namespace IslaApocalypse.Tools
{
	/// <summary>
	/// The presentation dials — everything about how a heightmap is SHOWN, and nothing about how it
	/// is MADE. → `Design - Rendering - Roughness Is Presentation.md`.
	///
	/// ⚠ Config-gated for the same reason every shaping change is: a look decision should be an A/B
	/// pair, not a memory of last week's render, and a rejected look should cost a flipped default
	/// rather than a reverted commit. → `Design - Tooling - Iteration and Batching.md`.
	///
	/// ⚠ Kept DELIBERATELY SMALL. This is a taste gate, and iteration fatigue on a subjective gate
	/// is a real failure mode — a handful of variants the eye can actually judge beats a wall of
	/// near-duplicates. Three named looks, chosen so each pair isolates one question.
	/// </summary>
	public sealed class LookConfig
	{
		/// <summary>Short label, used in output filenames.</summary>
		public string Name = "atlas";

		/// <summary>Which hypsometric palette. → <see cref="ReliefPalette.Kind"/>.</summary>
		public ReliefPalette.Kind Palette = ReliefPalette.Kind.Atlas;

		/// <summary>
		/// Vertical exaggeration for the relief normal. ⚠ A LOOK DIAL, NOT A PHYSICAL CLAIM — the
		/// raw height units are not metres. See <see cref="Hillshade"/> for the measured slope
		/// table this was chosen from.
		/// </summary>
		public float ZExaggeration = 75f;

		/// <summary>Compass degrees clockwise from north. 315° (NW) is the cartographic standard.</summary>
		public float LightAzimuth = 315f;

		/// <summary>Degrees above the horizon. 45° standard; lower = longer, more dramatic shadows.</summary>
		public float LightAltitude = 45f;

		/// <summary>
		/// How much the relief moves the tint. 0 = flat hypsometric tint, no shading at all;
		/// 1 = full relief. Above ~0.85 the tint starts washing out and the map reads as a
		/// greyscale DEM wearing colour.
		/// </summary>
		public float HillshadeStrength = 0.55f;

		/// <summary>
		/// Relief multiplier BELOW sea level.
		///
		/// ⚠ Deliberately much weaker than on land, and the reason is the deferral: the seabed is
		/// RAW — no coast shelf, no islets, both Phase-2 items — so it is steep and noisy in a way
		/// the finished terrain will not be. Shading it at full strength drags the eye to the one
		/// part of the map that is knowingly unfinished. Cartographic bathymetry is conventionally
		/// shown flat or lightly shaded anyway, so the convention and the deferral agree.
		/// </summary>
		public float SeaHillshadeFactor = 0.35f;

		/// <summary>
		/// How much of the lit side is allowed to lift toward white. Highlights SCREEN rather than
		/// multiply, so sunlit slopes brighten without blowing out to paper.
		/// </summary>
		public float HighlightGain = 0.5f;

		/// <summary>The colour boundary. NOT a water surface — no water is modelled (Phase 2).</summary>
		public float SeaLevel = 0.15f;

		/// <summary>
		/// The three looks offered to the taste gate. Each pair isolates one question:
		///   gradient_flat     ⭐ the hero — wide colour, NO relief
		///   subtle_relief     the same gradient with gentle relief, for comparison
		///   diagnostic_relief ⚠ a DEV VIEW for spotting artifacts. Never the pretty map.
		///   atlas / dusk      the task-03 plates, kept reachable
		/// </summary>
		public static LookConfig[] Variants() => new[]
		{
			// ⭐ THE HERO. A wide, vivid gradient rendered FLAT — no relief at all.
			//
			// The developer's reference maps get their look from WIDE COLOUR + subtle relief +
			// COHERENT TERRAIN. We have the first; the third is Phase 2's curve and erosion. On raw
			// pre-Phase-2 noise a hillshade has nothing coherent to shade, so it renders the fine
			// fractal bumpiness as visual fuzz and actively HIDES the elevation the colour is
			// showing. So the pretty map leads with colour and no relief, and gets its shape from
			// relief later, once there is shape worth lighting.
			new LookConfig
			{
				Name = "gradient_flat", Palette = ReliefPalette.Kind.CostaRica,
				HillshadeStrength = 0f,
			},

			// Tasteful relief, for comparison. ⚠ Still fuzzes on raw noise — that is the terrain,
			// not the setting. Comes into its own after Phase 2 carves coherent landforms.
			new LookConfig
			{
				Name = "subtle_relief", Palette = ReliefPalette.Kind.CostaRica,
				ZExaggeration = 18f, LightAzimuth = 315f, LightAltitude = 45f,
				HillshadeStrength = 0.30f,
			},

			// ⚠⚠ A DIAGNOSTIC, NOT A PRETTY MAP. Strong exaggeration makes slope artifacts jump
			// out — a centre-line crease, a stair-step, a seam. Its bumpiness is EXAGGERATED SLOPE,
			// not extra terrain. Never present this as the deliverable.
			new LookConfig
			{
				Name = "diagnostic_relief", Palette = ReliefPalette.Kind.CostaRica,
				ZExaggeration = 100f, LightAzimuth = 315f, LightAltitude = 45f,
				HillshadeStrength = 0.80f,
			},

			// The task-03 atlas plates, kept so that look is still reachable for comparison.
			new LookConfig
			{
				Name = "atlas", Palette = ReliefPalette.Kind.Atlas,
				ZExaggeration = 75f, LightAzimuth = 315f, LightAltitude = 45f,
				HillshadeStrength = 0.55f,
			},
			new LookConfig
			{
				Name = "dusk", Palette = ReliefPalette.Kind.Dusk,
				ZExaggeration = 100f, LightAzimuth = 300f, LightAltitude = 35f,
				HillshadeStrength = 0.70f,
			},
		};

		public override string ToString() =>
			$"{Name}: palette={Palette} zex={ZExaggeration:F0} light={LightAzimuth:F0}°/{LightAltitude:F0}° " +
			$"strength={HillshadeStrength:F2} sea×{SeaHillshadeFactor:F2}";
	}
}