' => intval( $_POST['category_id'] ),
        'date'        => sanitize_text_field( $_POST['date'] ),
        'title'       => sanitize_text_field( $_POST['title'] ),
        'distance'    => $distance,
        'duration'    => sanitize_text_field( $_POST['duration'] ),
        'calories'    => intval( $_POST['calories'] ),
        'comment'     => sanitize_textarea_field( $_POST['comment'] ),
        'strava_url'  => $null_if_empty( esc_url_raw( $_POST['strava_url'] ) ),
        'avg_heart_rate' => $null_if_empty( intval( $_POST['avg_heart_rate'] ) ),
        'max_heart_rate' => $null_if_empty( intval( $_POST['max_heart_rate'] ) ),
        'avg_speed'   => $null_if_empty( floatval( str_replace( ',', '.', $_POST['avg_speed'] ) ) ),
        'max_speed'   => $null_if_empty( floatval( str_replace( ',', '.', $_POST['max_speed'] ) ) ),
        'avg_cadence' => $null_if_empty( intval( $_POST['avg_cadence'] ) ),
        'max_cadence' => $null_if_empty( intval( $_POST['max_cadence'] ) ),
        'total_elevation_gain' => $null_if_empty( intval( $_POST['total_elevation_gain'] ) ),
        'total_elevation_loss' => $null_if_empty( intval( $_POST['total_elevation_loss'] ) ),
        'min_altitude' => $null_if_empty( intval( $_POST['min_altitude'] ) ),
        'max_altitude' => $null_if_empty( intval( $_POST['max_altitude'] ) ),
        'equipment_id'   => $null_if_empty( intval( $_POST['equipment_id'] ) ),
        'gpx_url'     => $null_if_empty( esc_url_raw( $_POST['gpx_url'] ) ),
        'event_type_id'  => $null_if_empty( intval( $_POST['event_type_id'] ) ),
    );

    // Format danych dla $wpdb->insert
    $format = array( 
        '%d', '%s', '%s', '%f', '%s', '%d', '%s', // Pola podstawowe
        '%s', '%d', '%d', '%f', '%f', '%d', '%d', // Tętno, prędkość, kadencja
        '%d', '%d', '%d', '%d', '%d', '%s', '%d'  // Wysokość, sprzęt, linki, typ wydarzenia
    );

    if ( $activity_id > 0 ) {
        // UPDATE
        $result = $wpdb->update( $table_activities, $data, [ 'id' => $activity_id ], $format, [ '%d' ] );
        $message = 'Trening zaktualizowany pomyślnie!';
    } else {
        // INSERT
        $result = $wpdb->insert( $table_activities, $data, $format );
        $message = 'Trening dodany pomyślnie!';
    }

    if ( $result !== false ) {
        echo '<div class="notice notice-success is-dismissible"><p>' . esc_html( $message ) . '</p></div>';
    } else {
        echo '<div class="notice notice-error is-dismissible"><p>Wystąpił błąd podczas zapisu do bazy.</p></div>';
    }
}

/**
 * Renderowanie formularza HTML
 */
function mystat_render_add_form( $activity = null ) {
    // Enqueue media scripts for the uploader
    wp_enqueue_media();

    global $wpdb;
    $table_categories = $wpdb->prefix . 'mystat_categories';
    $table_event_types = $wpdb->prefix . 'mystat_event_types';
    $table_equipment = $wpdb->prefix . 'mystat_equipment';
    $categories = $wpdb->get_results( "SELECT * FROM $table_categories ORDER BY name ASC" );
    $event_types = $wpdb->get_results( "SELECT * FROM $table_event_types ORDER BY name ASC" );
    $equipment_list = $wpdb->get_results( "SELECT * FROM $table_equipment ORDER BY name ASC" );
    
    $is_edit_mode = ! is_null( $activity );
    $nonce_action = $is_edit_mode ? 'mystat_edit_entry_' . $activity->id : 'mystat_add_entry';
    $form_title = $is_edit_mode ? 'Edytuj Aktywność' : 'Dodaj Nową Aktywność';
    $button_text = $is_edit_mode ? 'Zaktualizuj Trening' : 'Zapisz Trening';

