// Reference: https://www.behance.net/gallery/44375157/Free-Motion-Camera-Rig
using UnityEngine;
using System.Collections.Generic;
using System.Linq;
using System;
#if UNITY_EDITOR
using UnityEditor;
#endif

namespace UltraCombos
{
    [ExecuteAlways]
    public class FreeMotionCameraRig : MonoBehaviour
    {
        [SerializeField] private int trailLength = 100;

        [Header("Rotations")]
        public float distance;
        public float horizontal;
        public float vertical;

        [Header("Head Extra")]
        [Range(-90, 90)] public float roll;
        [Range(-90, 90)] public float tilt;
        [Range(-90, 90)] public float pan;
        public float slide;

        [Header("Controllers")]
        [SerializeField] private Transform tiltPivot;
        [SerializeField] private Transform panPivot;
        [SerializeField] private Transform rollPivot;

        [Header("Automatic")]
        [SerializeField] private float horizontalSpeed = 0;

        private Queue<Vector3> trail = new Queue<Vector3>();


        private void Start()
        {

        }

        private void Update()
        {
            distance = Mathf.Max(distance, 0);
            if (Mathf.Abs(horizontalSpeed) > 0)
            {
                horizontal = Mathf.Repeat(horizontal + horizontalSpeed * Time.deltaTime, 360);
            }

            transform.localEulerAngles = new Vector3(vertical, horizontal, 0);

            if (tiltPivot)
            {
                tiltPivot.localPosition = new Vector3(0, 0, -distance);
                tiltPivot.localEulerAngles = new Vector3(tilt, 0, 0);
            }

            if (panPivot)
            {
                panPivot.localEulerAngles = new Vector3(0, pan, 0);
            }

            if (rollPivot)
            {
                rollPivot.localPosition = new Vector3(0, 0, -slide);
                rollPivot.localEulerAngles = new Vector3(0, 0, -roll);
            }

            trail.Enqueue(rollPivot.position);
            if (trail.Count > trailLength)
            {
                trail.Dequeue();
            }
        }

        private void OnDrawGizmosSelected()
        {
#if UNITY_EDITOR
            var rot = Quaternion.Euler(0, transform.localEulerAngles.y, 0);
            var trs = Matrix4x4.TRS(transform.position, rot, transform.localScale);
            using (new Handles.DrawingScope(new Color32(5, 169, 245, 255), trs))
            {
                Handles.DrawWireDisc(Vector3.zero, Vector3.up, distance);
                var d = distance * 1.1f;
                var r = distance * 0.08f;
                var triangle = GetPoints(3, true)
                    .Select(p => p * r * 2 + new Vector3(0, 0, d))
                    .ToArray();
                Handles.DrawPolyLine(triangle);
                Handles.DrawWireDisc(new Vector3(+d, 0, 0), Vector3.up, r);
                Handles.DrawWireDisc(new Vector3(-d, 0, 0), Vector3.up, r);
                var circle = GetPoints(32, false);
                var lines = new List<Vector3>();
                var cr = distance * 0.9f;
                for (var i = 0; i < circle.Count; ++i)
                {
                    var i2 = (i + 1) % circle.Count;
                    lines.Add(circle[i] * cr);
                    lines.Add(circle[i2] * cr);
                }
                Handles.DrawDottedLines(lines.ToArray(), 4);
            }

            var size = distance * 0.1f;

            if (tiltPivot)
            {

            }

            if (panPivot)
            {
                using var scp = new Handles.DrawingScope(new Color32(194, 153, 0, 255), panPivot.localToWorldMatrix);
                var w = size;
                var h = size * 2;
                var points = new Vector3[] {
                        new Vector3(+w, 0, 0),
                        new Vector3(0, 0, +h),
                        new Vector3(-w, 0, 0),
                        new Vector3(0, 0, -h),
                        new Vector3(w, 0, 0) };
                Handles.DrawPolyLine(points);
            }

            if (rollPivot)
            {
                using var scp = new Handles.DrawingScope(new Color32(56, 186, 110, 255), rollPivot.localToWorldMatrix);
                var p0 = rollPivot.InverseTransformPoint(transform.position);
                Handles.DrawLine(p0, Vector3.zero);
                var p1 = rollPivot.InverseTransformPoint(trs.MultiplyPoint(new Vector3(0, 0, -distance)));
                Handles.DrawLine(p1, Vector3.zero);

                var w = size * 1.2f;
                var h = size * 0.2f;
                var points = new Vector3[] {
                        new Vector3(+w, 0, -h),
                        new Vector3(-w, 0, -h),
                        new Vector3(0, 0, h * 4),
                        new Vector3(+w, 0, -h) };
                Handles.DrawPolyLine(points);
            }

            Handles.DrawPolyLine(trail.ToArray());
#endif
        }

        private List<Vector3> GetPoints(int sides, bool close)
        {
            var da = 2 * Mathf.PI / sides;
            var points = new List<Vector3>();
            for (var i = 0; i < sides; i++)
            {
                var a = da * i + Mathf.PI / 2;
                points.Add(new Vector3(Mathf.Cos(a), 0, Mathf.Sin(a)));
            }
            if (close)
            {
                points.Add(points.First());
            }
            return points;
        }
    }

}