refactor function diffText (#3615)

VERSION

@@ -1 +1 @@
-0.158.0
+0.158.1

protocol/messenger_mention.go

@@ -139,10 +139,11 @@ type MentionState struct {
 	AtSignIdx    int
 	AtIdxs       []*AtIndexEntry
 	MentionEnd   int
-	PreviousText string  // searched text
+	PreviousText string
-	NewText      *string // the matched username
+	NewText      string
-	Start        int     // position after the @
+	Start        int
-	End          int     // position of the end of newText
+	End          int
+	operation    textOperation
 }
 
 func (ms *MentionState) String() string {
@@ -154,7 +155,7 @@ func (ms *MentionState) String() string {
 		atIdxsStr += fmt.Sprintf("%+v", entry)
 	}
 	return fmt.Sprintf("MentionState{AtSignIdx: %d, AtIdxs: [%s], MentionEnd: %d, PreviousText: %q, NewText: %s, Start: %d, End: %d}",
-		ms.AtSignIdx, atIdxsStr, ms.MentionEnd, ms.PreviousText, *ms.NewText, ms.Start, ms.End)
+		ms.AtSignIdx, atIdxsStr, ms.MentionEnd, ms.PreviousText, ms.NewText, ms.Start, ms.End)
 }
 
 type ChatMentionContext struct {
@@ -206,7 +207,7 @@ func (m *MentionManager) getChatMentionContext(chatID string) *ChatMentionContex
 }
 
 func (m *MentionManager) getMentionableUser(chatID string, pk string) (*MentionableUser, error) {
-	mentionableUsers, err := m.getMentionableUsers(chatID)
+	mentionableUsers, err := m.mentionableUserGetter.getMentionableUsers(chatID)
 	if err != nil {
 		return nil, err
 	}
@@ -283,7 +284,7 @@ func (m *MentionManager) ReplaceWithPublicKey(chatID, text string) (string, erro
 	if chat == nil {
 		return "", fmt.Errorf("chat not found when check mentions, chatID: %s", chatID)
 	}
-	mentionableUsers, err := m.getMentionableUsers(chatID)
+	mentionableUsers, err := m.mentionableUserGetter.getMentionableUsers(chatID)
 	if err != nil {
 		return "", err
 	}
@@ -292,28 +293,29 @@ func (m *MentionManager) ReplaceWithPublicKey(chatID, text string) (string, erro
 	return newText, nil
 }
 
-func (m *MentionManager) OnChangeText(chatID, text string) (*ChatMentionContext, error) {
+func (m *MentionManager) OnChangeText(chatID, fullText string) (*ChatMentionContext, error) {
 	ctx := m.getChatMentionContext(chatID)
-	diff := diffText(ctx.PreviousText, text)
+	diff := diffText(ctx.PreviousText, fullText)
 	if diff == nil {
 		return ctx, nil
 	}
-	ctx.PreviousText = text
+	ctx.PreviousText = fullText
 	if ctx.MentionState == nil {
 		ctx.MentionState = &MentionState{}
 	}
 	ctx.MentionState.PreviousText = diff.previousText
-	ctx.MentionState.NewText = &diff.newText
+	ctx.MentionState.NewText = diff.newText
 	ctx.MentionState.Start = diff.start
 	ctx.MentionState.End = diff.end
+	ctx.MentionState.operation = diff.operation
 
 	ctx.MentionState.AtIdxs = calcAtIdxs(ctx.MentionState)
 	m.logger.Debug("OnChangeText", zap.String("chatID", chatID), zap.Any("state", ctx.MentionState))
-	return m.CalculateSuggestions(chatID, text)
+	return m.calculateSuggestions(chatID, fullText)
 }
 
 func (m *MentionManager) recheckAtIdxs(chatID string, text string, publicKey string) (*ChatMentionContext, error) {
-	user, err := m.getMentionableUser(chatID, publicKey)
+	user, err := m.mentionableUserGetter.getMentionableUser(chatID, publicKey)
 	if err != nil {
 		return nil, err
 	}
@@ -326,58 +328,61 @@ func (m *MentionManager) recheckAtIdxs(chatID string, text string, publicKey str
 	return ctx, nil
 }
 
