move (reorder) and move updates

1 files changed, 71 insertions, 30 deletions

diff --git a/main.go b/main.go
index 29724b2..c5023f6 100644
--- a/main.go
+++ b/main.go
@@ -24,33 +24,6 @@ var templates map[string]*template.Template
 const debug = true
 var db *mysql.Client
 
-// given an id ('abcd1234'), return the pid (1)
-func getpid(id string) int {
-	query, err := db.Prepare("SELECT `pid` FROM `playlist` WHERE `id` = ?;")
-	if err != nil {
-		return -1
-	}
-	err = query.BindParams(id)
-	if err != nil {
-		return -1
-	}
-	err = query.Execute()
-	if err != nil {
-		return -1
-	}
-	var pid int
-	query.BindResult(&pid)
-	_, err = query.Fetch()
-	if err != nil {
-		return -1
-	}
-	err = query.FreeResult()
-	if err != nil {
-		return -1
-	}
-	return pid
-}
-
 func home(w http.ResponseWriter, r *http.Request) {
 	fmt.Fprintf(w, "path is %s", r.URL.Path[1:])
 }
@@ -91,7 +64,7 @@ func add(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	sql :="INSERT INTO `song` (`pid`,`yid`,`title`,`user`) VALUES(%d,'%s','%s','%s')"
+	sql := "INSERT INTO `song` (`pid`,`yid`,`title`,`user`) VALUES(%d,'%s','%s','%s')"
 	sql = fmt.Sprintf(sql, pid,
 			db.Escape(q.Get("yid")),
 			db.Escape(q.Get("title")),
@@ -115,7 +88,7 @@ func remove(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	sql :="DELETE FROM `song` WHERE `pid` = %d AND yid = '%s'"
+	sql := "DELETE FROM `song` WHERE `pid` = %d AND yid = '%s'"
 	sql = fmt.Sprintf(sql, pid, q.Get("yid"))
 	err := db.Query(sql)
 	if err != nil {
@@ -127,11 +100,78 @@ func remove(w http.ResponseWriter, r *http.Request) {
 	addUpdate(pid, removeAction, &Song{Yid: q.Get("yid")})
 }
 
+func move(w http.ResponseWriter, r *http.Request) {
+	q := r.URL.Query()
+	pid := getpid(q.Get("pid"))
+	if pid == -1 {
+		http.Error(w, "invalid pid", http.StatusInternalServerError)
+		return
+	}
+
+	direction, err := strconv.Atoui(q.Get("direction"))
+	if err != nil {
+		http.Error(w, err.String(), http.StatusInternalServerError)
+		return
+	}
+
+	err = db.Start()
+	if err != nil {
+		http.Error(w, err.String(), http.StatusInternalServerError)
+		return
+	}
+
+	order, err := queryInt("SELECT `order` FROM `song` WHERE `yid` = ? AND `pid` = ?",
+		q.Get("yid"), pid)
+	if err != nil {
+		http.Error(w, err.String(), http.StatusInternalServerError)
+		return
+	}
+	newOrder := order
+	if direction == moveUpAction && order > 0 {
+		newOrder--
+	} else if direction == moveDownAction {
+		newOrder++
+	} else {
+		http.Error(w, "invalid direction or cannot move up", http.StatusInternalServerError)
+		return
+	}
+
+	sql := "UPDATE `song` SET `order` = %d WHERE `order` = %d AND pid = %d"
+	sql = fmt.Sprintf(sql, order, newOrder, pid)
+	err = db.Query(sql)
+	if err != nil {
+		http.Error(w, err.String(), http.StatusInternalServerError)
+		return
+	} else if db.AffectedRows != 1 {
+		db.Rollback()
+		http.Error(w, "invalid direction for this song", http.StatusInternalServerError)
+		return
+	}
+	// there are now two songs with that order, so also check yid
+	sql = "UPDATE `song` SET `order` = %d WHERE `order` = %d AND pid = %d AND yid = '%s'"
+	sql = fmt.Sprintf(sql, newOrder, order, pid, q.Get("yid"))
+	err = db.Query(sql)
+	if err != nil {
+		db.Rollback()
+		http.Error(w, err.String(), http.StatusInternalServerError)
+		return
+	}
+
+	err = db.Commit()
+	if err != nil {
+		http.Error(w, err.String(), http.StatusInternalServerError)
+		return
+	}
+
+	w.Write([]byte("1"))
+	addUpdate(pid, direction, &Song{Yid: q.Get("yid")})
+}
+
 func poll(w http.ResponseWriter, r *http.Request) {
 	q := r.URL.Query()
 	timestamp := q.Get("timestamp")
 	if timestamp == "0" {
-		query, err := db.Prepare("SELECT `yid`,`title`,`user` FROM `playlist` JOIN `song` WHERE `id` = ?;")
+		query, err := db.Prepare("SELECT `yid`,`title`,`user` FROM `playlist` JOIN `song` WHERE `id` = ? ORDER BY `order` ASC")
 		if err != nil {
 			http.Error(w, err.String(), http.StatusInternalServerError)
 			return
@@ -227,6 +267,7 @@ func main() {
 	http.HandleFunc("/p/", playlist)
 	http.HandleFunc("/add/", add)
 	http.HandleFunc("/remove/", remove)
+	http.HandleFunc("/move/", move)
 	http.HandleFunc("/poll/", poll)
 	err = http.ListenAndServe("localhost:8000", nil)
 	if err != nil {