using System;
using AcDream.Core.Net.Messages;
using Xunit;

namespace AcDream.Core.Net.Tests.Messages;

/// <summary>
/// Phase I.6: <see cref="SetTurbineChatChannels"/> 10-u32 GameEvent
/// payload parser.
///
/// <para>
/// Golden fixture taken from holtburger
/// <c>references/holtburger/crates/holtburger-protocol/src/messages/chat/turbine.rs</c>
/// lines 654-679 (test <c>set_turbine_chat_channels_fixture</c>) — itself
/// generated by ACE's <c>SyntheticProtocolTests.GenerateTurbineChatFixtures</c>.
/// </para>
/// </summary>
public sealed class SetTurbineChatChannelsTests
{
    [Fact]
    public void TryParse_HoltburgerGoldenFixture_RoundTrips()
    {
        // Full game-message body from turbine.rs:655-657:
        //   B0F70000  – outer 0xF7B0 GameEvent opcode
        //   00000000  – guid 0
        //   21000000  – sequence 0x21
        //   95020000  – eventType 0x0295 (SetTurbineChatChannels)
        //   <40-byte payload>
        byte[] full = HexDecode(
            "B0F7000000000000210000009502000078563412" +
            "020000000300000004000000050000000A000000" +
            "09000000070000000800000009000000");

        // The parser consumes only the 40-byte payload after the
        // GameEventEnvelope header (16 bytes).
        var env = GameEventEnvelope.TryParse(full);
        Assert.NotNull(env);
        Assert.Equal(GameEventType.SetTurbineChatChannels, env!.Value.EventType);

        var parsed = SetTurbineChatChannels.TryParse(env.Value.Payload.Span);
        Assert.NotNull(parsed);
        // Allegiance: 0x12345678 (Unknown id used in fixture).
        Assert.Equal(0x12345678u, parsed!.Value.AllegianceRoom);
        // General..Olthoi
        Assert.Equal(2u, parsed.Value.GeneralRoom);
        Assert.Equal(3u, parsed.Value.TradeRoom);
        Assert.Equal(4u, parsed.Value.LfgRoom);
        Assert.Equal(5u, parsed.Value.RoleplayRoom);
        Assert.Equal(10u, parsed.Value.OlthoiRoom);
        // Society = SocietyRadiantBlood (id 9) per fixture
        Assert.Equal(9u, parsed.Value.SocietyRoom);
        // Sub-society rooms 7, 8, 9
        Assert.Equal(7u, parsed.Value.SocietyCelestialHandRoom);
        Assert.Equal(8u, parsed.Value.SocietyEldrytchWebRoom);
        Assert.Equal(9u, parsed.Value.SocietyRadiantBloodRoom);
    }

    [Fact]
    public void Serialize_RoundTripsThroughTryParse()
    {
        var original = new SetTurbineChatChannels.Parsed(
            AllegianceRoom: 0x100,
            GeneralRoom: 0x200,
            TradeRoom: 0x300,
            LfgRoom: 0x400,
            RoleplayRoom: 0x500,
            OlthoiRoom: 0x600,
            SocietyRoom: 0x700,
            SocietyCelestialHandRoom: 0x800,
            SocietyEldrytchWebRoom: 0x900,
            SocietyRadiantBloodRoom: 0xA00);

        byte[] payload = SetTurbineChatChannels.Serialize(original);
        Assert.Equal(SetTurbineChatChannels.PayloadSize, payload.Length);

        var roundTripped = SetTurbineChatChannels.TryParse(payload);
        Assert.NotNull(roundTripped);
        Assert.Equal(original, roundTripped!.Value);
    }

    [Fact]
    public void TryParse_TruncatedPayload_ReturnsNull()
    {
        // 39 bytes — one short of the 40-byte minimum.
        Assert.Null(SetTurbineChatChannels.TryParse(new byte[39]));
    }

    private static byte[] HexDecode(string hex)
    {
        if ((hex.Length & 1) != 0) throw new ArgumentException("hex length must be even");
        byte[] result = new byte[hex.Length / 2];
        for (int i = 0; i < result.Length; i++)
            result[i] = Convert.ToByte(hex.Substring(i * 2, 2), 16);
        return result;
    }
}