<?php
/**
 * Cache-proof option storage for job/lock state.
 *
 * Reads and writes go straight to the main site's options table with SQL, so a persistent object cache
 * (Redis/Memcached), a switched blog on multisite, or a stale alloptions cache can never make two
 * requests disagree about the job (§16 "Object cache").
 *
 * @package DatabaseExportGenie
 */

namespace DatabaseExportGenie;

defined( 'ABSPATH' ) || exit;

/**
 * Tiny key/value store on {base_prefix}options.
 */
class Options {

	/**
	 * @return string Table name of the main site's options table.
	 */
	public static function table() {
		global $wpdb;
		return $wpdb->base_prefix . 'options';
	}

	/**
	 * @param string $name    Option name.
	 * @param mixed  $default Returned when missing.
	 * @return mixed
	 */
	public static function get( $name, $default = null ) {
		global $wpdb;
		$table = self::table();
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery
		$raw = $wpdb->get_var( $wpdb->prepare( "SELECT option_value FROM %i WHERE option_name = %s LIMIT 1", $table, $name ) );
		if ( null === $raw ) {
			return $default;
		}
		return maybe_unserialize( $raw );
	}

	/**
	 * Upsert. Returns false when the database refused the write.
	 *
	 * @param string $name  Option name.
	 * @param mixed  $value Value (serialized when needed).
	 * @return bool
	 */
	public static function set( $name, $value ) {
		global $wpdb;
		$table = self::table();
		$data  = maybe_serialize( $value );
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery
		$ok = $wpdb->query( $wpdb->prepare( "INSERT INTO %i (option_name, option_value, autoload) VALUES (%s, %s, 'no') ON DUPLICATE KEY UPDATE option_value = VALUES(option_value)", $table, $name, $data ) );
		self::forget( $name );
		return false !== $ok;
	}

	/**
	 * Insert only if absent. True when this call created the row (atomic).
	 *
	 * @param string $name  Option name.
	 * @param mixed  $value Value.
	 * @return bool
	 */
	public static function add( $name, $value ) {
		global $wpdb;
		$table = self::table();
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery
		$wpdb->query( $wpdb->prepare( "INSERT IGNORE INTO %i (option_name, option_value, autoload) VALUES (%s, %s, 'no')", $table, $name, maybe_serialize( $value ) ) );
		self::forget( $name );
		return 1 === (int) $wpdb->rows_affected;
	}

	/**
	 * Compare-and-swap. True when exactly one row changed from $old to $new.
	 *
	 * @param string $name Option name.
	 * @param string $old  Expected current raw value.
	 * @param string $new  New raw value.
	 * @return bool
	 */
	public static function swap( $name, $old, $new ) {
		global $wpdb;
		$table = self::table();
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery
		$wpdb->query( $wpdb->prepare( "UPDATE %i SET option_value = %s WHERE option_name = %s AND option_value = %s", $table, $new, $name, $old ) );
		self::forget( $name );
		return 1 === (int) $wpdb->rows_affected;
	}

	/**
	 * Delete; with $only_if, only when the stored raw value matches.
	 *
	 * @param string      $name    Option name.
	 * @param string|null $only_if Expected raw value.
	 */
	public static function delete( $name, $only_if = null ) {
		global $wpdb;
		$table = self::table();
		if ( null === $only_if ) {
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery
			$wpdb->query( $wpdb->prepare( "DELETE FROM %i WHERE option_name = %s", $table, $name ) );
		} else {
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery
			$wpdb->query( $wpdb->prepare( "DELETE FROM %i WHERE option_name = %s AND option_value = %s", $table, $name, $only_if ) );
		}
		self::forget( $name );
	}

	/**
	 * Delete every dbmg_* option (uninstall / delete-all).
	 */
	public static function delete_all() {
		global $wpdb;
		$table = self::table();
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery
		$wpdb->query( $wpdb->prepare( 'DELETE FROM %i WHERE option_name LIKE %s', $table, $wpdb->esc_like( 'dbmg_' ) . '%' ) );
		wp_cache_delete( 'alloptions', 'options' );
	}

	/**
	 * Keep WordPress's own option cache honest after a direct write.
	 *
	 * @param string $name Option name.
	 */
	private static function forget( $name ) {
		wp_cache_delete( $name, 'options' );
	}
}