using System.Numerics;
using AcDream.Core.Physics;
using AcDream.Core.Physics.Motion;
using Xunit;

namespace AcDream.Core.Tests.Physics.Motion;

/// <summary>
/// R4-V2 — <c>HandleUpdateTarget</c> (<c>0052a7d0</c>, raw 307802-307867,
/// decomp §6d): the P4 TargetTracker feed's deferred-start lifecycle
/// (Initialized=false = the first callback vs true = an in-flight retarget),
/// context/target-id filtering, self-target instant success, NoObject vs
/// ObjectGone status handling, and the retarget progress-clock reset.
/// </summary>
public sealed class MoveToManagerHandleUpdateTargetTests
{
    private const uint TargetId = 0x50004444u;

    private static MoveToManagerHarness ArmMoveToObject(float ownRadius = 0.5f, float ownHeight = 2f)
    {
        var h = new MoveToManagerHarness { OwnRadius = ownRadius, OwnHeight = ownHeight };
        h.WorldPosition = new Position(1u, Vector3.Zero, Quaternion.Identity);
        h.Heading = 0f;
        h.Manager.MoveToObject(TargetId, TargetId, radius: 1f, height: 2f, new MovementParameters());
        return h;
    }

    [Fact]
    public void IgnoresUpdate_ForADifferentTarget()
    {
        var h = ArmMoveToObject();
        var wrongTargetPos = new Position(1u, new Vector3(5f, 5f, 0f), Quaternion.Identity);

        h.Manager.HandleUpdateTarget(new TargetInfo(0x59999999u, TargetStatus.Ok, wrongTargetPos, wrongTargetPos));

        Assert.False(h.Manager.Initialized);
        Assert.Empty(h.Manager.PendingActions);
    }

    [Fact]
    public void FirstCallback_NonOkStatus_CancelsAsNoObject()
    {
        var h = ArmMoveToObject();
        var pos = new Position(1u, Vector3.Zero, Quaternion.Identity);

        h.Manager.HandleUpdateTarget(new TargetInfo(TargetId, TargetStatus.ExitWorld, pos, pos));

        Assert.Equal(MovementType.Invalid, h.Manager.MovementTypeState);
    }

    [Fact]
    public void FirstCallback_OkStatus_BuildsNodePlan_SetsInitialized()
    {
        var h = ArmMoveToObject();
        var target = new Position(1u, new Vector3(10f, 0f, 0f), Quaternion.Identity);

        h.Manager.HandleUpdateTarget(new TargetInfo(TargetId, TargetStatus.Ok, target, target));

        Assert.True(h.Manager.Initialized);
        Assert.NotEmpty(h.Manager.PendingActions);
    }

    [Fact]
    public void FirstCallback_OrdinaryTarget_DoesNotFireMoveToComplete()
    {
        // MoveToObject's OWN self-target branch (§3b) already short-circuits
        // via CleanUp+StopCompletely BEFORE any HandleUpdateTarget ever
        // fires for a same-id target — so HandleUpdateTarget's self-target
        // instant-success path (§6d: "top_level_object_id ==
        // physics_obj->id") is reachable only in the deferred-start window,
        // and is covered by construction in
        // MoveToManagerNodePlanTests.MoveToObject_SelfTarget_*
        // (MoveToObject never even reaches SetTarget for a self-id, so the
        // callback path is dead in practice — retail's redundant guard).
        // This test isolates the ORDINARY path: MoveToComplete's only
        // trigger is CleanUpAndCallWeenie, never a plain node-plan build.
        var h = ArmMoveToObject();
        var target = new Position(1u, new Vector3(10f, 0f, 0f), Quaternion.Identity);

        h.Manager.HandleUpdateTarget(new TargetInfo(TargetId, TargetStatus.Ok, target, target));

