<?php
/**
 * Admin pages: document list with drop zone, edit screen, settings.
 *
 * @package DropDMS
 */

defined( 'ABSPATH' ) || exit;

require_once DROPDMS_DIR . 'includes/class-dropdms-list-table.php';
require_once DROPDMS_DIR . 'includes/class-dropdms-pro-hints.php';

/**
 * Menu, pages, form handlers and scripts of the admin area.
 */
final class DropDMS_Admin {

	/** Hook suffix of the document page. */
	private static $page_hook = '';

	/** Hook suffix of the settings page. */
	private static $settings_hook = '';

	/**
	 * Document list (created in the load hook, before the screen options read the columns).
	 *
	 * @var DropDMS_List_Table|null
	 */
	private static $table = null;

	/** Registers the hooks. */
	public static function init() {
		DropDMS_Pro_Hints::init();

		add_action( 'admin_menu', array( __CLASS__, 'menu' ) );
		add_action( 'admin_init', array( __CLASS__, 'register_settings' ) );
		add_action( 'admin_enqueue_scripts', array( __CLASS__, 'enqueue' ) );
		add_action( 'admin_post_dropdms_save', array( __CLASS__, 'handle_save' ) );
		add_action( 'admin_post_dropdms_delete', array( __CLASS__, 'handle_delete' ) );
		add_action( 'admin_post_dropdms_optimize', array( __CLASS__, 'handle_optimize' ) );
		add_filter( 'parent_file', array( __CLASS__, 'parent_file' ) );
		add_filter( 'set-screen-option', array( __CLASS__, 'set_screen_option' ), 10, 3 );
		add_filter( 'plugin_action_links_' . plugin_basename( DROPDMS_FILE ), array( __CLASS__, 'action_links' ) );
	}

	// ------------------------------------------------------------------ URLs

	/**
	 * Edit screen of a document.
	 *
	 * @param int $id Document ID.
	 */
	public static function edit_url( $id ) {
		return add_query_arg(
			array(
				'page'   => 'dropdms',
				'action' => 'edit',
				'id'     => (int) $id,
			),
			admin_url( 'admin.php' )
		);
	}

	/**
	 * File URL (REST, with nonce for the cookie authentication).
	 *
	 * @param int  $id     Document ID.
	 * @param bool $inline Show in the browser.
	 */
	public static function file_url( $id, $inline ) {
		$args = array( '_wpnonce' => wp_create_nonce( 'wp_rest' ) );

		if ( $inline ) {
			$args['inline'] = 1;
		}

		return add_query_arg( $args, rest_url( DropDMS_Rest::NS . '/documents/' . (int) $id . '/file' ) );
	}

	/**
	 * Thumbnail URL.
	 *
	 * @param int $id Document ID.
	 */
	public static function thumb_url( $id ) {
		return add_query_arg( '_wpnonce', wp_create_nonce( 'wp_rest' ), rest_url( DropDMS_Rest::NS . '/documents/' . (int) $id . '/thumb' ) );
	}

	/**
	 * Delete URL with nonce.
	 *
	 * @param int $id Document ID.
	 */
	public static function delete_url( $id ) {
		return wp_nonce_url(
			add_query_arg(
				array(
					'action' => 'dropdms_delete',
					'id'     => (int) $id,
				),
				admin_url( 'admin-post.php' )
			),
			'dropdms_delete_' . (int) $id
		);
	}

	/**
	 * Formats a UTC datetime from the database in the site time zone and language.
	 *
	 * @param string $gmt Y-m-d H:i:s (UTC).
	 */
	public static function local_date( $gmt ) {
		return mysql2date( get_option( 'date_format' ) . ' ' . get_option( 'time_format' ), get_date_from_gmt( $gmt ) );
	}

	// ------------------------------------------------------------------ Menu

	/** Admin menu. */
	public static function menu() {
		self::$page_hook = add_menu_page(
			__( 'DropDMS – Documents', 'dropdms' ),
			'DropDMS',
			'dropdms_view',
			'dropdms',
			array( __CLASS__, 'render_documents_page' ),
			'dashicons-media-document',
			26
		);

		add_submenu_page( 'dropdms', __( 'Documents', 'dropdms' ), __( 'Documents', 'dropdms' ), 'dropdms_view', 'dropdms', array( __CLASS__, 'render_documents_page' ) );
		add_submenu_page( 'dropdms', __( 'Categories', 'dropdms' ), __( 'Categories', 'dropdms' ), 'dropdms_manage', 'edit-tags.php?taxonomy=' . DropDMS_Categories::TAXONOMY );
		self::$settings_hook = add_submenu_page( 'dropdms', __( 'DropDMS Settings', 'dropdms' ), __( 'Settings', 'dropdms' ), 'dropdms_manage', 'dropdms-settings', array( __CLASS__, 'render_settings_page' ) );

		add_action( 'load-' . self::$page_hook, array( __CLASS__, 'load_documents_page' ) );
	}

