<?php
/**
 * Module registry.
 *
 * @package ElevenRank
 * @since   1.0.0
 */

namespace ElevenRank;

defined( 'ABSPATH' ) || exit;

/**
 * Holds every module and boots the ones that are active.
 *
 * Core modules are always active. Optional modules are active unless the
 * `modules` setting explicitly switches them off.
 *
 * @since 1.0.0
 */
final class Module_Registry {

	/**
	 * Settings store.
	 *
	 * @since 1.0.0
	 *
	 * @var Settings
	 */
	private $settings;

	/**
	 * Registered modules keyed by id.
	 *
	 * @since 1.0.0
	 *
	 * @var array<string, array{module: Module, core: bool}>
	 */
	private $modules = array();

	/**
	 * Whether boot() already ran.
	 *
	 * @since 1.0.0
	 *
	 * @var bool
	 */
	private $booted = false;

	/**
	 * Constructor.
	 *
	 * @since 1.0.0
	 *
	 * @param Settings $settings Settings store.
	 */
	public function __construct( Settings $settings ) {
		$this->settings = $settings;
	}

	/**
	 * Registers a module. Must happen before boot().
	 *
	 * @since 1.0.0
	 *
	 * @param Module $module Module instance.
	 * @param bool   $core   Whether the module is always on.
	 * @return void
	 */
	public function register( Module $module, bool $core = false ): void {
		$id = $module->id();

		if ( $this->booted || isset( $this->modules[ $id ] ) || 1 !== preg_match( '/^[a-z0-9_]+$/', $id ) ) {
			_doing_it_wrong(
				__METHOD__,
				sprintf( 'Module "%s" is invalid, a duplicate, or registered after boot.', esc_html( $id ) ),
				esc_html( ELEVENRANK_VERSION )
			);
			return;
		}

		$this->modules[ $id ] = array(
			'module' => $module,
			'core'   => $core,
		);
	}

	/**
	 * Whether a registered module is active.
	 *
	 * @since 1.0.0
	 *
	 * @param string $id Module id.
	 * @return bool
	 */
	public function is_active( string $id ): bool {
		if ( ! isset( $this->modules[ $id ] ) ) {
			return false;
		}

		if ( $this->modules[ $id ]['core'] ) {
			return true;
		}

		$states = $this->settings->get( 'modules' );

		return ! isset( $states[ $id ] ) || (bool) $states[ $id ];
	}

	/**
	 * Every registered module with its name and state, for the admin screens.
	 *
	 * Only call this after the `init` action: module names are translated.
	 *
	 * @since 1.0.0
	 *
	 * @return array<int, array{id: string, label: string, core: bool, active: bool}>
	 */
	public function describe(): array {
		$modules = array();

		foreach ( $this->modules as $id => $entry ) {
			$modules[] = array(
				'id'     => (string) $id,
				'label'  => $entry['module']->label(),
				'core'   => $entry['core'],
				'active' => $this->is_active( (string) $id ),
			);
		}

		return $modules;
	}

	/**
	 * Boots every active module, once.
	 *
	 * @since 1.0.0
	 *
	 * @return void
	 */
	public function boot(): void {
		if ( $this->booted ) {
			return;
		}

		$this->booted = true;

		foreach ( $this->modules as $id => $entry ) {
			if ( $this->is_active( $id ) ) {
				$entry['module']->boot();
			}
		}
	}
}