Add hashes for each book

Check if the uploaded book is already in the library

lib/database/books.go

@@ -1,6 +1,8 @@
 package database
 
 import (
+	log "github.com/cihub/seelog"
+
 	"strings"
 	"time"
 
@@ -17,9 +19,10 @@ type Book struct {
 	Description string
 	Tags        []string `pg:"tags,array"`
 	Date        string
-	Lang        string    `pg:"type:varchar(3)"`
-	Isbn        string    `pg:"type:varchar(13)"`
-	FileSize    int       `pg:"type:integer"`
+	Lang        string `pg:"type:varchar(3)"`
+	Isbn        string `pg:"type:varchar(13)"`
+	FileSize    int    `pg:"type:integer"`
+	FileHash    []byte
 	Cover       bool      `pg:",notnull"`
 	Active      bool      `pg:",notnull"`
 	UploadDate  time.Time `pg:"type:timestamp"`
@@ -165,6 +168,18 @@ func (db *pgDB) IsBookActive(id string) bool {
 	return active[0]
 }
 
+// ExistsBookHash checks if the given hash matches the hash of any book in the lbirary
+func (db *pgDB) ExistsBookHash(hash []byte) bool {
+	count, err := db.sql.Model(&Book{}).
+		Where("file_hash = ?", hash).
+		Count()
+	if err != nil {
+		log.Warnf("There was an error looking for the hash: %v", err)
+		return false
+	}
+	return count > 0
+}
+
 type columnq struct {
 	column string
 	value  string