<?php
/**
 * Registers the Seeb Abilities ability categories and abilities.
 *
 * @package SeebAbilities
 */

namespace SeebAbilities;

defined( 'ABSPATH' ) || exit;

/**
 * Plugin bootstrap.
 */
final class Plugin {

	/**
	 * Ability namespace.
	 */
	const PREFIX = 'seeb-abilities';

	/**
	 * Single instance.
	 *
	 * @var Plugin|null
	 */
	private static ?Plugin $instance = null;

	/**
	 * Ability groups, created on first use.
	 *
	 * @var Abilities\Group[]|null
	 */
	private ?array $groups = null;

	/**
	 * Errors from the last permission check of each ability, returned by its execute callback.
	 *
	 * @var array<string, \WP_Error|null>
	 */
	private array $permission_errors = [];

	/**
	 * Returns the plugin instance.
	 *
	 * @return Plugin
	 */
	public static function instance(): Plugin {

		if ( null === self::$instance ) {
			self::$instance = new self();
		}

		return self::$instance;
	}

	/**
	 * Hooks into WordPress. Does nothing when the Abilities API isn't available (WordPress < 6.9).
	 *
	 * @return void
	 */
	public function init() {

		if ( ! function_exists( 'wp_register_ability' ) ) {
			return;
		}

		add_action( 'wp_abilities_api_categories_init', [ $this, 'register_categories' ] );
		add_action( 'wp_abilities_api_init', [ $this, 'register_abilities' ] );

		if ( is_admin() ) {
			( new Settings( $this ) )->init();
		}
	}

	/**
	 * Returns the ability groups. Each group is registered as one ability category.
	 *
	 * @return Abilities\Group[]
	 */
	public function get_groups(): array {

		if ( null === $this->groups ) {
			$this->groups = [
				new Abilities\Content(),
				new Abilities\Taxonomies(),
				new Abilities\Blocks(),
				new Abilities\SiteEditor(),
				new Abilities\Navigation(),
				new Abilities\Media(),
				new Abilities\Comments(),
				new Abilities\Users(),
				new Abilities\Site(),
				new Abilities\Audit(),
			];
		}

		return $this->groups;
	}

	/**
	 * Registers one ability category per group.
	 *
	 * @return void
	 */
	public function register_categories() {

		foreach ( $this->get_groups() as $group ) {
			wp_register_ability_category(
				$group->get_category(),
				[
					'label'       => $group->get_label(),
					'description' => $group->get_description(),
				]
			);
		}
	}

	/**
	 * Registers all enabled abilities.
	 *
	 * @return void
	 */
	public function register_abilities() {

		foreach ( $this->get_groups() as $group ) {
			foreach ( $group->get_abilities() as $slug => $args ) {

				$name = self::PREFIX . '/' . $slug;

				if ( ! $this->is_enabled( $name, $group->get_slug() ) ) {
					continue;
				}

				$args['category'] = $group->get_category();
				$args['meta']     = array_merge(
					[
						'public'       => true,
						'show_in_rest' => true,
					],
					$args['meta'] ?? []
				);

				/**
				 * Filters the arguments of a Seeb Abilities ability before it is registered.
				 *
				 * @param array  $args Ability arguments, as passed to wp_register_ability().
				 * @param string $name Ability name, e.g. "seeb-abilities/post-create".
				 */
				$args = apply_filters( 'seeb_abilities_ability_args', $args, $name );

				wp_register_ability( $name, $this->forward_permission_errors( $name, $args ) );
			}
		}
	}

	/**
	 * Makes the reason a permission check failed reach the caller.
	 *
	 * WP_Ability::execute() replaces a WP_Error from the permission callback with a generic
	 * "does not have necessary permission" error, so "post not found" or "use the draft status"
	 * would never reach the agent. Instead, the permission callback passes and the execute
	 * callback returns the error without running.
	 *
	 * @param string $name Ability name.
	 * @param array  $args Ability arguments.
	 *
	 * @return array
	 */
	private function forward_permission_errors( string $name, array $args ): array {

		$permission_callback = $args['permission_callback'] ?? null;
		$execute_callback    = $args['execute_callback'] ?? null;

		if ( ! is_callable( $permission_callback ) || ! is_callable( $execute_callback ) ) {
			return $args;
		}

		$args['permission_callback'] = function ( ...$input ) use ( $name, $permission_callback ) {

			$result = $permission_callback( ...$input );

			$this->permission_errors[ $name ] = is_wp_error( $result ) ? $result : null;

			return is_wp_error( $result ) || (bool) $result;
		};

		$args['execute_callback'] = function ( ...$input ) use ( $name, $execute_callback ) {

			$error = $this->permission_errors[ $name ] ?? null;

			unset( $this->permission_errors[ $name ] );

			return $error ?? $execute_callback( ...$input );
		};

		return $args;
	}

	/**
	 * Whether an ability is enabled.
	 *
	 * @param string $name  Ability name, e.g. "seeb-abilities/post-create".
	 * @param string $group Group slug, e.g. "content".
	 *
	 * @return bool
	 */
	public function is_enabled( string $name, string $group ): bool {

		$settings = Settings::get();
		$enabled  = ! in_array( $group, $settings['disabled_categories'], true )
			&& ! in_array( $name, $settings['disabled_abilities'], true );

		/**
		 * Filters whether a Seeb Abilities ability is registered.
		 *
		 * @param bool   $enabled Whether the ability is enabled in the settings.
		 * @param string $name    Ability name, e.g. "seeb-abilities/post-create".
		 * @param string $group   Group slug, e.g. "content".
		 */
		return (bool) apply_filters( 'seeb_abilities_enabled', $enabled, $name, $group );
	}
}