Add stop option + optimizations

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2025 Sukikui
+Copyright (c) 2026 Sukikui
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -2,24 +2,31 @@
 
 # BiomeMap
 
-BiomeMap generates a lightweight JSON file mapping each world region to its dominant biome. Ideal for creating stylized biome maps on external web apps.
+Generates a lightweight JSON file mapping each world region to its dominant biome. Ideal for creating stylized biome maps on external web apps.
 
 </div>
 
 ## 📋 Overview
 
-BiomeMap scans a configurable grid (default ±5000 blocks around spawn, sampled in 32×32 cells) and writes the dominant 
-biome for each cell to `plugins/BiomeMap/data/biome-map.json`.
-This JSON is meant for external dashboards or stylized maps—no world edits, 
-no database, just a clean file your frontend can colorize.
+BiomeMap exports the dominant biome of a rectangular selection.
+
+You choose a world and 2 corners (`x/z`), and the plugin builds a grid of cells over that area.  
+Then it samples biomes and writes:
+- a JSON file
+- optionally a PNG preview (`1 pixel = 1 cell`)
+
+It is read-only: no world edits, no database, no extra services.
 
 ## ✨ Features
 
-- Samples center + corners of every cell to smooth biome transitions
-- Handles `/biomemap [world] [cellSize]` with tab completion
-- Pretty-printed JSON with origin, dimensions, and biome ids (`minecraft:plains`, etc.)
-- Logs progress to console and in-game so you can monitor long exports
-- Read-only: the world is never modified
+- Rectangular selection defined by two coordinates (`/biomemap world x1 z1 x2 z2 [cellSize] [preview]`)
+- Cell size with chunk-friendly alignment (`8`, `16`, `32`, ...)
+- Chunk-based sampling to smooth biome transitions
+- Asynchronous processing with frequent progress updates (no server freeze)
+- One export at a time (global lock)
+- Stop command to cancel running exports cleanly
+- Structured JSON output with min/max bounds per cell and namespaced biome IDs
+- Optional PNG preview output (`1 pixel = 1 cell`) using a biome RGB palette
 
 ## 🚀 Installation
 
@@ -30,38 +37,98 @@ no database, just a clean file your frontend can colorize.
 
 ## 🕹 Command Usage
 
-| Command                        | Arguments                                                | Description                                                      |
-|--------------------------------|----------------------------------------------------------|------------------------------------------------------------------|
-| `/biomemap [world] [cellSize]` | `world` defaults to `world`, `cellSize` defaults to `32` | Generates/overwrites `data/biome-map.json` for the target world. |
+| Command | Arguments | Description |
+| --- | --- | --- |
+| `/biomemap <world> <x1> <z1> <x2> <z2> [cellSize] [preview]` | `world` required, `cellSize` default `16`, `preview` optional | Exports the full rectangle between the 2 points. If `preview` is present, also writes a PNG. |
+| `/biomemap stop` | none | Stops the current export. |
+
+Notes:
+- Good `cellSize` values: `8`, `16`, `32`, `64`, ...
+- `preview` can be written as `preview` or `--preview`
+- If an export is stopped, files for that run are deleted from `exports/`
+
+Example:
+```
+/biomemap world -512 -512 320 192 32
+```
+→ covers the area between `(-512,-512)` and `(320,192)` using 32×32-block cells (chunk-aligned).
 
-Typical console output:
+Preview example:
 ```
-[BiomeMap] Exporting biomes for world 'world' (cellSize=32)...
-[BiomeMap] Export complete: 97,344 cells saved to biome-map.json
+/biomemap world -512 -512 320 192 32 preview
 ```
+→ same JSON export + PNG preview with one pixel per cell.
+
+### 📁 Output files
+
+Exports are written to `plugins/BiomeMap/exports/`.
+
+JSON files use:
+- `<world>_<cellSize>_<index>.json`
+
+If the filename already exists, `index` is incremented (`world_32_1.json`, `world_32_2.json`, ...).
+
+If `preview` is enabled, the plugin also writes PNG files with the same base name as each JSON file:
+- `plugins/BiomeMap/exports/<world>_<cellSize>_<index>.png`
+
+Biome colors come from `src/main/java/fr/sukikui/biomemap/export/BiomeColorPalette.java` (vanilla 1.21.11 palette with deterministic fallback for unknown biome ids).
+
+### ⚙️ Configuration
+
+`config.yml` exposes performance throttles.
+
+| Key | Default | Description |
+| --- | --- | --- |
+| `performance.chunks-per-tick` | `1` | How many new chunk jobs are started each tick. Lower = safer, slower. |
+| `performance.max-in-flight` | `4` | Max number of BiomeMap jobs currently in pipeline (queued/running). |
+| `performance.max-concurrent-chunks` | `64` | Max real chunk loads at the same time (main server pressure knob). |
+
+Quick tuning guide:
+- If players feel lag, lower `max-concurrent-chunks` first.
+- If export feels too slow but server is stable, increase `chunks-per-tick` a bit.
+- Keep `max-in-flight >= chunks-per-tick`.
 
