// Tests for WbDrawDispatcher's Phase U.4 per-instance clip-slot resolution
// (ResolveEntitySlot / ResolveSlotForFrame). Code review of the U.4 commit
// (7993e06) flagged this gate-critical routing as untested: if it breaks,
// every indoor instance is sent to the wrong clip slot (or wrongly culled),
// producing total visual garbage at the portal-visibility gate. The logic is
// a pure function of (ServerGuid, ParentCellId, the clip-routing state), so we
// extract it to internal static helpers and test the branches directly — no GL
// context required.
//
// Branch map (ResolveSlotForFrame, the call-site policy):
//   routing inactive (outdoor root)        → slot 0, NOT culled (≡ U.3)
//   ServerGuid != 0 (live dynamic)         → slot 0, NOT culled (unclipped)
//   ParentCellId in cellIdToSlot           → that cell's slot
//   ParentCellId NOT in cellIdToSlot       → CULL
//   ParentCellId == null, outdoorVisible   → outdoorSlot
//   ParentCellId == null, !outdoorVisible  → CULL

using System.Collections.Generic;
using AcDream.App.Rendering.Wb;
using Xunit;

namespace AcDream.App.Tests.Rendering.Wb;

public sealed class WbDrawDispatcherClipSlotTests
{
    // Full cell-id space keys (lbMask | OtherCellId). 0xA9B4 is the Holtburg
    // landblock prefix used throughout the indoor-walking work; the low word is
    // the EnvCell index. ParentCellId on a cell static is the SAME full id — see
    // the L.2e bare-low-byte finding (a 0x29 low-byte key would cull everything).
    private const uint VisibleCellA = 0xA9B4_0164u;
    private const uint VisibleCellB = 0xA9B4_0165u;
    private const uint NotVisibleCell = 0xA9B4_0999u;

    private const int SlotA = 3;
    private const int SlotB = 7;
    private const int OutsideViewSlot = 11;

    private static IReadOnlyDictionary<uint, int> Routing() => new Dictionary<uint, int>
    {
        [VisibleCellA] = SlotA,
        [VisibleCellB] = SlotB,
    };

    // ── Raw resolver (ResolveEntitySlot): only reached when routing is active ──

    [Fact]
    public void RawResolve_LiveEntity_IsUnclippedSlot0_WhenParentCellNull()
    {
        // ServerGuid != 0 ⇒ unclipped (slot 0) regardless of cell state.
        int slot = WbDrawDispatcher.ResolveEntitySlot(
            serverGuid: 0x5000_000Au, parentCellId: null,
            cellIdToSlot: Routing(), outdoorSlot: OutsideViewSlot, outdoorVisible: true);

        Assert.Equal(0, slot);
    }

    [Fact]
    public void RawResolve_LiveEntity_IsUnclippedSlot0_EvenWhenParentCellVisible()
    {
        // A live entity whose ParentCellId IS a visible cell still goes to slot 0,
        // NOT SlotA — the live-dynamic check must precede the cell lookup.
        int slot = WbDrawDispatcher.ResolveEntitySlot(
            serverGuid: 0x5000_000Au, parentCellId: VisibleCellA,
            cellIdToSlot: Routing(), outdoorSlot: OutsideViewSlot, outdoorVisible: true);

        Assert.Equal(0, slot);
        Assert.NotEqual(SlotA, slot); // guards against ordering regression
    }

    [Fact]
    public void RawResolve_CellStatic_InVisibleSet_GetsThatCellSlot()
    {
        int slot = WbDrawDispatcher.ResolveEntitySlot(
            serverGuid: 0u, parentCellId: VisibleCellB,
            cellIdToSlot: Routing(), outdoorSlot: OutsideViewSlot, outdoorVisible: true);

        Assert.Equal(SlotB, slot);
    }

    [Fact]
    public void RawResolve_CellStatic_NotInVisibleSet_IsCulled()
    {
        int slot = WbDrawDispatcher.ResolveEntitySlot(
            serverGuid: 0u, parentCellId: NotVisibleCell,
            cellIdToSlot: Routing(), outdoorSlot: OutsideViewSlot, outdoorVisible: true);

        Assert.Equal(WbDrawDispatcher.ClipSlotCull, slot);
    }

    [Fact]
    public void RawResolve_OutdoorStab_OutdoorsVisible_GetsOutsideViewSlot()
    {
        int slot = WbDrawDispatcher.ResolveEntitySlot(
            serverGuid: 0u, parentCellId: null,
            cellIdToSlot: Routing(), outdoorSlot: OutsideViewSlot, outdoorVisible: true);

