Get unityVersion from ProjectVersion.txt (#84)

src/model/unity-version-parser.js

@@ -0,0 +1,26 @@
+import fs from 'fs';
+import path from 'path';
+
+class UnityVersionParser {
+  static get versionPattern() {
+    return /20\d{2}\.\d\.\w{3,4}|3/;
+  }
+
+  static parse(projectVersionTxt) {
+    const matches = projectVersionTxt.match(UnityVersionParser.versionPattern);
+    if (!matches || matches.length === 0) {
+      throw new Error(`Failed to parse version from "${projectVersionTxt}".`);
+    }
+    return matches[0];
+  }
+
+  static read(projectPath) {
+    const filePath = path.join(projectPath, 'ProjectSettings', 'ProjectVersion.txt');
+    if (!fs.existsSync(filePath)) {
+      return 'auto';
+    }
+    return UnityVersionParser.parse(fs.readFileSync(filePath, 'utf8'));
+  }
+}
+
+export default UnityVersionParser;