    ?>
    <div class="postbox">
        <div class="postbox-header"><h2 class="hndle"><?php echo esc_html( $form_title ); ?></h2></div>
        <div class="inside">
            <form method="post" action="">
                <input type="hidden" name="activity_id" value="<?php echo $is_edit_mode ? esc_attr( $activity->id ) : '0'; ?>">
                <?php wp_nonce_field( $nonce_action, '_wpnonce' ); ?>
                <table class="form-table">
                    <tr>
                        <th scope="row"><label for="title">Tytuł</label></th>
                        <td><input type="text" name="title" id="title" class="large-text" placeholder="np. Poranny trening w lesie" value="<?php echo $is_edit_mode ? esc_attr( $activity->title ) : ''; ?>" required></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="category_id">Kategoria</label></th>
                        <td>
                            <select name="category_id" id="category_id" required>
                                <?php foreach ( $categories as $cat ) : ?>
                                    <option value="<?php echo esc_attr( $cat->id ); ?>" <?php echo $is_edit_mode ? selected( $activity->category_id, $cat->id, false ) : selected( $cat->name, 'Rower', false ); ?>><?php echo esc_html( $cat->name ); ?></option>
                                <?php endforeach; ?>
                            </select>
                        </td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="date">Data</label></th>
                        <td><input type="date" name="date" id="date" value="<?php echo $is_edit_mode ? esc_attr( $activity->date ) : current_time( 'Y-m-d' ); ?>" class="regular-text" required></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="distance">Dystans (km)</label></th>
                        <td><input type="text" name="distance" id="distance" class="regular-text" placeholder="0,00" value="<?php echo $is_edit_mode ? esc_attr( number_format( (float)$activity->distance, 2, ',', '' ) ) : ''; ?>"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="duration">Czas (HH:MM:SS)</label></th>
                        <td><input type="time" name="duration" id="duration" step="1" value="<?php echo $is_edit_mode ? esc_attr( $activity->duration ) : '00:00:00'; ?>" class="regular-text"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="calories">Kalorie (kcal)</label></th>
                        <td><input type="number" name="calories" id="calories" class="regular-text" placeholder="0" value="<?php echo $is_edit_mode ? esc_attr( $activity->calories ) : ''; ?>"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="event_type_id">Typ wydarzenia</label></th>
                        <td>
                            <select name="event_type_id" id="event_type_id">
                                <option value="">-- Wybierz --</option>
                                <?php foreach ( $event_types as $type ) : ?>
                                    <option value="<?php echo esc_attr( $type->id ); ?>" <?php echo $is_edit_mode ? selected( $activity->event_type_id, $type->id, false ) : selected( $type->name, 'Trening', false ); ?>><?php echo esc_html( $type->name ); ?></option>
                                <?php endforeach; ?>
                            </select>
                        </td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="equipment_id">Sprzęt</label></th>
                        <td>
                            <select name="equipment_id" id="equipment_id">
                                <option value="">-- Wybierz --</option>
                                <?php foreach ( $equipment_list as $item ) : ?>
                                    <option value="<?php echo esc_attr( $item->id ); ?>" <?php if ( $is_edit_mode ) selected( $activity->equipment_id, $item->id ); ?>><?php echo esc_html( $item->name ); ?></option>
                                <?php endforeach; ?>
                            </select>
                        </td>
                    </tr>
                    <tr class="form-field">
                        <td colspan="2"><hr><h4>Dane szczegółowe (opcjonalne)</h4></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="avg_speed">Śr. prędkość (km/h)</label></th>
                        <td><input type="text" name="avg_speed" id="avg_speed" class="small-text" placeholder="0,0" value="<?php echo $is_edit_mode ? esc_attr( number_format( (float)$activity->avg_speed, 2, ',', '' ) ) : ''; ?>"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="max_speed">Maks. prędkość (km/h)</label></th>
                        <td><input type="text" name="max_speed" id="max_speed" class="small-text" placeholder="0,0" value="<?php echo $is_edit_mode ? esc_attr( number_format( (float)$activity->max_speed, 2, ',', '' ) ) : ''; ?>"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="avg_heart_rate">Śr. tętno</label></th>
