<?php
/**
 * Prints the Stand widget on public pages.
 *
 * @package StandChat
 */

namespace StandChat;

defined( 'ABSPATH' ) || exit;

/**
 * Adds the Stand chat widget to public pages.
 *
 * The widget script loads from Stand's CDN, unbundled and unconcatenated,
 * because it loads its interface relative to its own address. The Site ID is
 * printed twice, on the script tag and in window.StandChatConfig, so chat keeps
 * working when an optimizer moves or rewrites the script tag.
 */
final class Frontend {

	const WIDGET_HANDLE = 'stand-chat-widget';
	const HELPER_HANDLE = 'stand-chat-frontend';
	const DEMO_SITE_ID  = 'demo';

	/**
	 * Attributes that keep optimizers from delaying, deferring, combining or
	 * minifying the widget script.
	 */
	const OPTIMIZER_ATTRIBUTES = array(
		'data-cfasync'     => 'false',
		'data-no-optimize' => '1',
		'data-no-defer'    => '1',
		'nowprocket'       => true,
	);

	/**
	 * Whether a block or shortcode on this page needs the widget.
	 *
	 * @var bool
	 */
	private $needed_by_content = false;

	/**
	 * The decision made for this request, once made.
	 *
	 * @var array<string, mixed>|null
	 */
	private $decision = null;

	/**
	 * Hooks.
	 */
	public function register(): void {
		add_action( 'wp_enqueue_scripts', array( $this, 'register_scripts' ), 5 );
		add_action( 'wp_enqueue_scripts', array( $this, 'link_style' ) );
		add_action( 'wp_footer', array( $this, 'enqueue_for_page' ), 1 );
		add_filter( 'wp_script_attributes', array( $this, 'script_attributes' ) );
		add_filter( 'wp_inline_script_attributes', array( $this, 'inline_script_attributes' ) );
	}

	/**
	 * Registers the widget and the plugin's small front-end helper.
	 */
	public function register_scripts(): void {
		if ( wp_script_is( self::WIDGET_HANDLE, 'registered' ) ) {
			return;
		}
		// The CDN copy is evergreen; a ?ver= would only split the CDN cache.
		wp_register_script(
			self::WIDGET_HANDLE,
			Service_Urls::get( 'widget' ),
			array(),
			null, // phpcs:ignore WordPress.WP.EnqueuedResourceParameters.MissingVersion -- See above.
			array(
				'in_footer' => true,
				'strategy'  => 'defer',
			)
		);
		$asset = self::asset( 'frontend' );
		wp_register_script(
			self::HELPER_HANDLE,
			STAND_CHAT_URL . 'build/frontend.js',
			array(),
			$asset['version'],
			array(
				'in_footer' => true,
				'strategy'  => 'defer',
			)
		);
	}

	/**
	 * Links that open chat (#stand-chat, .stand-open-chat) stay hidden until
	 * the helper says someone can answer: before that, before cookie consent,
	 * or where chat doesn't load, a click would do nothing.
	 */
	public function link_style(): void {
		wp_register_style( 'stand-chat-links', false, array(), STAND_CHAT_VERSION );
		wp_enqueue_style( 'stand-chat-links' );
		// The menu items need :has(), in a rule of their own: a browser without
		// it drops the whole rule, and the links themselves stay hidden.
		wp_add_inline_style(
			'stand-chat-links',
			'html:not(.stand-chat-available) a[href$="#stand-chat"],'
			. 'html:not(.stand-chat-available) .stand-open-chat'
			. '{display:none!important}'
			. 'html:not(.stand-chat-available) li.menu-item:has(> a[href$="#stand-chat"]),'
			. 'html:not(.stand-chat-available) li.wp-block-navigation-item:has(a[href$="#stand-chat"])'
			. '{display:none!important}'
		);
	}

