Speedup & completion of download on errors. (#30)

* Replaces errors by warnings during image download.

If an error occurs during downloading an image from a set, a warning instead of
an error is emitted. This allows the rest of the set being downloaded.

* Avoids unnecessary Flickr accesses.

When image overrides are turned off, the check of an existing file should be
done before getting the available image sizes from Flickr. This avoids
unnecessary Flickr accesses and speeds up the process.

bin/flickr-set-get

@@ -122,6 +122,7 @@ function getSet(setId, userId, commandOptions) {
   var numProcessed = 0;
   var numDownloaded = 0;
   var numSkipped = 0;
+  var numWarnings = 0;
 
   api.on('setInfo', function onSetInfo(info) {
     cli.info('Downloading ' + info.total + ' photos from "' + info.title + '" by ' + info.ownername);
@@ -142,9 +143,13 @@ function getSet(setId, userId, commandOptions) {
   });
 
   api.on('done', function onDone(results) {
-    cli.ok('All done. ' + numDownloaded + ' photos downloaded, ' + numSkipped + ' skipped');
+    cli.ok('All done. ' + numDownloaded + ' photos downloaded, ' + numSkipped + ' skipped, ' + numWarnings + ' warnings');
   });
 
+  api.on('warning', function onWarning(error) {
+    numWarnings++;
+    cli.error(error);
+  });
   api.on('error', function onError(error) {
     cli.error(error);
     process.exit(1);

lib/Flickr.js

@@ -222,33 +222,37 @@ function Flickr(apiKey, options) {
       var tasks = info.photos.map(function mapTasks(currentValue, index, array) {
         var photoId = currentValue.id;
         return function asyncTask(cb) {
+          var path = _path.join(_this.options.outputDir, photoId + '.jpg');
+          if (_this.options.noOverwrite && fs.existsSync(path)) {
+            _this.emit('photoSkipped', photoId, path);
+            async.setImmediate(function onAsync() {
+              cb(null, path);
+            });
+
+            return;
+          }
+
           getPhotoSizes(photoId, function onGetPhotoSizes(err, sizes) {
 
             if (err) {
-              _this.emit('error', err);
-              return cb(err);
+              _this.emit('warning', err);
+              return cb(null, path);
             }
 
             _this.emit('photoSizes', photoId, sizes);
 
             if (!sizes[_this.options.size]) {
               var sizeErr = new Error('Size "' + _this.options.size + '" not available');
-              _this.emit('error', sizeErr);
-
-              return cb(sizeErr);
-            }
+              _this.emit('warning', sizeErr);
 
-            var path = _path.join(_this.options.outputDir, photoId + '.jpg');
-            if (_this.options.noOverwrite && fs.existsSync(path)) {
-              _this.emit('photoSkipped', photoId, path);
               return cb(null, path);
             }
 
             download(sizes[_this.options.size].source, path, function onDownloadComplete() {
 
               if (err) {
-                _this.emit('error', err);
-                return cb(err);
+                _this.emit('warning', err);
+                return cb(null, path);
               }
 
               _this.emit('photoDownloaded', photoId, path);

tests/Flickr.js

@@ -175,7 +175,7 @@ describe('Flickr', function ƒ() {
     it('should raise an error if a given size does not exists', function ƒ(done) {
       var f = new Flickr('apiKey', {concurrency: 1, outputDir: 'temp', size: 'Wrong size'});
 
-      f.on('error', function onError(error) {
+      f.on('warning', function onWarning(error) {
         rmDirSyncIfExists('temp');
         if (error.message.match(/Size "Wrong size" not available/)) {
           done();