-func (m *MentionManager) CalculateSuggestions(chatID, text string) (*ChatMentionContext, error) {
+func (m *MentionManager) calculateSuggestions(chatID, fullText string) (*ChatMentionContext, error) {
 	ctx := m.getChatMentionContext(chatID)
 
 	mentionableUsers, err := m.mentionableUserGetter.getMentionableUsers(chatID)
 	if err != nil {
 		return nil, err
 	}
-	m.logger.Debug("CalculateSuggestions", zap.String("chatID", chatID), zap.String("text", text), zap.Int("num of mentionable user", len(mentionableUsers)))
+	m.logger.Debug("calculateSuggestions", zap.String("chatID", chatID), zap.String("fullText", fullText), zap.Int("num of mentionable user", len(mentionableUsers)))
 
-	m.calculateSuggestions(chatID, text, mentionableUsers)
+	m.calculateSuggestionsWithMentionableUsers(chatID, fullText, mentionableUsers)
 
 	return ctx, nil
 }
 
-func (m *MentionManager) calculateSuggestions(chatID string, text string, mentionableUsers map[string]*MentionableUser) {
+func (m *MentionManager) calculateSuggestionsWithMentionableUsers(chatID string, fullText string, mentionableUsers map[string]*MentionableUser) {
 	ctx := m.getChatMentionContext(chatID)
 	state := ctx.MentionState
-	newText := state.NewText
-	if newText == nil {
-		newText = &text
-	}
 
 	if len(state.AtIdxs) == 0 {
 		state.AtIdxs = nil
 		ctx.MentionSuggestions = nil
 		ctx.InputSegments = []InputSegment{{
 			Type:  Text,
-			Value: text,
+			Value: fullText,
 		}}
 		return
 	}
 
-	newAtIdxs := checkIdxForMentions(text, state.AtIdxs, mentionableUsers)
+	newAtIndexEntries := checkIdxForMentions(fullText, state.AtIdxs, mentionableUsers)
-	calculatedInput := calculateInput(text, newAtIdxs)
+	calculatedInput := calculateInput(fullText, newAtIndexEntries)
-	addition := state.Start <= state.End
-	var end int
-	if addition {
-		end = state.Start + len([]rune(*newText))
-	} else {
-		end = state.Start
-	}
-	atSignIdx := lastIndexOf(text, charAtSign, state.End)
-	searchedText := strings.ToLower(subs(text, atSignIdx+1, end))
-	m.logger.Debug("calculateSuggestions", zap.Int("atSignIdx", atSignIdx), zap.String("searchedText", searchedText), zap.String("text", text), zap.Any("state", state))
 
+	var end int
+	switch state.operation {
+	case textOperationAdd:
+		end = state.Start + len([]rune(state.NewText))
+	case textOperationDelete:
+		end = state.Start
+	case textOperationReplace:
+		end = state.Start + len([]rune(state.NewText))
+	default:
+		m.logger.Error("calculateSuggestionsWithMentionableUsers: unknown textOperation", zap.String("chatID", chatID), zap.String("fullText", fullText), zap.Any("state", state))
+	}
+
+	atSignIdx := lastIndexOf(fullText, charAtSign, end)
 	var suggestions map[string]*MentionableUser
-	if (atSignIdx <= state.Start && end-atSignIdx <= 100) || text[len(text)-1] == charAtSign[0] {
+	if atSignIdx != -1 {
+		searchedText := strings.ToLower(subs(fullText, atSignIdx+1, end))
+		m.logger.Debug("calculateSuggestionsWithMentionableUsers", zap.Int("atSignIdx", atSignIdx), zap.String("searchedText", searchedText), zap.String("fullText", fullText), zap.Any("state", state), zap.Int("end", end))
+		if end-atSignIdx <= 100 {
 			suggestions = getUserSuggestions(mentionableUsers, searchedText, -1)
 		}
+	}
 
 	state.AtSignIdx = atSignIdx
-	state.AtIdxs = newAtIdxs
+	state.AtIdxs = newAtIndexEntries
 	state.MentionEnd = end
 	ctx.InputSegments = calculatedInput
 	ctx.MentionSuggestions = suggestions
@@ -403,7 +408,13 @@ func (m *MentionManager) SelectMention(chatID, text, primaryName, publicKey stri
 
 	ctx.NewText = string(tr[:atSignIdx+1]) + primaryName + space + string(tr[mentionEnd:])
 
