using Godot;
using System.IO;
using System.Collections.Generic;

namespace IslaApocalypse.Core
{
	// 1. The Data Container
	// This holds the unpacked data in RAM so the Server can ask it questions 
	// without having to re-read the hard drive every single frame.
	public struct TownLocation
	{
		public Vector2 Position;
		public TownTier Tier;

		// Whether the generator marked this settlement as a highway node (it drives the
		// road topology at generation time). Carried by the v2 blueprint; always false
		// when loading a legacy v1 file, which never stored it. Nothing server-side
		// consumes it yet — it is carried and exposed, not acted on.
		public bool IsHighwayNode;
	}

	/// <summary>
	/// The resolved generation inputs embedded in a v2 blueprint, so a file is
	/// self-describing and config desync is detectable. Null on a legacy v1 load.
	/// A v2 file re-encoded from a v1 source carries the BlueprintFormat sentinel
	/// values instead of real inputs.
	/// </summary>
	public class BlueprintParams
	{
		public int WorldSeed;              // the generator's RESOLVED noise seed (names the file)
		public int MapSize;
		public float CraterRadius;
		public float DensityMultiplier;
		public Vector2 ImpactCenter;       // the crater's _impactCenter, in map pixels
		public string GeneratedUtc = "";   // stamped at write time, ISO-8601
		public string GeneratorGitHash = ""; // short hash of the generator repo, "" if unknown
	}

	public class WorldBlueprint
	{
		public int MapSize;
		public float[,] HeightMap;
		public Biome[,] BiomeMap;
		public List<TownLocation> Towns = new List<TownLocation>();

		// All 4 road tiers!
		public List<Vector2[]> Highways = new List<Vector2[]>();
		public List<Vector2[]> BranchRoads = new List<Vector2[]>();
		public List<Vector2[]> RuggedRoads = new List<Vector2[]>();
		public List<Vector2[]> TrailRoads = new List<Vector2[]>();

		// Which on-disk format this blueprint was parsed from (1 or 2), and the embedded
		// generation parameters. Params is null when the source was a legacy v1 file.
		public int FormatVersion = 1;
		public BlueprintParams Params;
	}

	// 2. The Parser Utility
	public static class MapDataParser
	{
		public static WorldBlueprint LoadMapData(string seedStr)
		{
			string filePath = ProjectSettings.GlobalizePath($"user://MapData_Seed_{seedStr}.dat");
			return LoadMapDataFromPath(filePath);
		}

		/// <summary>
		/// Loads a blueprint from an explicit absolute path. Same result as LoadMapData;
		/// exists so tooling (the round-trip harness) can load files that do not follow
		/// the seed-derived naming.
		/// </summary>
		public static WorldBlueprint LoadMapDataFromPath(string filePath)
		{
			if (!File.Exists(filePath))
			{
				GD.PrintErr($"[MapDataParser] CRITICAL ERROR: Map file not found at {filePath}");
				return null;
			}

			using (FileStream stream = File.OpenRead(filePath))
			{
				using (BinaryReader reader = new BinaryReader(stream))
				{
					return LoadV1(reader);
				}
			}
		}

		// ===============================================================
		// LEGACY v1 PARSE PATH — the original "ISLA_V1" positional format.
		// Kept intact and untouched; do not extend it. New content belongs
		// in the v2 tagged-section format.
		// ===============================================================
		private static WorldBlueprint LoadV1(BinaryReader reader)
		{
			WorldBlueprint blueprint = new WorldBlueprint();

			{
				{
					// 1. Header Validation (CRITICAL: Must read string first to align bytes!)
					string header = reader.ReadString();
					if (header != "ISLA_V1")
					{
						GD.PrintErr("[MapDataParser] ERROR: Invalid map version or corrupted file.");
						return null;
					}

					// 2. Read Map Dimensions & Initialize Arrays
					blueprint.MapSize = reader.ReadInt32();
					blueprint.HeightMap = new float[blueprint.MapSize, blueprint.MapSize];
					blueprint.BiomeMap = new Biome[blueprint.MapSize, blueprint.MapSize];

					// 3. Read Raw Voxel Data (Height & Biome)
					for (int x = 0; x < blueprint.MapSize; x++)
					{
						for (int y = 0; y < blueprint.MapSize; y++)
						{
							blueprint.HeightMap[x, y] = reader.ReadSingle();
							blueprint.BiomeMap[x, y] = (Biome)reader.ReadInt32();
						}
					}

					// 4. Read Logistical Anchors (Towns & POIs)
					int townCount = reader.ReadInt32();
					for (int i = 0; i < townCount; i++)
					{
						TownLocation town = new TownLocation();
						town.Position = new Vector2(reader.ReadSingle(), reader.ReadSingle());
						town.Tier = (TownTier)reader.ReadInt32();
						blueprint.Towns.Add(town);
					}

					// 5. Read Road Networks
					// Highway
					int highwayCount = reader.ReadInt32();
					for (int i = 0; i < highwayCount; i++)
					{
						int pathLength = reader.ReadInt32();
						Vector2[] path = new Vector2[pathLength];
						for (int p = 0; p < pathLength; p++) { path[p] = new Vector2(reader.ReadSingle(), reader.ReadSingle()); }
						blueprint.Highways.Add(path);
					}

					// Branch
					int branchCount = reader.ReadInt32();
					for (int i = 0; i < branchCount; i++)
					{
						int pathLength = reader.ReadInt32();
						Vector2[] path = new Vector2[pathLength];
						for (int p = 0; p < pathLength; p++) { path[p] = new Vector2(reader.ReadSingle(), reader.ReadSingle()); }
						blueprint.BranchRoads.Add(path);
					}

					// Rugged
					int ruggedCount = reader.ReadInt32();
					for (int i = 0; i < ruggedCount; i++)
					{
						int pathLength = reader.ReadInt32();
						Vector2[] path = new Vector2[pathLength];
						for (int p = 0; p < pathLength; p++) { path[p] = new Vector2(reader.ReadSingle(), reader.ReadSingle()); }
						blueprint.RuggedRoads.Add(path);
					}

					// Trails
					int trailCount = reader.ReadInt32();
					for (int i = 0; i < trailCount; i++)
					{
						int pathLength = reader.ReadInt32();
						Vector2[] path = new Vector2[pathLength];
						for (int p = 0; p < pathLength; p++) { path[p] = new Vector2(reader.ReadSingle(), reader.ReadSingle()); }
						blueprint.TrailRoads.Add(path);
					}
				}
			}
			
			GD.Print($"[MapDataParser] Successfully loaded v1 Blueprint. Dimension: {blueprint.MapSize}x{blueprint.MapSize}.");
			return blueprint;
		}
	}
}