	/**
	 * Highlights the DropDMS menu on the category screens.
	 *
	 * @param string $parent_file Parent menu file.
	 */
	public static function parent_file( $parent_file ) {
		global $submenu_file;

		$screen = get_current_screen();

		if ( $screen && DropDMS_Categories::TAXONOMY === $screen->taxonomy ) {
			$submenu_file = 'edit-tags.php?taxonomy=' . DropDMS_Categories::TAXONOMY; // phpcs:ignore WordPress.WP.GlobalVariablesOverride.Prohibited -- intended to highlight the submenu.

			return 'dropdms';
		}

		return $parent_file;
	}

	/**
	 * Saves the "documents per page" screen option.
	 *
	 * @param mixed  $status Value to save or false.
	 * @param string $option Option name.
	 * @param int    $value  New value.
	 */
	public static function set_screen_option( $status, $option, $value ) {
		return 'dropdms_per_page' === $option ? min( 200, max( 1, (int) $value ) ) : $status;
	}

	/**
	 * Settings link on the plugins screen.
	 *
	 * @param array $links Links.
	 */
	public static function action_links( $links ) {
		if ( current_user_can( 'dropdms_manage' ) ) {
			array_unshift( $links, '<a href="' . esc_url( admin_url( 'admin.php?page=dropdms-settings' ) ) . '">' . esc_html__( 'Settings', 'dropdms' ) . '</a>' );
		}

		return $links;
	}

	// ------------------------------------------------------------------ Assets

	/**
	 * Loads CSS/JS on the DropDMS pages.
	 *
	 * @param string $hook Hook suffix.
	 */
	public static function enqueue( $hook ) {
		if ( $hook !== self::$page_hook && $hook !== self::$settings_hook ) {
			return;
		}

		wp_enqueue_style( 'dropdms-admin', DROPDMS_URL . 'assets/css/admin.css', array(), DROPDMS_VERSION );

		if ( $hook !== self::$page_hook ) {
			return;
		}

		self::register_upload_script();
		wp_enqueue_script( 'dropdms-upload' );
	}

	/** Registers the upload/OCR script with its options (also used by the Pro add-on). */
	public static function register_upload_script() {
		if ( wp_script_is( 'dropdms-upload', 'registered' ) ) {
			return;
		}

		$vendor = DROPDMS_URL . 'assets/vendor/';

		wp_register_script( 'dropdms-upload', DROPDMS_URL . 'assets/js/upload.js', array( 'wp-i18n' ), DROPDMS_VERSION, true );
		wp_set_script_translations( 'dropdms-upload', 'dropdms', DROPDMS_DIR . 'languages' );

		$options = array(
			'restUrl'  => esc_url_raw( rest_url( DropDMS_Rest::NS . '/' ) ),
			'nonce'    => wp_create_nonce( 'wp_rest' ),
			'editUrl'  => esc_url_raw( admin_url( 'admin.php?page=dropdms&action=edit&id=' ) ),
			'maxBytes' => DropDMS_Settings::max_upload_bytes(),
			'maxPages' => (int) DropDMS_Settings::get( 'pdf_max_pages' ),
			'ocrLang'  => (string) DropDMS_Settings::get( 'ocr_lang' ),
			// Bundled libraries (no CDN): Tesseract.js 5.1.1, tesseract.js-core 5.1.1, tessdata_fast 4.1.0 (as JSON),
			// pdf.js 4.10.38.
			'vendor'   => array(
				'tesseract'   => $vendor . 'tesseract/tesseract.min.js',
				'worker'      => $vendor . 'tesseract/worker.min.js',
				'core'        => $vendor . 'tesseract-core/',
				'lang'        => $vendor . 'tessdata/',
				'pdfjs'       => $vendor . 'pdfjs/pdf.min.js',
				'pdfjsWorker' => $vendor . 'pdfjs/pdf.worker.min.js',
			),
		);

		wp_add_inline_script( 'dropdms-upload', 'window.dropdmsUpload = ' . wp_json_encode( $options ) . ';', 'before' );
	}

