using System;
using Xunit;
using XWorld.Framework.Protocol;

namespace XWorld.Framework.Tests
{
    public class FrameCodecTests
    {
        [Fact]
        public void Frame_RoundTrips()
        {
            var original = new Frame(Channel.Game, 7, new byte[] { 10, 20, 30 });
            byte[] wire = FrameCodec.Encode(original);
            Frame decoded = FrameCodec.Decode(wire);

            Assert.Equal(Channel.Game, decoded.Channel);
            Assert.Equal((ushort)7, decoded.Opcode);
            Assert.Equal(new byte[] { 10, 20, 30 }, decoded.Payload);
        }

        [Fact]
        public void Frame_EmptyPayload_RoundTrips()
        {
            var original = new Frame(Channel.Framework, 1, null);
            Frame decoded = FrameCodec.Decode(FrameCodec.Encode(original));
            Assert.Equal(Channel.Framework, decoded.Channel);
            Assert.Equal((ushort)1, decoded.Opcode);
            Assert.Empty(decoded.Payload);
        }

        [Fact]
        public void Encode_WireLayout_IsChannelOpcodeLenPayload()
        {
            var f = new Frame(Channel.Game, 0x0102, new byte[] { 0xAA });
            byte[] wire = FrameCodec.Encode(f);
            // channel=1, opcode 小端 = 02 01, len varuint = 1, payload = AA
            Assert.Equal(new byte[] { 0x01, 0x02, 0x01, 0x01, 0xAA }, wire);
        }

        [Fact]
        public void Decode_Truncated_Throws()
        {
            Assert.Throws<FormatException>(() => FrameCodec.Decode(new byte[] { 0x00 }));
        }
    }
}