                        <td><input type="number" name="avg_heart_rate" id="avg_heart_rate" class="small-text" placeholder="0" value="<?php echo $is_edit_mode ? esc_attr( $activity->avg_heart_rate ) : ''; ?>"></td>
                    </tr>
                     <tr>
                        <th scope="row"><label for="max_heart_rate">Maks. tętno</label></th>
                        <td><input type="number" name="max_heart_rate" id="max_heart_rate" class="small-text" placeholder="0" value="<?php echo $is_edit_mode ? esc_attr( $activity->max_heart_rate ) : ''; ?>"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="avg_cadence">Śr. rytm pedałowania</label></th>
                        <td><input type="number" name="avg_cadence" id="avg_cadence" class="small-text" placeholder="0" value="<?php echo $is_edit_mode ? esc_attr( $activity->avg_cadence ) : ''; ?>"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="max_cadence">Maks. rytm pedałowania</label></th>
                        <td><input type="number" name="max_cadence" id="max_cadence" class="small-text" placeholder="0" value="<?php echo $is_edit_mode ? esc_attr( $activity->max_cadence ) : ''; ?>"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="total_elevation_gain">Całkowity wznios (m)</label></th>
                        <td><input type="number" name="total_elevation_gain" id="total_elevation_gain" class="small-text" placeholder="0" value="<?php echo $is_edit_mode ? esc_attr( $activity->total_elevation_gain ) : ''; ?>"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="total_elevation_loss">Całkowity spadek (m)</label></th>
                        <td><input type="number" name="total_elevation_loss" id="total_elevation_loss" class="small-text" placeholder="0" value="<?php echo $is_edit_mode ? esc_attr( $activity->total_elevation_loss ) : ''; ?>"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="min_altitude">Min. wysokość (m)</labe></th>
                        <td><input type="number" name="min_altitude" id="min_altitude" class="small-text" placeholder="0" value="<?php echo $is_edit_mode ? esc_attr( $activity->min_altitude ) : ''; ?>"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="max_altitude">Maks. wysokość (m)</label></th>
                        <td><input type="number" name="max_altitude" id="max_altitude" class="small-text" placeholder="0" value="<?php echo $is_edit_mode ? esc_attr( $activity->max_altitude ) : ''; ?>"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="comment">Komentarz</label></th>
                        <td><textarea name="comment" id="comment" rows="3" class="large-text"><?php echo $is_edit_mode ? esc_textarea( $activity->comment ) : ''; ?></textarea></td>
                    </tr>
                    <tr class="form-field">
                        <td colspan="2"><hr><h4>Linki zewnętrzne (opcjonalne)</h4></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="strava_url">Link do Strava</label></th>
                        <td><input type="url" name="strava_url" id="strava_url" class="large-text" placeholder="https://www.strava.com/activities/..." value="<?php echo $is_edit_mode ? esc_attr( $activity->strava_url ) : ''; ?>"></td>
                    </tr>
                    <tr>
                        <th scope="row"><label for="gpx_url">Link do pliku GPX</label></th>
                        <td>
                            <input type="text" name="gpx_url" id="gpx_url" class="large-text" placeholder="Wklej URL lub wgraj plik..." value="<?php echo $is_edit_mode ? esc_attr( $activity->gpx_url ) : ''; ?>">
                            <button type="button" class="button" id="upload_gpx_button" style="margin-top: 5px;">Wgraj lub wybierz plik</button>
                        </td>
                    </tr>
                </table>
                <p class="submit">
                    <input type="submit" name="mystat_submit_activity" id="submit" class="button button-primary" value="<?php echo esc_attr( $button_text ); ?>">
                </p>
            </form>
            <script>
            jQuery(document).ready(function($) {
                $('#upload_gpx_button').click(function(e) {
                    e.preventDefault();
                    var gpx_uploader = wp.media({
                        title: 'Wybierz plik GPX',
                        button: { text: 'Użyj tego pliku' },
                        multiple: false,
                        library: { type: ['application/gpx+xml', 'application/xml', 'text/plain'] }
                    })
                    .on('select', function() {
                        var attachment = gpx_uploader.state().get('selection').first().toJSON();
                        $('#gpx_url').val(attachment.url).trigger('change');
                    }).open();
                });
            });
            </script>
        </div>
    </div>
    <?php
}