	// ------------------------------------------------------------------ Documents page

	/** Runs before the documents page is output: screen options and bulk actions. */
	public static function load_documents_page() {
		add_screen_option(
			'per_page',
			array(
				'label'   => __( 'Documents per page', 'dropdms' ),
				'default' => 20,
				'option'  => 'dropdms_per_page',
			)
		);

		self::handle_bulk();

		self::$table = new DropDMS_List_Table();
	}

	/** Bulk delete from the list (GET form of WP_List_Table, nonce "bulk-documents"). */
	private static function handle_bulk() {
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- the nonce is checked below before acting.
		$action = isset( $_REQUEST['action'] ) ? sanitize_key( wp_unslash( $_REQUEST['action'] ) ) : '';

		if ( '-1' === $action || '' === $action ) {
			// phpcs:ignore WordPress.Security.NonceVerification.Recommended
			$action = isset( $_REQUEST['action2'] ) ? sanitize_key( wp_unslash( $_REQUEST['action2'] ) ) : '';
		}

		if ( 'delete' !== $action || empty( $_REQUEST['document'] ) ) { // phpcs:ignore WordPress.Security.NonceVerification.Recommended
			return;
		}

		check_admin_referer( 'bulk-documents' );

		if ( ! current_user_can( 'dropdms_delete' ) ) {
			wp_die( esc_html__( 'You are not allowed to delete documents.', 'dropdms' ), 403 );
		}

		$ids     = array_map( 'absint', (array) wp_unslash( $_REQUEST['document'] ) );
		$deleted = DropDMS_Documents::delete( $ids );

		wp_safe_redirect(
			add_query_arg(
				array(
					'page'    => 'dropdms',
					'deleted' => $deleted,
				),
				admin_url( 'admin.php' )
			)
		);
		exit;
	}

	/** Output of the documents page (list or edit screen). */
	public static function render_documents_page() {
		// phpcs:disable WordPress.Security.NonceVerification.Recommended -- read-only view parameters.
		$action = isset( $_GET['action'] ) ? sanitize_key( wp_unslash( $_GET['action'] ) ) : '';
		$id     = isset( $_GET['id'] ) ? absint( $_GET['id'] ) : 0;
		// phpcs:enable

		if ( 'edit' === $action && $id ) {
			self::render_edit( $id );
			return;
		}

		$table = self::$table ? self::$table : new DropDMS_List_Table();
		$table->prepare_items();
		$filters = DropDMS_List_Table::filters();

		echo '<div class="wrap dropdms">';
		echo '<h1 class="wp-heading-inline">' . esc_html__( 'Documents', 'dropdms' ) . '</h1>';
		echo '<hr class="wp-header-end">';

		self::notices();

		if ( current_user_can( 'dropdms_upload' ) ) {
			self::render_dropzone();
		}

		/**
		 * Fires above the document list (e.g. for buttons of the Pro add-on).
		 */
		do_action( 'dropdms_before_list' );

		echo '<form method="get" id="dropdms-list-form">';
		echo '<input type="hidden" name="page" value="dropdms" />';
		$table->search_box( __( 'Search documents', 'dropdms' ), 'dropdms-search' );
		$table->display();
		echo '</form>';

		if ( '' !== $filters['search'] ) {
			echo '<p class="description">' . esc_html(
				'fulltext' === DropDMS_Settings::get( 'search_mode' )
					? __( 'Full-text search: finds word beginnings in title, file name, note and recognized text.', 'dropdms' )
					: __( 'Partial word search in title, file name, note and recognized text. All terms must match.', 'dropdms' )
			) . '</p>';
		}

