<?php
/**
 * The class for retrieving configuration values from a file.
 *
 * @since 0.1.0
 *
 * @package SolidWP\Performance
 */

declare( strict_types=1 );

namespace SolidWP\Performance\Config\Strategies;

use Closure;
use SolidWP\Performance\Config\Config;
use SolidWP\Performance\Config\Contracts\Strategy;
use SolidWP\Performance\Config\Provider;
use SolidWP\Performance\Container;
use SolidWP\Performance\StellarWP\Arrays\Arr;

/**
 * Stores and retrieves configuration values from a file.
 *
 * @since 0.1.0
 *
 * @package SolidWP\Performance
 */
class Site implements Strategy {

	/**
	 * The full decoded configuration.
	 *
	 * @since 0.1.0
	 *
	 * @var null|array<string,mixed>
	 */
	protected ?array $config = null;

	/**
	 * @var Container
	 */
	protected Container $container;

	/**
	 * @param  Container $container The container.
	 */
	public function __construct( Container $container ) {
		$this->container = $container;
	}

	/**
	 * {@inheritdoc}
	 */
	public function get( string $key, ?Closure $next = null ) {
		$config = $this->fetch();
		$value  = Arr::get( $config, explode( '.', $key ) );

		if ( isset( $value ) ) {
			return $value;
		}

		return $next === null ? null : $next( $key );
	}

	/**
	 * {@inheritdoc}
	 */
	public function save( array $changes, ?Closure $next = null ) {
		// Filter the current changes down to only the ones this strategy is responsible for.
		$responsible_changes = array_filter(
			$changes,
			function ( $key ) {
				return $this->is_responsible_for( $key );
			},
			ARRAY_FILTER_USE_KEY
		);

		$expanded_changes = [];

		// Expand array back into multidimensional array.
		foreach ( $responsible_changes as $key => $value ) {
			$expanded_changes = Arr::set( $expanded_changes, explode( '.', $key ), $value );
		}

		// Save the changes in one transaction.
		if ( count( $expanded_changes ) > 0 ) {
			$config          = $this->fetch();
			$updated_changes = array_merge( $config, $expanded_changes );

			$option_key = Config::OPTION_KEY;

			remove_action( "update_option_{$option_key}", $this->container->callback( Provider::class, 'save_via_config' ) );
			update_option( Config::OPTION_KEY, $updated_changes );
			add_action( "update_option_{$option_key}", $this->container->callback( Provider::class, 'save_via_config' ), 10, 2 );
		}

		if ( $next !== null ) {
			return $next( $changes );
		}
	}

	/**
	 * {@inheritdoc}
	 */
	public function is_responsible_for( string $option_key ): bool {
		// All keys should be stored in the options table.
		return true;
	}

	/**
	 * Fetches & caches the config from the options table.
	 *
	 * @return array
	 */
	private function fetch(): array {
		if ( ! function_exists( 'get_option' ) ) {
			return [];
		}

		if ( $this->config === null ) {
			$this->config = (array) get_option( Config::OPTION_KEY, [] );
		}

		return $this->config;
	}
}