using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using Godot;
using IslaApocalypse.Core;

namespace IslaApocalypse.Tools
{
	/// <summary>
	/// The taste-gate renderer: re-colours existing height fields into shaded-relief maps across a
	/// small set of named looks, and writes an INDEX.md for browsing.
	///
	/// ⚠ IT RE-COLOURS; IT DOES NOT REGENERATE. Height fields are LOADED from the `.f32` dumps a
	/// generation run left behind, so a look change provably cannot move the terrain. Only when a
	/// dump is missing for the requested size — a showpiece at 4096, say, where no dump exists —
	/// does it generate one, deterministically from the same seed. Same seed, same island.
	///
	/// ═══ RUNNING IT ═══
	///
	///   Godot_v4.7.2-stable_mono_linux.x86_64 --headless \
	///     --path ~/celerNexus/islaApocalypse-v2 res://Tools/Scenes/ReliefRenderTool.tscn
	///
	///   ISLA_MAPSIZE   side in columns             (default 2048)
	///   ISLA_SEEDS     comma-separated positive    (default: the 4 pinned seeds)
	///   ISLA_LOOKS     comma-separated look names  (default: atlas,relief,dusk)
	///   ISLA_TASK      authoring task number       (default 3)
	///   ISLA_BATCH     descriptor, NO prefix       (default "relief_taste")
	///   ISLA_SOURCE    batch to read .f32 from     (default 01_pass1_port)
	///   ISLA_DUMP_RAW  "1" to also dump .f32 when a field had to be generated
	/// </summary>
	public partial class ReliefRenderTool : Node
	{
		private static readonly int[] DefaultSeeds = { 1063685222, 20260819, 777001, 424242 };

		public override void _Ready()
		{
			ToolingPaths.Configure(OS.GetUserDataDir());

			int mapSize    = EnvInt("ISLA_MAPSIZE", 2048);
			int[] seeds    = EnvSeeds("ISLA_SEEDS", DefaultSeeds);
			int task       = EnvInt("ISLA_TASK", 3);            // the task that authored this batch
			string batch   = EnvStr("ISLA_BATCH", "relief_taste");
			string source  = EnvStr("ISLA_SOURCE", "01_pass1_port");
			bool dumpRaw   = EnvStr("ISLA_DUMP_RAW", "0") == "1";
			LookConfig[] looks = SelectLooks(EnvStr("ISLA_LOOKS", null));

			// ⚠ Composed by BatchRoot, never free-form: the prefix is the AUTHORING TASK number,
			// not a counter, and a descriptor carrying its own prefix is refused. → Tools/README.md.
			string batchRoot = ToolingPaths.BatchRoot(task, batch);
			string sourceRoot = Path.Combine(ToolingPaths.BatchesRoot, source);
			DirAccess.MakeDirRecursiveAbsolute(batchRoot);
			DirAccess.MakeDirRecursiveAbsolute(ToolingPaths.BatchScratch(batchRoot));

			GD.Print("==================================================================");
			GD.Print("  SHADED RELIEF — hypsometric tint + hillshade (Phase 1, the look)");
			GD.Print("==================================================================");
			GD.Print($"MapSize : {mapSize}");
			GD.Print($"seeds   : {string.Join(", ", seeds)}");
			GD.Print($"looks   : {string.Join(", ", Array.ConvertAll(looks, l => l.Name))}");
			GD.Print($"source  : {sourceRoot}   (.f32 dumps; generated only if absent)");
			GD.Print($"out     : {batchRoot}");
			GD.Print("------------------------------------------------------------------");
			foreach (var l in looks) GD.Print($"  {l}");
			GD.Print("==================================================================");

			var rows = new List<string>();

			foreach (int seed in seeds)
			{
				// --- get the height field: LOAD if a dump exists, generate only as a fallback ---
				ulong t0 = Time.GetTicksMsec();
				string dumpPath = Path.Combine(sourceRoot, $"{seed}_full", "height.f32");
				float[,] height = HeightField.Load(dumpPath, mapSize);
				string origin;

				if (height != null)
				{
					origin = "loaded";
				}
				else
				{
					var cfg = new TerrainGenConfig { MapSize = mapSize, Seed = seed, VariantLabel = "full" };
					Pass1Result r = Topography.Generate(cfg);
					height = r.Height;
					origin = "generated";
					if (dumpRaw)
					{
						string dir = Path.Combine(batchRoot, $"{seed}_source");
						DirAccess.MakeDirRecursiveAbsolute(dir);
						HeightField.Save(height, mapSize, Path.Combine(dir, "height.f32"));
					}
				}
				ulong tLoad = Time.GetTicksMsec() - t0;

				float hMin = float.MaxValue, hMax = float.MinValue;
				for (int x = 0; x < mapSize; x++)
					for (int y = 0; y < mapSize; y++)
					{
						float v = height[x, y];
						if (v < hMin) hMin = v;
						if (v > hMax) hMax = v;
					}

				GD.Print($"\n  seed {seed}  [{origin} in {tLoad} ms]  h[{hMin:F3} .. {hMax:F3}]");

				foreach (LookConfig look in looks)
				{
					ulong t1 = Time.GetTicksMsec();
					string dir = Path.Combine(batchRoot, $"{seed}_{look.Name}");
					DirAccess.MakeDirRecursiveAbsolute(dir);
					ReliefRenderer.SavePng(height, mapSize, look, Path.Combine(dir, "relief.png"));
					ulong ms = Time.GetTicksMsec() - t1;