		echo '</div>';
	}

	/** Drop zone with category selection and upload queue. */
	private static function render_dropzone() {
		$max = DropDMS_Settings::max_upload_bytes();
		?>
		<div class="dropdms-upload">
			<div id="dropdms-dropzone" class="dropdms-dropzone" role="button" tabindex="0" aria-describedby="dropdms-hint">
				<span class="dashicons dashicons-upload" aria-hidden="true"></span>
				<strong><?php esc_html_e( 'Drop documents here or click to choose files', 'dropdms' ); ?></strong>
				<span id="dropdms-hint" class="dropdms-hint">
					<?php
					echo esc_html(
						sprintf(
							/* translators: %s: maximum file size, e.g. "20 MB" */
							__( 'PDF, JPG, PNG, WebP, GIF – up to %s per file. Text recognition runs in your browser; duplicates are detected before upload.', 'dropdms' ),
							size_format( $max )
						)
					);
					?>
				</span>
				<input type="file" id="dropdms-fileinput" class="screen-reader-text" multiple accept=".pdf,.jpg,.jpeg,.png,.webp,.gif,application/pdf,image/jpeg,image/png,image/webp,image/gif" />
			</div>
			<noscript><p class="notice notice-warning"><?php esc_html_e( 'The upload needs JavaScript.', 'dropdms' ); ?></p></noscript>
			<p class="dropdms-catselect">
				<label for="dropdms-category"><?php esc_html_e( 'Category for new documents:', 'dropdms' ); ?></label>
				<?php DropDMS_Categories::dropdown( 'dropdms_category', 0, __( '— No category —', 'dropdms' ), 'dropdms-category' ); ?>
			</p>
			<div id="dropdms-queue" class="dropdms-queue" aria-live="polite"></div>
			<div id="dropdms-summary" class="dropdms-summary" aria-live="polite"></div>
		</div>
		<?php
	}

	/** Messages after redirects. */
	private static function notices() {
		// phpcs:disable WordPress.Security.NonceVerification.Recommended -- display of a message only.
		if ( isset( $_GET['deleted'] ) ) {
			$count = absint( $_GET['deleted'] );
			/* translators: %s: number of documents */
			$text = sprintf( _n( '%s document deleted.', '%s documents deleted.', $count, 'dropdms' ), number_format_i18n( $count ) );
			echo '<div class="notice notice-success is-dismissible"><p>' . esc_html( $text ) . '</p></div>';
		}

		if ( isset( $_GET['saved'] ) ) {
			echo '<div class="notice notice-success is-dismissible"><p>' . esc_html__( 'Document saved.', 'dropdms' ) . '</p></div>';
		}
		// phpcs:enable
	}

	// ------------------------------------------------------------------ Edit screen

	/**
	 * Edit screen of a document (read-only without dropdms_edit).
	 *
	 * @param int $id Document ID.
	 */
	private static function render_edit( $id ) {
		$doc = DropDMS_Documents::get( $id );

		if ( ! $doc ) {
			echo '<div class="wrap"><h1>' . esc_html__( 'Document not found.', 'dropdms' ) . '</h1></div>';
			return;
		}

		$can_edit = current_user_can( 'dropdms_edit' );
		$readonly = $can_edit ? '' : ' readonly';
		$user     = get_userdata( (int) $doc->created_by );
		$back     = admin_url( 'admin.php?page=dropdms' );
		?>
		<div class="wrap dropdms">
			<h1 class="wp-heading-inline"><?php echo esc_html( $can_edit ? __( 'Edit document', 'dropdms' ) : __( 'Document', 'dropdms' ) ); ?></h1>
			<a class="page-title-action" href="<?php echo esc_url( $back ); ?>"><?php esc_html_e( 'Back to the list', 'dropdms' ); ?></a>
			<hr class="wp-header-end">
			<?php self::notices(); ?>

			<form method="post" action="<?php echo esc_url( admin_url( 'admin-post.php' ) ); ?>" class="dropdms-edit">
				<input type="hidden" name="action" value="dropdms_save" />
				<input type="hidden" name="id" value="<?php echo (int) $doc->id; ?>" />
				<?php wp_nonce_field( 'dropdms_save_' . (int) $doc->id ); ?>

