<?php

namespace AOP\App;

/**
 * One-off messages and data that survive a redirect, kept per user.
 * Replaces the global `aop_session_handler` option that every user shared.
 */
class Flash
{
    private const TTL = 5 * MINUTE_IN_SECONDS;

    /**
     * @var array<int, array> Per-request cache, keyed by user id.
     */
    private static $cache = [];

    private static function key(): string
    {
        return Plugin::PREFIX_ . 'flash_' . get_current_user_id();
    }

    public static function all(): array
    {
        $userId = get_current_user_id();

        if (!isset(self::$cache[$userId])) {
            $stored = get_transient(self::key());

            self::$cache[$userId] = is_array($stored) ? $stored : [];
        }

        return self::$cache[$userId];
    }

    public static function get($item)
    {
        $all = self::all();

        return array_key_exists($item, $all) ? $all[$item] : false;
    }

    /**
     * Replaces everything that was flashed before.
     */
    public static function add(array $items): void
    {
        self::$cache[get_current_user_id()] = $items;

        set_transient(self::key(), $items, self::TTL);
    }

    public static function delete($item): void
    {
        $all = self::all();
        unset($all[$item]);

        self::add($all);
    }

    public static function destroy(): void
    {
        self::$cache[get_current_user_id()] = [];

        delete_transient(self::key());
    }

    /**
     * Uninstall: remove the flash data of every user and the old global session option.
     */
    public static function purgeAll(): void
    {
        global $wpdb;

        $prefix = '_transient_' . Plugin::PREFIX_ . 'flash_';
        $names = $wpdb->get_col(
            $wpdb->prepare("SELECT option_name FROM {$wpdb->options} WHERE option_name LIKE %s", $wpdb->esc_like($prefix) . '%')
        );

        // delete_transient() also clears the timeout row and the object cache.
        foreach ($names as $name) {
            delete_transient(substr($name, strlen('_transient_')));
        }

        delete_option(Plugin::PREFIX_ . 'session_handler');
    }
}