 ## 🗺 JSON Format
 
 ```json
 {
-  "cellSize": 32,
-  "origin": { "x": -5000, "z": -5000 },
-  "width": 312,
-  "height": 312,
+  "cellSize": 16,
+  "selectionMin": { "x": -200, "z": -200 },
+  "selectionMax": { "x": -50, "z": -20 },
+  "gridOrigin": { "x": -208, "z": -208 },
+  "width": 10,
+  "height": 12,
   "cells": [
-    { "i": 0, "j": 0, "biome": "minecraft:plains" },
-    { "i": 1, "j": 0, "biome": "minecraft:forest" }
+    {
+      "i": 0,
+      "j": 0,
+      "bounds": {
+        "min": { "x": -208, "z": -208 },
+        "max": { "x": -193, "z": -193 }
+      },
+      "biome": "minecraft:plains"
+    },
+    {
+      "i": 1,
+      "j": 0,
+      "bounds": {
+        "min": { "x": -192, "z": -208 },
+        "max": { "x": -177, "z": -193 }
+      },
+      "biome": "minecraft:forest"
+    }
   ]
 }
 ```
 
-| Field                   | Type     | Description                                               |
-|-------------------------|----------|-----------------------------------------------------------|
-| `cellSize`              | `number` | Width/height of each grid cell in blocks.                 |
-| `origin.x`,`origin.z`   | `number` | Southwest corner of the scanned square (spawn − radius).  |
-| `width`,`height`        | `number` | Number of cells sampled on each axis.                     |
-| `cells[].i`,`cells[].j` | `number` | Grid indices; world coords = `origin + index * cellSize`. |
-| `cells[].biome`         | `string` | Namespaced biome id returned by Paper.                    |
+| Field | Type | Description |
+| --- | --- | --- |
+| `cellSize` | `number` | Cell size in blocks (minimum 8; values above that are aligned to the chunk grid). |
+| `selectionMin/Max` | `object` | Raw coordinates provided in the command. |
+| `gridOrigin` | `object` | North-west corner of the grid (min X, min Z). |
+| `width`, `height` | `number` | Number of cells on the X and Z axes. |
+| `cells[].bounds.min/max` | `object` | Inclusive bounds delimiting the cell. |
+| `cells[].biome` | `string` | Namespaced biome ID (e.g. `minecraft:savanna`). |
 
 ---
 

src/main/java/fr/sukikui/biomemap/BiomeMap.java

@@ -14,29 +14,53 @@
  */
 public final class BiomeMap extends JavaPlugin {
 
-  public static final int DEFAULT_CELL_SIZE = 32;
-  public static final int SCAN_RADIUS = 5000;
+  public static final int DEFAULT_CELL_SIZE = 16;
+
+  private BiomeMapCommand commandHandler;
+  private int chunksPerTick;
+  private int maxInFlight;
+  private int maxConcurrentChunks;
 
   @Override
   public void onEnable() {
     PaperLib.suggestPaper(this);
     ensureDataFolder();
+    saveDefaultConfig();
+    loadPerformanceSettings();
 
     Logger logger = getLogger();
     File dataFolder = getDataFolder();
-    BiomeExporter exporter = new BiomeExporter(dataFolder, SCAN_RADIUS);
+    BiomeExporter exporter = new BiomeExporter(dataFolder);
 
-    BiomeMapCommand commandHandler = new BiomeMapCommand(exporter, logger, DEFAULT_CELL_SIZE);
+    commandHandler =
+        new BiomeMapCommand(
+            this, exporter, logger, DEFAULT_CELL_SIZE, chunksPerTick, maxInFlight,
+            maxConcurrentChunks);
     PluginCommand biomemapCommand =
         Objects.requireNonNull(
             getCommand("biomemap"), "Command biomemap not defined in plugin.yml");
     biomemapCommand.setExecutor(commandHandler);
     biomemapCommand.setTabCompleter(commandHandler);
   }
 
+  @Override
+  public void onDisable() {
+    if (commandHandler != null) {
+      commandHandler.cancelAllExports();
+    }
+  }
+
   private void ensureDataFolder() {
     if (!getDataFolder().exists() && !getDataFolder().mkdirs()) {
       getLogger().warning("Unable to create plugin data folder. Exports may fail.");
     }
   }
+
+  private void loadPerformanceSettings() {
+    chunksPerTick = Math.max(1, getConfig().getInt("performance.chunks-per-tick", 1));
+    int configuredMaxInFlight = getConfig().getInt("performance.max-in-flight", chunksPerTick * 2);
+    maxInFlight = Math.max(chunksPerTick, configuredMaxInFlight);
+    maxConcurrentChunks = Math.max(
+        1, getConfig().getInt("performance.max-concurrent-chunks", 64));
+  }
 }