				<div class="dropdms-edit-grid">
					<div class="dropdms-edit-main">
						<table class="form-table" role="presentation">
							<tr>
								<th scope="row"><label for="dropdms-title"><?php esc_html_e( 'Title', 'dropdms' ); ?></label></th>
								<td><input type="text" class="large-text" id="dropdms-title" name="title" value="<?php echo esc_attr( $doc->title ); ?>" required maxlength="255"<?php echo esc_attr( $readonly ); ?> /></td>
							</tr>
							<tr>
								<th scope="row"><label for="dropdms-edit-category"><?php esc_html_e( 'Category', 'dropdms' ); ?></label></th>
								<td>
									<?php
									if ( $can_edit ) {
										DropDMS_Categories::dropdown( 'category', (int) $doc->category_id, __( '— No category —', 'dropdms' ), 'dropdms-edit-category' );
									} else {
										$names = DropDMS_Categories::names();
										echo esc_html( $names[ (int) $doc->category_id ] ?? '—' );
									}
									?>
								</td>
							</tr>
							<tr>
								<th scope="row"><label for="dropdms-date"><?php esc_html_e( 'Document date', 'dropdms' ); ?></label></th>
								<td>
									<input type="date" id="dropdms-date" name="document_date" value="<?php echo esc_attr( (string) $doc->document_date ); ?>"<?php echo esc_attr( $readonly ); ?> />
									<p class="description"><?php esc_html_e( 'Date of the receipt or letter, e.g. the invoice date.', 'dropdms' ); ?></p>
								</td>
							</tr>
							<tr>
								<th scope="row"><?php esc_html_e( 'Status', 'dropdms' ); ?></th>
								<td>
									<label><input type="checkbox" name="status" value="1" <?php checked( (int) $doc->status, 1 ); ?><?php disabled( ! $can_edit ); ?> /> <?php esc_html_e( 'Published', 'dropdms' ); ?></label>
									<p class="description"><?php esc_html_e( 'Unpublished documents stay in the archive but are hidden from lists on the website (DropDMS Pro).', 'dropdms' ); ?></p>
								</td>
							</tr>
							<tr>
								<th scope="row"><label for="dropdms-note"><?php esc_html_e( 'Note', 'dropdms' ); ?></label></th>
								<td><textarea class="large-text" rows="3" id="dropdms-note" name="note"<?php echo esc_attr( $readonly ); ?>><?php echo esc_textarea( (string) $doc->note ); ?></textarea></td>
							</tr>
							<tr>
								<th scope="row"><label for="dropdms-ocr-text"><?php esc_html_e( 'Recognized text', 'dropdms' ); ?></label></th>
								<td>
									<textarea class="large-text code" rows="16" id="dropdms-ocr-text" name="ocr_text"<?php echo esc_attr( $readonly ); ?>><?php echo esc_textarea( (string) $doc->ocr_text ); ?></textarea>
									<?php if ( $can_edit ) : ?>
										<p>
											<button type="button" class="button" id="dropdms-reocr" data-id="<?php echo (int) $doc->id; ?>"><?php esc_html_e( 'Run text recognition again', 'dropdms' ); ?></button>
											<span id="dropdms-reocr-status" class="dropdms-item-status" aria-live="polite"></span>
										</p>
										<p class="description"><?php esc_html_e( 'Replaces the text and the thumbnail. Manual corrections of the text are lost.', 'dropdms' ); ?></p>
									<?php endif; ?>
								</td>
							</tr>
						</table>
						<?php
						if ( $can_edit ) {
							submit_button( __( 'Save document', 'dropdms' ) );
						}
						?>
					</div>

					<div class="dropdms-edit-side">
						<?php self::render_preview( $doc ); ?>
						<dl class="dropdms-meta">
							<dt><?php esc_html_e( 'File', 'dropdms' ); ?></dt>
							<dd><?php echo esc_html( $doc->filename ); ?></dd>
							<dt><?php esc_html_e( 'Type / size', 'dropdms' ); ?></dt>
							<dd><?php echo esc_html( $doc->mime . ' · ' . size_format( (int) $doc->filesize, 1 ) ); ?></dd>
							<dt><?php esc_html_e( 'Added', 'dropdms' ); ?></dt>
							<dd><?php echo esc_html( DropDMS_Admin::local_date( $doc->created ) . ( $user ? ' · ' . $user->display_name : '' ) ); ?></dd>
							<?php if ( $doc->modified ) : ?>
								<dt><?php esc_html_e( 'Modified', 'dropdms' ); ?></dt>
								<dd><?php echo esc_html( DropDMS_Admin::local_date( $doc->modified ) ); ?></dd>
							<?php endif; ?>
							<dt><?php esc_html_e( 'SHA-256', 'dropdms' ); ?></dt>
							<dd class="dropdms-hash"><?php echo esc_html( $doc->sha256 ); ?></dd>
						</dl>
						<p>
							<a class="button" href="<?php echo esc_url( self::file_url( $doc->id, true ) ); ?>" target="_blank" rel="noopener"><?php esc_html_e( 'Open file', 'dropdms' ); ?></a>
							<a class="button" href="<?php echo esc_url( self::file_url( $doc->id, false ) ); ?>"><?php esc_html_e( 'Download', 'dropdms' ); ?></a>
							<?php if ( current_user_can( 'dropdms_delete' ) ) : ?>
								<a class="button button-link-delete" href="<?php echo esc_url( self::delete_url( $doc->id ) ); ?>" onclick="return confirm(<?php echo esc_attr( wp_json_encode( __( 'Delete this document permanently?', 'dropdms' ) ) ); ?>);"><?php esc_html_e( 'Delete', 'dropdms' ); ?></a>
							<?php endif; ?>
						</p>
					</div>
				</div>
			</form>
		</div>
		<?php
	}

