<?php
/**
 * Typed busy-interval provider registry (docs/05 §2).
 *
 * @package Bookline
 */

declare( strict_types=1 );

namespace Bookline\Domain\Availability;

/**
 * Last write wins for a given identifier.
 *
 * @since 0.30.0
 */
final class BusyProviderRegistry {

	/**
	 * Providers keyed by identifier.
	 *
	 * @var array<string, BusyIntervalProvider>
	 */
	private array $providers = [];

	/**
	 * Register a provider.
	 *
	 * @param BusyIntervalProvider $provider Provider.
	 */
	public function register( BusyIntervalProvider $provider ): void {
		$this->providers[ $provider->identifier() ] = $provider;
	}

	/**
	 * Replace the set (after the busy_providers filter).
	 *
	 * @param list<BusyIntervalProvider> $providers Providers.
	 */
	public function replace( array $providers ): void {
		$this->providers = [];
		foreach ( $providers as $provider ) {
			if ( $provider instanceof BusyIntervalProvider ) {
				$this->register( $provider );
			}
		}
	}

	/**
	 * Registered providers.
	 *
	 * @return list<BusyIntervalProvider>
	 */
	public function all(): array {
		return array_values( $this->providers );
	}

	/**
	 * Union of every provider for this query.
	 *
	 * @param AvailabilityQuery $query Query.
	 */
	public function union( AvailabilityQuery $query ): IntervalSet {
		$set = IntervalSet::empty();
		foreach ( $this->all() as $provider ) {
			$set = $set->union( $provider->get_busy_intervals( $query ) );
		}
		return $set;
	}
}