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|
package backendutil
import (
"github.com/emersion/go-imap"
)
// UpdateFlags executes a flag operation on the flag set current.
func UpdateFlags(current []string, op imap.FlagsOp, flags []string) []string {
// Don't modify contents of 'flags' slice. Only modify 'current'.
// See https://github.com/golang/go/wiki/SliceTricks
// Re-use current's backing store
newFlags := current[:0]
switch op {
case imap.SetFlags:
hasRecent := false
// keep recent flag
for _, flag := range current {
if flag == imap.RecentFlag {
newFlags = append(newFlags, imap.RecentFlag)
hasRecent = true
break
}
}
// append new flags
for _, flag := range flags {
if flag == imap.RecentFlag {
// Make sure we don't add the recent flag multiple times.
if hasRecent {
// Already have the recent flag, skip.
continue
}
hasRecent = true
}
// append new flag
newFlags = append(newFlags, flag)
}
case imap.AddFlags:
// keep current flags
newFlags = current
// Only add new flag if it isn't already in current list.
for _, addFlag := range flags {
found := false
for _, flag := range current {
if addFlag == flag {
found = true
break
}
}
// new flag not found, add it.
if !found {
newFlags = append(newFlags, addFlag)
}
}
case imap.RemoveFlags:
// Filter current flags
for _, flag := range current {
remove := false
for _, removeFlag := range flags {
if removeFlag == flag {
remove = true
}
}
if !remove {
newFlags = append(newFlags, flag)
}
}
default:
// Unknown operation, return current flags unchanged
newFlags = current
}
return newFlags
}
|
