Add .env file support

.gitignore

@@ -3,3 +3,4 @@ backend
 lib
 testOut
 dev.*
+.env

src/backend.ts

@@ -10,7 +10,11 @@
  * [Express.js applications]: https://expressjs.com/en/5x/api.html#app
  */
 //#region -c backend imports
+import * as path from 'path'
+import * as fs from 'fs'
 import * as exp from 'express'
+import * as cfg from './config'
+import * as log from './logging'
 //#endregion
 /**
  * ## Express Middleware
@@ -52,4 +56,30 @@ export function invalidateBackend() {
         app = undefined
         delete require.cache[bundle] 
     }
+}
+/**
+ * ## Read `.env` file
+ * 
+ * If the root folder contains a file called `.env` load environment variables
+ * from it.
+ */
+const varDefRE = /^([A-Za-z]\w*)\s*\=\s*(.+)$/
+
+export function loadEnvFile() {
+    let envpath = path.resolve(cfg.getOptions().baseDir, ".env")
+    if (fs.existsSync(envpath)) {
+        let content = fs.readFileSync(envpath, 'utf-8').split(/\r?\n/)
+        for (let i = 0; i < content.length; ++i) {
+            let line = content[i].trim()
+            if (line && !line.startsWith("#")) {
+                let match = line.match(varDefRE)
+                if (match)
+                    process.env[match[1]] = match[2]
+                else {
+                    log.warn("Invalid line skipped in .env file:\n" + line)
+                    log.info("Correct format is <VARNAME>=<VARVALUE><newline>\n")
+                }
+            }
+        }
+    }
 }

src/server.ts

@@ -63,6 +63,7 @@ export function start(opts: cfg.Options) {
         })
     }
     app.use(exp.static(opts.outDir))
+    bak.loadEnvFile()
     app.use(bak.backend)
     app.get('/litscript', notifyHandler)
     let { host, port } = opts.serveOptions