Import source: handler/fs/fs

Import the existing local project snapshot. This commit organizes existing files; it does not represent newly developed functionality.

handler/fs/fs.go

@@ -0,0 +1,84 @@
+package fs
+
+import (
+	"io"
+	"path"
+	"reactor-crw"
+)
+
+// PathResolver defines a simple interface to resolve path for content
+// before saving it.
+type pathResolver interface {
+	// CreateFolder creates a new folder in the "current" dir. The current
+	// directory is specified in Config.SavePath provided by a user. If dir
+	// with such name already exists it'll skip creation step.
+	CreateFolder(name string) error
+
+	// CreateFile creates a new file for downloaded content in the directory
+	// created by the CreateFolder function and returns the corresponding
+	// io.WriteCloser. If a file with such a name already exists then it'll
+	// be overwritten.
+	CreateFile(name string) (io.WriteCloser, error)
+
+	// Remove removes a file or folder by its name. If provided path does not
+	// exist it'll be skipped.
+	Remove(name string)
+}
+
+// FileSaver defines ContentHandler implementation that will download content
+// and save it to the host's file system. It resolves the corresponding file
+// path with PathResolver.
+type FileSaver struct {
+	pr pathResolver
+	t  reactor_crw.Transport
+}
+
+// NewFileSaver creates a new FileSaver instance along with a new folder that
+// will act as a context for a new instance. All files will be processed within
+// this new folder.
+func NewFileSaver(pr pathResolver, t reactor_crw.Transport, baseFolder string) (*FileSaver, error) {
+	err := pr.CreateFolder(baseFolder)
+	if err != nil {
+		return nil, err
+	}
+
+	return &FileSaver{
+		pr: pr,
+		t:  t,
+	}, nil
+}
+
+// Process downloads content by the corresponding URL by making an HTTP request
+// and saves the result to the file system. In case of error during saving the
+// content the corresponding file will be deleted from the file system.
+func (f *FileSaver) Process(url string, progress chan<- int, e chan<- error) {
+	defer func() {
+		progress <- 1
+	}()
+
+	data, err := f.t.FetchData(url)
+	if err != nil {
+		e <- err
+		return
+	}
+
+	defer func(b io.ReadCloser) {
+		_ = b.Close()
+	}(data)
+
+	file, err := f.pr.CreateFile(path.Base(url))
+	if err != nil {
+		e <- err
+		return
+	}
+
+	defer func(f io.WriteCloser) {
+		_ = f.Close()
+	}(file)
+
+	_, err = io.Copy(file, data)
+	if err != nil {
+		f.pr.Remove(path.Base(url))
+		e <- err
+	}
+}