	/**
	 * Preview: PDF in a frame, images as image.
	 *
	 * @param object $doc Document.
	 */
	private static function render_preview( $doc ) {
		$url = self::file_url( $doc->id, true );

		if ( 'application/pdf' === $doc->mime ) {
			printf( '<iframe class="dropdms-preview" src="%s" title="%s"></iframe>', esc_url( $url ), esc_attr( $doc->title ) );
		} else {
			printf( '<img class="dropdms-preview-img" src="%s" alt="%s" />', esc_url( $url ), esc_attr( $doc->title ) );
		}
	}

	/** Saves the edit form. */
	public static function handle_save() {
		$id = isset( $_POST['id'] ) ? absint( $_POST['id'] ) : 0;

		check_admin_referer( 'dropdms_save_' . $id );

		if ( ! current_user_can( 'dropdms_edit' ) ) {
			wp_die( esc_html__( 'You are not allowed to edit documents.', 'dropdms' ), 403 );
		}

		if ( ! DropDMS_Documents::get( $id ) ) {
			wp_die( esc_html__( 'Document not found.', 'dropdms' ), 404 );
		}

		$title    = isset( $_POST['title'] ) ? sanitize_text_field( wp_unslash( $_POST['title'] ) ) : '';
		$category = isset( $_POST['category'] ) ? absint( $_POST['category'] ) : 0;
		$date     = isset( $_POST['document_date'] ) ? sanitize_text_field( wp_unslash( $_POST['document_date'] ) ) : '';
		$valid    = preg_match( '/^(\d{4})-(\d{2})-(\d{2})$/', $date, $m ) && checkdate( (int) $m[2], (int) $m[3], (int) $m[1] );

		DropDMS_Documents::update(
			$id,
			array(
				'title'         => '' !== $title ? mb_substr( $title, 0, 255 ) : __( 'Untitled', 'dropdms' ),
				'category_id'   => DropDMS_Categories::exists( $category ) ? $category : 0,
				'status'        => empty( $_POST['status'] ) ? 0 : 1,
				'document_date' => $valid ? $date : null,
				// Note and recognized text are plain text and may contain "<" etc.; they are cleaned of control
				// characters and always escaped on output.
				'note'          => isset( $_POST['note'] ) ? mb_substr( DropDMS_Documents::clean_text( wp_unslash( $_POST['note'] ) ), 0, 65000 ) : '', // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized
				'ocr_text'      => isset( $_POST['ocr_text'] ) ? DropDMS_Documents::clean_text( wp_unslash( $_POST['ocr_text'] ) ) : '', // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized
			)
		);

		wp_safe_redirect( add_query_arg( 'saved', 1, self::edit_url( $id ) ) );
		exit;
	}

	/** Deletes one document (row action / edit screen). */
	public static function handle_delete() {
		$id = isset( $_GET['id'] ) ? absint( $_GET['id'] ) : 0;

		check_admin_referer( 'dropdms_delete_' . $id );

		if ( ! current_user_can( 'dropdms_delete' ) ) {
			wp_die( esc_html__( 'You are not allowed to delete documents.', 'dropdms' ), 403 );
		}

		$deleted = DropDMS_Documents::delete( array( $id ) );

		wp_safe_redirect(
			add_query_arg(
				array(
					'page'    => 'dropdms',
					'deleted' => $deleted,
				),
				admin_url( 'admin.php' )
			)
		);
		exit;
	}

