<?php
/**
 * The full-screen dashboard page.
 *
 * @package PulseCast
 */

namespace PulseCast\Frontend;

use PulseCast\Domain\Dashboard;
use PulseCast\Domain\Dashboard_Repository;
use PulseCast\Rest\Public_Controller;

/**
 * Serves `/feedmarquee/{key}/` (or `?feedmarquee={key}` with plain permalinks) as a standalone HTML
 * document that does not use the active theme. The page contains no feed content: its script
 * fetches the cached public REST payload.
 */
final class Display_Route {

	public const QUERY_VAR    = 'feedmarquee';
	public const RULE_REGEX   = '^feedmarquee/([a-f0-9]{20})/?$';
	public const FLUSH_OPTION = 'pulsecast_rewrite_version';

	/**
	 * Dashboards.
	 *
	 * @var Dashboard_Repository
	 */
	private Dashboard_Repository $dashboards;

	/**
	 * Constructor.
	 *
	 * @param Dashboard_Repository $dashboards Dashboards.
	 */
	public function __construct( Dashboard_Repository $dashboards ) {
		$this->dashboards = $dashboards;
	}

	/**
	 * Hooks the route into WordPress.
	 */
	public function register(): void {
		add_action( 'init', array( self::class, 'add_rules' ) );
		add_action( 'init', array( self::class, 'maybe_flush' ), 20 );
		add_filter( 'query_vars', array( $this, 'add_query_var' ) );
		add_action( 'template_redirect', array( $this, 'handle' ) );
	}

	/**
	 * Adds the pretty URL rule.
	 */
	public static function add_rules(): void {
		add_rewrite_rule( self::RULE_REGEX, 'index.php?' . self::QUERY_VAR . '=$matches[1]', 'top' );
	}

	/**
	 * Removes the pretty URL rule from the rules WordPress holds in memory.
	 */
	public static function remove_rules(): void {
		global $wp_rewrite;

		unset( $wp_rewrite->extra_rules_top[ self::RULE_REGEX ] );
	}

	/**
	 * Flushes rewrite rules once per plugin version, not on every request.
	 */
	public static function maybe_flush(): void {
		if ( PULSECAST_VERSION !== get_option( self::FLUSH_OPTION ) ) {
			flush_rewrite_rules( false );
			update_option( self::FLUSH_OPTION, PULSECAST_VERSION, false );
		}
	}

	/**
	 * Registers the query variable.
	 *
	 * @param array<int,string> $vars Query variables.
	 * @return array<int,string>
	 */
	public function add_query_var( array $vars ): array {
		$vars[] = self::QUERY_VAR;

		return $vars;
	}

	/**
	 * Serves the dashboard, or a generic 404 for an unknown or disabled one.
	 */
	public function handle(): void {
		$key = get_query_var( self::QUERY_VAR );

		if ( ! is_string( $key ) || '' === $key ) {
			return;
		}

		$dashboard = $this->dashboards->find_by_key( $key );

		if ( null === $dashboard ) {
			global $wp_query;
			$wp_query->set_404();
			status_header( 404 );
			nocache_headers();
			self::send_header( 'X-Robots-Tag', 'noindex' );

			return;
		}

		foreach ( self::headers() as $name => $value ) {
			self::send_header( $name, $value );
		}

		echo self::render( $dashboard ); // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- Built from escaped parts in render().
		exit;
	}

	/**
	 * Sends a header unless output has already started.
	 *
	 * @param string $name  Header name.
	 * @param string $value Header value.
	 */
	private static function send_header( string $name, string $value ): void {
		if ( ! headers_sent() ) {
			header( $name . ': ' . $value );
		}
	}

	/**
	 * Security and caching headers for the page.
	 *
	 * @return array<string,string>
	 */
	public static function headers(): array {
		return array(
			'Content-Type'            => 'text/html; charset=utf-8',
			'Cache-Control'           => 'no-cache',
			'X-Robots-Tag'            => 'noindex, nofollow',
			'Referrer-Policy'         => 'no-referrer',
			'X-Content-Type-Options'  => 'nosniff',
			'Content-Security-Policy' => "default-src 'none'; script-src 'self'; style-src 'self'; img-src https:; connect-src 'self'; frame-ancestors 'self'; base-uri 'none'; form-action 'none'",
		);
	}

