using AcDream.Core.Items;
using Xunit;

namespace AcDream.Core.Tests.Items;

/// <summary>
/// #297: pins <see cref="PlayerKillerStatusBitfield.Apply"/> — the ported
/// retail <c>PublicWeenieDesc::SetPlayerKillerStatus@0x005AC7C0</c> bit
/// rewrite — byte-for-byte against
/// <c>acclient_2013_pseudo_c.txt:441868-441890</c>. Covers all four arms
/// (PK / PKLite / Free / else-clears-all) and mutual exclusivity.
/// </summary>
public sealed class PlayerKillerStatusBitfieldTests
{
    [Fact]
    public void Pk_SetsPkBit_ClearsFreeAndPkLite()
    {
        // Starting bitfield already has Free(0x200000) and PKLite(0x2000000)
        // set (shouldn't happen in practice, but the mask must still clear
        // them — mutual exclusivity is enforced by the rewrite, not by the
        // caller).
        uint result = PlayerKillerStatusBitfield.Apply(
            bitfield: 0x2200000u,
            pkStatus: PlayerKillerStatusBitfield.Pk);
        Assert.Equal(0x20u, result);
    }

    [Fact]
    public void PkLite_SetsPkLiteBit_ClearsPkAndFree()
    {
        uint result = PlayerKillerStatusBitfield.Apply(
            bitfield: 0x200020u,
            pkStatus: PlayerKillerStatusBitfield.PkLite);
        Assert.Equal(0x2000000u, result);
    }

    [Fact]
    public void Free_SetsFreeBit_ClearsPkAndPkLite()
    {
        uint result = PlayerKillerStatusBitfield.Apply(
            bitfield: 0x2000020u,
            pkStatus: PlayerKillerStatusBitfield.Free);
        Assert.Equal(0x200000u, result);
    }

    [Fact]
    public void OtherValue_ClearsAllThreeBits()
    {
        // Retail's implicit "NPK" default (any arg2 not in {4, 0x20, 0x40})
        // clears PK/Free/PKLite and sets nothing.
        uint result = PlayerKillerStatusBitfield.Apply(
            bitfield: 0x2200020u,
            pkStatus: 0);
        Assert.Equal(0u, result);
    }

    [Theory]
    [InlineData(PlayerKillerStatusBitfield.Pk)]
    [InlineData(PlayerKillerStatusBitfield.PkLite)]
    [InlineData(PlayerKillerStatusBitfield.Free)]
    [InlineData(0)]
    public void NeverTouchesUnrelatedBits(int pkStatus)
    {
        // BF_PLAYER (0x8) and every other PWD bit must survive every arm —
        // the retail masks only ever touch bits 5/21/25.
        const uint unrelatedBits = 0x8u | 0x100u | 0x400000u;
        uint result = PlayerKillerStatusBitfield.Apply(
            bitfield: unrelatedBits,
            pkStatus: pkStatus);
        Assert.Equal(unrelatedBits, result & unrelatedBits);
    }

    [Fact]
    public void MutualExclusivity_TransitioningPkToFreeToPkLite()
    {
        uint bitfield = 0u;
        bitfield = PlayerKillerStatusBitfield.Apply(bitfield, PlayerKillerStatusBitfield.Pk);
        Assert.Equal(0x20u, bitfield);

        bitfield = PlayerKillerStatusBitfield.Apply(bitfield, PlayerKillerStatusBitfield.Free);
        Assert.Equal(0x200000u, bitfield);

        bitfield = PlayerKillerStatusBitfield.Apply(bitfield, PlayerKillerStatusBitfield.PkLite);
        Assert.Equal(0x2000000u, bitfield);

        bitfield = PlayerKillerStatusBitfield.Apply(bitfield, pkStatus: -1);
        Assert.Equal(0u, bitfield);
    }
}