	// ------------------------------------------------------------------ Settings

	/** Settings API registration. */
	public static function register_settings() {
		register_setting(
			'dropdms_settings',
			DropDMS_Settings::OPTION,
			array(
				'type'              => 'array',
				'sanitize_callback' => array( 'DropDMS_Settings', 'sanitize' ),
				'default'           => DropDMS_Settings::defaults(),
			)
		);

		add_settings_section( 'dropdms_upload', __( 'Upload and text recognition', 'dropdms' ), '__return_false', 'dropdms-settings' );
		add_settings_section( 'dropdms_search', __( 'Search', 'dropdms' ), '__return_false', 'dropdms-settings' );
		add_settings_section( 'dropdms_data', __( 'Data', 'dropdms' ), '__return_false', 'dropdms-settings' );

		$fields = array(
			'max_upload_mb'       => array( __( 'Maximum file size (MB)', 'dropdms' ), 'dropdms_upload' ),
			'ocr_lang'            => array( __( 'Recognition language', 'dropdms' ), 'dropdms_upload' ),
			'pdf_max_pages'       => array( __( 'PDF pages to read', 'dropdms' ), 'dropdms_upload' ),
			'search_mode'         => array( __( 'Search mode', 'dropdms' ), 'dropdms_search' ),
			'delete_on_uninstall' => array( __( 'On uninstall', 'dropdms' ), 'dropdms_data' ),
		);

		foreach ( $fields as $key => $field ) {
			add_settings_field(
				'dropdms_' . $key,
				$field[0],
				array( __CLASS__, 'render_field' ),
				'dropdms-settings',
				$field[1],
				array(
					'key'       => $key,
					'label_for' => 'dropdms_' . $key,
				)
			);
		}
	}

	/**
	 * One settings field.
	 *
	 * @param array $args Field arguments.
	 */
	public static function render_field( $args ) {
		$key   = $args['key'];
		$value = DropDMS_Settings::get( $key );
		$name  = DropDMS_Settings::OPTION . '[' . $key . ']';
		$id    = 'dropdms_' . $key;

		switch ( $key ) {
			case 'max_upload_mb':
				printf( '<input type="number" min="1" max="2048" class="small-text" id="%s" name="%s" value="%d" />', esc_attr( $id ), esc_attr( $name ), (int) $value );
				echo '<p class="description">' . esc_html(
					sprintf(
						/* translators: %s: effective limit, e.g. "16 MB" */
						__( 'Effective limit including PHP and database limits: %s.', 'dropdms' ),
						size_format( DropDMS_Settings::max_upload_bytes() )
					)
				) . '</p>';
				break;

			case 'ocr_lang':
				$labels = array(
					'deu+eng' => __( 'German + English', 'dropdms' ),
					'deu'     => __( 'German', 'dropdms' ),
					'eng'     => __( 'English', 'dropdms' ),
				);
				printf( '<select id="%s" name="%s">', esc_attr( $id ), esc_attr( $name ) );
				foreach ( $labels as $lang => $label ) {
					printf( '<option value="%s"%s>%s</option>', esc_attr( $lang ), selected( $value, $lang, false ), esc_html( $label ) );
				}
				echo '</select>';
				echo '<p class="description">' . esc_html__( 'Used for scans and images. PDFs with a text layer are read directly.', 'dropdms' ) . '</p>';
				break;

			case 'pdf_max_pages':
				printf( '<input type="number" min="1" max="500" class="small-text" id="%s" name="%s" value="%d" />', esc_attr( $id ), esc_attr( $name ), (int) $value );
				break;

			case 'search_mode':
				printf( '<select id="%s" name="%s">', esc_attr( $id ), esc_attr( $name ) );
				printf( '<option value="like"%s>%s</option>', selected( $value, 'like', false ), esc_html__( 'Partial words (finds "voice" in "invoice")', 'dropdms' ) );
				printf( '<option value="fulltext"%s>%s</option>', selected( $value, 'fulltext', false ), esc_html__( 'Full-text index (faster with many documents, matches word beginnings)', 'dropdms' ) );
				echo '</select>';
				break;

			case 'delete_on_uninstall':
				printf(
					'<label><input type="checkbox" id="%s" name="%s" value="1"%s /> %s</label>',
					esc_attr( $id ),
					esc_attr( $name ),
					checked( (int) $value, 1, false ),
					esc_html__( 'Delete all documents, categories and settings when the plugin is deleted', 'dropdms' )
				);
				echo '<p class="description">' . esc_html__( 'Off by default, so deleting the plugin by mistake does not destroy your archive.', 'dropdms' ) . '</p>';
				break;
		}
	}

