using UnityEngine;
using System.Collections.Generic;
using Assets.WasapiAudio.Scripts.Unity;

[RequireComponent(typeof(Material))]
public class ThemeShaderBinder : MonoBehaviour
{
    public Material material;
    public Preferences preferences;

    private Texture2D _texture;
    private Color[] _colorCache;
    private int textureSize = 128;
    private Gradient _theme;

    private void Start() {
        if (preferences == null) {
            Debug.Log("Theme Shader Binder needs Preferences.");
            gameObject.SetActive(false);
        }
    }

    private void Update() {
        UpdateTexture();
        UpdateBinding();
    }

    public Color DecomposeHdrColor(Color linearColorHdr) {
        var maxColorComponent = linearColorHdr.maxColorComponent;
        float scaleFactor = 191f / maxColorComponent;
        float exposure = Mathf.Log(255f / scaleFactor) / Mathf.Log(2f);
        float factor = 1f / exposure;

        if (exposure <= 1f) {
            return linearColorHdr;
        }

        float r = linearColorHdr.r * factor;
        float g = linearColorHdr.g * factor;
        float b = linearColorHdr.b * factor;

        return new Color(r, g, b, linearColorHdr.a);
    }

    private void UpdateTexture() {
        if (_theme == preferences.Theme()) return;

        Debug.Log("Reinitialising Theme texture...");
        _texture = new Texture2D(textureSize, 1);
        _theme = preferences.Theme();
        _colorCache = new Color[textureSize];
        _texture.name = $"ThemeTexture{textureSize}";
        _texture.wrapMode = TextureWrapMode.Clamp;

        for (int i = 0; i < textureSize; i++) {
            // Color decomposed = DecomposeHdrColor(_theme.Evaluate((float)i / (float)textureSize));
            if (_theme == null) return;
            Color color = _theme.Evaluate((float)i / (float)textureSize);
            _colorCache[i] = color;
        }

        _texture.SetPixels(_colorCache);
        _texture.Apply();
    }

    public void UpdateBinding() {
        UpdateTexture();
        material.SetFloat("_ThemeSize", textureSize);
        material.SetTexture("_ThemeTexture", _texture);
    }
}