function mystat_render_history_table() {
    global $wpdb;
    
    // Definicje nazw tabel (z uwzględnieniem prefixu WP, jeśli był użyty przy tworzeniu)
    // Zakładam, że tabele nazywają się dokładnie tak jak w dokumentacji, ale dobrą praktyką jest $wpdb->prefix
    // Jeśli tabele są "sztywne" (bez prefixu wp_), usuń $wpdb->prefix.
    $table_activities = $wpdb->prefix . 'mystat_activities'; 
    $table_categories = $wpdb->prefix . 'mystat_categories';

    // --- 1. OBSŁUGA USUWANIA (DELETE) ---
    if ( isset( $_GET['action'], $_GET['id'], $_GET['_wpnonce'] ) && $_GET['action'] === 'mystat_delete' ) {
        $activity_id = intval( $_GET['id'] );
        
        // Weryfikacja bezpieczeństwa (Nonce)
        if ( wp_verify_nonce( $_GET['_wpnonce'], 'mystat_delete_' . $activity_id ) ) {
            $result = $wpdb->delete( 
                $table_activities, 
                array( 'id' => $activity_id ), 
                array( '%d' ) 
            );

            if ( $result ) {
                echo '<div class="notice notice-success is-dismissible"><p>Aktywność została usunięta.</p></div>';
            } else {
                echo '<div class="notice notice-error is-dismissible"><p>Wystąpił błąd podczas usuwania.</p></div>';
            }
        } else {
            echo '<div class="notice notice-error is-dismissible"><p>Błąd weryfikacji bezpieczeństwa (Nonce).</p></div>';
        }
    }

    // --- 2. POBIERANIE DANYCH (SELECT) ---
    // Pobieramy ostatnie 10 wpisów, łącząc z tabelą kategorii, aby mieć nazwę i ikonę
    $sql = $wpdb->prepare("
        SELECT a.*, c.name as category_name, c.icon, c.color, et.name as event_type_name, eq.name as equipment_name
        FROM $table_activities a
        LEFT JOIN $table_categories c ON a.category_id = c.id
        LEFT JOIN {$wpdb->prefix}mystat_event_types et ON a.event_type_id = et.id
        LEFT JOIN {$wpdb->prefix}mystat_equipment eq ON a.equipment_id = eq.id
        ORDER BY a.date DESC, a.id DESC
        LIMIT %d
    ", 10);
    
    $activities = $wpdb->get_results( $sql );

    // --- 3. WIDOK TABELI (HTML) ---
    ?>
    <div class="wrap">
        <h2>Ostatnie Aktywności</h2>
        
        <table class="wp-list-table widefat fixed striped table-view-list">
            <thead>
                <tr>
                    <th scope="col" style="width: 50px;">Ikona</th>
                    <th scope="col">Data</th>
                    <th scope="col">Tytuł</th>
                    <th scope="col" style="width: 120px;">Kategoria</th>
                    <th scope="col">Typ</th>
                    <th scope="col">Sprzęt</th>
                    <th scope="col">Dystans (km)</th>
                    <th scope="col">Czas</th>
                    <th scope="col">Śr. prędkość</th>
                    <th scope="col" style="width: 180px;">Akcja</th>
                </tr>
            </thead>
            <tbody>
                <?php if ( ! empty( $activities ) ) : ?>
                    <?php foreach ( $activities as $row ) : ?>
                        <?php 
                            // Generowanie URL-i akcji
                            $delete_url = add_query_arg( array(
                                'page'      => $_REQUEST['page'], // Zachowaj obecną stronę admina
                                'action'    => 'mystat_delete',
                                'id'        => $row->id,
                                '_wpnonce'  => wp_create_nonce( 'mystat_delete_' . $row->id )
                            ), admin_url( 'admin.php' ) );

                            $edit_url = add_query_arg( array(
                                'page' => 'mystat-edit-activity',
                                'id'   => $row->id
                            ), admin_url( 'admin.php' ) );

