<?php

namespace App\Core;

/**
 * Core Redis Client for managing connections.
 * Strict environment variable enforcement (No default fallbacks).
 */
class RedisClient
{
    private static ?\Redis $instance = null;

    /**
     * Get the singleton Redis connection instance
     */
    public static function getInstance(): \Redis
    {
        if (self::$instance === null) {
            $host     = getenv('REDIS_HOST');
            $port     = getenv('REDIS_PORT');
            $password = getenv('REDIS_PASSWORD') ?: null;

            $missing = [];
            if ($host === false || $host === '') $missing[] = 'REDIS_HOST';
            if ($port === false || $port === '') $missing[] = 'REDIS_PORT';

            if (!empty($missing)) {
                throw new \RuntimeException("Redis Configuration Error: Missing environment variable(s): " . implode(', ', $missing));
            }

            try {
                $redis = new \Redis();
                
                // Connect with a 2.5 second timeout
                if (!$redis->connect($host, (int)$port, 2.5)) {
                    throw new \RuntimeException("Could not connect to Redis server at {$host}:{$port}");
                }

                // Authenticate if password is provided
                if ($password) {
                    if (!$redis->auth($password)) {
                        throw new \RuntimeException("Redis authentication failed for host {$host}:{$port}.");
                    }
                }

                // Set prefix for Saqel to avoid collisions
                $redis->setOption(\Redis::OPT_PREFIX, 'saqel:');

                self::$instance = $redis;
            } catch (\Exception $e) {
                error_log("Redis Connection Error: " . $e->getMessage());
                throw new \RuntimeException("Redis connection failed ({$host}:{$port}): " . $e->getMessage());
            }
        }

        return self::$instance;
    }
    
    /**
     * Helper to close the connection explicitly
     */
    public static function close(): void
    {
        if (self::$instance !== null) {
            self::$instance->close();
            self::$instance = null;
        }
    }
}