<?php
/**
 * Language switcher block (addblack-lang/switcher). Each language links to the
 * current page's translation; when there is none, to that language's home
 * (or the item is hidden, see "hideMissing"). Rendered on the server.
 * Also available as the [blocklingo_switcher] shortcode for places without
 * blocks (classic widgets, page builders, shortcode blocks in patterns).
 */

declare( strict_types = 1 );

namespace AddBlack\Lang\Switcher;

defined( 'ABSPATH' ) || exit;

use AddBlack\Lang\Hookable;
use AddBlack\Lang\Hooks;
use AddBlack\Lang\Routing\Alternates;
use AddBlack\Lang\Routing\CurrentLanguage;
use AddBlack\Lang\Routing\Urls;
use AddBlack\Lang\Settings\SettingsRepository;

final class SwitcherBlock implements Hookable {

	public const NAME = 'addblack-lang/switcher';

	public const SHORTCODE = 'blocklingo_switcher';

	public function __construct(
		private readonly CurrentLanguage $current,
		private readonly SettingsRepository $settings,
		private readonly Alternates $alternates,
		private readonly Urls $urls
	) {}

	public function register(): void {
		Hooks::action( 'init', array( $this, 'register_block' ) );
		Hooks::action( 'init', array( $this, 'register_shortcode' ) );
	}

	public function register_shortcode(): void {
		add_shortcode( self::SHORTCODE, \AddBlack\Lang\Failsafe::guard( array( $this, 'shortcode' ), 'shortcode ' . self::SHORTCODE, false ) ); // Error: empty output, page still renders.
	}

	/**
	 * [blocklingo_switcher display="code|name|flag|flag-code|flag-name" hide_current="1" hide_missing="1"]
	 *
	 * @param mixed $atts Shortcode attributes ('' when there are none).
	 */
	public function shortcode( mixed $atts = array() ): string {
		$atts    = shortcode_atts(
			array(
				'display'      => 'code',
				'hide_current' => '',
				'hide_missing' => '',
			),
			is_array( $atts ) ? $atts : array(),
			self::SHORTCODE
		);
		$display = (string) $atts['display'];
		wp_enqueue_style( 'blocklingo-switcher' );
		return $this->render(
			array(
				'display'     => in_array( $display, self::displays(), true ) ? $display : 'code',
				'hideCurrent' => self::truthy( $atts['hide_current'] ),
				'hideMissing' => self::truthy( $atts['hide_missing'] ),
			)
		);
	}

	/** "1", "true", "yes", "on" -> true. */
	private static function truthy( mixed $value ): bool {
		return in_array( strtolower( trim( (string) $value ) ), array( '1', 'true', 'yes', 'on' ), true );
	}

	/** @return string[] How each language is shown. */
	public static function displays(): array {
		return array( 'code', 'name', 'flag', 'flag-code', 'flag-name' );
	}

	/** @return array<string, array<string, mixed>> */
	public static function attributes(): array {
		return array(
			'display'     => array(
				'type'    => 'string',
				'enum'    => self::displays(),
				'default' => 'code',
			),
			'hideCurrent' => array(
				'type'    => 'boolean',
				'default' => false,
			),
			'hideMissing' => array(
				'type'    => 'boolean',
				'default' => false,
			),
			'className'   => array( 'type' => 'string' ),
		);
	}

	public function register_block(): void {
		wp_register_style( 'blocklingo-switcher', BLOCKLINGO_URL . 'assets/switcher.css', array(), BLOCKLINGO_VERSION );
		wp_register_script(
			'blocklingo-switcher-editor',
			BLOCKLINGO_URL . 'assets/switcher.js',
			array( 'wp-blocks', 'wp-element', 'wp-components', 'wp-block-editor', 'wp-server-side-render', 'wp-i18n' ),
			BLOCKLINGO_VERSION . '.' . (string) filemtime( BLOCKLINGO_DIR . 'assets/switcher.js' ),
			true
		);
		wp_set_script_translations( 'blocklingo-switcher-editor', 'blocklingo', BLOCKLINGO_DIR . 'languages' );
		register_block_type(
			self::NAME,
			array(
				'api_version'     => '3',
				'title'           => __( 'Language switcher', 'blocklingo' ),
				'category'        => 'widgets',
				'icon'            => 'translation',
				'description'     => __( 'Links to this page in the other languages.', 'blocklingo' ),
				'attributes'      => self::attributes(),
				'supports'        => array(
					'html'       => false,
					'typography' => array( 'fontSize' => true ),
					'spacing'    => array( 'margin' => true ),
				),
				'editor_script'   => 'blocklingo-switcher-editor',
				'style'           => 'blocklingo-switcher',
				'render_callback' => \AddBlack\Lang\Failsafe::guard( array( $this, 'render' ), 'block ' . self::NAME, false ),
			)
		);
	}

