<?php
/**
 * Fastless Cache admin screen.
 *
 * Registers the top-level menu page and renders the full Fastless-style panel:
 * header, tab navigation, notices/toasts and the active tab's content. Owns the
 * `admin_post_*` handlers for save, clear, reset, export and import. The preload
 * runs through admin-ajax instead (see Fastless_Cache_Preload_AJAX).
 *
 * @package Fastless_Cache
 */

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

class Fastless_Cache_Admin
{
    /**
     * Menu slug for the top-level page.
     */
    const SLUG = 'fastless-cache';

    /**
     * Singleton instance.
     *
     * @var Fastless_Cache_Admin|null
     */
    private static $instance = null;

    /**
     * Get the singleton.
     *
     * @return Fastless_Cache_Admin
     */
    public static function instance()
    {
        if (null === self::$instance) {
            self::$instance = new self();
        }

        return self::$instance;
    }

    /**
     * Register hooks.
     *
     * @return void
     */
    public function init()
    {
        add_action('admin_menu', array($this, 'register_menu'));
        add_action('admin_enqueue_scripts', array($this, 'enqueue_assets'));

        // Settings save.
        add_action('admin_post_fastless_cache_save', array($this, 'handle_save'));

        // Action handlers (all nonce + capability checked).
        add_action('admin_post_fastless_cache_clear', array($this, 'handle_clear'));
        add_action('admin_post_fastless_cache_reset', array($this, 'handle_reset'));
        add_action('admin_post_fastless_cache_export', array($this, 'handle_export'));
        add_action('admin_post_fastless_cache_import', array($this, 'handle_import'));
    }

    /**
     * Register the top-level menu page.
     *
     * @return void
     */
    public function register_menu()
    {
        add_menu_page(
            __('Fastless Cache', 'fastless-cache'),
            __('Fastless Cache', 'fastless-cache'),
            'manage_options',
            self::SLUG,
            array($this, 'render_page'),
            'dashicons-performance',
            80
        );
    }

    /**
     * Enqueue admin assets.
     *
     * @param string $hook Current admin page hook.
     * @return void
     */
    public function enqueue_assets($hook)
    {
        if (false === strpos($hook, self::SLUG)) {
            return;
        }

        $css = FASTLESS_CACHE_DIR . '/admin/css/admin.css';
        $js  = FASTLESS_CACHE_DIR . '/admin/js/admin.js';

        if (file_exists($css)) {
            wp_enqueue_style('fastless-cache-admin', FASTLESS_CACHE_URL . 'admin/css/admin.css', array(), filemtime($css));
        }

        if (file_exists($js)) {
            wp_enqueue_script('fastless-cache-admin', FASTLESS_CACHE_URL . 'admin/js/admin.js', array(), filemtime($js), true);

            wp_localize_script('fastless-cache-admin', 'fastlessCacheAdmin', array(
                'ajaxUrl' => admin_url('admin-ajax.php'),
                'nonce'   => wp_create_nonce('fastless_cache_admin'),
                'siteUrl' => home_url('/'),
                'labels'  => array(
                    'cacheCleared' => __('Cache cleared.', 'fastless-cache'),
                    'settingsSaved' => __('Settings saved.', 'fastless-cache'),
                    'imported' => __('Settings imported.', 'fastless-cache'),
                    'error' => __('Something went wrong.', 'fastless-cache'),
                ),
                'preload' => array(
                    'start'          => __('Preload cache', 'fastless-cache'),
                    'starting'       => __('Starting preload…', 'fastless-cache'),
                    'running'        => __('Preloading…', 'fastless-cache'),
                    'stop'           => __('Stop', 'fastless-cache'),
                    'stopping'       => __('Stopping…', 'fastless-cache'),
                    'confirmStop'    => __('Stop the preload? Progress so far is kept and you can start again later.', 'fastless-cache'),
                    'resumed'        => __('Preload resumed.', 'fastless-cache'),
                    'connectionLost' => __('Connection lost - the preload is paused. Reload this page to resume it.', 'fastless-cache'),
                ),
            ));
        }
    }

    /**
     * Render the admin page.
     *
     * @return void
     */
    public function render_page()
    {
        $nav = Fastless_Cache_Tabs::nav();
        $tab = isset($_GET['tab']) ? sanitize_key($_GET['tab']) : 'dashboard'; // phpcs:ignore WordPress.Security.NonceVerification -- read-only display parameter, sanitized with sanitize_key() and restricted to the manage_options screen.

        if (! array_key_exists($tab, $nav)) {
            $tab = 'dashboard';
        }

        // Populate the dynamic tools fields before rendering that tab.
        if ('tools' === $tab) {
            $this->render_tools_content();
        }

