namespace OnlineMsgServer.Core
{
    internal sealed class SecurityConfig
    {
        public int ListenPort { get; init; } = 13173;
        public bool RequireWss { get; init; } = false;
        public string? TlsCertPath { get; init; }
        public string? TlsCertPassword { get; init; }

        public string? ServerPrivateKeyBase64 { get; init; }
        public string? ServerPrivateKeyPath { get; init; }
        public bool AllowEphemeralServerKey { get; init; }

        public int MaxConnections { get; init; } = 1000;
        public int MaxMessageBytes { get; init; } = 64 * 1024;
        public int RateLimitCount { get; init; } = 30;
        public int RateLimitWindowSeconds { get; init; } = 10;
        public int IpBlockSeconds { get; init; } = 120;

        public int ChallengeTtlSeconds { get; init; } = 120;
        public int MaxClockSkewSeconds { get; init; } = 60;
        public int ReplayWindowSeconds { get; init; } = 120;
        public string PeerNodeName { get; init; } = "server";
        public bool PeerNodeNameExplicitlyConfigured { get; init; }
        public string PeerUserPrefix { get; init; } = "peer:";
        public string[] PeerUrls { get; init; } = [];
        public int PeerReconnectSeconds { get; init; } = 5;
        public int SeenCacheSeconds { get; init; } = 120;

        public static SecurityConfig LoadFromEnvironment()
        {
            string? rawPeerNodeName = GetString("PEER_NODE_NAME");
            return new SecurityConfig
            {
                ListenPort = GetInt("LISTEN_PORT", 13173, 1),
                RequireWss = GetBool("REQUIRE_WSS", false),
                TlsCertPath = GetString("TLS_CERT_PATH"),
                TlsCertPassword = GetString("TLS_CERT_PASSWORD"),
                ServerPrivateKeyBase64 = GetString("SERVER_PRIVATE_KEY_B64"),
                ServerPrivateKeyPath = GetString("SERVER_PRIVATE_KEY_PATH"),
                AllowEphemeralServerKey = GetBool("ALLOW_EPHEMERAL_SERVER_KEY", false),
                MaxConnections = GetInt("MAX_CONNECTIONS", 1000, 1),
                MaxMessageBytes = GetInt("MAX_MESSAGE_BYTES", 64 * 1024, 512),
                RateLimitCount = GetInt("RATE_LIMIT_COUNT", 30, 1),
                RateLimitWindowSeconds = GetInt("RATE_LIMIT_WINDOW_SECONDS", 10, 1),
                IpBlockSeconds = GetInt("IP_BLOCK_SECONDS", 120, 1),
                ChallengeTtlSeconds = GetInt("CHALLENGE_TTL_SECONDS", 120, 10),
                MaxClockSkewSeconds = GetInt("MAX_CLOCK_SKEW_SECONDS", 60, 1),
                ReplayWindowSeconds = GetInt("REPLAY_WINDOW_SECONDS", 120, 10),
                PeerNodeName = rawPeerNodeName ?? CreateGuestName(),
                PeerNodeNameExplicitlyConfigured = !string.IsNullOrWhiteSpace(rawPeerNodeName),
                PeerUserPrefix = GetString("PEER_USER_PREFIX") ?? "peer:",
                PeerUrls = GetCsv("PEER_URLS"),
                PeerReconnectSeconds = GetInt("PEER_RECONNECT_SECONDS", 5, 1),
                SeenCacheSeconds = GetInt("SEEN_CACHE_SECONDS", 120, 1),
            };
        }

        private static string? GetString(string key)
        {
            string? value = Environment.GetEnvironmentVariable(key);
            if (string.IsNullOrWhiteSpace(value))
            {
                return null;
            }
            return value.Trim();
        }

        private static bool GetBool(string key, bool defaultValue)
        {
            string? value = Environment.GetEnvironmentVariable(key);
            if (string.IsNullOrWhiteSpace(value))
            {
                return defaultValue;
            }

            if (bool.TryParse(value, out bool parsed))
            {
                return parsed;
            }

            return value.Trim() switch
            {
                "1" => true,
                "0" => false,
                _ => defaultValue
            };
        }

        private static int GetInt(string key, int defaultValue, int minValue)
        {
            string? value = Environment.GetEnvironmentVariable(key);
            if (string.IsNullOrWhiteSpace(value))
            {
                return defaultValue;
            }

            if (!int.TryParse(value, out int parsed))
            {
                return defaultValue;
            }

            return Math.Max(parsed, minValue);
        }

        private static string[] GetCsv(string key)
        {
            string? value = Environment.GetEnvironmentVariable(key);
            if (string.IsNullOrWhiteSpace(value))
            {
                return [];
            }

            return value
                .Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
                .Where(item => !string.IsNullOrWhiteSpace(item))
                .Distinct(StringComparer.Ordinal)
                .ToArray();
        }

        private static string CreateGuestName()
        {
            return $"guest-{Random.Shared.Next(100000, 1000000)}";
        }
    }
}