<?php
/**
 * Moving settings between sites.
 *
 * Only settings that mean the same on another site travel. Test delivery and its
 * inbox, the uninstall choice, constants from wp-config.php and every credential
 * stay with each site. Imported settings are listed beside the current ones and
 * change only when ticked.
 *
 * @package AccessibleForms
 */

namespace AccessibleForms\Portability;

use AccessibleForms\{Audit, Extensions, Settings, Spam};
use AccessibleForms\Admin\SettingsPage;

if ( ! defined( 'ABSPATH' ) ) {
	exit();
}

class SettingsTransfer {
	/** Core settings that may move between sites. */
	const KEYS = array( 'mail_from', 'mail_from_name', 'spam_provider', 'max_links', 'rate_limit', 'retention_days', 'spam_retention_days' );

	/** Verification methods that need nothing from the site they run on. */
	const PORTABLE_PROVIDERS = array( 'basic', 'altcha' );

	public static function labels() {
		return array(
			'mail_from'           => __( 'From address', 'accessible-forms-by-accessible-org' ),
			'mail_from_name'      => __( 'From name', 'accessible-forms-by-accessible-org' ),
			'spam_provider'       => __( 'Spam verification', 'accessible-forms-by-accessible-org' ),
			'max_links'           => __( 'Maximum links per message', 'accessible-forms-by-accessible-org' ),
			'rate_limit'          => __( 'Submissions per hour, per IP address', 'accessible-forms-by-accessible-org' ),
			'retention_days'      => __( 'Keep received entries (days, 0 = until deleted)', 'accessible-forms-by-accessible-org' ),
			'spam_retention_days' => __( 'Keep spam and held messages (days)', 'accessible-forms-by-accessible-org' ),
		);
	}

	/**
	 * Portable settings, grouped by owner: `core`, plus one group per add-on.
	 *
	 * @return array<string, array>
	 */
	public static function export() {
		$stored = Settings::get();
		$core   = array();
		foreach ( self::KEYS as $key ) {
			if ( ! Settings::is_constant( $key ) && array_key_exists( $key, $stored ) ) {
				$core[ $key ] = $stored[ $key ];
			}
		}
		if ( isset( $core['spam_provider'] ) && ! in_array( $core['spam_provider'], self::PORTABLE_PROVIDERS, true ) ) {
			unset( $core['spam_provider'] );
		}
		$settings = (array) Extensions::filter( 'accessible_forms_portable_settings', array( 'core' => $core ) );
		Audit::record( 'settings_exported' );
		return array_filter( $settings );
	}

	/**
	 * Incoming settings beside the current ones.
	 *
	 * @param array $incoming The file's `settings` section.
	 * @return array[] Rows: id, group, label, current, incoming, value, changed, note.
	 */
	public static function review( array $incoming ) {
		$rows    = array();
		$current = Settings::get();
		$labels  = self::labels();
		$core    = is_array( $incoming['core'] ?? null ) ? $incoming['core'] : array();
		foreach ( self::KEYS as $key ) {
			if ( ! array_key_exists( $key, $core ) || ! is_scalar( $core[ $key ] ) ) {
				continue;
			}
			$value = SettingsPage::sanitize_setting( $key, $core[ $key ], $current[ $key ] ?? '' );
			$note  = '';
			if ( Settings::is_constant( $key ) ) {
				$note = __( 'Set in wp-config.php on this site, so it is not changed.', 'accessible-forms-by-accessible-org' );
			} elseif ( 'spam_provider' === $key && ( ! in_array( (string) $core[ $key ], self::PORTABLE_PROVIDERS, true ) || ! isset( Spam::providers()[ (string) $core[ $key ] ] ) ) ) {
				$note = __( 'This method needs setting up on this site. Choose it under Settings, Spam protection.', 'accessible-forms-by-accessible-org' );
			}
			$rows[] = array(
				'id'       => 'core.' . $key,
				'group'    => 'core',
				'label'    => $labels[ $key ],
				'current'  => self::display( $key, $current[ $key ] ?? '' ),
				'incoming' => self::display( $key, $value ),
				'value'    => $value,
				'changed'  => (string) ( $current[ $key ] ?? '' ) !== (string) $value,
				'note'     => $note,
			);
		}
		return (array) Extensions::filter( 'accessible_forms_settings_review', $rows, $incoming );
	}

	/**
	 * Apply the ticked rows.
	 *
	 * @param array    $incoming The file's `settings` section.
	 * @param string[] $selected Row IDs, such as `core.mail_from`.
	 * @return int|\WP_Error Number of settings changed.
	 */
	public static function apply( array $incoming, array $selected ) {
		$selected = array_flip( array_filter( $selected, 'is_string' ) );
		$changed  = 0;
		$settings = Settings::get();
		$previous = $settings;
		foreach ( self::review( $incoming ) as $row ) {
			if ( 'core' !== $row['group'] || ! isset( $selected[ $row['id'] ] ) || $row['note'] || ! $row['changed'] ) {
				continue;
			}
			$settings[ substr( $row['id'], 5 ) ] = $row['value'];
			++$changed;
		}
		if ( $changed ) {
			$checked = Extensions::filter( 'accessible_forms_settings_before_save', $settings, $previous, 'import' );
			if ( is_wp_error( $checked ) ) {
				return $checked;
			}
			if ( ! Settings::update( is_array( $checked ) ? $checked : $settings ) ) {
				return new \WP_Error( 'storage', __( 'The settings could not be saved. Nothing was changed.', 'accessible-forms-by-accessible-org' ) );
			}
		}
		// Add-ons apply their own ticked rows and report how many changed.
		$changed += (int) Extensions::filter( 'accessible_forms_import_settings', 0, $incoming, array_keys( $selected ) );
		if ( $changed ) {
			Audit::record( 'settings_imported' );
		}
		return $changed;
	}

	private static function display( $key, $value ) {
		if ( 'spam_provider' === $key ) {
			$provider = Spam::providers()[ $value ] ?? null;
			return is_array( $provider ) ? (string) $provider[0] : (string) $value;
		}
		if ( 'retention_days' === $key && 0 === (int) $value ) {
			return __( 'Until deleted', 'accessible-forms-by-accessible-org' );
		}
		return '' === (string) $value ? __( '(not set)', 'accessible-forms-by-accessible-org' ) : (string) $value;
	}
}