Add hashes for each book

Check if the uploaded book is already in the library

lib/upload.go

@@ -1,13 +1,14 @@
 package trantor
 
 import (
-	"net/http"
-
 	log "github.com/cihub/seelog"
 
 	"crypto/rand"
+	"crypto/sha256"
 	"encoding/base64"
+	"io"
 	"mime/multipart"
+	"net/http"
 
 	"github.com/meskio/epubgo"
 	"gitlab.com/trantor/trantor/lib/database"
@@ -41,6 +42,19 @@ func uploadWorker(database database.DB, store storage.Store) {
 func (req uploadRequest) processFile(db database.DB, store storage.Store) {
 	defer req.file.Close()
 
+	h := sha256.New()
+	if _, err := io.Copy(h, req.file); err != nil {
+		log.Warn("Can't read uploaded file ", req.header.Filename, ": ", err)
+		db.UpdateSubmission(req.id, "There was a problem with the uploaded book, try again later.", nil)
+		return
+	}
+	fileHash := h.Sum(nil)
+	if db.ExistsBookHash(fileHash) {
+		log.Info("Uploaded file ", req.header.Filename, " already in the library.")
+		db.UpdateSubmission(req.id, "The uploaded book is already in the library (it could be in the moderation queue)", nil)
+		return
+	}
+
 	epub, err := epubgo.Load(req.file, req.header.Size)
 	if err != nil {
 		log.Warn("Not valid epub uploaded file ", req.header.Filename, ": ", err)
@@ -61,6 +75,7 @@ func (req uploadRequest) processFile(db database.DB, store storage.Store) {
 	}
 
 	book.FileSize = int(size)
+	book.FileHash = fileHash
 	book.Cover = GetCover(epub, book.ID, store)
 
 	err = db.AddBook(book)