using Godot;
using System.Collections.Generic;

// Regression for the crag (no player), checked on the SAVED scenes/maps/crag.tscn (route = its
// Route markers; rebuild with tools/rebuild_maps.tscn): the route is climbable on paper — consecutive route points
// within human reach, every point in free space, route pieces not buried in each other or the
// rock — the summit is high enough, and it's in plain view from spawn. Prints "CRAG: overall PASS".
public partial class CragSpike : Node3D
{
    public const float MaxHoldToHold = 1.0f;      // m between consecutive holds (two hands span the chimney)
    public const float MaxHoldGain = 0.7f;        // m of height gained per hand move
    public const float MaxReachAboveFeet = 2.3f;  // standing overhead grip height, 1.75 m person
    public const float MaxReachOut = 1.0f;
    public const float MaxMantle = 1.3f;          // m a stand-to-stand step may rise (mantle / jump)
    public const float MaxGap = 1.0f;             // m horizontal between stand points across a rise or a gap

    private Crag _crag;
    private int _frame;
    private readonly List<string> _fails = new();

    public override void _Ready()
    {
        StaticBody3D floor = new();
        floor.AddToGroup(PropGrabber.NoGrabGroup);
        floor.AddChild(new CollisionShape3D { Shape = new BoxShape3D { Size = new Vector3(80, 0.1f, 80) }, Position = new Vector3(0, -0.05f, 0) });
        AddChild(floor);
        // The SAVED scenes (as the game loads them, hand edits included), not a fresh rebuild.
        AddChild(GD.Load<PackedScene>("res://scenes/maps/playground.tscn").Instantiate());
        _crag = GD.Load<PackedScene>("res://scenes/maps/crag.tscn").Instantiate<Crag>();
        AddChild(_crag);
    }

    public override void _PhysicsProcess(double delta)
    {
        if (++_frame < 3)
            return;
        PhysicsDirectSpaceState3D space = GetWorld3D().DirectSpaceState;
        CheckReach();
        CheckFreeSpace(space);
        CheckWalks(space);
        CheckOverlaps();
        Check(Crag.SummitHeight >= 25f, $"summit {Crag.SummitHeight} m >= 25 m");
        CheckView(space);
        foreach (string f in _fails)
            GD.Print("CRAG: FAIL " + f);
        GD.Print($"CRAG: {_crag.Route.Count} route points, {_crag.RoutePieces.Count} route pieces, {_crag.MassPieces.Count} rock pieces, {_crag.GetChildCount()} nodes");
        GD.Print(_fails.Count == 0 ? "CRAG: overall PASS" : $"CRAG: overall FAIL ({_fails.Count})");
        GetTree().Quit();
    }

    private void Check(bool ok, string what)
    {
        if (!ok)
            _fails.Add(what);
    }

    private static float Flat(Vector3 a, Vector3 b) => new Vector2(a.X - b.X, a.Z - b.Z).Length();

    private void CheckReach()
    {
        var r = _crag.Route;
        for (int i = 1; i < r.Count; i++)
        {
            var (ka, a, na) = r[i - 1];
            var (kb, b, nb) = r[i];
            string pair = $"'{na}' -> '{nb}'";
            if (ka == Crag.Step.Hold && kb == Crag.Step.Hold)
            {
                Check(a.DistanceTo(b) <= MaxHoldToHold, $"{pair}: holds {a.DistanceTo(b):0.00} m apart");
                Check(b.Y - a.Y <= MaxHoldGain, $"{pair}: hand move gains {b.Y - a.Y:0.00} m");
            }
            else if (ka == Crag.Step.Stand && kb == Crag.Step.Hold)
            {
                Check(b.Y - a.Y <= MaxReachAboveFeet && b.Y - a.Y >= -0.3f, $"{pair}: hold {b.Y - a.Y:0.00} m above feet");
                Check(Flat(a, b) <= MaxReachOut, $"{pair}: hold {Flat(a, b):0.00} m out");
            }
            else if (ka == Crag.Step.Hold && kb == Crag.Step.Stand)
            {
                Check(b.Y <= a.Y + 0.3f, $"{pair}: stand {b.Y - a.Y:0.00} m above the last hold");
                Check(Flat(a, b) <= MaxReachOut, $"{pair}: stand {Flat(a, b):0.00} m from the last hold");
            }
            else
            {
                float rise = b.Y - a.Y;
                Check(rise <= MaxMantle, $"{pair}: rise {rise:0.00} m");
                if (Mathf.Abs(rise) > 0.05f)
                    Check(Flat(a, b) <= MaxGap, $"{pair}: {Flat(a, b):0.00} m across a {rise:0.00} m step");
            }
        }
    }

