<?php
/**
 * Add-on registry.
 *
 * Allows third-party plugins to register as AICommerce add-ons
 * via the aicommerce/addons/registered filter.
 *
 * @package AICommerce\Core
 */

declare(strict_types=1);

namespace AICommerce\Core;

/**
 * Manages third-party add-on registration and discovery.
 */
class AddonRegistry {

	/**
	 * Registered add-ons.
	 *
	 * @var array<int, array>
	 */
	private static array $addons = array();

	/**
	 * Whether add-ons have been collected.
	 *
	 * @var bool
	 */
	private static bool $initialized = false;

	/**
	 * Required keys for a valid add-on registration.
	 *
	 * @var string[]
	 */
	private const REQUIRED_KEYS = array( 'id', 'name', 'version' );

	/**
	 * Valid plan slugs.
	 *
	 * @var string[]
	 */
	private const VALID_PLANS = array( 'free', 'pro', 'business', 'agency' );

	/**
	 * Register an add-on.
	 *
	 * @param array $addon Add-on data.
	 *
	 * @return bool True if registered successfully.
	 */
	public static function register_addon( array $addon ): bool {
		foreach ( self::REQUIRED_KEYS as $key ) {
			if ( empty( $addon[ $key ] ) ) {
				return false;
			}
		}

		// Check for duplicate IDs.
		foreach ( self::$addons as $existing ) {
			if ( $existing['id'] === $addon['id'] ) {
				return false;
			}
		}

		// Validate plan.
		if ( isset( $addon['requires_plan'] ) && ! in_array( $addon['requires_plan'], self::VALID_PLANS, true ) ) {
			$addon['requires_plan'] = 'free';
		}

		// Set defaults.
		$addon = array_merge(
			array(
				'description'   => '',
				'author'        => '',
				'author_url'    => '',
				'requires_plan' => 'free',
				'active'        => true,
			),
			$addon
		);

		self::$addons[] = $addon;

		return true;
	}

	/**
	 * Get all registered add-ons.
	 *
	 * Applies the aicommerce/addons/registered filter on first call.
	 *
	 * @return array<int, array>
	 */
	public static function get_registered_addons(): array {
		if ( ! self::$initialized ) {
			/**
			 * Filters the list of registered AICommerce add-ons.
			 *
			 * Third-party plugins should hook here to register their add-ons.
			 *
			 * @param array $addons Array of registered add-on data.
			 */
			$external = apply_filters( 'aicommerce/addons/registered', array() );

			if ( is_array( $external ) ) {
				foreach ( $external as $addon ) {
					if ( is_array( $addon ) ) {
						self::register_addon( $addon );
					}
				}
			}

			self::$initialized = true;

			/**
			 * Fires after all add-ons have been registered.
			 *
			 * Third-party plugins can safely initialize their code here,
			 * knowing the registry is complete.
			 */
			do_action( 'aicommerce/addons/init' );
		}

		return self::$addons;
	}

	/**
	 * Reset the registry (for testing).
	 *
	 * @return void
	 */
	public static function reset(): void {
		self::$addons      = array();
		self::$initialized = false;
	}

	/**
	 * Get add-on count.
	 *
	 * @return int
	 */
	public static function count(): int {
		return count( self::get_registered_addons() );
	}

	/**
	 * Handle REST request to list add-ons.
	 *
	 * @return \WP_REST_Response
	 */
	public static function handle_list_addons(): \WP_REST_Response {
		return new \WP_REST_Response( self::get_registered_addons(), 200 );
	}
}