using System.Collections.Generic;
using System.Numerics;
using AcDream.App.World;
using Xunit;

namespace AcDream.App.Tests.World;

public class TeleportArrivalControllerTests
{
    // Records each Place(destPos, destCell, forced) call.
    private sealed record PlaceCall(Vector3 Pos, uint Cell, bool Forced);

    private static TeleportArrivalController Make(
        ArrivalReadiness verdict,
        List<PlaceCall> placed,
        int maxHoldFrames = TeleportArrivalController.DefaultMaxHoldFrames)
        => new(
            readiness: (_, _) => verdict,
            place: (pos, cell, forced) => placed.Add(new PlaceCall(pos, cell, forced)),
            maxHoldFrames: maxHoldFrames);

    [Fact]
    public void BeginArrival_EntersHolding()
    {
        var placed = new List<PlaceCall>();
        var c = Make(ArrivalReadiness.NotReady, placed);

        c.BeginArrival(new Vector3(1, 2, 3), 0x01250126u);

        Assert.Equal(TeleportArrivalPhase.Holding, c.Phase);
        Assert.Empty(placed);
    }

    [Fact]
    public void Tick_WhenIdle_IsNoOp()
    {
        var placed = new List<PlaceCall>();
        var c = Make(ArrivalReadiness.Ready, placed);

        c.Tick(); // never began

        Assert.Equal(TeleportArrivalPhase.Idle, c.Phase);
        Assert.Empty(placed);
    }

    [Fact]
    public void Tick_NotReady_KeepsHolding_DoesNotPlace()
    {
        var placed = new List<PlaceCall>();
        var c = Make(ArrivalReadiness.NotReady, placed);
        c.BeginArrival(new Vector3(1, 2, 3), 0x01250126u);

        c.Tick();
        c.Tick();

        Assert.Equal(TeleportArrivalPhase.Holding, c.Phase);
        Assert.Empty(placed);
    }

    [Fact]
    public void Tick_Ready_PlacesUnforced_AndIdles()
    {
        var placed = new List<PlaceCall>();
        var c = Make(ArrivalReadiness.Ready, placed);
        c.BeginArrival(new Vector3(30, -60, 6.005f), 0x01250126u);

        c.Tick();

        Assert.Equal(TeleportArrivalPhase.Idle, c.Phase);
        var call = Assert.Single(placed);
        Assert.False(call.Forced);
        Assert.Equal(0x01250126u, call.Cell);
        Assert.Equal(new Vector3(30, -60, 6.005f), call.Pos);
    }

    [Fact]
    public void Tick_Impossible_PlacesForced_AndIdles()
    {
        var placed = new List<PlaceCall>();
        var c = Make(ArrivalReadiness.Impossible, placed);
        c.BeginArrival(new Vector3(1, 2, 3), 0x0125FF00u);

        c.Tick();

        Assert.Equal(TeleportArrivalPhase.Idle, c.Phase);
        var call = Assert.Single(placed);
        Assert.True(call.Forced);
    }

    [Fact]
    public void Tick_Timeout_PlacesForced_AfterMaxHoldFrames()
    {
        var placed = new List<PlaceCall>();
        var c = Make(ArrivalReadiness.NotReady, placed, maxHoldFrames: 3);
        c.BeginArrival(new Vector3(1, 2, 3), 0x01250126u);

        c.Tick(); // 1
        c.Tick(); // 2
        Assert.Empty(placed);
        Assert.Equal(TeleportArrivalPhase.Holding, c.Phase);

        c.Tick(); // 3 -> timeout

        var call = Assert.Single(placed);
        Assert.True(call.Forced);
        Assert.Equal(TeleportArrivalPhase.Idle, c.Phase);
    }

    [Fact]
    public void BeginArrival_AfterPlace_ReArms()
    {
        var placed = new List<PlaceCall>();
        var c = Make(ArrivalReadiness.Ready, placed);

        c.BeginArrival(new Vector3(1, 0, 0), 0x01250126u);
        c.Tick(); // places #1, idle
        c.BeginArrival(new Vector3(2, 0, 0), 0x01250127u);
        c.Tick(); // places #2, idle

        Assert.Equal(2, placed.Count);
        Assert.Equal(0x01250127u, placed[1].Cell);
    }

    [Fact]
    public void BeginArrival_DuringHold_ResetsTimeoutCounter()
    {
        var placed = new List<PlaceCall>();
        var c = Make(ArrivalReadiness.NotReady, placed, maxHoldFrames: 3);

        c.BeginArrival(new Vector3(1, 0, 0), 0x01250126u);
        c.Tick(); // held=1
        c.Tick(); // held=2 (one short of the timeout)

        // Re-arm mid-hold with a fresh destination: the counter must restart.
        c.BeginArrival(new Vector3(2, 0, 0), 0x01250199u);
        c.Tick(); // held=1 again (NOT 3 -> no placement yet)
        c.Tick(); // held=2
        Assert.Empty(placed);
        Assert.Equal(TeleportArrivalPhase.Holding, c.Phase);

        c.Tick(); // held=3 -> timeout, forced place of the SECOND destination
        var call = Assert.Single(placed);
        Assert.True(call.Forced);
        Assert.Equal(0x01250199u, call.Cell);
        Assert.Equal(new Vector3(2, 0, 0), call.Pos);
    }
}