﻿using System;
using System.Collections;
using UnityEngine;

namespace UnitySampleAssets.Utility
{

    [Serializable]
    public class FOVKick
    {

        public Camera Camera; // optional camera setup, if null the main camera will be used
        [HideInInspector] public float OriginalFOV; // the original fov
        public float FOVIncrease = 3f; // the amount the field of view increases when going into a run
        public float TimeToIncrease = 1f; // the amount of time the field of view will increase over
        public float TimeToDecrease = 1f; // the amount of time the field of view will take to return to its original size
        public AnimationCurve IncreaseCurve;

        public void Setup(Camera camera)
        {
            CheckStatus(camera);

            Camera = camera;
            OriginalFOV = camera.fieldOfView;
        }

        private void CheckStatus(Camera camera)
        {
            if (camera == null)
                throw new Exception("FOVKick camera is null, please supply the camera to the constructor");

            if (IncreaseCurve == null)
                throw new Exception(
                    "FOVKick Increase curve is null, please define the curve for the field of view kicks");
        }

        public void ChangeCamera(Camera camera)
        {
            Camera = camera;
        }

        public IEnumerator FOVKickUp()
        {
            float t = Mathf.Abs((Camera.fieldOfView - OriginalFOV)/FOVIncrease);
            while (t < TimeToIncrease)
            {
                Camera.fieldOfView = OriginalFOV + (IncreaseCurve.Evaluate(t/TimeToIncrease)*FOVIncrease);
                t += Time.deltaTime;
                yield return new WaitForEndOfFrame();
            }
        }

        public IEnumerator FOVKickDown()
        {
            float t = Mathf.Abs((Camera.fieldOfView - OriginalFOV)/FOVIncrease);
            while (t > 0)
            {
                Camera.fieldOfView = OriginalFOV + (IncreaseCurve.Evaluate(t/TimeToDecrease)*FOVIncrease);
                t -= Time.deltaTime;
                yield return new WaitForEndOfFrame();
            }
            //make sure that fov returns to the original size
            Camera.fieldOfView = OriginalFOV;
        }
    }
}