                            $details_url = add_query_arg( array(
                                'page' => 'mystat-view-activity',
                                'id'   => $row->id
                            ), admin_url( 'admin.php' ) );
                        ?>
                        <tr>
                            <td>
                                <?php if ( ! empty( $row->icon ) ) : ?>
                                    <span class="dashicons <?php echo esc_attr( $row->icon ); ?>" style="color: <?php echo esc_attr( $row->color ); ?>;"></span>
                                <?php endif; ?>
                            </td>
                            <td><?php echo esc_html( $row->date ); ?></td>
                            <td><strong><a href="<?php echo esc_url( $details_url ); ?>"><?php echo esc_html( $row->title ? wp_trim_words( $row->title, 6 ) : '(bez tytułu)' ); ?></a></strong></td>
                            <td><?php echo esc_html( $row->category_name ); ?></td>
                            <td><?php echo esc_html( $row->event_type_name ); ?></td>
                            <td><?php echo esc_html( $row->equipment_name ); ?></td>
                            <td><?php echo number_format( $row->distance, 2, ',', ' ' ); ?></td>
                            <td><?php echo esc_html( $row->duration ); ?></td>
                            <td><?php echo $row->avg_speed ? number_format( $row->avg_speed, 1, ',', ' ' ) . ' km/h' : '-'; ?></td>
                            <td>
                                <a href="<?php echo esc_url( $edit_url ); ?>" class="button button-small">Edytuj</a>
                                <a href="<?php echo esc_url( $details_url ); ?>" class="button button-small">Szczegóły</a>
                                <a href="<?php echo esc_url( $delete_url ); ?>" 
                                   class="button button-small button-link-delete"
                                   onclick="return confirm('Czy na pewno chcesz usunąć ten wpis?');">
                                   Usuń
                                </a>
                            </td>
                        </tr>
                    <?php endforeach; ?>
                <?php else : ?>
                    <tr>
                        <td colspan="10">Brak zarejestrowanych aktywności. Dodaj pierwszy trening powyżej!</td>
                    </tr>
                <?php endif; ?>
            </tbody>
        </table>
    </div>
    <?php
}
?>

<?php
// --- 3. SHORTCODE DO WYŚWIETLANIA NA FRONCIE ---

/**
 * Rejestruje shortcode [moje_statystyki].
 */
function mystat_register_shortcode() {
    add_shortcode( 'moje_statystyki', 'mystat_shortcode_handler' );
    add_shortcode( 'moje_statystyki_wpis', 'mystat_single_activity_shortcode_handler' );
}
add_action( 'init', 'mystat_register_shortcode' );

/**
 * Funkcja obsługująca shortcode.
 * @param array $atts Atrybuty shortcode'u (np. year, month).
 * @return string HTML do wyświetlenia.
 */
function mystat_shortcode_handler( $atts ) {
    global $wpdb;

    // Ustawienie domyślnych atrybutów (bieżący rok i miesiąc)
    $atts = shortcode_atts( array(
        'year'  => current_time( 'Y' ),
        'month' => current_time( 'n' ),
    ), $atts, 'moje_statystyki' );

    $year = intval( $atts['year'] );
    $month = intval( $atts['month'] );

    // Pobieranie danych z bazy
    $table_activities = $wpdb->prefix . 'mystat_activities';
    $sql = $wpdb->prepare("
        SELECT a.*, c.name as category_name, eq.name as equipment_name
        FROM $table_activities a
        LEFT JOIN {$wpdb->prefix}mystat_categories c ON a.category_id = c.id
        LEFT JOIN {$wpdb->prefix}mystat_equipment eq ON a.equipment_id = eq.id
        WHERE YEAR(a.date) = %d AND MONTH(a.date) = %d
        ORDER BY a.date ASC
    ", $year, $month);

    $activities = $wpdb->get_results( $sql );

    // Obliczanie podsumowań
    $total_distance = 0;
    $total_seconds = 0;
    foreach ($activities as $activity) {
        $total_distance += $activity->distance;
        if ( ! empty( $activity->duration ) ) {
            list($h, $m, $s) = explode(':', $activity->duration);
            $total_seconds += $h * 3600 + $m * 60 + $s;
        }
    }
    $hours = floor($total_seconds / 3600);
    $minutes = floor(($total_seconds % 3600) / 60);
    $total_duration_formatted = sprintf('%d godz. %d min.', $hours, $minutes);