	/**
	 * Blocks and shortcodes call this. Pages left out of "Where chat appears"
	 * still load the widget for them, without the corner chat button.
	 */
	public function content_needs_widget(): void {
		$this->needed_by_content = true;
		if ( ! did_action( 'wp_footer' ) || did_action( 'wp_print_footer_scripts' ) ) {
			return;
		}
		// Content rendered inside the footer, after the decision point and
		// before the scripts print: a page left out of "Where chat appears"
		// loads the widget for it after all. The other reasons still hold.
		if ( null === $this->decision || 'page_excluded' === $this->decision['reason'] ) {
			$this->decision = null;
			$this->enqueue_for_page();
		}
	}

	/**
	 * Whether pages show the demo rather than the saved Site ID: on a site
	 * that isn't live, when set to.
	 *
	 * @param array<string, mixed> $settings   Settings.
	 * @param bool                 $production Whether this is a production install.
	 */
	public static function shows_demo( array $settings, bool $production ): bool {
		return ! $production && 'demo' === ( $settings['non_production'] ?? '' );
	}

	/**
	 * Decides whether and how to load chat on this request.
	 *
	 * @return array{load: bool, reason: string, site_id: string, hide_button: bool, demo: bool}
	 */
	public function decide(): array {
		$no = static function ( string $reason ): array {
			return array(
				'load'        => false,
				'reason'      => $reason,
				'site_id'     => '',
				'hide_button' => true,
				'demo'        => false,
			);
		};

		if ( is_admin() || is_feed() || is_robots() || is_trackback() || is_embed() || wp_is_json_request() ) {
			return $no( 'not_public' );
		}
		$settings = Settings::all();
		if ( ! $settings['chat_enabled'] ) {
			return $no( 'off' );
		}
		$site_id = $settings['site_id'];
		if ( '' === $site_id ) {
			return $no( 'no_site_id' );
		}
		$hidden = Environment::hidden_reason();
		if ( '' !== $hidden ) {
			return $no( $hidden );
		}
		if ( $settings['hide_for_admins'] && current_user_can( 'manage_options' ) ) {
			return $no( 'administrator' );
		}

		$included = Visibility::current_page_included();
		if ( ! $included && ! $this->needed_by_content ) {
			return $no( 'page_excluded' );
		}

		$demo = self::shows_demo( $settings, Environment::is_production() );
		return array(
			'load'        => true,
			'reason'      => '',
			'site_id'     => $demo ? self::DEMO_SITE_ID : $site_id,
			'hide_button' => ! $settings['corner_button'] || ! $included,
			'demo'        => $demo,
		);
	}

	/**
	 * Enqueues the widget, or the loader that adds it after consent.
	 */
	public function enqueue_for_page(): void {
		if ( null !== $this->decision ) {
			return;
		}
		$this->decision = $this->decide();
		if ( ! $this->decision['load'] ) {
			return;
		}
		$this->register_scripts();

		$settings = Settings::all();
		$config   = $this->widget_config();
		$helper   = array(
			'links'    => true,
			'identity' => Identity::for_current_user(),
		);
		if ( null !== $helper['identity'] && ! defined( 'DONOTCACHEPAGE' ) ) {
			// The page names this visitor. WordPress already sends no-store for
			// logged-in visitors; page caches that skip it still honor this.
			define( 'DONOTCACHEPAGE', true ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedConstantFound -- The constant page caches check.
		}

		$needs_consent = 'consent' === $settings['consent']['mode'];
		if ( $needs_consent || $settings['loader'] ) {
			$helper['load'] = array(
				'src'        => Service_Urls::get( 'widget' ),
				'attributes' => $this->widget_attributes(),
				'config'     => $config,
				'consent'    => $needs_consent ? $settings['consent']['category'] : '',
			);
		} else {
			wp_add_inline_script( self::WIDGET_HANDLE, 'window.StandChatConfig = ' . wp_json_encode( $config ) . ';', 'before' );
			wp_enqueue_script( self::WIDGET_HANDLE );
		}

		wp_add_inline_script( self::HELPER_HANDLE, 'window.StandChatWordPress = ' . wp_json_encode( $helper ) . ';', 'before' );
		wp_enqueue_script( self::HELPER_HANDLE );
	}

