admin: Implement sychronization backends

We are now able, depending on configuration, to retrieve files from either WebDAV or local file system.

admin/api/exercice.go

@@ -2,10 +2,12 @@ package api
 
 import (
 	"encoding/json"
+	"encoding/hex"
 	"errors"
 	"strings"
 
 	"srs.epita.fr/fic-server/libfic"
+	"srs.epita.fr/fic-server/admin/sync"
 
 	"github.com/julienschmidt/httprouter"
 )
@@ -125,7 +127,6 @@ type uploadedHint struct {
 	Content    string
 	Cost       int64
 	URI        string
-	Path       string
 }
 
 func createExerciceHint(exercice fic.Exercice, body []byte) (interface{}, error) {
@@ -136,9 +137,9 @@ func createExerciceHint(exercice fic.Exercice, body []byte) (interface{}, error)
 
 	if len(uh.Content) != 0 {
 		return exercice.AddHint(uh.Title, uh.Content, uh.Cost)
-	} else if len(uh.Path) != 0 || len(uh.URI) != 0 {
-		return importFile(uploadedFile{Path: uh.Path, URI: uh.URI},
-			func(filePath string, origin string, digest []byte) (interface{}, error) {
+	} else if len(uh.URI) != 0 {
+		return sync.ImportFile(uh.URI,
+			func(filePath string, origin string) (interface{}, error) {
 				return exercice.AddHint(uh.Title, "$FILES" + strings.TrimPrefix(filePath, fic.FilesDir), uh.Cost)
 			})
 	} else {
@@ -209,7 +210,14 @@ func createExerciceFile(exercice fic.Exercice, body []byte) (interface{}, error)
 		return nil, err
 	}
 
-	return importFile(uf, exercice.ImportFile)
+	return sync.ImportFile(uf.URI,
+		func(filePath string, origin string) (interface{}, error) {
+			if digest, err := hex.DecodeString(uf.Digest); err != nil {
+				return nil, err
+			} else {
+				return exercice.ImportFile(filePath, origin, digest)
+			}
+		})
 }
 
 func showExerciceFile(file fic.EFile, body []byte) (interface{}, error) {