using Godot;

namespace IslaApocalypse.Tools
{
	/// <summary>
	/// PURE HILLSHADE (chat2/11) — a grayscale slope/aspect plate with no hypsometric tint, for
	/// reading low-amplitude surface detail (erosion's drainage is half a metre on average) that the
	/// palette-blended relief hides. Land shaded; sea a flat dark. ⚠ PRESENTATION ONLY — a look dial,
	/// never a claim about the world (→ Hillshade).
	/// </summary>
	public static class ShadeRenderer
	{
		public static Image Render(float[,] height, int mapSize, float sea, float zExaggeration, float azimuth, float altitude)
		{
			var (lx, ly, lz) = Hillshade.LightVector(azimuth, altitude);
			var img = Image.CreateEmpty(mapSize, mapSize, false, Image.Format.Rgb8);
			var seaColor = new Color(0.10f, 0.14f, 0.22f);
			for (int x = 0; x < mapSize; x++)
				for (int y = 0; y < mapSize; y++)
				{
					if (height[x, y] < sea) { img.SetPixel(x, y, seaColor); continue; }
					float s = Hillshade.At(height, mapSize, x, y, zExaggeration, lx, ly, lz);
					img.SetPixel(x, y, new Color(s, s, s));
				}
			return img;
		}

		public static void SavePng(float[,] height, int mapSize, float sea, float zExaggeration, float azimuth, float altitude, string absolutePath)
		{
			Error err = Render(height, mapSize, sea, zExaggeration, azimuth, altitude).SavePng(absolutePath);
			if (err != Error.Ok) GD.PrintErr($"[ShadeRenderer] SavePng failed ({err}) for {absolutePath}");
		}
	}
}