use default from existing .env file

Author: with-shrey

package-lock.json

@@ -26,6 +26,7 @@
   "license": "MIT",
   "devDependencies": {
     "@types/common-tags": "^1.8.0",
+    "@types/dotenv": "^8.2.0",
     "@types/google-libphonenumber": "^7.4.19",
     "@types/jest": "^24.0.23",
     "@types/mock-fs": "^4.10.0",
@@ -48,6 +49,7 @@
   },
   "dependencies": {
     "@types/node": "^14.0.13",
+    "dotenv": "^14.1.0",
     "email-regex": "^4.0.0",
     "google-libphonenumber": "^3.2.10",
     "log-symbols": "^3.0.0",

package.json

@@ -56,6 +56,14 @@ export async function getExampleContent(fileName: string): Promise<string> {
   return readFile(fullPath, 'utf8');
 }
 
+
+export async function getOutputContent(fileName: string): Promise<string | undefined> {
+  const fullPath = resolve(process.cwd(), fileName);
+  if(fs.existsSync(fullPath)) {
+    return readFile(fullPath, 'utf8');
+  }
+}
+
 export function getOutputStream(fileName: string): fs.WriteStream {
   const fullPath = resolve(process.cwd(), fileName);
   return fs.createWriteStream(fullPath);
@@ -68,11 +76,13 @@ export async function cli(
 ) {
   const options = parseArgs(args);
   const exampleFileContent = await getExampleContent(options.input);
+  const outputFileContent = await getOutputContent(options.output);
   const output = !ttyOutStream.isTTY
     ? ((ttyOutStream as unknown) as fs.WriteStream)
     : getOutputStream(options.output);
 
   const config: Config = {
+    outputFileContent,
     exampleFileContent,
     output,
     promptStream,

src/cli.ts

@@ -11,11 +11,23 @@ export type Config = {
   output: fs.WriteStream;
   promptStream: tty.WriteStream;
   exampleFileContent: string;
+  outputFileContent?: string;
 };
 
 export async function configureEnv(config: Config) {
   const parsedExample = parserLib.parse(config.exampleFileContent);
-
+  // Use default from existing .env values if file exists
+  if(config.outputFileContent) {
+    config.promptStream.write(
+      `${info} ${config.output.path} already present using existing values as defaults\n`
+    );
+    const parsedEnv = await parserLib.parseAsObject(config.outputFileContent);
+    parsedExample.variables.forEach(variable => {
+      if ( variable.configurable && parsedEnv[variable.key]) {
+        variable.default = parsedEnv[variable.key];
+      }
+    })
+  }
   config.promptStream.write(
     `Configuring your environment. Please fill out the following info\n`
   );

src/index.ts

@@ -1,5 +1,6 @@
 import fs from 'fs';
 import os from 'os';
+import dotenv from 'dotenv';
 
 export const VALID_BASE_FORMATS = [
   'text',
@@ -334,3 +335,7 @@ export async function parseFile(
   const fileContent = await fs.promises.readFile(filePath, 'utf8');
   return parse(fileContent);
 }
+
+export async function parseAsObject(fileContent: string): Promise<{ [_: string]: any }> {
+  return dotenv.parse(Buffer.from(fileContent))
+}