        $version = defined('FASTLESS_CACHE_VERSION') ? FASTLESS_CACHE_VERSION : '';
        ?>
        <div class="fastless-cache-shell">
            <header class="fastless-cache-header">
                <div class="fastless-cache-header__inner">
                    <div class="fastless-cache-header__brand">
                        <span class="fastless-cache-logo"><?php if (class_exists('Fastless_Cache_Icons')) { Fastless_Cache_Icons::icon('bolt', 22); } ?></span>
                        <span class="fastless-cache-header__title"><?php esc_html_e('Fastless Cache', 'fastless-cache'); ?></span>
                        <?php if ($version) : ?>
                            <span class="fastless-cache-version"><?php echo esc_html($version); ?></span>
                        <?php endif; ?>
                    </div>
                    <div class="fastless-cache-header__meta">
                        <?php if (Fastless_Cache_Tabs::has_form($tab)) : ?>
                            <button type="submit" form="<?php echo esc_attr(Fastless_Cache_Tabs::FORM_ID); ?>" class="fastless-cache-button fastless-cache-button--save">
                                <?php esc_html_e('Save changes', 'fastless-cache'); ?>
                            </button>
                        <?php endif; ?>
                    </div>
                </div>
            </header>

            <div class="wrap fastless-cache-wrap">
                <?php $this->render_notices(); ?>

                <div class="fastless-cache-panel">
                    <nav class="fastless-cache-nav" aria-label="<?php esc_attr_e('Fastless Cache sections', 'fastless-cache'); ?>">
                        <?php foreach ($nav as $key => $definition) : ?>
                            <a class="fastless-cache-nav__item <?php echo $key === $tab ? 'is-active' : ''; ?>" href="<?php echo esc_url($this->admin_url(array('tab' => $key))); ?>">
                                <span class="fastless-cache-nav__icon"><?php if (class_exists('Fastless_Cache_Icons')) { Fastless_Cache_Icons::icon($definition['icon'], 18); } ?></span>
                                <span class="fastless-cache-nav__label"><?php echo esc_html($definition['label']); ?></span>
                            </a>
                        <?php endforeach; ?>
                    </nav>

                    <main class="fastless-cache-main">
                        <?php Fastless_Cache_Tabs::render($tab); ?>
                    </main>
                </div>
            </div>
        </div>
        <?php
    }

    /**
     * Render the notice / toast stack based on the current query flags.
     *
     * @return void
     */
    private function render_notices()
    {
        $toasts = array();

        if (isset($_GET['fastless_saved'])) { // phpcs:ignore WordPress.Security.NonceVerification -- isset-only check of post-redirect-get notice flags; no form processing occurs here.
            $toasts[] = array('type' => 'success', 'message' => __('Settings saved.', 'fastless-cache'));
        }
        if (isset($_GET['fastless_cache_cleared'])) { // phpcs:ignore WordPress.Security.NonceVerification -- isset-only check of post-redirect-get notice flags; no form processing occurs here.
            $toasts[] = array('type' => 'success', 'message' => __('Cache cleared.', 'fastless-cache'));
        }
        if (isset($_GET['fastless_reset'])) { // phpcs:ignore WordPress.Security.NonceVerification -- isset-only check of post-redirect-get notice flags; no form processing occurs here.
            $toasts[] = array('type' => 'success', 'message' => __('Settings reset.', 'fastless-cache'));
        }
        if (isset($_GET['fastless_imported'])) { // phpcs:ignore WordPress.Security.NonceVerification -- isset-only check of post-redirect-get notice flags; no form processing occurs here.
            $toasts[] = array('type' => 'success', 'message' => __('Settings imported.', 'fastless-cache'));
        }
        if (isset($_GET['fastless_error'])) { // phpcs:ignore WordPress.Security.NonceVerification -- isset-only check of post-redirect-get notice flags; no form processing occurs here.
            $toasts[] = array('type' => 'error', 'message' => sanitize_text_field(wp_unslash($_GET['fastless_error']))); // phpcs:ignore WordPress.Security.NonceVerification -- isset-only check of post-redirect-get notice flags; no form processing occurs here.
        }

        if (empty($toasts)) {
            return;
        }
        ?>
        <div class="fastless-cache-toasts" role="status" aria-live="polite">
            <?php foreach ($toasts as $toast) : ?>
                <div class="fastless-cache-toast fastless-cache-toast--<?php echo esc_attr($toast['type']); ?>"<?php echo 'success' === $toast['type'] || 'info' === $toast['type'] ? ' data-autohide' : ''; ?>>
                    <span class="fastless-cache-toast__icon" aria-hidden="true"></span>
                    <p class="fastless-cache-toast__text"><?php echo esc_html($toast['message']); ?></p>
                    <button type="button" class="fastless-cache-toast__close" aria-label="<?php esc_attr_e('Dismiss', 'fastless-cache'); ?>">&times;</button>
                </div>
            <?php endforeach; ?>
        </div>
        <?php
    }

