sync: Implement writable importer

admin/sync/file.go

@@ -53,6 +53,12 @@ type ForgeLinkedImporter interface {
 	GetExerciceLink(e *fic.Exercice) (*url.URL, error)
 }
 
+// WritableImporter abstracts importer that we can also write on
+type WritableImporter interface {
+	// writeFile write the given buffer to the file at the given location.
+	writeFile(filename string, reader io.Reader) error
+}
+
 // GlobalImporter stores the main importer instance to use for global imports.
 var GlobalImporter Importer
 
@@ -189,3 +195,12 @@ func ImportFile(i Importer, URI string, next func(string, string) (interface{},
 
 	return next(dest, URI)
 }
+
+// WriteFileContent save the given content to the given text file.
+func WriteFileContent(i Importer, URI string, content []byte) error {
+	if wi, ok := i.(WritableImporter); ok {
+		return wi.writeFile(URI, bytes.NewReader(content))
+	} else {
+		return fmt.Errorf("%t is not capable of writing", i)
+	}
+}