-	return m.recheckAtIdxs(chatID, ctx.NewText, publicKey)
+	ctx, err := m.recheckAtIdxs(chatID, ctx.NewText, publicKey)
+	if err != nil {
+		return nil, err
+	}
+	ctx.PreviousText = ctx.NewText
+	m.clearSuggestions(chatID)
+	return ctx, nil
 }
 
 func (m *MentionManager) clearSuggestions(chatID string) {
@@ -420,7 +431,7 @@ func (m *MentionManager) ClearMentions(chatID string) {
 }
 
 func (m *MentionManager) ToInputField(chatID, text string) (*ChatMentionContext, error) {
-	mentionableUsers, err := m.getMentionableUsers(chatID)
+	mentionableUsers, err := m.mentionableUserGetter.getMentionableUsers(chatID)
 	if err != nil {
 		return nil, err
 	}
@@ -821,25 +832,20 @@ type AtIndexEntry struct {
 	Checked bool
 
 	Mentioned bool
-	Mention   bool
 	NextAtIdx int
 }
 
+func (e *AtIndexEntry) String() string {
+	return fmt.Sprintf("{From: %d, To: %d, Checked: %t, Mentioned: %t, NextAtIdx: %d}", e.From, e.To, e.Checked, e.Mentioned, e.NextAtIdx)
+}
+
 // implementation reference: https://github.com/status-im/status-react/blob/04d0252e013d9c67862e77a3467dd32c3abde934/src/status_im/chat/models/mentions.cljs#L433
 func calcAtIdxs(state *MentionState) []*AtIndexEntry {
-	newIdxs := getAtSignIdxs(*state.NewText, state.Start)
+	newAtSignIndexes := getAtSignIdxs(state.NewText, state.Start)
-	newIdxCnt := len(newIdxs)
+	newAtSignIndexesCount := len(newAtSignIndexes)
-	var lastNewIdx *int
-	if newIdxCnt > 0 {
-		idx := newIdxs[newIdxCnt-1]
-		lastNewIdx = &idx
-	}
-	newTextLen := len([]rune(*state.NewText))
-	oldTextLen := len([]rune(state.PreviousText))
-	oldEnd := state.Start + oldTextLen
 	if len(state.AtIdxs) == 0 {
-		result := make([]*AtIndexEntry, newIdxCnt)
+		result := make([]*AtIndexEntry, newAtSignIndexesCount)
-		for i, idx := range newIdxs {
+		for i, idx := range newAtSignIndexes {
 			result[i] = &AtIndexEntry{
 				From:    idx,
 				Checked: false,
@@ -848,6 +854,9 @@ func calcAtIdxs(state *MentionState) []*AtIndexEntry {
 		return result
 	}
 
+	newTextLen := len([]rune(state.NewText))
+	oldTextLen := len([]rune(state.PreviousText))
+	oldEnd := state.Start + oldTextLen
 	diff := newTextLen - oldTextLen
 	var keptAtIdxs []*AtIndexEntry
 	for _, entry := range state.AtIdxs {
@@ -870,21 +879,26 @@ func calcAtIdxs(state *MentionState) []*AtIndexEntry {
 		}
 	}
 
-	var newState []*AtIndexEntry
+	var newAtIndexEntries []*AtIndexEntry
 	var added bool
+	var lastNewIdx *int
+	if newAtSignIndexesCount > 0 {
+		idx := newAtSignIndexes[newAtSignIndexesCount-1]
+		lastNewIdx = &idx
+	}
 	for _, entry := range keptAtIdxs {
 		if lastNewIdx != nil && entry.From > *lastNewIdx && !added {
-			newState = append(newState, makeAtIdxs(newIdxs)...)
+			newAtIndexEntries = append(newAtIndexEntries, makeAtIdxs(newAtSignIndexes)...)
-			newState = append(newState, entry)
+			newAtIndexEntries = append(newAtIndexEntries, entry)
 			added = true
 		} else {
-			newState = append(newState, entry)
+			newAtIndexEntries = append(newAtIndexEntries, entry)
 		}
 	}
 	if !added {
-		newState = append(newState, makeAtIdxs(newIdxs)...)
+		newAtIndexEntries = append(newAtIndexEntries, makeAtIdxs(newAtSignIndexes)...)
 	}
-	return newState
+	return newAtIndexEntries
 }
 
 func makeAtIdxs(idxs []int) []*AtIndexEntry {
@@ -898,26 +912,28 @@ func makeAtIdxs(idxs []int) []*AtIndexEntry {
 	return result
 }
 
