// Copyright 2012-2026 The NATS Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using System.Net;
using ZB.MOM.NatsNet.Server.Protocol;

namespace ZB.MOM.NatsNet.Server;

/// <summary>
/// Client-side PROXY protocol compatibility surface for Batch 3 mappings.
/// </summary>
public sealed partial class ClientConnection
{
    private IPEndPoint? _proxyRemoteEndPoint;

    /// <summary>
    /// Returns the proxied remote endpoint when available, otherwise socket remote endpoint.
    /// Mirrors Go <c>proxyConn.RemoteAddr()</c>.
    /// </summary>
    public EndPoint? RemoteAddr()
    {
        lock (_mu) { return _proxyRemoteEndPoint ?? GetRemoteEndPoint(); }
    }

    internal void SetProxyRemoteAddress(ProxyProtocolAddress? address)
    {
        lock (_mu)
        {
            _proxyRemoteEndPoint = address is null
                ? null
                : new IPEndPoint(address.SrcIp, address.SrcPort);
        }
    }

    internal static (int version, byte[] header) DetectProxyProtoVersion(Stream conn) =>
        ProxyProtocolParser.DetectVersion(conn);

    internal static ProxyProtocolAddress? ReadProxyProtoV1Header(Stream conn) =>
        ProxyProtocolParser.ReadV1Header(conn);

    internal static ProxyProtocolAddress? ReadProxyProtoHeader(Stream conn) =>
        ProxyProtocolParser.ReadProxyProtoHeader(conn);

    internal static ProxyProtocolAddress? ReadProxyProtoV2Header(Stream conn) =>
        ProxyProtocolParser.ReadProxyProtoV2Header(conn);

    internal static ProxyProtocolAddress? ParseProxyProtoV2Header(Stream conn, byte[] header) =>
        ProxyProtocolParser.ParseV2Header(conn, header.AsSpan());

    internal static ProxyProtocolAddress ParseIPv4Addr(Stream conn, ushort addrLen) =>
        ProxyProtocolParser.ParseIPv4Addr(conn, addrLen);

    internal static ProxyProtocolAddress ParseIPv6Addr(Stream conn, ushort addrLen) =>
        ProxyProtocolParser.ParseIPv6Addr(conn, addrLen);
}
