Parse locale from filename

Author: eemeli

example/src/index.js

@@ -1,4 +1,4 @@
-import messages from './messages.properties'
+import messages from './messages_en.properties'
 const { format, messages: errors } = messages.errors
 
 function component() {

example/src/messages.properties example/src/messages_en.propertiesexample/src/messages.properties renamed to example/src/messages_en.properties

@@ -12,9 +12,7 @@ module.exports = {
         test: /\.properties$/,
         loader: require.resolve('messageformat-properties-loader'),
         options: {
-          biDiSupport: false,
-          locales: 'en',
-          path: true
+          keyPath: true
         }
       }
     ]

example/webpack.config.js

@@ -1,11 +1,25 @@
 const { parse } = require('dot-properties')
 const loaderUtils = require('loader-utils')
 const MessageFormat = require('messageformat')
+const path = require('path')
+
+// expected to follow the pattern baseName_language[_script]_country_variant.properties
+// source: https://docs.oracle.com/javase/9/docs/api/java/util/ResourceBundle.html#getBundle-java.lang.String-java.util.Locale-java.lang.ClassLoader-
+function localeFromResourcePath (resourcePath, pathSep, defaultLocale) {
+  const parts = path.basename(resourcePath).split(pathSep)
+  const locale = parts[1] && parts[1].replace(/\..*$/, '').toLowerCase()
+  if (locale === 'pt-pt' || (locale === 'pt' && /^pt/i.test(parts[2]))) {
+    // European Portuguese is the only locale for which subtags matter
+    return 'pt-PT'
+  }
+  return /^[a-z]{2,3}$/.test(locale || '') ? locale : defaultLocale
+}
 
 module.exports = function (input) {
-  let { biDiSupport, locales, path } = loaderUtils.getOptions(this)
-  const translations = parse(input, path || false)
-  const mf = new MessageFormat(locales)
+  const { biDiSupport, defaultLocale, keyPath, pathSep } = loaderUtils.getOptions(this)
+  const translations = parse(input, keyPath || false)
+  const locale = localeFromResourcePath(this.resourcePath, pathSep || '_', defaultLocale || 'en')
+  const mf = new MessageFormat(locale)
   if (biDiSupport) mf.setBiDiSupport()
   return mf.compile(translations).toString('module.exports')
 }