    // Rozpoczęcie buforowania wyjścia
    ob_start();
    ?>
    <div class="mystats-shortcode-container">
        
        <h3>Podsumowanie miesiąca</h3>
        <table class="mystats-summary-table">
            <thead>
                <tr>
                    <th>Całkowity dystans</th>
                    <th>Całkowity czas</th>
                </tr>
            </thead>
            <tbody>
                <tr>
                    <td><?php echo number_format( $total_distance, 2, ',', ' ' ); ?> km</td>
                    <td><?php echo esc_html( $total_duration_formatted ); ?></td>
                </tr>
            </tbody>
        </table>

        <h3>Lista aktywności</h3>
        <table class="mystats-activity-table">
            <thead>
                <tr>
                    <th>Data</th>
                    <th>Tytuł</th>
                    <th>Kategoria</th>
                    <th>Dystans</th>
                    <th>Czas</th>
                    <th>Sprzęt</th>
                </tr>
            </thead>
            <tbody>
                <?php if ( ! empty( $activities ) ) : ?>
                    <?php foreach ( $activities as $row ) : ?>
                        <tr>
                            <td><?php echo esc_html( date_i18n( 'd.m.Y', strtotime( $row->date ) ) ); ?></td>
                            <td><?php echo esc_html( $row->title ); ?></td>
                            <td><?php echo esc_html( $row->category_name ); ?></td>
                            <td><?php echo number_format( $row->distance, 2, ',', ' ' ); ?> km</td>
                            <td><?php echo esc_html( $row->duration ); ?></td>
                            <td><?php echo esc_html( $row->equipment_name ); ?></td>
                        </tr>
                    <?php endforeach; ?>
                <?php else : ?>
                    <tr>
                        <td colspan="6">Brak aktywności w tym miesiącu.</td>
                    </tr>
                <?php endif; ?>
            </tbody>
        </table>
    </div>
    <style>
        .mystats-shortcode-container table { width: 100%; border-collapse: collapse; margin-bottom: 2em; }
        .mystats-shortcode-container th, .mystats-shortcode-container td { padding: 8px 12px; border: 1px solid #ddd; text-align: left; }
        .mystats-shortcode-container th { background-color: #f4f4f4; }
        .mystats-activity-table td:nth-child(4), .mystats-activity-table td:nth-child(5) { text-align: right; }
    </style>
    <?php
    // Zwrócenie zawartości bufora
    return ob_get_clean();
}
?>

<?php
/**
 * Funkcja obsługująca shortcode [moje_statystyki_wpis].
 * @param array $atts Atrybuty shortcode'u (np. id).
 * @return string HTML do wyświetlenia.
 */
function mystat_single_activity_shortcode_handler( $atts ) {
    global $wpdb;

    $atts = shortcode_atts( array(
        'id' => 0,
    ), $atts, 'moje_statystyki_wpis' );

    $activity_id = intval( $atts['id'] );

    if ( $activity_id === 0 ) {
        return '<p><strong>Błąd:</strong> Nie podano ID wpisu w shortcode.</p>';
    }

    // Pobieranie danych z bazy
    $table_activities = $wpdb->prefix . 'mystat_activities';
    $sql = $wpdb->prepare("
        SELECT a.*, c.name as category_name, et.name as event_type_name, eq.name as equipment_name
        FROM $table_activities a
        LEFT JOIN {$wpdb->prefix}mystat_categories c ON a.category_id = c.id
        LEFT JOIN {$wpdb->prefix}mystat_event_types et ON a.event_type_id = et.id
        LEFT JOIN {$wpdb->prefix}mystat_equipment eq ON a.equipment_id = eq.id
        WHERE a.id = %d
    ", $activity_id);

    $activity = $wpdb->get_row( $sql );

    if ( ! $activity ) {
        return '<p><strong>Błąd:</strong> Nie znaleziono wpisu o ID ' . esc_html($activity_id) . '.</p>';
    }