    // Every route point is in the open; standing points have a body's worth of room above them
    // and ground right under them.
    private void CheckFreeSpace(PhysicsDirectSpaceState3D space)
    {
        foreach (var (kind, p, name) in _crag.Route)
        {
            var pq = new PhysicsPointQueryParameters3D { Position = p + (kind == Crag.Step.Stand ? Vector3.Up * 0.05f : Vector3.Zero) };
            Check(space.IntersectPoint(pq, 1).Count == 0, $"'{name}' point is inside geometry");
            if (kind != Crag.Step.Stand)
                continue;
            var box = new PhysicsShapeQueryParameters3D
            {
                Shape = new BoxShape3D { Size = new Vector3(0.3f, 1.2f, 0.3f) },
                Transform = new Transform3D(Basis.Identity, p + Vector3.Up * 0.7f),
            };
            Check(space.IntersectShape(box, 1).Count == 0, $"'{name}' has no room to stand");
            var ray = PhysicsRayQueryParameters3D.Create(p + Vector3.Up * 0.05f, p + Vector3.Down * 0.1f);
            Check(space.IntersectRay(ray).Count > 0, $"'{name}' has nothing underfoot");
        }
    }

    // Level stand-to-stand moves are walks: there is ground all along the way.
    private void CheckWalks(PhysicsDirectSpaceState3D space)
    {
        var r = _crag.Route;
        for (int i = 1; i < r.Count; i++)
        {
            if (r[i - 1].Kind != Crag.Step.Stand || r[i].Kind != Crag.Step.Stand || Mathf.Abs(r[i].Point.Y - r[i - 1].Point.Y) > 0.05f)
                continue;
            for (float t = 0.1f; t < 1f; t += 0.1f)
            {
                Vector3 p = r[i - 1].Point.Lerp(r[i].Point, t);
                var ray = PhysicsRayQueryParameters3D.Create(p + Vector3.Up * 0.05f, p + Vector3.Down * 0.1f);
                if (space.IntersectRay(ray).Count == 0)
                {
                    _fails.Add($"walk '{r[i - 1].Name}' -> '{r[i].Name}': no ground at {p}");
                    break;
                }
            }
        }
    }

    // No route piece is buried in another piece or in the rock (touching is fine).
    private void CheckOverlaps()
    {
        var route = _crag.RoutePieces;
        for (int i = 0; i < route.Count; i++)
        {
            for (int j = i + 1; j < route.Count; j++)
                CheckPair(route[i], route[j]);
            foreach (var m in _crag.MassPieces)
                CheckPair(route[i], m);
        }
    }

    private void CheckPair((CollisionObject3D Body, Aabb Box) a, (CollisionObject3D Body, Aabb Box) b)
    {
        if (!a.Box.Intersects(b.Box))
            return;
        Aabb i = a.Box.Intersection(b.Box);
        float depth = Mathf.Min(i.Size.X, Mathf.Min(i.Size.Y, i.Size.Z));
        if (depth > 0.01f)
            _fails.Add($"{a.Body.Name} overlaps {b.Body.Name} by {depth:0.000} m");
    }

    // From the spawn point's eye height, the summit's front edge, both flags and the foot of the route are in view.
    private void CheckView(PhysicsDirectSpaceState3D space)
    {
        Vector3 eye = new(0f, 1.7f, 2.5f);
        foreach (Vector3 target in new[] { new Vector3(Crag.SummitPoint.X, Crag.SummitHeight - 0.1f, -15.95f), new Vector3(-5.6f, 1f, -9.6f), new Vector3(-2.7f, 6f, -12.8f), new Vector3(-5.3f, 10.6f, -13.7f), new Vector3(-4.3f, 18.6f, -15.2f) })
        {
            var hit = space.IntersectRay(PhysicsRayQueryParameters3D.Create(eye, target));
            bool clear = hit.Count == 0 || ((Vector3)hit["position"]).DistanceTo(target) < 1f;
            Check(clear, $"no line of sight from spawn to {target}" + (hit.Count > 0 ? $" (blocked at {(Vector3)hit["position"]})" : ""));
        }
    }
}