using System.Collections.Generic;
using UnityEngine;

namespace UDE_HAND_INTERACTION
{
    public interface ISurface
    {
        Transform Transform { get; }

        bool Raycast(in Ray ray, out SurfaceHit hit, float maxDistance = 0);

        bool ClosestSurfacePoint(in Vector3 point, out SurfaceHit hit, float maxDistance = 0);
    }

    public struct SurfaceHit
    {
        public Vector3 Point { get; set; }

        public Vector3 Normal { get; set; }

        public float Distance { get; set; }
    }

    public interface ISurfacePatch : ISurface
    {
        ISurface BackingSurface { get; }
    }
    public static class SurfaceUtils
    {

        public static float ComputeDistanceAbove(ISurfacePatch surfacePatch, Vector3 point, float radius)
        {
            surfacePatch.BackingSurface.ClosestSurfacePoint(point, out SurfaceHit hit);
            Vector3 surfaceToPoint = point - hit.Point;
            return Vector3.Dot(surfaceToPoint, hit.Normal) - radius;
        }

        public static float ComputeTangentDistance(ISurfacePatch surfacePatch, Vector3 point, float radius)
        {
            surfacePatch.ClosestSurfacePoint(point, out SurfaceHit patchHit);
            surfacePatch.BackingSurface.ClosestSurfacePoint(point, out SurfaceHit backingHit);
            Vector3 proximityToPoint = point - patchHit.Point;
            Vector3 projOnNormal = Vector3.Dot(proximityToPoint, backingHit.Normal) *
                backingHit.Normal;
            Vector3 lateralVec = proximityToPoint - projOnNormal;
            return lateralVec.magnitude - radius;
        }

        public static float ComputeDepth(ISurfacePatch surfacePatch, Vector3 point, float radius)
        {
            return Mathf.Max(0f, -ComputeDistanceAbove(surfacePatch, point, radius));
        }

        public static float ComputeDistanceFrom(ISurfacePatch surfacePatch, Vector3 point, float radius)
        {
            surfacePatch.ClosestSurfacePoint(point, out SurfaceHit hit);
            Vector3 surfaceToPoint = point - hit.Point;
            return surfaceToPoint.magnitude - radius;
        }

        public static bool Clip(this Bounds bounds,
            in Bounds clipper, out Bounds result)
        {
            result = new Bounds();
            Vector3 min = Vector3.Max(bounds.min, clipper.min);
            Vector3 max = Vector3.Min(bounds.max, clipper.max);

            if (min.x > max.x ||
                min.y > max.y ||
                min.z > max.z)
            {
                return false;
            }

            result.SetMinMax(min, max);
            return true;
        }
    }
    public interface IBounds
    {
        Bounds Bounds { get; }
    }

    public interface IBoundsClipper
    {
        public bool GetLocalBounds(Transform localTo, out Bounds bounds);
    }
    public interface IClippedSurface<TClipper> : ISurfacePatch
    {
        IEnumerable<TClipper> GetClippers();
    }
}