Id should always represent position in file

sort.go

@@ -34,9 +34,6 @@ func (timerlist *TimerList) Sort(sortFlag int) error {
 }
 func (timerlist *TimerList) refresh() {
 	timerlist.Sort(timerlist.SortFlag)
-	for i, t := range timerlist.Timers {
-		t.Id = i
-	}
 }
 
 type timerlistSort struct {

timerlist.go

@@ -184,6 +184,16 @@ func (timerlist *TimerList) GetActiveTimers() *TimerList {
 	return &t
 }
 
+func (timerlist *TimerList) GetNextId() int {
+	nextId := 0
+	for _, v := range timerlist.Timers {
+		if v.Id > nextId {
+			nextId = v.Id
+		}
+	}
+	return nextId + 1
+}
+
 // String returns a complete list of timers in timer.txt format.
 func (timerlist *TimerList) String() string {
 	var ret string
@@ -195,14 +205,16 @@ func (timerlist *TimerList) String() string {
 
 // AddTimer prepends a Timer to the current TimerList and takes care to set the Timer.Id correctly
 func (timerlist *TimerList) AddTimer(timer *Timer) {
+	timer.Id = timerlist.GetNextId()
 	timerlist.Timers = append(timerlist.Timers, timer)
 	timerlist.refresh()
 }
 
 // AddTimers adds all passed in timers to the list, sorts the list, then updates the Timer.Id values.
 func (timerlist *TimerList) AddTimers(timers []*Timer) {
-	timerlist.Timers = append(timerlist.Timers, timers...)
-	timerlist.Sort(SortStartDateAsc)
+	for _, v := range timers {
+		timerlist.AddTimer(v)
+	}
 }
 func (timerlist *TimerList) Combine(other *TimerList) { timerlist.AddTimers(other.Timers) }
 
@@ -285,6 +297,14 @@ func (timerlist *TimerList) Filter(predicate func(*Timer) bool) *TimerList {
 	return &newList
 }
 
+func (timerlist *TimerList) ResetIds() {
+	timerId := 1
+	for _, v := range timerlist.Timers {
+		v.Id = timerId
+		timerId++
+	}
+}
+
 // LoadFromFile loads a TimerList from *os.File.
 // Note: This will clear the current TimerList and overwrite it's contents with whatever is in *os.File.
 func (timerlist *TimerList) LoadFromFile(file *os.File) error {
@@ -317,7 +337,11 @@ func (timerlist *TimerList) WriteToFile(file *os.File) error {
 	writer := bufio.NewWriter(file)
 	_, err := writer.WriteString(timerlist.String())
 	writer.Flush()
+	if err != nil {
 		return err
+	}
+	timerlist.ResetIds()
+	return nil
 }
 
 // LoadFromFilename loads a TimerList from the filename.
@@ -332,7 +356,11 @@ func (timerlist *TimerList) LoadFromFilename(filename string) error {
 
 // WriteToFilename writes a TimerList to the specified file (most likely called "timer.txt").
 func (timerlist *TimerList) WriteToFilename(filename string) error {
-	return ioutil.WriteFile(filename, []byte(timerlist.String()), 0640)
+	if err := ioutil.WriteFile(filename, []byte(timerlist.String()), 0640); err != nil {
+		return err
+	}
+	timerlist.ResetIds()
+	return nil
 }
 
 // LoadFromFile loads and returns a TimerList from *os.File.