using MrGameEng.Net;
using Xunit;

namespace MrGameEng.Net.Tests;

public class WebSocketProtocolTests
{
    [Fact]
    public void AcceptKey_MatchesRfc6455Example()
    {
        // Пример рукопожатия прямо из RFC 6455, раздел 1.3.
        Assert.Equal(
            "s3pPLMBiTxaQ9kYGzzhZRbK+xOo=",
            WebSocketProtocol.AcceptKey("dGhlIHNhbXBsZSBub25jZQ==")
        );
    }

    [Theory]
    [InlineData(0)]
    [InlineData(125)]
    [InlineData(126)]
    [InlineData(70_000)]
    public void Frame_Roundtrips_Unmasked(int payloadLength)
    {
        var payload = MakePayload(payloadLength);
        var frame = WebSocketProtocol.EncodeFrame(payload, WebSocketOpcode.Binary);

        using var stream = new MemoryStream(frame);
        Assert.True(
            WebSocketProtocol.TryReadFrame(stream, out var opcode, out var fin, out var decoded)
        );
        Assert.Equal(WebSocketOpcode.Binary, opcode);
        Assert.True(fin);
        Assert.Equal(payload, decoded);
    }

    [Fact]
    public void Frame_Roundtrips_Masked()
    {
        var payload = MakePayload(1000);
        var frame = WebSocketProtocol.EncodeFrame(
            payload,
            WebSocketOpcode.Binary,
            maskKey: [0x12, 0x34, 0x56, 0x78]
        );

        using var stream = new MemoryStream(frame);
        Assert.True(WebSocketProtocol.TryReadFrame(stream, out _, out _, out var decoded));
        Assert.Equal(payload, decoded);
    }

    [Fact]
    public void TryReadHandshakeKey_ExtractsHeader()
    {
        var request =
            "GET /chat HTTP/1.1\r\n"
            + "Host: localhost\r\n"
            + "Upgrade: websocket\r\n"
            + "Connection: Upgrade\r\n"
            + "Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==\r\n"
            + "Sec-WebSocket-Version: 13\r\n"
            + "\r\n";
        using var stream = new MemoryStream(System.Text.Encoding.ASCII.GetBytes(request));

        Assert.True(WebSocketProtocol.TryReadHandshakeKey(stream, out var key));
        Assert.Equal("dGhlIHNhbXBsZSBub25jZQ==", key);
    }

    [Fact]
    public void TryReadFrame_TruncatedStream_ReturnsFalse()
    {
        var frame = WebSocketProtocol.EncodeFrame(MakePayload(100), WebSocketOpcode.Binary);
        using var stream = new MemoryStream(frame, 0, frame.Length - 10);

        Assert.False(WebSocketProtocol.TryReadFrame(stream, out _, out _, out _));
    }

    private static byte[] MakePayload(int length)
    {
        var payload = new byte[length];
        for (var i = 0; i < length; i++)
        {
            payload[i] = (byte)(i * 31);
        }

        return payload;
    }
}