using System;
using UnityEngine;

public class TilesetOverlayUsingShader : MonoBehaviour
{
    public OnlineMapsTileSetControl control;
    
    // Overlay texture in mercator projection
    public Texture texture;

    /// <summary>
    /// Border coordinates of the overlay
    /// </summary>
    public double leftLongitude;
    public double topLatitude;
    public double rightLongitude;
    public double bottomLatitude;

    // Overlay transparency
    [Range(0, 1)]
    public float alpha = 1;
    
    private float _alpha = 1;

    private void Start()
    {
        if (control == null) control = OnlineMapsTileSetControl.instance;
        
        // Subscribe to events
        OnlineMapsTileSetControl.instance.OnMeshUpdated += UpdateOverlay;
        UpdateOverlay();
    }

    private void Update()
    {
        if (_alpha != alpha)
        {
            _alpha = alpha;
            UpdateOverlay();
        }
    }

    private void UpdateOverlay()
    {
        Vector3 p1 = control.GetWorldPosition(leftLongitude, topLatitude);
        Vector3 p2 = control.GetWorldPosition(rightLongitude, bottomLatitude);
        Shader.SetGlobalTexture("_OverlayTex", texture);
        Shader.SetGlobalFloat("_OverlayAlpha", _alpha);
        Shader.SetGlobalVector("_OverlayTL", p1);
        Shader.SetGlobalVector("_OverlayBR", p2);
    }
}