	/** Settings page including storage usage. */
	public static function render_settings_page() {
		if ( ! current_user_can( 'dropdms_manage' ) ) {
			return;
		}

		$usage  = DropDMS_Storage::usage();
		$packet = DropDMS_Storage::max_packet();
		?>
		<div class="wrap dropdms">
			<h1><?php esc_html_e( 'DropDMS Settings', 'dropdms' ); ?></h1>
			<?php
			// phpcs:disable WordPress.Security.NonceVerification.Recommended -- display of a message only.
			if ( isset( $_GET['optimized'] ) ) {
				$freed = absint( $_GET['optimized'] );
				/* translators: %s: freed space, e.g. "12 MB" */
				echo '<div class="notice notice-success is-dismissible"><p>' . esc_html( sprintf( __( 'Storage optimized, %s freed.', 'dropdms' ), size_format( $freed ) ) ) . '</p></div>';
			}
			if ( isset( $_GET['optimize_error'] ) ) {
				echo '<div class="notice notice-error"><p>' . esc_html__( 'The storage could not be optimized. Your database user may lack the permission for OPTIMIZE TABLE.', 'dropdms' ) . '</p></div>';
			}
			// phpcs:enable
			?>
			<form method="post" action="options.php">
				<?php
				settings_fields( 'dropdms_settings' );
				do_settings_sections( 'dropdms-settings' );
				submit_button();
				?>
			</form>

			<h2><?php esc_html_e( 'Storage', 'dropdms' ); ?></h2>
			<p><?php esc_html_e( 'Files are stored in the database together with their text and thumbnail. They are only delivered through WordPress after a permission check.', 'dropdms' ); ?></p>
			<table class="widefat striped dropdms-storage">
				<tbody>
					<tr><th scope="row"><?php esc_html_e( 'Files and thumbnails', 'dropdms' ); ?></th><td><?php echo esc_html( size_format( $usage['content'], 1 ) ); ?></td></tr>
					<tr><th scope="row"><?php esc_html_e( 'Allocated in the database', 'dropdms' ); ?></th><td><?php echo esc_html( size_format( $usage['allocated'], 1 ) ); ?></td></tr>
					<tr><th scope="row"><?php esc_html_e( 'Of which free (reusable)', 'dropdms' ); ?></th><td><?php echo esc_html( size_format( $usage['free'], 1 ) ); ?></td></tr>
					<tr><th scope="row"><code>max_allowed_packet</code></th><td><?php echo esc_html( size_format( $packet ) ); ?></td></tr>
					<tr><th scope="row"><code>upload_max_filesize</code> / <code>post_max_size</code></th><td><?php echo esc_html( ini_get( 'upload_max_filesize' ) . ' / ' . ini_get( 'post_max_size' ) ); ?></td></tr>
				</tbody>
			</table>
			<form method="post" action="<?php echo esc_url( admin_url( 'admin-post.php' ) ); ?>" class="dropdms-optimize">
				<input type="hidden" name="action" value="dropdms_optimize" />
				<?php wp_nonce_field( 'dropdms_optimize' ); ?>
				<?php submit_button( __( 'Free up space', 'dropdms' ), 'secondary', 'submit', false ); ?>
				<p class="description"><?php esc_html_e( 'Rebuilds the table (OPTIMIZE TABLE) and returns space of deleted or replaced files to the server. Can take a while with large archives.', 'dropdms' ); ?></p>
			</form>
			<?php
			/**
			 * Fires at the end of the settings page.
			 */
			do_action( 'dropdms_settings_after' );
			?>
		</div>
		<?php
	}

	/** "Free up space": OPTIMIZE TABLE. */
	public static function handle_optimize() {
		check_admin_referer( 'dropdms_optimize' );

		if ( ! current_user_can( 'dropdms_manage' ) ) {
			wp_die( esc_html__( 'You are not allowed to do this.', 'dropdms' ), 403 );
		}

		$before = DropDMS_Storage::usage();
		$args   = array( 'page' => 'dropdms-settings' );

		try {
			DropDMS_Storage::optimize();
			$after             = DropDMS_Storage::usage();
			$args['optimized'] = max( 0, $before['allocated'] - $after['allocated'] );
		} catch ( Throwable $e ) {
			$args['optimize_error'] = 1;
		}

		wp_safe_redirect( add_query_arg( $args, admin_url( 'admin.php' ) ) );
		exit;
	}
}