-func getAtSignIdxs(text string, start int) []int {
+// getAtSignIdxs returns the indexes of all @ signs in the text.
-	return getAtSignIdxsHelper(text, start, 0, []int{})
+// delta is the offset of the text within the original text.
+func getAtSignIdxs(text string, delta int) []int {
+	return getAtSignIdxsHelper(text, delta, 0, []int{})
 }
 
-func getAtSignIdxsHelper(text string, start int, from int, idxs []int) []int {
+func getAtSignIdxsHelper(text string, delta int, from int, idxs []int) []int {
 	tr := []rune(text)
 	idx := strings.Index(string(tr[from:]), charAtSign)
 	if idx != -1 {
 		idx += from
-		idxs = append(idxs, start+idx)
+		idxs = append(idxs, delta+idx)
-		return getAtSignIdxsHelper(text, start, idx+1, idxs)
+		return getAtSignIdxsHelper(text, delta, idx+1, idxs)
 	}
 	return idxs
 }
 
-func checkEntry(text string, entry *AtIndexEntry, mentionableUsers map[string]*MentionableUser) *AtIndexEntry {
+func checkAtIndexEntry(fullText string, entry *AtIndexEntry, mentionableUsers map[string]*MentionableUser) *AtIndexEntry {
 	if entry.Checked {
 		return entry
 	}
-	result := MatchMention(text+charAtSign, mentionableUsers, entry.From)
+	result := MatchMention(fullText+charAtSign, mentionableUsers, entry.From)
 	if result != nil && result.Match != "" {
 		return &AtIndexEntry{
 			From:      entry.From,
@@ -928,36 +944,34 @@ func checkEntry(text string, entry *AtIndexEntry, mentionableUsers map[string]*M
 	}
 	return &AtIndexEntry{
 		From:    entry.From,
-		To:      len([]rune(text)),
+		To:      len([]rune(fullText)),
 		Checked: true,
-		Mention: false, // Mention vs Mentioned? wrong spelling?
 	}
 }
 
-func checkIdxForMentions(text string, idxs []*AtIndexEntry, mentionableUsers map[string]*MentionableUser) []*AtIndexEntry {
+func checkIdxForMentions(fullText string, currentAtIndexEntries []*AtIndexEntry, mentionableUsers map[string]*MentionableUser) []*AtIndexEntry {
-	var newIdxs []*AtIndexEntry
+	var newIndexEntries []*AtIndexEntry
-	for _, entry := range idxs {
+	for _, entry := range currentAtIndexEntries {
-		previousEntryIdx := len(newIdxs) - 1
+		previousEntryIdx := len(newIndexEntries) - 1
-		newEntry := checkEntry(text, entry, mentionableUsers)
+		newEntry := checkAtIndexEntry(fullText, entry, mentionableUsers)
-		if previousEntryIdx >= 0 && !newIdxs[previousEntryIdx].Mentioned {
+		if previousEntryIdx >= 0 && !newIndexEntries[previousEntryIdx].Mentioned {
-			newIdxs[previousEntryIdx].To = entry.From - 1
+			newIndexEntries[previousEntryIdx].To = entry.From - 1
 		}
 		if previousEntryIdx >= 0 {
-			newIdxs[previousEntryIdx].NextAtIdx = entry.From
+			newIndexEntries[previousEntryIdx].NextAtIdx = entry.From
 		}
-		// simulate (dissoc new-entry :next-at-idx)
 		newEntry.NextAtIdx = intUnknown
-		newIdxs = append(newIdxs, newEntry)
+		newIndexEntries = append(newIndexEntries, newEntry)
 	}
 
-	if len(newIdxs) > 0 {
+	if len(newIndexEntries) > 0 {
-		lastIdx := len(newIdxs) - 1
+		lastIdx := len(newIndexEntries) - 1
-		if newIdxs[lastIdx].Mentioned {
+		if newIndexEntries[lastIdx].Mentioned {
-			return newIdxs
+			return newIndexEntries
 		}
-		newIdxs[lastIdx].To = len([]rune(text)) - 1
+		newIndexEntries[lastIdx].To = len([]rune(fullText)) - 1
-		newIdxs[lastIdx].Checked = false
+		newIndexEntries[lastIdx].Checked = false
-		return newIdxs
+		return newIndexEntries
 	}
 
 	return nil
@@ -1129,7 +1143,7 @@ func toInfo(inputSegments []InputSegment) *MentionState {
 		AtIdxs:       []*AtIndexEntry{},
 		MentionEnd:   0,
 		PreviousText: "",
-		NewText:      &newText,
+		NewText:      newText,
 		Start:        intUnknown,
 	}
 
