feat: automate editing env files

- adds a script which edits and writes env values into files
- added basic input validation for env values

Author: Gowtham118

package.json

@@ -14,7 +14,8 @@
     "lint": "eslint .",
     "prettier:format": "prettier './**/*.{js,json,md,sol,ts,yml}' --write && yarn run lint --fix",
     "prettier:check": "prettier './**/*.{js,json,md,sol,ts,yml}' --check && yarn run lint",
-    "testAll": "tests/runAll.sh"
+    "testAll": "tests/runAll.sh",
+    "setup-envs": "node scripts/setup-envs.js"
   },
   "devDependencies": {
     "@offchainlabs/eslint-config-typescript": "^0.2.1",

scripts/setup-envs.js

@@ -0,0 +1,155 @@
+#!/usr/bin/env node
+
+/*
+ * Environment setup script for Arbitrum Tutorials.
+ * Usage:
+ *   yarn setup-envs
+ */
+
+/* eslint-disable no-await-in-loop */
+
+const fs = require('fs');
+const path = require('path');
+const readline = require('readline');
+
+const VARS = ['PRIVATE_KEY', 'CHAIN_RPC', 'PARENT_CHAIN_RPC', 'L1_RPC'];
+
+function log(msg) {
+  console.log(msg);
+}
+function warn(msg) {
+  console.warn(msg);
+}
+function error(msg) {
+  console.error(msg);
+}
+
+async function promptForValues() {
+  const values = {};
+  const rl = readline.createInterface({ input: process.stdin, output: process.stdout });
+  const ask = (q) => new Promise((res) => rl.question(q, (ans) => res(ans.trim())));
+  for (const v of VARS) {
+    const optional = v === 'L1_RPC';
+    const existing = process.env[v] ? ` [default: ${process.env[v]}]` : '';
+    const prompt = optional ? `${v} (optional)${existing}: ` : `${v}${existing}: `;
+    const ans = await ask(prompt);
+    if (ans) {
+      values[v] = ans;
+    } else if (process.env[v]) {
+      values[v] = process.env[v];
+    } else if (!optional) {
+      error(`Required value missing: ${v}`);
+      process.exit(1);
+    }
+  }
+  rl.close();
+  return values;
+}
+
+function replaceOrAppend(contentLines, key, value) {
+  const prefix = key + '=';
+  let replaced = false;
+  for (let i = 0; i < contentLines.length; i++) {
+    const line = contentLines[i];
+    if (line.startsWith(prefix)) {
+      contentLines[i] = `${key}="${value}"`;
+      replaced = true;
+      break;
+    }
+  }
+  if (!replaced) contentLines.push(`${key}="${value}"`);
+}
+
+function processSampleFile(samplePath, envPath, values) {
+  const lines = fs.readFileSync(samplePath, 'utf8').split(/\r?\n/);
+  while (lines.length && lines[lines.length - 1].trim() === '') lines.pop();
+  for (const v of VARS) {
+    if (values[v]) replaceOrAppend(lines, v, values[v]);
+  }
+
+  const newContent = lines.join('\n') + '\n';
+  fs.writeFileSync(envPath, newContent, 'utf8');
+  if (samplePath !== envPath) {
+    fs.unlinkSync(samplePath); // remove sample after successful creation
+  }
+}
+
+function processDirectory(dir, values, summary) {
+  const samplePath = path.join(dir, '.env-sample');
+  const envPath = path.join(dir, '.env');
+  const hasSample = fs.existsSync(samplePath);
+  const hasEnv = fs.existsSync(envPath);
+
+  if (!hasSample && !hasEnv) return;
+
+  try {
+    if (hasSample) {
+      processSampleFile(samplePath, envPath, values);
+      summary.updated.push(dir);
+    } else if (hasEnv) {
+      processSampleFile(envPath, envPath, values);
+      summary.updated.push(dir);
+    }
+  } catch (e) {
+    summary.errors.push({ dir, error: e.message });
+  }
+}
+
+function validate(values) {
+  const pk = values.PRIVATE_KEY;
+  if (!/^0x[a-fA-F0-9]{64}$/.test(pk)) {
+    throw new Error('PRIVATE_KEY must be 0x + 64 hex characters.');
+  }
+  ['CHAIN_RPC', 'PARENT_CHAIN_RPC'].forEach((k) => {
+    if (!/^https?:\/\/\\S+$/i.test(values[k])) {
+      throw new Error(`${k} must be an http(s) URL.`);
+    }
+  });
+  if (values.L1_RPC && !/^https?:\/\/\\S+$/i.test(values.L1_RPC)) {
+    throw new Error('L1_RPC must be an http(s) URL if provided.');
+  }
+}
+
+async function main() {
+  log('Arbitrum Tutorials environment setup starting...');
+  const values = await promptForValues();
+
+  if (!values.PRIVATE_KEY || !values.CHAIN_RPC || !values.PARENT_CHAIN_RPC) {
+    error('PRIVATE_KEY, CHAIN_RPC, and PARENT_CHAIN_RPC are required.');
+    process.exit(1);
+  }
+
+  validate(values);
+
+  const rootDir = path.resolve(__dirname, '..');
+  const packagesDir = path.join(rootDir, 'packages');
+
+  const summary = { updated: [], errors: [] };
+
+  processDirectory(rootDir, values, summary);
+
+  if (fs.existsSync(packagesDir)) {
+    const entries = fs.readdirSync(packagesDir);
+    for (const entry of entries) {
+      const fullPath = path.join(packagesDir, entry);
+      if (fs.statSync(fullPath).isDirectory()) {
+        processDirectory(fullPath, values, summary);
+      }
+    }
+  }
+
+  log('Environment setup complete.');
+  log(`Updated: ${summary.updated.length}`);
+  if (summary.errors.length) {
+    warn('Errors encountered:');
+    for (const e of summary.errors) warn(` - ${e.dir}: ${e.error}`);
+  }
+
+  log('\nExample: run a tutorial script after env creation:');
+  log('  cd packages/greeter && npx hardhat run scripts/sendParentMessage.ts');
+}
+
+main().catch((e) => {
+  error(e.stack || e.message);
+  process.exit(1);
+});