refactor: add main.ts decomposition guardrails and extract core helpers

src/core/utils/config-gen.ts

@@ -0,0 +1,78 @@
+import * as fs from "fs";
+import * as path from "path";
+import * as readline from "readline";
+import { CliArgs } from "../../cli/args";
+
+function formatBackupTimestamp(date = new Date()): string {
+  const pad = (v: number): string => String(v).padStart(2, "0");
+  return `${date.getFullYear()}${pad(date.getMonth() + 1)}${pad(date.getDate())}-${pad(date.getHours())}${pad(date.getMinutes())}${pad(date.getSeconds())}`;
+}
+
+function promptYesNo(question: string): Promise<boolean> {
+  return new Promise((resolve) => {
+    const rl = readline.createInterface({
+      input: process.stdin,
+      output: process.stdout,
+    });
+    rl.question(question, (answer) => {
+      rl.close();
+      const normalized = answer.trim().toLowerCase();
+      resolve(normalized === "y" || normalized === "yes");
+    });
+  });
+}
+
+export async function generateDefaultConfigFile(
+  args: CliArgs,
+  options: {
+    configDir: string;
+    defaultConfig: unknown;
+    generateTemplate: (config: unknown) => string;
+  },
+): Promise<number> {
+  const targetPath = args.configPath
+    ? path.resolve(args.configPath)
+    : path.join(options.configDir, "config.jsonc");
+  const template = options.generateTemplate(options.defaultConfig);
+
+  if (fs.existsSync(targetPath)) {
+    if (args.backupOverwrite) {
+      const backupPath = `${targetPath}.bak.${formatBackupTimestamp()}`;
+      fs.copyFileSync(targetPath, backupPath);
+      fs.writeFileSync(targetPath, template, "utf-8");
+      console.log(`Backed up existing config to ${backupPath}`);
+      console.log(`Generated config at ${targetPath}`);
+      return 0;
+    }
+
+    if (!process.stdin.isTTY || !process.stdout.isTTY) {
+      console.error(
+        `Config exists at ${targetPath}. Re-run with --backup-overwrite to back up and overwrite.`,
+      );
+      return 1;
+    }
+
+    const confirmed = await promptYesNo(
+      `Config exists at ${targetPath}. Back up and overwrite? [y/N] `,
+    );
+    if (!confirmed) {
+      console.log("Config generation cancelled.");
+      return 0;
+    }
+
+    const backupPath = `${targetPath}.bak.${formatBackupTimestamp()}`;
+    fs.copyFileSync(targetPath, backupPath);
+    fs.writeFileSync(targetPath, template, "utf-8");
+    console.log(`Backed up existing config to ${backupPath}`);
+    console.log(`Generated config at ${targetPath}`);
+    return 0;
+  }
+
+  const parentDir = path.dirname(targetPath);
+  if (!fs.existsSync(parentDir)) {
+    fs.mkdirSync(parentDir, { recursive: true });
+  }
+  fs.writeFileSync(targetPath, template, "utf-8");
+  console.log(`Generated config at ${targetPath}`);
+  return 0;
+}