					GD.Print($"    {look.Name,-8} -> {dir}/relief.png   {ms} ms");
					rows.Add($"| `{seed}_{look.Name}` | {seed} | {look.Name} | {look.Palette} | " +
							 $"{look.ZExaggeration:F0} | {look.LightAzimuth:F0}°/{look.LightAltitude:F0}° | " +
							 $"{look.HillshadeStrength:F2} | {ms} ms |");
				}
			}

			WriteIndex(batchRoot, mapSize, seeds, looks, source, rows);

			GD.Print("\n==================================================================");
			GD.Print($"  DONE — {rows.Count} renders in {batchRoot}");
			GD.Print("==================================================================");
			GetTree().Quit(0);
		}

		private static LookConfig[] SelectLooks(string csv)
		{
			LookConfig[] all = LookConfig.Variants();
			if (string.IsNullOrWhiteSpace(csv)) return all;

			var picked = new List<LookConfig>();
			foreach (string want in csv.Split(',', StringSplitOptions.RemoveEmptyEntries))
				foreach (LookConfig l in all)
					if (string.Equals(l.Name, want.Trim(), StringComparison.OrdinalIgnoreCase))
						picked.Add(l);
			return picked.Count > 0 ? picked.ToArray() : all;
		}

		private static void WriteIndex(string batchRoot, int mapSize, int[] seeds,
			LookConfig[] looks, string source, List<string> rows)
		{
			var (landLo, landHi) = ReliefPalette.LandAnchors;
			var sb = new StringBuilder();
			sb.AppendLine("# Batch — shaded relief, the taste gate (Phase 1)");
			sb.AppendLine();
			sb.AppendLine("**Presentation only.** These are the *same* height fields as");
			sb.AppendLine($"`{source}` — loaded from its `.f32` dumps, not regenerated. Nothing here can move the");
			sb.AppendLine("terrain; only its colours and its lighting differ.");
			sb.AppendLine();
			sb.AppendLine($"- **MapSize:** {mapSize}");
			sb.AppendLine($"- **Sea colour boundary:** 0.15 — a *colour* boundary, **not a water surface.** No water is modelled (Phase 2).");
			sb.AppendLine($"- **Palette anchors (FIXED across every image):** land {landLo} .. {landHi}; sea compressed by `d/(d+{ReliefPalette.SeaCompression})`");
			sb.AppendLine($"- **Seeds:** {string.Join(", ", seeds)}");
			sb.AppendLine();
			sb.AppendLine("## ⭐ Pick a look");
			sb.AppendLine();
			sb.AppendLine("Three, deliberately — a subjective gate drowns in a wall of near-duplicates. Each pair");
			sb.AppendLine("isolates one question:");
			sb.AppendLine();
			sb.AppendLine("| Look | Palette | Z-exag | Light | Strength | The question it answers |");
			sb.AppendLine("|---|---|---|---|---|---|");
			foreach (LookConfig l in looks)
			{
				string q = l.Name switch
				{
					"atlas"  => "the baseline — classic physical-atlas plate, tint-forward",
					"relief" => "**vs `atlas`:** how strong should the relief be? (same palette + light)",
					"dusk"   => "**vs `atlas`:** warmer palette and a lower sun — better, or too much?",
					_        => "",
				};
				sb.AppendLine($"| `{l.Name}` | {l.Palette} | {l.ZExaggeration:F0} | {l.LightAzimuth:F0}°/{l.LightAltitude:F0}° | {l.HillshadeStrength:F2} | {q} |");
			}
			sb.AppendLine();
			sb.AppendLine("Compare the **same seed** across the three folders. `1063685222` is the reference's own");
			sb.AppendLine("commented seed and the one used throughout tasks 02–03.");
			sb.AppendLine();
			sb.AppendLine("> ⚠ **The seabed is raw, and that is expected — not unfinished-because-broken.** The");
			sb.AppendLine("> submarine coast shelf and the offshore islets are DEFERRED Phase-2 items; they act only");
			sb.AppendLine("> below sea level and are judged once water renders. Relief is deliberately dialled back");
			sb.AppendLine("> underwater so the eye is not dragged to the one surface that is knowingly incomplete.");
			sb.AppendLine();
			sb.AppendLine("> ⚠ **No biome colour here.** This is height + slope + above/below sea, on a continuous");
			sb.AppendLine("> ramp. White at the top is snow-*coloured cartography*, not a snow biome.");
			sb.AppendLine();
			sb.AppendLine("## Renders");
			sb.AppendLine();
			sb.AppendLine("| Folder | Seed | Look | Palette | Z-exag | Light | Strength | Time |");
			sb.AppendLine("|---|---|---|---|---|---|---|---|");
			foreach (string r in rows) sb.AppendLine(r);
			sb.AppendLine();
			sb.AppendLine("`scratch/` is persistent and is never cleaned.");

			using var f = Godot.FileAccess.Open(Path.Combine(batchRoot, "INDEX.md"), Godot.FileAccess.ModeFlags.Write);
			if (f == null) { GD.PrintErr("could not write INDEX.md"); return; }
			f.StoreString(sb.ToString());
		}

		private static string EnvStr(string k, string fallback)
		{
			string v = System.Environment.GetEnvironmentVariable(k);
			return string.IsNullOrWhiteSpace(v) ? fallback : v;
		}

		private static int EnvInt(string k, int fallback)
			=> int.TryParse(EnvStr(k, null) ?? "", out int v) ? v : fallback;

		private static int[] EnvSeeds(string k, int[] fallback)
		{
			string v = EnvStr(k, null);
			if (v == null) return fallback;
			var o = new List<int>();
			foreach (string p in v.Split(',', StringSplitOptions.RemoveEmptyEntries))
				if (int.TryParse(p.Trim(), out int s) && s > 0) o.Add(s);
			return o.Count > 0 ? o.ToArray() : fallback;
		}
	}
}