Rework argv parsing

README.md

@@ -12,6 +12,27 @@ Things to note:
 
 Contributions are welcome! Open a pull request to fix a bug, or open an issue to discuss a new feature or change.
 
+### Usage
+
+- Read JSON file:
+
+  ```sh
+  node json-to-go.js sample.json
+  ```
+
+- Read JSON file from stdin:
+
+  ```sh
+  node json-to-go.js < sample.json
+  cat sample.json | node json-to-go.js
+  ```
+
+- Read large JSON file from stdin:
+
+  ```sh
+  node json-to-go.js --big < sample.json
+  cat sample.json | node json-to-go.js --big
+  ```
 
 ### Credits
 

json-to-go.js

@@ -494,27 +494,53 @@ function jsonToGo(json, typename, flatten = true, example = false, allOmitempty
 }
 
 if (typeof module != 'undefined') {
-    if (!module.parent) {
-        if (process.argv.length > 2 && process.argv[2] === '-big') {
-            bufs = []
-            process.stdin.on('data', function(buf) {
-                bufs.push(buf)
-            })
-            process.stdin.on('end', function() {
-                const json = Buffer.concat(bufs).toString('utf8')
-                process.stdout.write(jsonToGo(json).go)
-            })
-        } else if (process.argv.length === 3) {
-            const fs = require('fs');
-            const json = fs.readFileSync(process.argv[2], 'utf8');
-            process.stdout.write(jsonToGo(json).go)
-        } else {
-            process.stdin.on('data', function(buf) {
-                const json = buf.toString('utf8')
-                process.stdout.write(jsonToGo(json).go)
-            })
-        }
-    } else {
-        module.exports = jsonToGo
-    }
+	if (!module.parent) {
+		let bigstdin = false
+		let filename = null
+
+		process.argv.forEach((val, index) => {
+			if (index < 2)
+				return
+
+			if (!val.startsWith('-')) {
+				filename = val
+				return
+			}
+
+			const argument = val.replace(/-/g, '')
+			if (argument === "big")
+				bigstdin = true
+			else {
+				console.error(`Unexpected argument ${val} received`)
+				process.exit(1)
+			}
+		})
+
+		if (filename) {
+			const fs = require('fs');
+			const json = fs.readFileSync(filename, 'utf8');
+			process.stdout.write(jsonToGo(json).go)
+			return
+		}
+
+		if (bigstdin) {
+			bufs = []
+			process.stdin.on('data', function(buf) {
+				bufs.push(buf)
+			})
+			process.stdin.on('end', function() {
+				const json = Buffer.concat(bufs).toString('utf8')
+				process.stdout.write(jsonToGo(json).go)
+			})
+			return
+		}
+
+		// read from stdin
+		process.stdin.on('data', function(buf) {
+			const json = buf.toString('utf8')
+			process.stdout.write(jsonToGo(json).go)
+		})
+	} else {
+		module.exports = jsonToGo
+	}
 }