<?php

namespace Nest\Database;

use Nest\Application;
use Nest\Database\Configuration\DatabasesConfiguration;
use Nest\Database\Exceptions\Configuration\MissingRequiredConfigurationValueException;
use Nest\Database\Exceptions\UnknownDatabaseException;

/**
 * Databases manager.
 */
class Databases
{
	/**
	 * Loaded databases.
	 * @var array<string, Database>
	 */
	private array $databases;

	/**
	 * @param Application $application Application of the databases.
	 * @param DatabasesConfiguration $configuration Configuration of the databases.
	 * @throws MissingRequiredConfigurationValueException
	 */
	public function __construct(protected Application $application, protected DatabasesConfiguration $configuration)
	{
		$this->load();
	}

	/**
	 * Load databases from their factories.
	 * @return void
	 * @throws MissingRequiredConfigurationValueException
	 */
	public function load(): void
	{
		foreach ($this->configuration->getFactories() as $identifier => $databaseFactory)
		{ // Load all databases from their factories.
			$this->databases[$identifier] = $databaseFactory->make();
		}
	}

	/**
	 * @param string $identifier Database identifier.
	 * @return Database Database corresponding to the given identifier.
	 * @throws UnknownDatabaseException
	 */
	public function db(string $identifier): Database
	{
		if (empty($this->databases[$identifier]))
			// Cannot find a database with this identifier, throwing an exception.
			throw new UnknownDatabaseException($identifier);

		return $this->databases[$identifier]; // Return loaded database.
	}
}