	/**
	 * Items for the current request: lang => url, name, flag, locale, current, missing.
	 *
	 * @return array<string, array{url: string, name: string, flag: string, locale: string, current: bool, missing: bool}>
	 */
	public function items(): array {
		$settings = $this->settings->get();
		$current  = $this->current->get();
		$current  = '' !== $current ? $current : $settings->default_code();
		$alts     = $this->alternates->current_page();
		// Home pages exist in every language, so nothing is "missing" there.
		$special = is_front_page() || ( is_home() && ! get_option( 'page_for_posts' ) );
		$out     = array();

		foreach ( $settings->languages() as $code => $lang ) {
			$code         = (string) $code;
			$has          = isset( $alts[ $code ] );
			$out[ $code ] = array(
				'url'     => $has ? $alts[ $code ] : $this->urls->lang_home( $code ),
				'name'    => $lang->name,
				'flag'    => $lang->flag,
				'locale'  => $lang->locale,
				'current' => $code === $current,
				'missing' => ! $has && ! $special && $code !== $current,
			);
		}
		return $out;
	}

	/**
	 * The links to show, after the hide options: label HTML is escaped.
	 *
	 * @param array<string, mixed> $attributes Block attributes (display, hideCurrent, hideMissing).
	 * @return list<array{code: string, url: string, hreflang: string, current: bool, html: string, aria: string}>
	 */
	public function links( array $attributes = array() ): array {
		$defaults = array();
		foreach ( self::attributes() as $name => $def ) {
			if ( array_key_exists( 'default', $def ) ) {
				$defaults[ $name ] = $def['default'];
			}
		}
		$attributes = wp_parse_args( $attributes, $defaults );
		$out        = array();

		foreach ( $this->items() as $code => $item ) {
			if ( ( $item['current'] && $attributes['hideCurrent'] ) || ( $item['missing'] && $attributes['hideMissing'] ) ) {
				continue;
			}
			$label = self::label( $code, $item, (string) $attributes['display'] );
			$out[] = array(
				'code'     => $code,
				'url'      => $item['url'],
				'hreflang' => str_replace( '_', '-', '' !== $item['locale'] ? $item['locale'] : $code ),
				'current'  => $item['current'],
				'html'     => $label['html'],
				'aria'     => $label['aria'],
			);
		}
		return $out;
	}

	/**
	 * The switcher HTML. Also used by the blocklingo_language_switcher template tag.
	 *
	 * @param array<string, mixed> $attributes Block attributes.
	 */
	public function render( array $attributes = array() ): string {
		$li = '';
		foreach ( $this->links( $attributes ) as $link ) {
			$li .= sprintf(
				'<li class="blocklingo-switcher__item%1$s"><a href="%2$s" hreflang="%3$s" lang="%3$s"%4$s%5$s>%6$s</a></li>',
				$link['current'] ? ' is-current' : '',
				esc_url( $link['url'] ),
				esc_attr( $link['hreflang'] ),
				$link['current'] ? ' aria-current="true"' : '',
				'' !== $link['aria'] ? ' aria-label="' . esc_attr( $link['aria'] ) . '"' : '',
				$link['html']
			);
		}
		if ( '' === $li ) {
			return '';
		}
		$wrapper = \WP_Block_Supports::$block_to_render
			? get_block_wrapper_attributes( array( 'class' => 'blocklingo-switcher' ) )
			: 'class="blocklingo-switcher"';
		return '<nav ' . $wrapper . ' aria-label="' . esc_attr__( 'Language', 'blocklingo' ) . '"><ul class="blocklingo-switcher__list">' . $li . '</ul></nav>';
	}

	/**
	 * @param array{name: string, flag: string} $item
	 * @return array{html: string, aria: string}
	 */
	private static function label( string $code, array $item, string $display ): array {
		$code_txt = esc_html( strtoupper( $code ) );
		$name     = esc_html( $item['name'] );
		$flag     = '' !== $item['flag'] ? '<span class="blocklingo-switcher__flag wp-exclude-emoji" aria-hidden="true">' . esc_html( $item['flag'] ) . '</span>' : '';
		return match ( $display ) {
			'name'      => array(
				'html' => $name,
				'aria' => '',
			),
			'flag'      => array(
				'html' => '' !== $flag ? $flag : $code_txt,
				'aria' => $item['name'],
			),
			'flag-code' => array(
				'html' => $flag . $code_txt,
				'aria' => $item['name'],
			),
			'flag-name' => array(
				'html' => $flag . $name,
				'aria' => '',
			),
			default     => array(
				'html' => $code_txt,
				'aria' => $item['name'],
			),
		};
	}
}