@@ -1157,8 +1171,7 @@ func toInfo(inputSegments []InputSegment) *MentionState {
 		}
 
 		state.MentionEnd += len(tr)
-		nt := string(tr[len(tr)-1])
+		state.NewText = string(tr[len(tr)-1])
-		state.NewText = &nt
 		state.Start += len(tr)
 		state.End += len(tr)
 	}
@@ -1201,26 +1214,20 @@ func reverse(r []rune) string {
 	return string(r)
 }
 
+type textOperation int
+
+const (
+	textOperationAdd textOperation = iota + 1
+	textOperationDelete
+	textOperationReplace
+)
+
 type TextDiff struct {
 	previousText string
-	newText      string // we always set it to empty if it's a delete operation
+	newText      string // if add operation, newText is the added text; if replace operation, newText is the text used to replace the previousText
-	start        int
+	start        int    // start index of the operation relate to previousText
-	end          int
+	end          int    // end index of the operation relate to previousText, always the same as start if the operation is add, range: start<=end<=len(previousText)-1
-}
+	operation    textOperation
-
-// hasCommonCharSequence checks if str1 has a common character sequence with str2.
-// It iterates through both strings and compares their characters one by one.
-// The function returns true if all characters in str1 can be found in str2 in the same order, but not necessarily consecutively.
-// This is helpful for determining if there is an insertion or deletion operation between two strings.
-func hasCommonCharSequence(str1, str2 []rune) bool {
-	i, j := 0, 0
-	for i < len(str1) && j < len(str2) {
-		if str1[i] == str2[j] {
-			i++
-		}
-		j++
-	}
-	return i == len(str1)
 }
 
 func diffText(oldText, newText string) *TextDiff {
@@ -1232,10 +1239,10 @@ func diffText(oldText, newText string) *TextDiff {
 	oldLen := len(t1)
 	newLen := len(t2)
 	if oldLen == 0 {
-		return &TextDiff{previousText: oldText, newText: newText, start: 0, end: 0}
+		return &TextDiff{previousText: oldText, newText: newText, start: 0, end: 0, operation: textOperationAdd}
 	}
 	if newLen == 0 {
-		return &TextDiff{previousText: oldText, newText: "", start: 0, end: oldLen}
+		return &TextDiff{previousText: oldText, newText: "", start: 0, end: oldLen, operation: textOperationReplace}
 	}
 
 	// if we reach here, t1 and t2 are not empty
@@ -1251,16 +1258,21 @@ func diffText(oldText, newText string) *TextDiff {
 	}
 
 	diff := &TextDiff{previousText: oldText, start: start}
-	if hasCommonCharSequence(t1, t2) { // is just a insert operation
+	if newLen > oldLen && (start == oldLen || oldEnd == 0 || start == oldEnd) {
+		diff.operation = textOperationAdd
 		diff.end = start
 		diff.newText = string(t2[start:newEnd])
+	} else if newLen < oldLen && (start == newLen || newEnd == 0 || start == newEnd) {
+		diff.operation = textOperationDelete
+		diff.end = oldEnd - 1
 	} else {
-		diff.end = newEnd
+		diff.operation = textOperationReplace
-		if oldLen > newLen {
+		if start == 0 && oldEnd == oldLen { // full replace
-			diff.end = oldEnd
+			diff.end = oldLen - 1
-		}
+			diff.newText = newText
-		if !hasCommonCharSequence(t2, t1) { // is not a delete operation
+		} else { // partial replace
-			diff.newText = string(t2[start:diff.end])
+			diff.end = oldEnd - 1
+			diff.newText = string(t2[start:newEnd])
 		}
 	}
 	return diff

protocol/messenger_mention_test.go

@@ -252,12 +252,11 @@ func TestGetAtSignIdxs(t *testing.T) {
 }
 
 func TestCalcAtIdxs(t *testing.T) {
-	newText := "@abc"
 	state := MentionState{
 		AtIdxs: []*AtIndexEntry{
 			{From: 0, To: 3, Checked: false},
 		},
-		NewText:      &newText,
+		NewText:      "@abc",
 		PreviousText: "",
 		Start:        0,
 	}
@@ -288,7 +287,7 @@ func TestToInfo(t *testing.T) {
 			},
 			MentionEnd:   19,
 			PreviousText: "",
-			NewText:      &newText,
+			NewText:      newText,
 			Start:        18,
 			End:          18,
 		}
@@ -505,6 +504,9 @@ func TestLastIndexOf(t *testing.T) {
 	//at-sign-idx 0 text @t searched-text t start 2 end 2 new-text
 	atSignIdx = lastIndexOf("@t", charAtSign, 2)
 	require.Equal(t, 0, atSignIdx)
+
+	atSignIdx = lastIndexOf("at", charAtSign, 3)
+	require.Equal(t, -1, atSignIdx)
 }
 