	/**
	 * The dashboard's public address.
	 *
	 * @param string $key Dashboard key.
	 */
	public static function url( string $key ): string {
		return get_option( 'permalink_structure' ) ? home_url( '/feedmarquee/' . $key . '/' ) : add_query_arg( self::QUERY_VAR, $key, home_url( '/' ) );
	}

	/**
	 * Translated strings the display script uses.
	 *
	 * @return array<string,string>
	 */
	public static function strings(): array {
		return array(
			'unavailable'     => __( 'This dashboard is unavailable', 'feedmarquee' ),
			'offline'         => __( 'Offline. Showing the last update', 'feedmarquee' ),
			'loading'         => __( 'Loading feeds', 'feedmarquee' ),
			'stale'           => __( 'Content may be out of date', 'feedmarquee' ),
			'liveUnavailable' => __( 'Unavailable', 'feedmarquee' ),
			'liveOffline'     => __( 'Offline', 'feedmarquee' ),
			'liveLoading'     => __( 'Loading', 'feedmarquee' ),
			'liveDelayed'     => __( 'Delayed', 'feedmarquee' ),
			'live'            => __( 'Live', 'feedmarquee' ),
			'latest'          => __( 'Latest Headlines', 'feedmarquee' ),
			/* translators: %d: number of feeds (one). */
			'feedOne'         => __( '%d feed', 'feedmarquee' ),
			/* translators: %d: number of feeds. */
			'feedOther'       => __( '%d feeds', 'feedmarquee' ),
			/* translators: %d: number of stories (one). */
			'storyOne'        => __( '%d story', 'feedmarquee' ),
			/* translators: %d: number of stories. */
			'storyOther'      => __( '%d stories', 'feedmarquee' ),
		);
	}

	/**
	 * Builds the HTML document.
	 *
	 * @param Dashboard $dashboard Dashboard.
	 */
	public static function render( Dashboard $dashboard ): string {
		$settings = $dashboard->settings;

		wp_register_style( 'pulsecast-display', plugins_url( 'assets/css/display.css', PULSECAST_FILE ), array(), PULSECAST_VERSION );
		wp_register_script( 'pulsecast-display', plugins_url( 'assets/js/display.js', PULSECAST_FILE ), array(), PULSECAST_VERSION, true );

		ob_start();
		wp_print_styles( 'pulsecast-display' );
		$styles = (string) ob_get_clean();

		ob_start();
		wp_print_scripts( 'pulsecast-display' );
		$scripts = (string) ob_get_clean();

		$flag = static fn( string $name ): string => $settings[ $name ] ? '1' : '0';

		return '<!DOCTYPE html>' . "\n"
			. '<html lang="' . esc_attr( get_bloginfo( 'language' ) ) . '" data-theme="' . esc_attr( $settings['theme'] ) . '" data-palette="' . esc_attr( $settings['palette'] ) . '" data-layout="' . esc_attr( $settings['layout'] ) . '">' . "\n"
			. '<head><meta charset="utf-8">'
			. '<meta name="viewport" content="width=device-width, initial-scale=1">'
			. '<meta name="robots" content="noindex, nofollow"><meta name="referrer" content="no-referrer">'
			. '<title>' . esc_html__( 'FeedMarquee', 'feedmarquee' ) . '</title>' . $styles . '</head>' . "\n"
			. '<body><main id="pulsecast" data-strings="' . esc_attr( (string) wp_json_encode( self::strings() ) ) . '" data-endpoint="' . esc_url( rest_url( Public_Controller::NAMESPACE . '/dashboards/' . $dashboard->key ) ) . '" data-poll="60" data-reload="21600"'
			. ' data-show-source="' . esc_attr( $flag( 'show_source' ) ) . '" data-show-time="' . esc_attr( $flag( 'show_time' ) ) . '" data-show-images="' . esc_attr( $flag( 'show_images' ) ) . '">'
			. '<h1 class="pc-sr">' . esc_html__( 'FeedMarquee dashboard', 'feedmarquee' ) . '</h1>'
			. '<div class="pc-stage"></div><div class="pc-status" role="status" hidden></div></main>'
			. '<noscript>' . esc_html__( 'This dashboard needs JavaScript.', 'feedmarquee' ) . '</noscript>'
			. $scripts . '</body></html>';
	}
}