namespace IslaApocalypse.Core
{
	/// <summary>
	/// A row in the BUILDING material schema — what players construct with.
	/// → `Design - Data - Material Schema.md` §2, D-054.
	///
	/// ⚠ DELIBERATELY A SEPARATE SCHEMA FROM <see cref="TerrainMaterial"/>, NOT A TAG ON ONE TABLE.
	/// Natural stone and a placed stone block are not the same thing tagged differently: one is a
	/// resource you harvest, the other is something you craft and build with. One tagged table was
	/// considered and REJECTED — it blurs the resource→product relationship that IS the survival
	/// loop, and invites the two concerns to bleed into each other the way biomes bled into terrain.
	/// The bridge between the two schemas is <see cref="RecipeRegistry"/>, not a shared row type.
	///
	/// ⚠ NO MESH-STYLE FIELD HERE EITHER — same rule, same reason. See <see cref="TerrainMaterial"/>.
	///
	/// APPEND-ONLY. Adding a material is one new row.
	/// </summary>
	public sealed class BuildingMaterial
	{
		/// <summary>Identity. A registry key, not an ordinal.</summary>
		public MaterialKey Key { get; }

		/// <summary>Human-facing name. Presentation only.</summary>
		public string DisplayName { get; }

		/// <summary>
		/// How far this material carries structural support from an anchor, before decay.
		/// → `Design - Systems - Structural Integrity.md` (D-055: per-material reach).
		/// </summary>
		public float SupportReach { get; }

		/// <summary>How fast support falls off across that reach. 0 = no decay, 1 = immediate.</summary>
		public float SupportDecay { get; }

		/// <summary>Weight the material imposes on what carries it.</summary>
		public float Weight { get; }

		/// <summary>Damage the material absorbs before failing.</summary>
		public float Durability { get; }

		/// <summary>
		/// Runtime-only dense index. ⚠⚠ NEVER SERIALIZED — see <see cref="TerrainMaterial.RuntimeIndex"/>.
		/// </summary>
		public int RuntimeIndex { get; internal set; } = -1;

		public BuildingMaterial(
			MaterialKey key,
			string displayName,
			float supportReach,
			float supportDecay,
			float weight,
			float durability)
		{
			Key = key;
			DisplayName = displayName;
			SupportReach = supportReach;
			SupportDecay = supportDecay;
			Weight = weight;
			Durability = durability;
		}

		public override string ToString() => $"BuildingMaterial({Key})";
	}
}