    /**
     * Populate the dynamic tools custom fields.
     *
     * @return void
     */
    private function render_tools_content()
    {
        Fastless_Cache_Fields::set_custom_content('tools', 'export_import_textarea', $this->render_export_import());
    }

    /**
     * The export / import block.
     *
     * The export is not on screen until asked for: the JSON rides along in an
     * inert application/json block (hex-escaped so it can never break out of
     * the script element) and the button copies it into the textarea, ready to
     * select and copy.
     *
     * @return string
     */
    private function render_export_import()
    {
        $export = wp_json_encode(Fastless_Cache_Options::all(), JSON_HEX_TAG | JSON_HEX_AMP | JSON_HEX_QUOT | JSON_HEX_APOS);
        ob_start();
        ?>
        <button type="button" id="fastless-cache-export-generate" class="fastless-cache-button fastless-cache-button--ghost">
            <?php if (class_exists('Fastless_Cache_Icons')) { Fastless_Cache_Icons::icon('download', 16); } ?>
            <?php esc_html_e('Generate settings export', 'fastless-cache'); ?>
        </button>
        <textarea id="fastless-cache-export" rows="8" readonly hidden aria-label="<?php esc_attr_e('Exported settings', 'fastless-cache'); ?>"></textarea>
        <script type="application/json" id="fastless-cache-export-data"><?php echo $export; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- hex-escaped JSON in an inert script element ?></script>

        <form method="post" action="<?php echo esc_url(admin_url('admin-post.php')); ?>" style="margin-top:10px;">
            <input type="hidden" name="action" value="fastless_cache_import">
            <?php wp_nonce_field('fastless_cache_admin', 'fastless_cache_nonce'); ?>
            <label class="fastless-cache-field__label" for="fastless-cache-import"><?php esc_html_e('Import', 'fastless-cache'); ?></label>
            <textarea id="fastless-cache-import" name="fastless_cache_import" rows="4" placeholder="<?php esc_attr_e('Paste a saved export here.', 'fastless-cache'); ?>"></textarea>
            <button type="submit" class="fastless-cache-button fastless-cache-button--primary"><?php esc_html_e('Import settings', 'fastless-cache'); ?></button>
        </form>
        <?php
        return ob_get_clean();
    }

    /**
     * Handle a settings save.
     *
     * @return void
     */
    public function handle_save()
    {
        if (! current_user_can('manage_options')) {
            wp_die(esc_html__('You do not have permission to do that.', 'fastless-cache'));
        }

        check_admin_referer('fastless_cache_save', 'fastless_cache_nonce');

        $sections = isset($_POST['fastless_cache']) && is_array($_POST['fastless_cache']) ? wp_unslash($_POST['fastless_cache']) : array(); // phpcs:ignore WordPress.Security.ValidatedSanitizedInput -- raw input is passed to Fastless_Cache_Options::save(), which applies schema-driven typed sanitization to every field before storage.

        $result = Fastless_Cache_Options::instance()->save($sections);

        if (is_wp_error($result)) {
            wp_safe_redirect(add_query_arg('fastless_error', urlencode($result->get_error_message()), $this->admin_url()));
            exit;
        }

        // update_option() skips its hooks when the new value equals the old
        // one, so a re-save of unchanged values would leave a stale settings
        // file behind (e.g. a footprint value that diverged on an earlier
        // install). Rewrite the file from the stored settings every time.
        if (class_exists('Fastless_Cache')) {
            Fastless_Cache::on_update_backend('fastless_cache', Fastless_Cache::get_settings(false));
        }

        if (Fastless_Cache_Options::enabled('clearing', 'clear_site_cache_on_saved_settings')) {
            Fastless_Cache::clear_site_cache();
        }

        wp_safe_redirect(add_query_arg('fastless_saved', 1, $this->admin_url()));
        exit;
    }

    /**
     * Handle a clear-cache request.
     *
     * @return void
     */
    public function handle_clear()
    {
        $this->verify_action_nonce();

        Fastless_Cache::clear_site_cache();

        wp_safe_redirect(add_query_arg('fastless_cache_cleared', 1, $this->admin_url()));
        exit;
    }

