1 files changed, 179 insertions, 0 deletions
diff --git a/lib/marker/marker.go b/lib/marker/marker.go
new file mode 100644
index 00000000..1b89fc80
--- /dev/null
+++ b/lib/marker/marker.go
@@ -0,0 +1,179 @@
+package marker
+
+// TODO: fix headers for message that are nil
+
+// Marker provides the interface for the marking behavior of messages
+type Marker interface {
+	Mark(uint32)
+	Unmark(uint32)
+	ToggleMark(uint32)
+	Remark()
+	Marked() []uint32
+	IsMarked(uint32) bool
+	ToggleVisualMark()
+	UpdateVisualMark()
+	ClearVisualMark()
+}
+
+// UIDProvider provides the underlying uids and the selected message index
+type UIDProvider interface {
+	Uids() []uint32
+	SelectedIndex() int
+}
+
+type controller struct {
+	uidProvider    UIDProvider
+	marked         map[uint32]struct{}
+	lastMarked     map[uint32]struct{}
+	visualStartUID uint32
+	visualMarkMode bool
+}
+
+// New returns a new Marker
+func New(up UIDProvider) Marker {
+	return &controller{
+		uidProvider: up,
+		marked:      make(map[uint32]struct{}),
+		lastMarked:  make(map[uint32]struct{}),
+	}
+}
+
+// Mark markes the uid as marked
+func (mc *controller) Mark(uid uint32) {
+	if mc.visualMarkMode {
+		// visual mode has override, bogus input from user
+		return
+	}
+	mc.marked[uid] = struct{}{}
+}
+
+// Unmark unmarks the uid
+func (mc *controller) Unmark(uid uint32) {
+	if mc.visualMarkMode {
+		// user probably wanted to clear the visual marking
+		mc.ClearVisualMark()
+		return
+	}
+	delete(mc.marked, uid)
+}
+
+// Remark restores the previous marks
+func (mc *controller) Remark() {
+	mc.marked = mc.lastMarked
+}
+
+// ToggleMark toggles the marked state for the given uid
+func (mc *controller) ToggleMark(uid uint32) {
+	if mc.visualMarkMode {
+		// visual mode has override, bogus input from user
+		return
+	}
+	if mc.IsMarked(uid) {
+		mc.Unmark(uid)
+	} else {
+		mc.Mark(uid)
+	}
+}
+
+// resetMark removes the marking from all messages
+func (mc *controller) resetMark() {
+	mc.lastMarked = mc.marked
+	mc.marked = make(map[uint32]struct{})
+}
+
+// removeStaleUID removes uids that are no longer presents in the UIDProvider
+func (mc *controller) removeStaleUID() {
+	for mark := range mc.marked {
+		present := false
+		for _, uid := range mc.uidProvider.Uids() {
+			if mark == uid {
+				present = true
+				break
+			}
+		}
+		if !present {
+			delete(mc.marked, mark)
+		}
+	}
+}
+
+// IsMarked checks whether the given uid has been marked
+func (mc *controller) IsMarked(uid uint32) bool {
+	_, marked := mc.marked[uid]
+	return marked
+}
+
+// Marked returns the uids of all marked messages
+func (mc *controller) Marked() []uint32 {
+	mc.removeStaleUID()
+	marked := make([]uint32, len(mc.marked))
+	i := 0
+	for uid := range mc.marked {
+		marked[i] = uid
+		i++
+	}
+	return marked
+}
+
+// ToggleVisualMark enters or leaves the visual marking mode
+func (mc *controller) ToggleVisualMark() {
+	mc.visualMarkMode = !mc.visualMarkMode
+	if mc.visualMarkMode {
+		// just entered visual mode, reset whatever marking was already done
+		mc.resetMark()
+		uids := mc.uidProvider.Uids()
+		if idx := mc.uidProvider.SelectedIndex(); idx >= 0 && idx < len(uids) {
+			mc.visualStartUID = uids[idx]
+			mc.marked[mc.visualStartUID] = struct{}{}
+		}
+	}
+}
+
+// ClearVisualMark leaves the visual marking mode and resets any marking
+func (mc *controller) ClearVisualMark() {
+	mc.resetMark()
+	mc.visualMarkMode = false
+	mc.visualStartUID = 0
+}
+
+// UpdateVisualMark updates the index with the currently selected message
+func (mc *controller) UpdateVisualMark() {
+	if !mc.visualMarkMode {
+		// nothing to do
+		return
+	}
+	startIdx := mc.visualStartIdx()
+	if startIdx < 0 {
+		// something deleted the startuid, abort the marking process
+		mc.ClearVisualMark()
+		return
+	}
+
+	selectedIdx := mc.uidProvider.SelectedIndex()
+	if selectedIdx < 0 {
+		return
+	}
+
+	uids := mc.uidProvider.Uids()
+
+	var visUids []uint32
+	if selectedIdx > startIdx {
+		visUids = uids[startIdx : selectedIdx+1]
+	} else {
+		visUids = uids[selectedIdx : startIdx+1]
+	}
+	mc.resetMark()
+	for _, uid := range visUids {
+		mc.marked[uid] = struct{}{}
+	}
+}
+
+// returns the index of needle in haystack or -1 if not found
+func (mc *controller) visualStartIdx() int {
+	for idx, u := range mc.uidProvider.Uids() {
+		if u == mc.visualStartUID {
+			return idx
+		}
+	}
+	return -1
+}