<?php
/**
 * Export, import and reset of the plugin's settings.
 *
 * @package ElevenRank
 * @since   1.0.0
 */

namespace ElevenRank\Modules\Tools;

use ElevenRank\Settings;

defined( 'ABSPATH' ) || exit;

/**
 * Settings travel as JSON. An import is validated by the same schema that guards every other way
 * of changing settings, so a file cannot put anything in that the settings screens could not.
 *
 * @since 1.0.0
 */
final class Settings_Transfer {

	/**
	 * Groups that are never exported or imported: the wizard's progress belongs to one site.
	 *
	 * @since 1.0.0
	 *
	 * @var string[]
	 */
	const LEFT_OUT = array( 'wizard_state' );

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

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

	/**
	 * The groups that can be exported, imported and reset.
	 *
	 * @since 1.0.0
	 *
	 * @return string[]
	 */
	public function groups(): array {
		return array_values( array_diff( $this->settings->groups(), self::LEFT_OUT ) );
	}

	/**
	 * Every setting as a document.
	 *
	 * @since 1.0.0
	 *
	 * @return array<string, mixed>
	 */
	public function export(): array {
		$settings = array();

		foreach ( $this->groups() as $group ) {
			$settings[ $group ] = $this->settings->get( $group );
		}

		return array(
			'plugin'   => 'elevenrank',
			'version'  => ELEVENRANK_VERSION,
			'exported' => gmdate( 'c' ),
			'settings' => $settings,
		);
	}

	/**
	 * Applies an exported document.
	 *
	 * Values are cleaned by the schema. The "delete all data on uninstall" switch is never taken from a
	 * file: a file from another site should not decide what happens to this site's data.
	 *
	 * @since 1.0.0
	 *
	 * @param array<string, mixed> $document Decoded JSON.
	 * @return array{imported: string[], ignored: string[]}|null Null when the document is not an export of this plugin.
	 */
	public function import( array $document ): ?array {
		if ( ( $document['plugin'] ?? '' ) !== 'elevenrank' || ! isset( $document['settings'] ) || ! is_array( $document['settings'] ) ) {
			return null;
		}

		$imported = array();
		$ignored  = array();

		foreach ( $document['settings'] as $group => $values ) {
			if ( ! is_string( $group ) || ! in_array( $group, $this->groups(), true ) || ! is_array( $values ) ) {
				$ignored[] = is_string( $group ) ? $group : '?';
				continue;
			}

			if ( 'general' === $group ) {
				unset( $values['delete_data_on_uninstall'] );
			}

			$this->settings->update( $group, $values );

			$imported[] = $group;
		}

		return array(
			'imported' => $imported,
			'ignored'  => $ignored,
		);
	}

	/**
	 * Puts groups back to their defaults.
	 *
	 * @since 1.0.0
	 *
	 * @param string[] $groups Groups to reset; unknown names are ignored.
	 * @return string[] The groups that were reset.
	 */
	public function reset( array $groups ): array {
		$done = array();

		foreach ( $groups as $group ) {
			if ( ! is_string( $group ) || ! in_array( $group, $this->groups(), true ) ) {
				continue;
			}

			delete_option( $this->settings->option_name( $group ) );

			$done[] = $group;
		}

		// The options are created again with their defaults.
		$this->settings->ensure_defaults();

		return $done;
	}
}