fix ID out of bounds detection; less unnecessary code

commands.go

@@ -490,8 +490,12 @@ func commandSwap(c *Client, args []string) {
 		id--
 		ids[i] = int(id)
 	}
-	c.Messagef("Swapping: %d and %d.", ids[0]+1, ids[1]+1)
+	if c.QueueSwap(ids[0], ids[1]) {
-	c.QueueSwap(ids[0], ids[1])
+		c.Messagef("Swapped %d and %d.", ids[0]+1, ids[1]+1)
+	} else {
+		c.Messagef("ID out of bounds.")
+		return
+	}
 }
 
 func commandShuffle(c *Client) {

main.go

@@ -130,7 +130,7 @@ func (c *Client) QueueLen() int {
 // ok field returns false if the index is out of bounds.
 func (c *Client) QueueAt(i int) (t Track, ok bool) {
 	l := c.QueueLen()
-	if i >= l {
+	if i >= l || i < 0 {
 		return Track{}, false
 	}
 	c.RLock()
@@ -180,7 +180,7 @@ func (c *Client) QueueSwap(a, b int) bool {
 		return true
 	}
 	l := c.QueueLen()
-	if a >= l || b >= l {
+	if a >= l || b >= l || a < 0 || b < 0 {
 		return false
 	}
 	c.Lock()
@@ -195,16 +195,6 @@ func (c *Client) QueueClear() {
 	c.Unlock()
 }
 
-func (c *Client) QueueFront() (t Track, ok bool) {
-	c.Lock()
-	defer c.Unlock()
-	if len(c.Queue) == 0 {
-		return Track{}, false
-	}
-	ret := *c.Queue[0]
-	return ret, true
-}
-
 ////////////////////////////////
 // Global variables.
 ////////////////////////////////