using System.Buffers.Binary;
using AcDream.Core.Net.Messages;
using AcDream.Core.Net.Packets;

namespace AcDream.Core.Net.Tests.Messages;

public class CharacterListTests
{
    [Fact]
    public void Parse_SingleCharacter_ExtractsGuidAndName()
    {
        // Hand-assemble a CharacterList body matching ACE's writer format:
        //   u32 opcode, u32 0, u32 count=1,
        //   u32 guid, String16L name, u32 deleteDelta,
        //   u32 0, u32 slotCount, String16L accountName,
        //   u32 useTurbineChat, u32 hasToD
        var w = new PacketWriter(128);
        w.WriteUInt32(CharacterList.Opcode);
        w.WriteUInt32(0);
        w.WriteUInt32(1);  // count
        w.WriteUInt32(0x50000001u);
        w.WriteString16L("+Acdream");
        w.WriteUInt32(0);  // deleteDelta
        w.WriteUInt32(0);
        w.WriteUInt32(11); // slotCount
        w.WriteString16L("testaccount");
        w.WriteUInt32(1);  // useTurbineChat
        w.WriteUInt32(1);  // hasToD

        var parsed = CharacterList.Parse(w.ToArray());

        Assert.Single(parsed.Characters);
        Assert.Equal(0x50000001u, parsed.Characters[0].Id);
        Assert.Equal("+Acdream", parsed.Characters[0].Name);
        Assert.Equal(0u, parsed.Characters[0].DeleteTimeDelta);
        Assert.Equal(11u, parsed.SlotCount);
        Assert.Equal("testaccount", parsed.AccountName);
        Assert.True(parsed.UseTurbineChat);
        Assert.True(parsed.HasThroneOfDestiny);
    }

    [Fact]
    public void Parse_MultipleCharacters_PreservesOrder()
    {
        var w = new PacketWriter(128);
        w.WriteUInt32(CharacterList.Opcode);
        w.WriteUInt32(0);
        w.WriteUInt32(3);  // count
        w.WriteUInt32(0x50000001u);
        w.WriteString16L("Alice");
        w.WriteUInt32(0);
        w.WriteUInt32(0x50000002u);
        w.WriteString16L("Bob");
        w.WriteUInt32(0);
        w.WriteUInt32(0x50000003u);
        w.WriteString16L("Carol");
        w.WriteUInt32(0);
        w.WriteUInt32(0);
        w.WriteUInt32(11);
        w.WriteString16L("acct");
        w.WriteUInt32(0);
        w.WriteUInt32(1);

        var parsed = CharacterList.Parse(w.ToArray());

        Assert.Equal(3, parsed.Characters.Count);
        Assert.Equal("Alice", parsed.Characters[0].Name);
        Assert.Equal("Bob",   parsed.Characters[1].Name);
        Assert.Equal("Carol", parsed.Characters[2].Name);
    }

    [Fact]
    public void Parse_WrongOpcode_Throws()
    {
        byte[] bytes = new byte[4];
        BinaryPrimitives.WriteUInt32LittleEndian(bytes, 0xDEADBEEFu);
        Assert.Throws<FormatException>(() => CharacterList.Parse(bytes));
    }

    [Fact]
    public void Parse_Truncated_Throws()
    {
        byte[] bytes = new byte[8];  // just opcode + first zero, missing count
        BinaryPrimitives.WriteUInt32LittleEndian(bytes, CharacterList.Opcode);
        Assert.Throws<FormatException>(() => CharacterList.Parse(bytes));
    }
}