[Misc] Add decrypt-save.js utility script (#5731)

* Add decrypt-save.js

* Update scripts/decrypt-save.js

Co-authored-by: Amani H. <109637146+xsn34kzx@users.noreply.github.com>

---------

Co-authored-by: Amani H. <109637146+xsn34kzx@users.noreply.github.com>

scripts/decrypt-save.js

@@ -0,0 +1,149 @@
+import pkg from "crypto-js";
+const { AES, enc } = pkg;
+// biome-ignore lint: This is how you import fs from node
+import * as fs from "node:fs";
+
+const SAVE_KEY = "x0i2O7WRiANTqPmZ";
+
+/**
+ * A map of condensed keynames to their associated full names
+ * NOTE: Update this if `src/system/game-data#systemShortKeys` ever changes!
+ */
+const systemShortKeys = {
+  seenAttr: "$sa",
+  caughtAttr: "$ca",
+  natureAttr: "$na",
+  seenCount: "$s",
+  caughtCount: "$c",
+  hatchedCount: "$hc",
+  ivs: "$i",
+  moveset: "$m",
+  eggMoves: "$em",
+  candyCount: "$x",
+  friendship: "$f",
+  abilityAttr: "$a",
+  passiveAttr: "$pa",
+  valueReduction: "$vr",
+  classicWinCount: "$wc",
+};
+
+/**
+ * Replace the shortened key names with their full names
+ * @param {string} dataStr - The string to convert
+ * @returns {string} The string with shortened keynames replaced with full names
+ */
+function convertSystemDataStr(dataStr) {
+  const fromKeys = Object.values(systemShortKeys);
+  const toKeys = Object.keys(systemShortKeys);
+  for (const k in fromKeys) {
+    dataStr = dataStr.replace(new RegExp(`${fromKeys[k].replace("$", "\\$")}`, "g"), toKeys[k]);
+  }
+
+  return dataStr;
+}
+
+/**
+ * Decrypt a save
+ * @param {string} path - The path to the encrypted save file
+ * @returns {string} The decrypted save data
+ */
+function decryptSave(path) {
+  // Check if the file exists
+  if (!fs.existsSync(path)) {
+    console.error(`File not found: ${path}`);
+    process.exit(1);
+  }
+  let fileData;
+  try {
+    fileData = fs.readFileSync(path, "utf8");
+  } catch (e) {
+    switch (e.code) {
+      case "ENOENT":
+        console.error(`File not found: ${path}`);
+        break;
+      case "EACCES":
+        console.error(`Could not open ${path}: Permission denied`);
+        break;
+      case "EISDIR":
+        console.error(`Unable to read ${path} as it is a directory`);
+        break;
+      default:
+        console.error(`Error reading file: ${e.message}`);
+    }
+    process.exit(1);
+  }
+  return convertSystemDataStr(AES.decrypt(fileData, SAVE_KEY).toString(enc.Utf8));
+}
+
+/* Print the usage message and exits */
+function printUsage() {
+  console.log(`
+Usage: node decrypt-save.js <encrypted-file> [save-file]
+
+Arguments:
+  file-path   Path to the encrypted save file to decrypt.
+  save-file   Path to where the decrypted data should be written. If not provided, the decrypted data will be printed to the console.
+
+Options:
+  -h, --help  Show this help message and exit.
+
+Description:
+  This script decrypts an encrypted pokerogue save file
+`);
+}
+
+/**
+ * Write `data` to `filePath`, gracefully communicating errors that arise
+ * @param {string} filePath
+ * @param {string} data
+ */
+function writeToFile(filePath, data) {
+  try {
+    fs.writeFileSync(filePath, data);
+  } catch (e) {
+    switch (e.code) {
+      case "EACCES":
+        console.error(`Could not open ${filePath}: Permission denied`);
+        break;
+      case "EISDIR":
+        console.error(`Unable to write to ${filePath} as it is a directory`);
+        break;
+      default:
+        console.error(`Error writing file: ${e.message}`);
+    }
+    process.exit(1);
+  }
+}
+
+function main() {
+  let args = process.argv.slice(2);
+  // Get options
+  const options = args.filter(arg => arg.startsWith("-"));
+  // get args
+  args = args.filter(arg => !arg.startsWith("-"));
+
+  if (args.length === 0 || options.includes("-h") || options.includes("--help") || args.length > 2) {
+    printUsage();
+    process.exit(0);
+  }
+  // If the user provided a second argument, check if the file exists already and refuse to write to it.
+  if (args.length === 2) {
+    const destPath = args[1];
+    if (fs.existsSync(destPath)) {
+      console.error(`Refusing to overwrite ${destPath}`);
+      process.exit(1);
+    }
+  }
+
+  // Otherwise, commence decryption.
+  const decrypt = decryptSave(args[0]);
+
+  if (args.length === 1) {
+    process.stdout.write(decrypt);
+    process.exit(0);
+  }
+
+  writeToFile(destPath, decrypt);
+}
+
+main();