using System.Threading.Tasks;
using UnityEngine;
using UnityEngine.UI;

namespace SC.XR.Unity
{
    public class ProgressIndicatorBar : MonoBehaviour, IProgressIndicator
    {
        const float SmoothProgressSpeed = 0.5f;

        [SerializeField]
        [Range(0f, 1f)]
        private float progress = 0f;

        public ProgressIndicatorState State { get { return state; } }
        public float Progress { get { return progress; } set { if (value >= 0 && value <= 1) { progress = value; } } }

        // The animated progress bar object
        [SerializeField]
        private Transform progressBar = null;

        // The progress text used by all non-'None' progress styles
        [SerializeField]
        private Text progressText = null;

        // Whether to display the percentage as text in addition to the loading bar
        [SerializeField]
        private bool displayPercentage = true;

        private float smoothProgress = 0f;
        private float lastSmoothProgress = -1;
        private ProgressIndicatorState state = ProgressIndicatorState.Closed;
        private Vector3 barScale = Vector3.one;


        public async Task OpenAsync()
        {
            if (state != ProgressIndicatorState.Closed)
            {
                throw new System.Exception("Can't open in state " + state);
            }

            smoothProgress = 0;
            lastSmoothProgress = 0;

            gameObject.SetActive(true);

            state = ProgressIndicatorState.Opening;

            await Task.Yield();

            state = ProgressIndicatorState.Open;
        }

        public async Task CloseAsync()
        {
            if (state != ProgressIndicatorState.Open)
            {
                throw new System.Exception("Can't close in state " + state);
            }

            state = ProgressIndicatorState.Closing;

            await Task.Yield();

            state = ProgressIndicatorState.Closed;

            gameObject.SetActive(false);
        }

        public async Task AwaitTransitionAsync()
        {
            while (isActiveAndEnabled)
            {
                switch (state)
                {
                    case ProgressIndicatorState.Open:
                    case ProgressIndicatorState.Closed:
                        return;

                    default:
                        break;
                }

                await Task.Yield();
            }
        }
        public void SetProgress(float p)
        {
            progress = p;
        }
        private void Update()
        {
            if (state != ProgressIndicatorState.Open)
            {
                return;
            }

            smoothProgress = Mathf.Lerp(smoothProgress, progress, SmoothProgressSpeed);

            if (smoothProgress > 0.99f)
            {
                smoothProgress = 1f;
            }

            barScale.x = Mathf.Clamp(smoothProgress, 0.01f, 1f);
            progressBar.localScale = barScale;

            progressText.gameObject.SetActive(displayPercentage);

            if (lastSmoothProgress != smoothProgress)
            {
                progressText.text = string.Format("{0:P0}", smoothProgress);
                lastSmoothProgress = smoothProgress;
            }
        }
    }
}