working hacky thing

.gitignore

@@ -1,2 +1,3 @@
 *.exe
-saves
+*.json
+*.hg

.vscode/settings.json

@@ -1,3 +1,3 @@
 {
-	"deno.enable": true
-}
+  "deno.enable": true
+}

README.md

@@ -0,0 +1,28 @@
+# NMS-Save-Decoder
+
+I needed something to decode a .hg file, in case save editors aren't updated, or I have some other weirdly specific issue with a save.
+
+So this is the solution :shrug:
+
+This is all very hacky and barely works. It uses a [Python file by Robert Maupin](https://gist.github.com/Chase-san/16076aaa90429ea6170550926b70f48b) to compress and decompress the save, and my own Typescript Deno code to apply the mapping and write it to the disc.
+
+The two parts are glued together by a Windows Batch file.
+
+## Usage
+
+### Decoding a Save
+
+Drag'n'drop your save.hg file on the `decode.bat` file.
+
+### Encoding a Save
+
+Drag'n'drop your save.json file on the `encode.bat` file.
+
+## Build the TS Part from Source
+
+1. [Install Deno](https://docs.deno.com/runtime/manual/getting_started/installation)
+2. Execute this command:
+
+```sh
+deno compile --allow-read --allow-write --allow-net applyMapping.ts
+```

applyMapping.ts

@@ -0,0 +1,90 @@
+// deno-lint-ignore-file no-explicit-any
+type Mapping = { Key: string; Value: string };
+
+interface MappingObject {
+  libMBIN_version: string;
+  Mapping: Mapping[];
+}
+
+const [file, mappingFileName] = Deno.args;
+
+let mapping;
+
+if (mappingFileName) {
+  const mappingFileData = Deno.readTextFileSync(mappingFileName);
+  mapping = JSON.parse(mappingFileData);
+} else {
+  mapping = await fetchMapping();
+}
+
+const fileData = Deno.readTextFileSync(file);
+
+let fileJson;
+console.log("parsing file...");
+try {
+  fileJson = JSON.parse(fileData);
+} catch {
+  fileJson = JSON.parse(fileData.slice(0, -1));
+}
+
+const isMapped = Boolean(fileJson.Version);
+
+const mappingFunction = isMapped ? reverseMapKeys : mapKeys;
+
+console.log("mapping...");
+const mappedSave = mappingFunction(fileJson, mapping);
+
+Deno.writeTextFileSync(
+  file,
+  JSON.stringify(mappedSave, null, isMapped ? undefined : 2), // minify when compressing
+);
+console.log("done!");
+
+function mapKeys(json: any, mapping: Mapping[]): any {
+  if (Array.isArray(json)) {
+    return json.map((item) => mapKeys(item, mapping));
+  } else if (typeof json === "object" && json !== null) {
+    const newJson: any = {};
+    for (const key in json) {
+      const mappedKey = mapping.find((m) => m.Key === key)?.Value;
+      if (mappedKey) {
+        newJson[mappedKey] = mapKeys(json[key], mapping);
+      } else {
+        newJson[key] = mapKeys(json[key], mapping);
+      }
+    }
+    return newJson;
+  } else {
+    return json;
+  }
+}
+
+function reverseMapKeys(json: any, mapping: Mapping[]): any {
+  if (Array.isArray(json)) {
+    return json.map((item) => reverseMapKeys(item, mapping));
+  } else if (typeof json === "object" && json !== null) {
+    const newJson: any = {};
+    for (const key in json) {
+      const originalKey = mapping.find((m) => m.Value === key)?.Key;
+      if (originalKey) {
+        newJson[originalKey] = reverseMapKeys(json[key], mapping);
+      } else {
+        newJson[key] = reverseMapKeys(json[key], mapping);
+      }
+    }
+    return newJson;
+  } else {
+    return json;
+  }
+}
+
+async function fetchMapping() {
+  const mappingUrl =
+    "https://github.com/monkeyman192/MBINCompiler/releases/latest/download/mapping.json";
+  console.log("downloading mapping...");
+  const fetchedFile = await fetch(mappingUrl);
+  const fetchedJson: MappingObject = await fetchedFile.json();
+  console.log("success!");
+
+  return fetchedJson.Mapping;
+}

