<?php
/**
 * The feature registry.
 *
 * @package WPAttributionTracker
 */

declare( strict_types=1 );

namespace WPAttributionTracker\Features;

defined( 'ABSPATH' ) || exit;

final class Registry {

	/**
	 * Registered features, keyed by id.
	 *
	 * @var array<string, Feature>
	 */
	private array $features = array();

	/**
	 * Ids of the features that actually registered their hooks.
	 *
	 * @var string[]
	 */
	private array $booted = array();

	/**
	 * Add one or more features. A repeated id replaces the earlier entry, which
	 * is what lets a site swap an implementation rather than only remove it.
	 */
	public function add( Feature ...$features ): self {
		foreach ( $features as $feature ) {
			$this->features[ $feature->id() ] = $feature;
		}

		return $this;
	}

	/**
	 * Remove a feature before the registry boots.
	 */
	public function remove( string $id ): self {
		unset( $this->features[ $id ] );

		return $this;
	}

	/**
	 * Every registered feature, keyed by id.
	 *
	 * @return array<string, Feature>
	 */
	public function all(): array {
		return $this->features;
	}

	/**
	 * A single feature, or null when it is not registered.
	 */
	public function get( string $id ): ?Feature {
		return $this->features[ $id ] ?? null;
	}

	/**
	 * Whether a feature is switched on, regardless of whether it can run.
	 */
	public function is_enabled( string $id ): bool {
		if ( ! isset( $this->features[ $id ] ) ) {
			return false;
		}

		/**
		 * Filters whether a feature is switched on.
		 *
		 * @param bool   $enabled Whether the feature should run.
		 * @param string $id      Feature identifier.
		 */
		return (bool) apply_filters( 'wpat_feature_enabled', true, $id );
	}

	/**
	 * Whether a feature registered its hooks in this request.
	 */
	public function is_active( string $id ): bool {
		return in_array( $id, $this->booted, true );
	}

	/**
	 * Register the hooks of every enabled, available feature.
	 */
	public function boot(): void {
		/**
		 * Fires before any feature registers its hooks.
		 *
		 * @param Registry $registry The registry.
		 */
		do_action( 'wpat_register_features', $this );

		foreach ( $this->features as $id => $feature ) {
			if ( ! $this->is_enabled( $id ) || ! $feature->is_available() ) {
				continue;
			}

			$feature->register();
			$this->booted[] = $id;
		}
	}

	/**
	 * A summary of every feature, for the admin and for debugging.
	 *
	 * @return array<int, array{id: string, label: string, description: string, enabled: bool, available: bool, active: bool}>
	 */
	public function summary(): array {
		$summary = array();

		foreach ( $this->features as $id => $feature ) {
			$summary[] = array(
				'id'          => $id,
				'label'       => $feature->label(),
				'description' => $feature->description(),
				'enabled'     => $this->is_enabled( $id ),
				'available'   => $feature->is_available(),
				'active'      => $this->is_active( $id ),
			);
		}

		return $summary;
	}
}