        Assert.Equal(OutsideViewSlot, slot);
    }

    [Fact]
    public void RawResolve_OutdoorStab_OutdoorsNotVisible_IsCulled()
    {
        int slot = WbDrawDispatcher.ResolveEntitySlot(
            serverGuid: 0u, parentCellId: null,
            cellIdToSlot: Routing(), outdoorSlot: OutsideViewSlot, outdoorVisible: false);

        Assert.Equal(WbDrawDispatcher.ClipSlotCull, slot);
    }

    // ── Call-site policy (ResolveSlotForFrame): adds the clipRoutingActive gate ──
    // Cases mirror the raw resolver but return the (slot, culled) pair the loop
    // body consumes, and add the routing-inactive (outdoor-root) branch.

    [Fact]
    public void ForFrame_RoutingInactive_EveryEntityIsSlot0AndNotCulled()
    {
        // The bit-identical-to-U.3 property: when the camera is at an outdoor root
        // (ClearClipRouting), ResolveEntitySlot is never consulted — every entity
        // maps to slot 0 and nothing is clip-culled. Exercised here for BOTH a
        // live entity and a cell static that would otherwise cull, with a null
        // routing map to prove the resolver is bypassed entirely.

        var live = WbDrawDispatcher.ResolveSlotForFrame(
            clipRoutingActive: false, serverGuid: 0x5000_000Au, parentCellId: null,
            cellIdToSlot: null, outdoorSlot: OutsideViewSlot, outdoorVisible: true);
        Assert.Equal(0u, live.Slot);
        Assert.False(live.Culled);

        var wouldCull = WbDrawDispatcher.ResolveSlotForFrame(
            clipRoutingActive: false, serverGuid: 0u, parentCellId: NotVisibleCell,
            cellIdToSlot: null, outdoorSlot: OutsideViewSlot, outdoorVisible: false);
        Assert.Equal(0u, wouldCull.Slot);
        Assert.False(wouldCull.Culled);
    }

    [Fact]
    public void ForFrame_RoutingActive_LiveEntity_Slot0NotCulled()
    {
        var r = WbDrawDispatcher.ResolveSlotForFrame(
            clipRoutingActive: true, serverGuid: 0x5000_000Au, parentCellId: VisibleCellA,
            cellIdToSlot: Routing(), outdoorSlot: OutsideViewSlot, outdoorVisible: true);

        Assert.Equal(0u, r.Slot);
        Assert.False(r.Culled);
    }

    [Fact]
    public void ForFrame_RoutingActive_CellStaticVisible_GetsCellSlotNotCulled()
    {
        var r = WbDrawDispatcher.ResolveSlotForFrame(
            clipRoutingActive: true, serverGuid: 0u, parentCellId: VisibleCellA,
            cellIdToSlot: Routing(), outdoorSlot: OutsideViewSlot, outdoorVisible: true);

        Assert.Equal((uint)SlotA, r.Slot);
        Assert.False(r.Culled);
    }

    [Fact]
    public void ForFrame_RoutingActive_CellStaticNotVisible_Culled()
    {
        var r = WbDrawDispatcher.ResolveSlotForFrame(
            clipRoutingActive: true, serverGuid: 0u, parentCellId: NotVisibleCell,
            cellIdToSlot: Routing(), outdoorSlot: OutsideViewSlot, outdoorVisible: true);

        Assert.True(r.Culled);
        // When culled the loop body forces slot 0 (the value is never emitted).
        Assert.Equal(0u, r.Slot);
    }

    [Fact]
    public void ForFrame_RoutingActive_OutdoorStabVisible_GetsOutsideViewSlot()
    {
        var r = WbDrawDispatcher.ResolveSlotForFrame(
            clipRoutingActive: true, serverGuid: 0u, parentCellId: null,
            cellIdToSlot: Routing(), outdoorSlot: OutsideViewSlot, outdoorVisible: true);

        Assert.Equal((uint)OutsideViewSlot, r.Slot);
        Assert.False(r.Culled);
    }

    [Fact]
    public void ForFrame_RoutingActive_OutdoorStabNotVisible_Culled()
    {
        var r = WbDrawDispatcher.ResolveSlotForFrame(
            clipRoutingActive: true, serverGuid: 0u, parentCellId: null,
            cellIdToSlot: Routing(), outdoorSlot: OutsideViewSlot, outdoorVisible: false);

        Assert.True(r.Culled);
        Assert.Equal(0u, r.Slot);
    }
}