/******************************************************************************
 * Copyright (C) Ultraleap, Inc. 2011-2021.                                   *
 *                                                                            *
 * Use subject to the terms of the Apache License 2.0 available at            *
 * http://www.apache.org/licenses/LICENSE-2.0, or another agreement           *
 * between Ultraleap and you, your company or other organization.             *
 ******************************************************************************/

using Leap.Unity.Attributes;
using System.Collections;
using UnityEngine;

namespace Leap.Unity
{
    /** 
    * The ConnectionMonitor class monitors the connection to the Leap Motion service
    * and displays a sprite in front of the camera when a connection is not
    * available. You can use the PluginLeapNotice sprites in the LeapMotion/Textures
    * folder or create your own.
*/
    [RequireComponent(typeof(SpriteRenderer))]
    public class ConnectionMonitor : MonoBehaviour
    {
        /** The LeapServiceProvider in the scene. */
        [Tooltip("The scene LeapServiceProvider.")]
        public LeapServiceProvider provider;
        /** The speed to fade the sprite alpha from 0 to 1. */
        [Tooltip("How fast to make the connection notice sprite visible.")]
        [Range(0.1f, 10.0f)]
        public float fadeInTime = 1.0f;
        /** The speed to fade the sprite alpha from 1 to 0. */
        [Tooltip("How fast to fade out the connection notice sprite.")]
        [Range(0.1f, 10.0f)]
        public float fadeOutTime = 1.0f;
        /** The easing curve. */
        [Tooltip("The easing curve for the fade in and out effect.")]
        public AnimationCurve fadeCurve = AnimationCurve.EaseInOut(0.0f, 0.0f, 1.0f, 1.0f);
        /** How often to check the connection. */
        [Tooltip("How frequently to check the connection.")]
        public int monitorInterval = 2;
        /** The fully on texture tint color. */
        [Tooltip("A tint applied to the connection notice sprite when on.")]
        public Color onColor = Color.white;
        /** The distance of the notification sprite from the camera in world units. */
        [Tooltip("How far to place the sprite in front of the camera.")]
        public float distanceToCamera = 12.0f;

        private float fadedIn = 0.0f;
        private SpriteRenderer spriteRenderer;
        private bool connected = false;

        void Start()
        {
            spriteRenderer = GetComponent<SpriteRenderer>();
            SetAlpha(0.0f);
            StartCoroutine(Monitor());
        }

        void SetAlpha(float alpha)
        {
            spriteRenderer.color = Color.Lerp(Color.clear, onColor, alpha);
        }

        void Update()
        {
            if (fadedIn > 0)
            {
                Camera cam = MainCameraProvider.mainCamera;
                Vector3 pos = cam.transform.position + cam.transform.forward * distanceToCamera;
                transform.position = pos;
                transform.LookAt(cam.transform);
            }
        }

        private IEnumerator Monitor()
        {
            yield return new WaitForSecondsRealtime(monitorInterval); //Give controller time to connect at startup
            while (true)
            { //forever
                connected = provider.IsConnected();
                if (connected)
                {
                    while (fadedIn > 0.0)
                    {
                        fadedIn -= Time.deltaTime / fadeOutTime;
                        fadedIn = Mathf.Clamp(fadedIn, 0.0f, 1.0f);
                        SetAlpha(fadeCurve.Evaluate(fadedIn));
                        yield return null;
                    }
                }
                else
                {
                    while (fadedIn < 1.0)
                    {
                        fadedIn += Time.deltaTime / fadeOutTime;
                        fadedIn = Mathf.Clamp(fadedIn, 0.0f, 1.0f);
                        SetAlpha(fadeCurve.Evaluate(fadedIn));
                        yield return null;
                    }
                }
                yield return new WaitForSecondsRealtime(monitorInterval);
            }
        }
    }
}