        Assert.Empty(h.MoveToCompleteCalls);
    }

    [Fact]
    public void Retarget_NonOkStatus_CancelsAsObjectGone()
    {
        var h = ArmMoveToObject();
        var target = new Position(1u, new Vector3(10f, 0f, 0f), Quaternion.Identity);
        h.Manager.HandleUpdateTarget(new TargetInfo(TargetId, TargetStatus.Ok, target, target));
        Assert.True(h.Manager.Initialized);

        h.Manager.HandleUpdateTarget(new TargetInfo(TargetId, TargetStatus.ExitWorld, target, target));

        Assert.Equal(MovementType.Invalid, h.Manager.MovementTypeState);
    }

    [Fact]
    public void Retarget_UpdatesPositions_ResetsProgressClock_DoesNotRequeueNodes()
    {
        var h = ArmMoveToObject();
        var target1 = new Position(1u, new Vector3(10f, 0f, 0f), Quaternion.Identity);
        h.Manager.HandleUpdateTarget(new TargetInfo(TargetId, TargetStatus.Ok, target1, target1));
        int nodeCountAfterFirst = System.Linq.Enumerable.Count(h.Manager.PendingActions);
        Assert.True(nodeCountAfterFirst > 0);

        h.Advance(3.0); // simulate time passing, progress clock advanced by BeginMoveForward

        var target2 = new Position(1u, new Vector3(20f, 5f, 0f), Quaternion.Identity);
        var interp2 = new Position(1u, new Vector3(19f, 5f, 0f), Quaternion.Identity);
        h.Manager.HandleUpdateTarget(new TargetInfo(TargetId, TargetStatus.Ok, target2, interp2));

        Assert.Equal(target2, h.Manager.CurrentTargetPosition);
        Assert.Equal(interp2, h.Manager.SoughtPosition);
        Assert.Equal(float.MaxValue, h.Manager.PreviousDistance);
        Assert.Equal(float.MaxValue, h.Manager.OriginalDistance);

        // Node count unchanged by the retarget itself (no requeue) — the
        // running MoveToPosition node keeps steering toward the moved
        // CurrentTargetPosition on its own next tick.
        Assert.Equal(nodeCountAfterFirst, System.Linq.Enumerable.Count(h.Manager.PendingActions));
    }

    [Fact]
    public void Retarget_TurnToObject_GetsNoRetargetHandling_HeadingFrozen()
    {
        var h = new MoveToManagerHarness();
        h.WorldPosition = new Position(1u, Vector3.Zero, Quaternion.Identity);
        h.Heading = 0f;
        h.Manager.TurnToObject(TargetId, TargetId, new MovementParameters());

        var target1 = new Position(1u, new Vector3(10f, 0f, 0f), Quaternion.Identity); // heading 90
        h.Manager.TurnToObject_Internal(target1); // first callback (direct, mirrors deferred-start call shape)
        Assert.True(h.Manager.Initialized);
        var soughtAfterFirst = h.Manager.SoughtPosition;

        // A retarget-shaped HandleUpdateTarget call for a TurnToObject
        // manager: since Initialized is already true, this takes the
        // "retarget" branch, which only updates state for MoveToObject —
        // TurnToObject gets NO handling at all (decomp §6d note).
        var target2 = new Position(1u, new Vector3(0f, 10f, 0f), Quaternion.Identity); // heading 0
        h.Manager.HandleUpdateTarget(new TargetInfo(TargetId, TargetStatus.Ok, target2, target2));

        Assert.Equal(soughtAfterFirst, h.Manager.SoughtPosition); // untouched
    }

    [Fact]
    public void NoPhysicsObj_CancelsWithNoPhysicsObjectCode()
    {
        var h = ArmMoveToObject();
        h.Manager.HasPhysicsObj = false;

        var target = new Position(1u, new Vector3(10f, 0f, 0f), Quaternion.Identity);
        h.Manager.HandleUpdateTarget(new TargetInfo(TargetId, TargetStatus.Ok, target, target));

        Assert.False(h.Manager.IsMovingTo());
    }
}