<?php
/**
 * Row-level rules: our own-state exclusion (§9.4), subsite user filtering (§9B.2) and prefix
 * conversion for standalone restores (§9B.3).
 *
 * @package DatabaseExportGenie
 */

namespace DatabaseExportGenie;

use DatabaseExportGenie\Db\Adapter_Mysql;

defined( 'ABSPATH' ) || exit;

/**
 * Decorates work entries with row_filter / rename_to / transform.
 */
class Multisite_Scope {

	/**
	 * @param array[] $work  Work entries.
	 * @param array   $scope Normalized scope.
	 * @return array[]
	 */
	public static function apply( array $work, array $scope ) {
		global $wpdb;
		$base = $wpdb->base_prefix;
		foreach ( $work as $i => $t ) {
			// §9.4: the only exclusion — our own job/lock rows.
			if ( $base . 'options' === $t['name'] ) {
				$work[ $i ]['transform'] = array(
					'col'         => 'option_name',
					'skip_prefix' => 'dbmg_',
				);
			} elseif ( $base . 'sitemeta' === $t['name'] ) {
				$work[ $i ]['transform'] = array(
					'col'         => 'meta_key',
					'skip_prefix' => 'dbmg_',
				);
			}
		}
		if ( 'subsite' !== $scope['type'] ) {
			return $work;
		}
		$blog_id = (int) $scope['blog_id'];
		$prefix  = Table_Catalog::blog_prefix( $blog_id );
		$cap_key = $prefix . 'capabilities';
		$members = $wpdb->prepare( 'SELECT dbmg_m.`user_id` FROM %i AS dbmg_m WHERE dbmg_m.`meta_key` = %s', $base . 'usermeta', $cap_key );
		// The filter is stored in the job and runs in later requests, whose placeholder token differs: put any '%' back now.
		$members = $wpdb->remove_placeholder_escape( $members );
		$convert = ! empty( $scope['convert_prefix'] );

		foreach ( $work as $i => $t ) {
			if ( $scope['include_users'] && $base . 'users' === $t['name'] ) {
				$work[ $i ]['row_filter'] = '`ID` IN (' . $members . ')';
			} elseif ( $scope['include_users'] && $base . 'usermeta' === $t['name'] ) {
				$work[ $i ]['row_filter'] = '`user_id` IN (' . $members . ')';
				if ( $convert ) {
					$work[ $i ]['transform'] = array(
						'col'        => 'meta_key',
						'rename'     => array(
							$prefix . 'capabilities' => $base . 'capabilities',
							$prefix . 'user_level'   => $base . 'user_level',
						),
						// Other sites' roles would grant access that doesn't exist in a standalone install.
						'drop_regex' => '/^' . preg_quote( $base, '/' ) . '(\d+_)?(capabilities|user_level)$/',
					);
				}
			} elseif ( $convert && $prefix !== $base && 0 === strpos( $t['name'], $prefix ) ) {
				$work[ $i ]['rename_to'] = $base . substr( $t['name'], strlen( $prefix ) );
				if ( $prefix . 'options' === $t['name'] ) {
					$work[ $i ]['transform'] = array(
						'col'    => 'option_name',
						'rename' => array( $prefix . 'user_roles' => $base . 'user_roles' ),
					);
				}
			}
		}
		return $work;
	}

	/**
	 * Apply a row transform. Returns null when the row must be skipped.
	 *
	 * @param array      $row       Row.
	 * @param array|null $transform Rule.
	 * @return array|null
	 */
	public static function transform_row( array $row, $transform ) {
		if ( ! $transform ) {
			return $row;
		}
		$col = $transform['col'];
		if ( ! array_key_exists( $col, $row ) || null === $row[ $col ] ) {
			return $row;
		}
		$value = (string) $row[ $col ];
		if ( ! empty( $transform['skip_prefix'] ) && 0 === strpos( $value, $transform['skip_prefix'] ) ) {
			return null;
		}
		if ( ! empty( $transform['rename'] ) && isset( $transform['rename'][ $value ] ) ) {
			$row[ $col ] = $transform['rename'][ $value ];
			return $row;
		}
		if ( ! empty( $transform['drop_regex'] ) && preg_match( $transform['drop_regex'], $value ) ) {
			return null;
		}
		return $row;
	}
}