From 5a61431e8b34cdde3c1acfbcbe2044b6791f9478 Mon Sep 17 00:00:00 2001
From: missinglink <insomnia@rcpt.at>
Date: Tue, 13 Aug 2019 17:28:18 +0200
Subject: [PATCH] feat(name): multi-stage fallback for when no default name was
 found

---
 stream/tag_mapper.js      | 32 +++++++++++++++++++++----
 test/stream/tag_mapper.js | 50 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+), 5 deletions(-)

diff --git a/stream/tag_mapper.js b/stream/tag_mapper.js
index 8c0d5a10..ba505ba8 100644
--- a/stream/tag_mapper.js
+++ b/stream/tag_mapper.js
@@ -67,12 +67,34 @@ module.exports = function(){
         }
       }
 
-      // Handle the case where no default name was set but there was
-      // an english name which we could use as the default.
+      // Handle the case where no default name was set but there were
+      // other names which we could use as the default.
       if( !doc.getName('default') ){
-        var en = doc.getName('en');
-        if( 'string' === typeof en ){
-          doc.setName('default', en);
+
+        var defaultName =
+          doc.getName('official') ||
+          doc.getName('international') ||
+          doc.getName('national') ||
+          doc.getName('regional') ||
+          doc.getName('en');
+
+        // use one of the preferred name tags listed above
+        if ( defaultName ){
+          doc.setName('default', defaultName);
+        }
+
+        // else try to use an available two-letter language name tag
+        else {
+          var keys = Object.keys(doc.name).filter(n => n.length === 2);
+
+          // unambiguous (there is only a single two-letter name tag)
+          if ( keys.length === 1 ){
+            doc.setName('default', doc.getName(keys[0]));
+          }
+
+          // note we do not handle ambiguous cases where the record contains >1
+          // two-letter name tags.
+          // see: https://github.com/pelias/openstreetmap/pull/498
         }
       }
 
diff --git a/test/stream/tag_mapper.js b/test/stream/tag_mapper.js
index 2e0a55e3..4079331d 100644
--- a/test/stream/tag_mapper.js
+++ b/test/stream/tag_mapper.js
@@ -156,6 +156,25 @@ module.exports.tests.accept_localized_keys = function(test, common) {
   });
 };
 
+// Use 'name:official' in situations where no other default name was available
+// https://github.com/pelias/openstreetmap/issues/497
+module.exports.tests.use_official_as_fallback_default = function (test, common) {
+  var doc = new Document('a', 'b', 1);
+  doc.setMeta('tags', { 'name:ru': 'test1', 'name:en': 'test2', 'official_name': 'test3' });
+  test('maps - use name:official as fallback default', function (t) {
+    var stream = mapper();
+    stream.pipe(through.obj(function (doc, enc, next) {
+      t.equal(doc.getName('default'), 'test3', 'name:en used as fallback');
+      t.equal(doc.getName('ru'), 'test1', 'correctly mapped');
+      t.equal(doc.getName('en'), 'test2', 'correctly mapped');
+      t.equal(doc.getName('official'), 'test3', 'correctly mapped');
+      t.end(); // test will fail if not called (or called twice).
+      next();
+    }));
+    stream.write(doc);
+  });
+};
+
 // Use 'name:en' in situations where no other default name was available
 // https://github.com/pelias/openstreetmap/issues/497
 module.exports.tests.use_en_as_fallback_default = function (test, common) {
@@ -175,6 +194,37 @@ module.exports.tests.use_en_as_fallback_default = function (test, common) {
   });
 };
 
+// Use the *only* available name:** tag as fallback
+module.exports.tests.unambiguous_default_name_fallback = function (test, common) {
+  var doc = new Document('a', 'b', 1);
+  doc.setMeta('tags', { 'name:ru': 'test1' });
+  test('maps - unambiguous name:** used as default name fallback', function (t) {
+    var stream = mapper();
+    stream.pipe(through.obj(function (doc, enc, next) {
+      t.equal(doc.getName('default'), 'test1', 'only name:** tag used as fallback');
+      t.equal(doc.getName('ru'), 'test1', 'correctly mapped');
+      t.end(); // test will fail if not called (or called twice).
+      next();
+    }));
+    stream.write(doc);
+  });
+};
+
+// In cases where there are multiple name:** tags, do not try to guess
+module.exports.tests.ambiguous_default_name_fallback = function (test, common) {
+  var doc = new Document('a', 'b', 1);
+  doc.setMeta('tags', { 'name:ru': 'test1', 'name:pl': 'test2' });
+  test('maps - ambiguous name:** not used as default name fallback', function (t) {
+    var stream = mapper();
+    stream.pipe(through.obj(function (doc, enc, next) {
+      t.false(doc.getName('default'), 'do not try to guess');
+      t.end(); // test will fail if not called (or called twice).
+      next();
+    }));
+    stream.write(doc);
+  });
+};
+
 module.exports.tests.lowercase_keys = function(test, common) {
   var doc = new Document('a','b',1);
   doc.setMeta('tags', { 'name:EN': 'test' });