    /**
     * Handle a settings reset.
     *
     * @return void
     */
    public function handle_reset()
    {
        $this->verify_action_nonce();

        Fastless_Cache_Options::reset();
        Fastless_Cache::update_backend();

        wp_safe_redirect(add_query_arg('fastless_reset', 1, $this->admin_url()));
        exit;
    }

    /**
     * Handle an export request: download the settings as a JSON file.
     *
     * @return void
     */
    public function handle_export()
    {
        if (! current_user_can('manage_options')) {
            wp_die(esc_html__('You do not have permission to do that.', 'fastless-cache'));
        }

        check_admin_referer('fastless_cache_admin', 'fastless_cache_nonce');

        $data = wp_json_encode(Fastless_Cache_Options::all());

        header('Content-Type: application/json');
        header('Content-Disposition: attachment; filename="fastless-cache-settings.json"');

        echo $data; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
        exit;
    }

    /**
     * Handle an import request.
     *
     * @return void
     */
    public function handle_import()
    {
        if (! current_user_can('manage_options')) {
            wp_die(esc_html__('You do not have permission to do that.', 'fastless-cache'));
        }

        check_admin_referer('fastless_cache_admin', 'fastless_cache_nonce');

        $raw = isset($_POST['fastless_cache_import']) ? wp_unslash($_POST['fastless_cache_import']) : ''; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput -- raw JSON input validated via json_decode() and schema-driven sanitization in sanitize_import_values().

        // Validate JSON: check for parse errors, ensure it's an array, allowlist keys.
        $data = json_decode($raw, true);

        if (json_last_error() !== JSON_ERROR_NONE || ! is_array($data)) {
            wp_safe_redirect(add_query_arg('fastless_error', urlencode(__('Invalid import data.', 'fastless-cache')), $this->admin_url()));
            exit;
        }

        // Allowlist expected top-level sections (schema-driven).
        $allowed_sections = array('general', 'clearing', 'exclusions', 'query_strings', 'cookies', 'tools');
        $filtered_data    = array();

        foreach ($data as $section => $values) {
            if (! in_array($section, $allowed_sections, true) || ! is_array($values)) {
                continue;
            }
            $filtered_data[$section] = $this->sanitize_import_values($values);
        }

        if (empty($filtered_data)) {
            wp_safe_redirect(add_query_arg('fastless_error', urlencode(__('No valid settings found in import data.', 'fastless-cache')), $this->admin_url()));
            exit;
        }

        $result = Fastless_Cache_Options::instance()->save($filtered_data);

        if (is_wp_error($result)) {
            wp_safe_redirect(add_query_arg('fastless_error', urlencode($result->get_error_message()), $this->admin_url()));
            exit;
        }

        // Same stale-file reasoning as handle_save(): force the rewrite even
        // when the imported values match what is already stored.
        if (class_exists('Fastless_Cache')) {
            Fastless_Cache::on_update_backend('fastless_cache', Fastless_Cache::get_settings(false));
        }

        wp_safe_redirect(add_query_arg('fastless_imported', 1, $this->admin_url()));
        exit;
    }

    /**
     * Recursively sanitize import values by type.
     *
     * @param array $values Raw values from JSON import.
     * @return array Sanitized values.
     */
    private function sanitize_import_values($values)
    {
        $sanitized = array();

        foreach ($values as $key => $value) {
            if (is_array($value)) {
                $sanitized[$key] = $this->sanitize_import_values($value);
            } elseif (is_bool($value)) {
                $sanitized[$key] = (bool) $value;
            } elseif (is_int($value)) {
                $sanitized[$key] = (int) $value;
            } elseif (is_float($value)) {
                $sanitized[$key] = (float) $value;
            } elseif (is_string($value)) {
                // Length limit for safety.
                $sanitized[$key] = substr(sanitize_text_field($value), 0, 4000);
            } else {
                // Skip null, objects, resources.
                continue;
            }
        }

        return $sanitized;
    }

    /**
     * Verify the capability and nonce shared by the action handlers.
     *
     * @return void
     */
    private function verify_action_nonce()
    {
        if (! current_user_can('manage_options')) {
            wp_die(esc_html__('You do not have permission to do that.', 'fastless-cache'));
        }

        check_admin_referer('fastless_cache_admin', 'fastless_cache_nonce');
    }

    /**
     * Build a URL to the panel with extra query args.
     *
     * @param array $args Query args.
     * @return string
     */
    private function admin_url($args = array())
    {
        return add_query_arg(array_merge(array('page' => self::SLUG), $args), admin_url('admin.php'));
    }
}