using UnityEngine;
using UnityEngine.Events;
using UnityEngine.UI;

public class ExtendSlider : MonoBehaviour
{
    [SerializeField] Slider slider;

    [SerializeField] Color[] colorLevelPerRate;
    [SerializeField] MaskableGraphic currentColorIndicator;
    [SerializeField] MaskableGraphic prevColorIndicator;

    [Range(0f, 10f)]
    [SerializeField] float animSpeed = 0f;

    float currentRate;
    float targetRate;
    int prevColorIdx = -1;

    bool HasColorLevel => colorLevelPerRate.Length > 0;

    public UnityEvent<float> OnChangedColorLevel;

    private void Update()
    {
        if (!HasColorLevel)
        {
            if (animSpeed > 0f)
            {
                float diff = targetRate - currentRate;
                float delta = diff * animSpeed * Time.fixedDeltaTime;

                if (Mathf.Abs(delta) >= Mathf.Abs(diff))
                    currentRate = targetRate;
                else
                    currentRate += delta;
            }
            else
            {
                currentRate = targetRate;
            }

            slider.value = currentRate;
        }
        else
        {
            if (animSpeed > 0f)
            {
                float diff = targetRate - currentRate;
                float delta = diff * animSpeed * Time.fixedDeltaTime;

                if (Mathf.Abs(delta) >= Mathf.Abs(diff))
                    currentRate = targetRate;
                else
                    currentRate += delta;
            }
            else
            {
                currentRate = targetRate;
            }

            GetColorIdxAndInnerRate(currentRate, out int colorIdx, out float innerRate);

            slider.value = innerRate;

            if (prevColorIdx != colorIdx)
            {
                if (currentColorIndicator != null)
                    currentColorIndicator.color = colorLevelPerRate[colorIdx];

                if (prevColorIndicator != null)
                    prevColorIndicator.color = colorIdx > 0 ? colorLevelPerRate[colorIdx - 1] : new Color(1f, 1f, 1f, 0.5f);

                OnChangedColorLevel?.Invoke(innerRate);
                prevColorIdx = colorIdx;
            }
        }
    }

    private void GetColorIdxAndInnerRate(float rate, out int colorIdx, out float innerRate)
    {
        colorIdx = Mathf.FloorToInt(rate);
        innerRate = rate - colorIdx;

        // 색의 경계선(마지막 레이트 값은 제외)에 있으면 이전 레벨로 색 표시.
        if (rate > 0 && innerRate == 0)
        {
            --colorIdx;
            innerRate = 1f;
        }
    }

    public void SetRate(float rate)
    {
        rate = Mathf.Clamp01(rate);

        if(HasColorLevel)
        {
            targetRate = rate * colorLevelPerRate.Length;
        }
        else
        {
            targetRate = rate;
        }
    }

    public void SetRate(float currentValue, float maxValue)
    {
        if (maxValue == 0)
            SetRate(0);
        else
            SetRate(currentValue / maxValue);
    }

    public void SetRateImmediate(float rate)
    {
        rate = Mathf.Clamp01(rate);

        if (HasColorLevel)
        {
            targetRate = rate * colorLevelPerRate.Length;
            currentRate = targetRate;

            GetColorIdxAndInnerRate(currentRate, out int colorIdx, out float innerRate);

            slider.value = innerRate;

            if (prevColorIdx != colorIdx)
            {
                if (currentColorIndicator != null)
                    currentColorIndicator.color = colorLevelPerRate[colorIdx];

                if (prevColorIndicator != null)
                    prevColorIndicator.color = colorIdx > 0 ? colorLevelPerRate[colorIdx - 1] : new Color(1f, 1f, 1f, 0.5f);

                OnChangedColorLevel?.Invoke(innerRate);
                prevColorIdx = colorIdx;
            }
        }
        else
        {
            targetRate = rate;
            currentRate = rate;
            slider.value = rate;
        }
    }

    public void SetRateImmediate(float currentValue, float maxValue)
    {
        if (maxValue == 0)
            SetRateImmediate(0);
        else
            SetRateImmediate(currentValue / maxValue);
    }

    private void OnValidate()
    {
        if (slider == null)
            slider = GetComponent<Slider>();
    }
}