decode.bat

@@ -0,0 +1,4 @@
+@echo off
+set "jsonfilename=%~n1.json"
+python3 nmssavetool.py decompress %1 %jsonfilename%
+applyMapping.exe %jsonfilename%

encode.bat

@@ -0,0 +1,4 @@
+@echo off
+set "compressedfilename=%~n1.hg"
+applyMapping.exe %1
+python3 nmssavetool.py compress %1 %compressedfilename%

nmssavetool.py

@@ -0,0 +1,103 @@
+#!/usr/bin/python3
+
+# Copyright 2021, Robert Maupin
+# Copying and distribution of this file, with or without modification, are
+# permitted in any medium without royalty, provided the copyright notice and
+# this notice are preserved. This file is offered as-is, without any warranty.
+
+import io
+import os
+import lz4.block
+import math
+import sys
+
+from glob import glob
+
+FILE_PATH = os.path.dirname(os.path.realpath(__file__))
+
+def uint32(data: bytes) -> int:
+  """Convert 4 bytes to a little endian unsigned integer."""
+  return int.from_bytes(data, byteorder='little', signed=False) & 0xffffffff
+
+def byte4(data: int):
+  """Convert unsigned 32 bit integer to 4 bytes."""
+  return data.to_bytes(4, byteorder='little', signed=False)
+
+# The important part
+def decompress(data):
+  """Decompresses the given save bytes."""
+  size = len(data)
+  din = io.BytesIO(data)
+  out = bytearray()
+  while din.tell() < size:
+    magic = uint32(din.read(4))
+    if magic != 0xfeeda1e5:
+      print("Invalid Block, bad file")
+      return bytes() # some unsupported format
+    compressedSize = uint32(din.read(4))
+    uncompressedSize = uint32(din.read(4))
+    din.seek(4, 1) # skip 4 bytes
+    out += lz4.block.decompress(din.read(compressedSize), uncompressed_size=uncompressedSize)
+  return out
+
+# The important part, part 2
+def compress(data):
+  """Compresses the given save bytes."""
+  size = len(data)
+  din = io.BytesIO(data)
+  out = bytearray()
+  while din.tell() < size:
+    uncompressedSize = min([0x80000, size - din.tell()])
+    block = lz4.block.compress(din.read(uncompressedSize), store_size=False)
+    out += byte4(0xfeeda1e5)
+    out += byte4(len(block))
+    out += byte4(uncompressedSize)
+    out += byte4(0)
+    out += block
+  return out
+
+def readFile(path):
+  fin = open(path, "rb")
+  data = fin.read()
+  fin.close()
+  return data
+
+def writeFile(path, data):
+  fout = open(path, "wb")
+  fout.write(data)
+  fout.close()
+
+
+def findSaveGames():
+  """Finds all saves on windows."""
+  return glob("C:\\Users\\*\\AppData\\Roaming\\HelloGames\\NMS\\*\\save*.hg")
+
+def usage(name):
+  print("No Man's Sky Save Tool v0.1")
+  print("Copyright (c) 2021 Robert Maupin. Permissive License.")
+  print("Usage: %s compress <input> <output>" % os.path.basename(name))
+  print("Usage: %s decompress <input> <output>" % os.path.basename(name))
+  print("Usage: %s list" % os.path.basename(name))
+  print("    compress       Decompress a given 'No Man's Sky' save file.")
+  print("    decompress     Compress a given 'No Man's Sky' save file.")
+  print("    list           Searchs for save files and outputs what files were found.")
+
+def main():
+  args = sys.argv
+  if len(args) == 2:
+    if args[1] == "l" or args[1] == "list":
+      for file in findSaveGames():
+        print(file)
+      return
+  if len(args) == 4:
+    if args[1] == "c" or args[1] == "compress":
+      writeFile(args[3], compress(readFile(args[2])))
+      print("done")
+      return
+    if args[1] == "d" or args[1] == "decompress":
+      writeFile(args[3], decompress(readFile(args[2])))
+      print("done")
+      return
+  usage(args[0])
+
+main()