    // Funkcja pomocnicza do wyświetlania wiersza
    $render_row = function($label, $value, $unit = '') {
        if ( ! is_null($value) && $value !== '' && $value != 0) {
            echo '<tr>';
            echo '<th>' . esc_html($label) . '</th>';
            echo '<td>' . esc_html($value) . ($unit ? ' ' . esc_html($unit) : '') . '</td>';
            echo '</tr>';
        }
    };

    ob_start();

    // Prepare map data if GPX exists
    $track_points = [];
    if ( ! empty( $activity->gpx_url ) ) {
        $track_points = mystat_get_track_from_gpx_url( $activity->gpx_url );

        if ( ! empty( $track_points ) ) {
            // Enqueue scripts for the frontend
            wp_enqueue_style('leaflet-css', 'https://unpkg.com/leaflet@1.9.4/dist/leaflet.css');
            wp_enqueue_script('leaflet-js', 'https://unpkg.com/leaflet@1.9.4/dist/leaflet.js', [], '1.9.4', true);
            
            $map_id = 'mystat-map-' . esc_attr( $activity->id );

            // Pass track data to a script
            wp_register_script('mystat-shortcode-map-loader-' . $activity->id, false);
            wp_enqueue_script('mystat-shortcode-map-loader-' . $activity->id);
            wp_add_inline_script('mystat-shortcode-map-loader-' . $activity->id,
                '(function() {
                    document.addEventListener("DOMContentLoaded", function() {
                        if (typeof L === "undefined") return;
                        const trackPoints = ' . json_encode( $track_points ) . ';
                        const mapId = "' . esc_js($map_id) . '";
                        
                        var container = L.DomUtil.get(mapId);
                        if(container != null) { container._leaflet_id = null; }

                        const map = L.map(mapId);
                        L.tileLayer("https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png", {
                            attribution: \'&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a>\'
                        }).addTo(map);
                        
                        const polyline = L.polyline(trackPoints, {color: "#3498db"}).addTo(map);
                        map.fitBounds(polyline.getBounds().pad(0.1));
                    });
                })();'
            );
        }
    }

    ?>
    <div class="mystat-single-activity-shortcode">
        <h4><?php echo esc_html( $activity->title ); ?></h4>
        <p><em><?php echo esc_html( date_i18n( 'j F Y', strtotime( $activity->date ) ) ); ?></em></p>
        
        <table class="mystat-single-summary-table">
            <tbody>
                <?php $render_row('Dystans', number_format($activity->distance, 2, ',', ' '), 'km'); ?>
                <?php $render_row('Czas trwania', $activity->duration); ?>
                <?php $render_row('Średnia prędkość', number_format($activity->avg_speed, 1, ',', ' '), 'km/h'); ?>
                <?php $render_row('Suma wzniosów', $activity->total_elevation_gain, 'm'); ?>
                <?php $render_row('Kategoria', $activity->category_name); ?>
                <?php $render_row('Sprzęt', $activity->equipment_name); ?>
                <?php if ( ! empty( $activity->strava_url ) ) : ?>
                    <tr><th>Strava</th><td><a href="<?php echo esc_url( $activity->strava_url ); ?>" target="_blank" rel="noopener noreferrer">Zobacz aktywność</a></td></tr>
                <?php endif; ?>
            </tbody>
        </table>

        <?php if ( ! empty( $track_points ) ) : ?>
            <div id="<?php echo $map_id; ?>" style="height: 350px; width: 100%; margin-top: 15px; border-radius: 5px;"></div>
        <?php endif; ?>
    </div>
    <style>
        .mystat-single-activity-shortcode { border: 1px solid #eee; padding: 15px; margin-bottom: 1.5em; border-radius: 5px; background: #f9f9f9; }
        .mystat-single-activity-shortcode h4 { margin-top: 0; }
        .mystat-single-activity-shortcode p em { color: #777; font-size: 0.9em; }
        .mystat-single-summary-table { width: 100%; border-collapse: collapse; }
        .mystat-single-summary-table th, .mystat-single-summary-table td { padding: 4px 0; border: none; text-align: left; vertical-align: top; }
        .mystat-single-summary-table th { font-weight: bold; width: 150px; }
    </style>
    <?php
    return ob_get_clean();
}
?>