//### Particles Static Bezier Flow Controller 
//This is a component that controlls behaviour of particle system mounted to the same game object it is.
//
//It controlls only particles path, it does not controll any other aspect ot their behaviour or loock.
//
//License information: [ASSET STORE TERMS OF SERVICE AND EULA](https://unity3d.com/legal/as_terms)
//
//Developed by [MathArtCode](https://www.assetstore.unity3d.com/en/#!/search/page=1/sortby=popularity/query=publisher:8738) team, 2015

using System;
using System.Collections.Generic;
using Assets.Scripts.BezierCurvedParticlesFlow.Utilities;
using UnityEngine;

#if !UNITY_3_5
namespace Assets.Scripts.BezierCurvedParticlesFlow {
#endif

    [AddComponentMenu( "Effects/MathArtCode/Particles Static Bezier Flow" )]
    [ExecuteInEditMode]
    [RequireComponent(typeof (ParticleSystem))]
    public sealed class ParticlesStaticBezierFlowController : MonoBehaviour {
        [SerializeField]
        private BezierLogic _bezierLogicLogic;

        private ParticleSystem.Particle[] _particles;

        [SerializeField]
        private Vector3[] _positions;

        [SerializeField]
        private int _samplesCount;

        private ParticleSystem _system;

        [SerializeField]
        private bool _usePositions;

        [SerializeField]
        private bool _useVelocities;

        [SerializeField]
        private Vector3[] _velocities;

#if UNITY_3_5
        [SerializeField]
        private int _maxParticles;

        //Unity3.5 ParticleSystem.MaxParticles
        public int MaxParticles {
            get { return _maxParticles; }
            set {
                _maxParticles = value;
                _particles = new ParticleSystem.Particle[_maxParticles];
            }
        }
#endif


        //Stores baked positions relative to host game object.
        private Vector3[] Positions {
            get {
                if (_positions == null) {
                    Rasterize();
                }
                return _positions;
            }
        }

        //Stores baked velocities relative to host game object.
        private Vector3[] Velocities {
            get {
                if (_velocities == null) {
                    Rasterize();
                }
                return _velocities;
            }
        }

        //Defines if pixel perfect positions as they are defined in bezier curve shall be used (which makes all particles follow one curve).
        public bool UsePositions {
            get { return _usePositions; }
            set { _usePositions = value; }
        }

        //Defines if each particle shall set its velocity relative to its life time (allowing you to use particle emmiter shape as flow form).
        public bool UseVelocities {
            get { return _useVelocities; }
            set { _useVelocities = value; }
        }

        //Hosts main curve related logic
        public BezierLogic BezierLogic {
            get { return _bezierLogicLogic ?? (_bezierLogicLogic = new BezierLogic()); }
        }

        //Defines how much samples shall be used in the resulting curve (sets size of arrays of positions and velocities updated on `Rasterize()` call).
        public int SamplesCount {
            get { return _samplesCount; }
            set { _samplesCount = value; }
        }

        //Allows to get a position which shall be taken by particle relative to its life time.
        private Vector3 GetPoint(float t) {
            t = Mathf.Clamp01(t)*(_samplesCount - 1);
            var i = (int) t;
            if (i >= Positions.Length) {
                i = Positions.Length-1;
            }
            return
                Positions[i];
        }

        //Allows to get a velocity which shall be taken by particle relative to its life time.
        private Vector3 GetVelocity(float t) {
            t = Mathf.Clamp01(t)*(_samplesCount - 1);
            var i = (int) t;
            if (i >= Velocities.Length) {
                i = Velocities.Length-1;
            }
            return
                Velocities[i];
        }

        //Updates baked values
        private void SetBakedData(Vector3[] positions, Vector3[] velocities) {
            _positions = positions;
            _velocities = velocities;
        }

        //Recalculates and updates baked values
        public void Rasterize() {
            var positions = new List<Vector3>();
            var velocities = new List<Vector3>();
            for (var i = 1; i < _samplesCount; i++) {
                var t = i/(float) _samplesCount;
                positions.Add(BezierLogic.GetPoint(t));
                velocities.Add(BezierLogic.GetVelocity(t));
            }

            SetBakedData(positions.ToArray(), velocities.ToArray());
        }

        //Resets component to its default values
        // ReSharper disable once UnusedMember.Local
        private void Reset() {
#if UNITY_3_5
            _maxParticles = 50;
#endif
            _samplesCount = 50;

            BezierLogic.Reset();
            Rasterize();

            _usePositions = true;
            _usePositions = true;
        }

        //Updates `ParticleSystem` particles setting positions and velocities if needed
        // ReSharper disable once UnusedMember.Local
        private void LateUpdate() {
            InitializeIfNeeded();

            var numParticlesAlive = _system.GetParticles(_particles);

                for (var i = 0; i < numParticlesAlive; i++) {
                    var p = _particles[i];
                    var t = (p.startLifetime - p.remainingLifetime)/p.startLifetime;
                    if (_useVelocities) {
                        _particles[i].velocity = GetVelocity(t);
                    }

                    if (_usePositions) {
                        _particles[i].position = GetPoint(t);
                    }
                }

            _system.SetParticles(_particles, numParticlesAlive);
        }

        //Gets GameObject particle system
        private void InitializeIfNeeded() {
            if (_system == null) {
                _system = GetComponent<ParticleSystem>();
            }

            if ( _particles == null ) {
#if !UNITY_3_5
                _particles = new ParticleSystem.Particle[_system.maxParticles];
#else
                _particles = new ParticleSystem.Particle[_maxParticles];
#endif
                _system.GetParticles( _particles );
            }
        }
    }
#if !UNITY_3_5
}
#endif