using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Playables;
using UnityEngine.Animations;
using UnityEngine.Timeline;

[RequireComponent (typeof(Animator))]
public class SimpleAnimator : MonoBehaviour
{
	PlayableGraph graph;
	AnimationMixerPlayable mixer;
	AnimationClipPlayable prePlayable, currentPlayable;

	Coroutine coroutinePlayAnimation;

	public List<AnimationClip> clipList;

	void OnEnable ()
	{
		graph = PlayableGraph.Create ();
		AnimationPlayableOutput.Create(graph, name, GetComponent<Animator>());

		mixer = AnimationMixerPlayable.Create (graph, 2, true);

		var output = graph.GetOutput (0);
		output.SetSourcePlayable (mixer);
		if (clipList.Count != 0) {
			currentPlayable = AnimationClipPlayable.Create (graph, clipList [0]);
			mixer.ConnectInput (0, currentPlayable, 0);
			mixer.SetInputWeight (0, 1);
			graph.Play ();
		}
	}

	void OnDisable()
	{
		graph.Destroy ();
	}

	public void CrossFade (string animation, float fadeLength)
	{
		CrossFade (clipList.Find ((c) => c.name == animation), fadeLength);
	}

	public void CrossFade (string animation)
	{
		CrossFade (animation, 0.3f);
	}

	public void CrossFade (AnimationClip clip)
	{
		CrossFade (clip, 0.3f);
	}

	public void CrossFade (AnimationClip clip, float fadeLength)
	{
		if( coroutinePlayAnimation != null)
			StopCoroutine (coroutinePlayAnimation);
		coroutinePlayAnimation = StartCoroutine (PlayAnimation (clip, fadeLength));
	}

	public void Play (string clipName)
	{
		Play (clipList.Find ((c) => c.name == clipName));
	}

	public void Play (AnimationClip newAnimation)
	{
		if (currentPlayable.IsValid ())
			currentPlayable.Destroy ();
		DisconnectPlayables ();
		currentPlayable = AnimationClipPlayable.Create (graph, newAnimation);
		mixer.ConnectInput (0, currentPlayable, 0);

		mixer.SetInputWeight (1, 0);
		mixer.SetInputWeight (0, 1);
	}

	void DisconnectPlayables ()
	{
		graph.Disconnect (mixer, 0);
		graph.Disconnect (mixer, 1);
		if (prePlayable.IsValid ())
			prePlayable.Destroy ();
	}

	IEnumerator PlayAnimation (AnimationClip newAnimation, float transitionTime)
	{
		DisconnectPlayables ();

		prePlayable = currentPlayable;
		currentPlayable = AnimationClipPlayable.Create (graph, newAnimation);
		mixer.ConnectInput (1, prePlayable, 0);
		mixer.ConnectInput (0, currentPlayable, 0);

		// 指定時間でアニメーションをブレンド
		float waitTime = Time.timeSinceLevelLoad + transitionTime;
		yield return new WaitWhile (() => {
			var diff = waitTime - Time.timeSinceLevelLoad;
			if (diff <= 0) {
				mixer.SetInputWeight (1, 0);
				mixer.SetInputWeight (0, 1);
				return false;
			} else {
				var rate = Mathf.Clamp01 (diff / transitionTime);
				mixer.SetInputWeight (1, rate);
				mixer.SetInputWeight (0, 1 - rate);
				return true;
			}
		});

		coroutinePlayAnimation = null;
	}
}