From c9207d8c5ff957e876f5d672c0d99c56730ae87c Mon Sep 17 00:00:00 2001
From: Marius <maerious@gmail.com>
Date: Tue, 19 Jan 2016 22:32:15 +0100
Subject: [PATCH] Extract GetReader into own interface

---
 datastore.go        | 26 ++++++++++++++++++--------
 handler.go          |  6 +++++-
 unrouted_handler.go | 15 +++++++++++++--
 3 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/datastore.go b/datastore.go
index 92b27d1..214eae9 100644
--- a/datastore.go
+++ b/datastore.go
@@ -43,14 +43,6 @@ type DataStore interface {
 	// requests. It may return an os.ErrNotExist which will be interpreted as a
 	// 404 Not Found.
 	GetInfo(id string) (FileInfo, error)
-	// Get an io.Reader to allow downloading the file. This feature is not
-	// part of the official tus specification. If this additional function
-	// should not be enabled any call to GetReader should return
-	// tusd.ErrNotImplemented. The length of the resource is determined by
-	// retrieving the offset using GetInfo.
-	// If the returned reader also implements the io.Closer interface, the
-	// Close() method will be invoked once everything has been read.
-	GetReader(id string) (io.Reader, error)
 }
 
 // TerminaterDataStore is the interface which must be implemented by DataStores
@@ -97,3 +89,21 @@ type LockerDataStore interface {
 	// UnlockUpload releases an existing lock for the given upload.
 	UnlockUpload(id string) error
 }
+
+// GetReaderDataStore is the interface which must be implemented if handler should
+// expose and support the GET route. It will allow clients to download the
+// content of an upload regardless whether it's finished or not.
+// Please, be aware that this feature is not part of the official tus
+// specification. Instead it's a custom mechanism by tusd.
+type GetReaderDataStore interface {
+	DataStore
+
+	// GetReader returns a reader which allows iterating of the content of an
+	// upload specified by its ID. It should attempt to provide a reader even if
+	// the upload has not been finished yet but it's not required.
+	// If the returned reader also implements the io.Closer interface, the
+	// Close() method will be invoked once everything has been read.
+	// If the given upload could not be found, the error tusd.ErrNotFound should
+	// be returned.
+	GetReader(id string) (io.Reader, error)
+}
diff --git a/handler.go b/handler.go
index 0aae179..146e442 100644
--- a/handler.go
+++ b/handler.go
@@ -38,7 +38,6 @@ func NewHandler(config Config) (*Handler, error) {
 
 	mux.Post("", http.HandlerFunc(handler.PostFile))
 	mux.Head(":id", http.HandlerFunc(handler.HeadFile))
-	mux.Get(":id", http.HandlerFunc(handler.GetFile))
 	mux.Add("PATCH", ":id", http.HandlerFunc(handler.PatchFile))
 
 	// Only attach the DELETE handler if the Terminate() method is provided
@@ -46,6 +45,11 @@ func NewHandler(config Config) (*Handler, error) {
 		mux.Del(":id", http.HandlerFunc(handler.DelFile))
 	}
 
+	// GET handler requires the GetReader() method
+	if _, ok := config.DataStore.(GetReaderDataStore); ok {
+		mux.Get(":id", http.HandlerFunc(handler.GetFile))
+	}
+
 	return routedHandler, nil
 }
 
diff --git a/unrouted_handler.go b/unrouted_handler.go
index 399fe7a..83ea194 100644
--- a/unrouted_handler.go
+++ b/unrouted_handler.go
@@ -402,6 +402,12 @@ func (handler *UnroutedHandler) PatchFile(w http.ResponseWriter, r *http.Request
 // GetFile handles requests to download a file using a GET request. This is not
 // part of the specification.
 func (handler *UnroutedHandler) GetFile(w http.ResponseWriter, r *http.Request) {
+	dataStore, ok := handler.dataStore.(GetReaderDataStore)
+	if !ok {
+		handler.sendError(w, r, ErrNotImplemented)
+		return
+	}
+
 	id, err := extractIDFromPath(r.URL.Path)
 	if err != nil {
 		handler.sendError(w, r, err)
@@ -430,7 +436,7 @@ func (handler *UnroutedHandler) GetFile(w http.ResponseWriter, r *http.Request)
 	}
 
 	// Get reader
-	src, err := handler.dataStore.GetReader(id)
+	src, err := dataStore.GetReader(id)
 	if err != nil {
 		handler.sendError(w, r, err)
 		return
@@ -545,10 +551,15 @@ func (handler *UnroutedHandler) sizeOfUploads(ids []string) (size int64, err err
 // Fill an empty upload with the content of the uploads by their ids. The data
 // will be written in the order as they appear in the slice
 func (handler *UnroutedHandler) fillFinalUpload(id string, uploads []string) error {
+	dataStore, ok := handler.dataStore.(GetReaderDataStore)
+	if !ok {
+		return ErrNotImplemented
+	}
+
 	readers := make([]io.Reader, len(uploads))
 
 	for index, uploadID := range uploads {
-		reader, err := handler.dataStore.GetReader(uploadID)
+		reader, err := dataStore.GetReader(uploadID)
 		if err != nil {
 			return err
 		}