fix(downloads): Replace stripped extensions, remember folder

spec/stores/file-download-store-spec.coffee

@@ -247,8 +247,8 @@ describe "FileDownloadStore", ->
 
   describe "_fetchAndSave", ->
     beforeEach ->
-      @savePath = "/Users/imaginary/.nylas/Downloads/b.png"
-      spyOn(NylasEnv, 'showSaveDialog').andCallFake (options, callback) => callback(@savePath)
+      @userSelectedPath = "/Users/imaginary/.nylas/Downloads/b.png"
+      spyOn(NylasEnv, 'showSaveDialog').andCallFake (options, callback) => callback(@userSelectedPath)
 
     it "should open a save dialog and prompt the user to choose a download path", ->
       spyOn(FileDownloadStore, '_runDownload').andCallFake =>
@@ -257,27 +257,6 @@ describe "FileDownloadStore", ->
       expect(NylasEnv.showSaveDialog).toHaveBeenCalled()
       expect(FileDownloadStore._runDownload).toHaveBeenCalledWith(@testfile)
 
-    it "should copy the file to the download path after it's been downloaded and open it after the stream has ended", ->
-      download = {targetPath: @savePath}
-      onEndEventCallback = null
-      streamStub =
-        pipe: ->
-        on: (eventName, eventCallback) =>
-          onEndEventCallback = eventCallback
-
-      spyOn(FileDownloadStore, '_runDownload').andCallFake =>
-        Promise.resolve(download)
-      spyOn(fs, 'createReadStream').andReturn(streamStub)
-      spyOn(fs, 'createWriteStream')
-
-      FileDownloadStore._fetchAndSave(@testfile)
-      advanceClock(1)
-      expect(fs.createReadStream).toHaveBeenCalledWith(download.targetPath)
-      expect(shell.showItemInFolder).not.toHaveBeenCalled()
-      onEndEventCallback()
-      advanceClock(1)
-      expect(shell.showItemInFolder).toHaveBeenCalledWith(download.targetPath)
-
     it "should open an error if the download fails", ->
       spyOn(FileDownloadStore, '_presentError')
       spyOn(FileDownloadStore, '_runDownload').andCallFake =>
@@ -286,6 +265,49 @@ describe "FileDownloadStore", ->
       advanceClock(1)
       expect(FileDownloadStore._presentError).toHaveBeenCalled()
 
+    describe "when the user confirms a path", ->
+      beforeEach ->
+        @download = {targetPath: 'bla'}
+        @onEndEventCallback = null
+        streamStub =
+          pipe: ->
+          on: (eventName, eventCallback) =>
+            @onEndEventCallback = eventCallback
+
+        spyOn(FileDownloadStore, '_runDownload').andCallFake =>
+          Promise.resolve(@download)
+        spyOn(fs, 'createReadStream').andReturn(streamStub)
+        spyOn(fs, 'createWriteStream')
+
+      it "should copy the file to the download path after it's been downloaded and open it after the stream has ended", ->
+        FileDownloadStore._fetchAndSave(@testfile)
+        advanceClock(1)
+        expect(fs.createReadStream).toHaveBeenCalledWith(@download.targetPath)
+        expect(shell.showItemInFolder).not.toHaveBeenCalled()
+        @onEndEventCallback()
+        advanceClock(1)
+        expect(shell.showItemInFolder).toHaveBeenCalledWith(@userSelectedPath)
+
+      it "should update the NylasEnv.savedState.lastDownloadDirectory", ->
+          NylasEnv.savedState.lastDownloadDirectory = null
+          @userSelectedPath = "/Users/imaginary/.nylas/Another Random Folder/file.jpg"
+          FileDownloadStore._fetchAndSave(@testfile)
+          advanceClock(1)
+          expect(NylasEnv.savedState.lastDownloadDirectory).toEqual('/Users/imaginary/.nylas/Another Random Folder')
+
+      describe "file extensions", ->
+        it "should allow the user to save the file with a different extension", ->
+          @userSelectedPath = "/Users/imaginary/.nylas/Downloads/b-changed.tiff"
+          FileDownloadStore._fetchAndSave(@testfile)
+          advanceClock(1)
+          expect(fs.createWriteStream).toHaveBeenCalledWith(@userSelectedPath)
+
+        it "should restore the extension if the user removed it entirely, because it's usually an accident", ->
+          @userSelectedPath = "/Users/imaginary/.nylas/Downloads/b-changed"
+          FileDownloadStore._fetchAndSave(@testfile)
+          advanceClock(1)
+          expect(fs.createWriteStream).toHaveBeenCalledWith("#{@userSelectedPath}.png")
+
   describe "_abortFetchFile", ->
     beforeEach ->
       @download =

src/flux/stores/file-download-store.coffee

@@ -210,8 +210,19 @@ FileDownloadStore = Reflux.createStore
       @_presentError(file)
 
   _fetchAndSave: (file) ->
-    NylasEnv.showSaveDialog {defaultPath: @_defaultSavePath(file)}, (savePath) =>
+    defaultPath = @_defaultSavePath(file)
+    defaultExtension = path.extname(defaultPath)
+
+    NylasEnv.showSaveDialog {defaultPath: defaultPath}, (savePath) =>
       return unless savePath
+      NylasEnv.savedState.lastDownloadDirectory = path.dirname(savePath)
+
+      saveExtension = path.extname(savePath)
+      didLoseExtension = defaultExtension isnt '' and saveExtension is ''
+      if didLoseExtension
+        savePath = savePath + defaultExtension
+
+      defaultPath = NylasEnv.savedState.lastDownloadDirectory
       @_runDownload(file).then (download) ->
         stream = fs.createReadStream(download.targetPath)
         stream.pipe(fs.createWriteStream(savePath))
@@ -236,13 +247,19 @@ FileDownloadStore = Reflux.createStore
   _defaultSavePath: (file) ->
     if process.platform is 'win32'
       home = process.env.USERPROFILE
-    else home = process.env.HOME
+    else
+      home = process.env.HOME
 
     downloadDir = path.join(home, 'Downloads')
     if not fs.existsSync(downloadDir)
       downloadDir = os.tmpdir()
 
-    path.join(downloadDir, file.displayName())
+    if NylasEnv.savedState.lastDownloadDirectory
+      if fs.existsSync(NylasEnv.savedState.lastDownloadDirectory)
+        downloadDir = NylasEnv.savedState.lastDownloadDirectory
+
+    filesafeName = file.displayName().replace(RegExpUtils.illegalPathCharactersRegexp(), '-')
+    path.join(downloadDir, filesafeName)
 
   _presentError: (file) ->
     dialog = require('remote').require('dialog')