	/**
	 * The decision for this request (after wp_footer), for tests and Site Health.
	 *
	 * @return array<string, mixed>|null
	 */
	public function last_decision(): ?array {
		return $this->decision;
	}

	/**
	 * The window.StandChatConfig object for the widget.
	 *
	 * @return array<string, mixed>
	 */
	private function widget_config(): array {
		$config = array(
			'siteId'     => $this->decision['site_id'],
			'hideButton' => (bool) $this->decision['hide_button'],
		);
		if ( ! Service_Urls::api_is_inferred() ) {
			$config['apiBaseUrl'] = Service_Urls::get( 'api' );
		}
		if ( '' !== Service_Urls::get( 'ws' ) ) {
			$config['wsBaseUrl'] = Service_Urls::get( 'ws' );
		}
		return $config;
	}

	/**
	 * Attributes for the widget's script tag.
	 *
	 * @return array<string, string|bool>
	 */
	private function widget_attributes(): array {
		$attributes = array( 'data-stand-id' => $this->decision['site_id'] );
		if ( $this->decision['hide_button'] ) {
			$attributes['data-stand-hide-button'] = 'true';
		}
		if ( ! Service_Urls::api_is_inferred() ) {
			$attributes['data-stand-api-base'] = Service_Urls::get( 'api' );
		}
		if ( '' !== Service_Urls::get( 'ws' ) ) {
			$attributes['data-stand-ws-base'] = Service_Urls::get( 'ws' );
		}
		return array_merge( $attributes, self::OPTIMIZER_ATTRIBUTES );
	}

	/**
	 * Adds the Site ID and optimizer exclusions to the widget's script tag.
	 *
	 * @param array<string, mixed> $attributes Script tag attributes.
	 * @return array<string, mixed>
	 */
	public function script_attributes( $attributes ) {
		if ( ! is_array( $attributes ) || null === $this->decision || empty( $this->decision['load'] ) ) {
			return $attributes;
		}
		$id = $attributes['id'] ?? '';
		if ( self::WIDGET_HANDLE . '-js' === $id ) {
			$extra = $this->widget_attributes();
		} elseif ( self::HELPER_HANDLE . '-js' === $id ) {
			$extra = self::OPTIMIZER_ATTRIBUTES;
		} else {
			return $attributes;
		}
		// Cloudflare Rocket Loader only honors data-cfasync when it comes before src.
		return array_merge( array( 'data-cfasync' => 'false' ), $attributes, $extra );
	}

	/**
	 * Keeps the inline configuration next to the script it configures.
	 *
	 * @param array<string, mixed> $attributes Inline script tag attributes.
	 * @return array<string, mixed>
	 */
	public function inline_script_attributes( $attributes ) {
		if ( ! is_array( $attributes ) ) {
			return $attributes;
		}
		$id = $attributes['id'] ?? '';
		if ( in_array( $id, array( self::WIDGET_HANDLE . '-js-before', self::HELPER_HANDLE . '-js-before' ), true ) ) {
			return array_merge( $attributes, self::OPTIMIZER_ATTRIBUTES );
		}
		return $attributes;
	}

	/**
	 * A built asset's dependencies and version.
	 *
	 * @param string $name Entry name in build/.
	 * @return array{dependencies: string[], version: string}
	 */
	public static function asset( string $name ): array {
		$file = STAND_CHAT_DIR . 'build/' . $name . '.asset.php';
		if ( is_readable( $file ) ) {
			$asset = include $file;
			if ( is_array( $asset ) ) {
				return array(
					'dependencies' => isset( $asset['dependencies'] ) && is_array( $asset['dependencies'] ) ? $asset['dependencies'] : array(),
					'version'      => isset( $asset['version'] ) ? (string) $asset['version'] : STAND_CHAT_VERSION,
				);
			}
		}
		return array(
			'dependencies' => array(),
			'version'      => STAND_CHAT_VERSION,
		);
	}
}