<?php
/**
 * Deleting all of Careback's data with the plugin, when the shop asked for it (N-104).
 *
 * @package Careback
 */

namespace Careback;

defined( 'ABSPATH' ) || exit;

/**
 * What "Delete all Careback data when the plugin is deleted" removes on top of
 * what uninstall.php always removes (the settings, the schedules, the temporary
 * keys): the two tables — the requests with their history, and the security
 * log; an add-on's columns in the requests table go with it — the key behind
 * the email fingerprints, and the `_careback_*` data Careback saved on orders
 * and order lines (delivery dates, tracking numbers, the replacement mark).
 * WooCommerce's orders and every note on them always stay, and so does what
 * any other plugin stored. uninstall.php calls erase() only when the box is
 * ticked and no installed plugin needs Careback; it loads this file itself,
 * without the rest of the plugin.
 */
class Data_Eraser {

	/** Prefix of the order and order-line meta Careback writes. */
	const META_PREFIX = '_careback_';

	/** The most rows one statement deletes. */
	const CHUNK = 5000;

	/** Careback's own tables, without the site's prefix. */
	const TABLES = array( 'careback_requests', 'careback_events' );

	/** The option holding the key behind the email fingerprints (Hash::KEY_OPTION). */
	const KEY_OPTION = 'careback_hash_key';

	/**
	 * Names of the installed plugins that need Careback (their "Requires
	 * Plugins" header names it), read from the plugins as installed. WordPress
	 * 6.5 and later read the header; before, none is listed.
	 *
	 * @param string $own Folder of this plugin; the one it was loaded from when empty.
	 * @return string[]
	 */
	public static function dependents( $own = '' ) {
		if ( ! function_exists( 'get_plugins' ) ) {
			require_once ABSPATH . 'wp-admin/includes/plugin.php';
		}

		$own = '' !== (string) $own ? strtolower( (string) $own ) : ( defined( 'CAREBACK_FILE' ) ? strtolower( dirname( plugin_basename( CAREBACK_FILE ) ) ) : 'careback' );
		$out = array();

		foreach ( get_plugins() as $file => $data ) {
			if ( strtolower( dirname( (string) $file ) ) === $own || empty( $data['RequiresPlugins'] ) ) {
				continue;
			}

			$required = array_map( 'trim', explode( ',', strtolower( (string) $data['RequiresPlugins'] ) ) );

			if ( in_array( $own, $required, true ) ) {
				$out[] = ! empty( $data['Name'] ) ? (string) $data['Name'] : (string) $file;
			}
		}

		return $out;
	}

	/**
	 * Removes the tables, the key and the data on orders of the site it runs on.
	 *
	 * @return void
	 */
	public static function erase() {
		global $wpdb;

		foreach ( self::TABLES as $table ) {
			$wpdb->query( 'DROP TABLE IF EXISTS `' . esc_sql( $wpdb->prefix . $table ) . '`' ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery,WordPress.DB.PreparedSQL.NotPrepared,WordPress.DB.DirectDatabaseQuery.SchemaChange -- the plugin's own tables, by the shop's choice.
		}

		delete_option( self::KEY_OPTION );

		// The order data: in the order tables (HPOS), in the posts' meta (posts
		// storage, or both while they are kept in sync), and on order lines.
		foreach ( array( $wpdb->prefix . 'wc_orders_meta', $wpdb->postmeta, $wpdb->prefix . 'woocommerce_order_itemmeta' ) as $table ) {
			self::delete_meta( $table );
		}
	}

	/**
	 * Deletes the rows of a meta table whose key starts with META_PREFIX, a
	 * chunk at a time.
	 *
	 * @param string $table Full table name.
	 * @return void
	 */
	private static function delete_meta( $table ) {
		global $wpdb;

		$exists = $wpdb->get_var( $wpdb->prepare( 'SHOW TABLES LIKE %s', $wpdb->esc_like( $table ) ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery

		if ( $table !== $exists ) {
			return;
		}

		$like = $wpdb->esc_like( self::META_PREFIX ) . '%';
		$safe = esc_sql( $table );

		do {
			$deleted = (int) $wpdb->query( $wpdb->prepare( "DELETE FROM `{$safe}` WHERE meta_key LIKE %s LIMIT %d", $like, self::CHUNK ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery,WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- a core or WooCommerce meta table, by its own name.
		} while ( $deleted >= self::CHUNK );
	}
}