 func TestDiffText(t *testing.T) {
@@ -521,6 +523,7 @@ func TestDiffText(t *testing.T) {
 				end:          0,
 				previousText: "",
 				newText:      "A",
+				operation:    textOperationAdd,
 			},
 		},
 		{
@@ -531,6 +534,7 @@ func TestDiffText(t *testing.T) {
 				end:          1,
 				previousText: "A",
 				newText:      "b",
+				operation:    textOperationAdd,
 			},
 		},
 		{
@@ -541,16 +545,18 @@ func TestDiffText(t *testing.T) {
 				end:          2,
 				previousText: "Ab",
 				newText:      "c",
+				operation:    textOperationAdd,
 			},
 		},
 		{
-			oldText: "Abc",
+			oldText: "Ab",
-			newText: "Ac",
+			newText: "cAb",
 			expected: &TextDiff{
-				start:        1,
+				start:        0,
-				end:          2,
+				end:          0,
-				previousText: "Abc",
+				previousText: "Ab",
-				newText:      "",
+				newText:      "c",
+				operation:    textOperationAdd,
 			},
 		},
 		{
@@ -561,6 +567,7 @@ func TestDiffText(t *testing.T) {
 				end:          1,
 				previousText: "Ac",
 				newText:      "d",
+				operation:    textOperationAdd,
 			},
 		},
 		{
@@ -571,6 +578,7 @@ func TestDiffText(t *testing.T) {
 				end:          2,
 				previousText: "Adc",
 				newText:      " ee ",
+				operation:    textOperationAdd,
 			},
 		},
 		{
@@ -581,6 +589,62 @@ func TestDiffText(t *testing.T) {
 				end:          1,
 				previousText: "Ad ee c",
 				newText:      " fff ",
+				operation:    textOperationAdd,
+			},
+		},
+		{
+			oldText: "Abc",
+			newText: "Ac",
+			expected: &TextDiff{
+				start:        1,
+				end:          1,
+				previousText: "Abc",
+				newText:      "",
+				operation:    textOperationDelete,
+			},
+		},
+		{
+			oldText: "Abcd",
+			newText: "Ab",
+			expected: &TextDiff{
+				start:        2,
+				end:          3,
+				previousText: "Abcd",
+				newText:      "",
+				operation:    textOperationDelete,
+			},
+		},
+		{
+			oldText: "Abcd",
+			newText: "bcd",
+			expected: &TextDiff{
+				start:        0,
+				end:          0,
+				previousText: "Abcd",
+				newText:      "",
+				operation:    textOperationDelete,
+			},
+		},
+		{
+			oldText: "Abcd你好",
+			newText: "Abcd你",
+			expected: &TextDiff{
+				start:        5,
+				end:          5,
+				previousText: "Abcd你好",
+				newText:      "",
+				operation:    textOperationDelete,
+			},
+		},
+		{
+			oldText: "Abcd你好",
+			newText: "Abcd",
+			expected: &TextDiff{
+				start:        4,
+				end:          5,
+				previousText: "Abcd你好",
+				newText:      "",
+				operation:    textOperationDelete,
 			},
 		},
 		{
@@ -588,9 +652,10 @@ func TestDiffText(t *testing.T) {
 			newText: " fff d ee c",
 			expected: &TextDiff{
 				start:        0,
-				end:          1,
+				end:          0,
 				previousText: "A fff d ee c",
 				newText:      "",
+				operation:    textOperationDelete,
 			},
 		},
 		{
@@ -598,9 +663,10 @@ func TestDiffText(t *testing.T) {
 			newText: " fffee c",
 			expected: &TextDiff{
 				start:        4,
-				end:          7,
+				end:          6,
 				previousText: " fff d ee c",
 				newText:      "",
+				operation:    textOperationDelete,
 			},
 		},
 		{
@@ -608,6 +674,94 @@ func TestDiffText(t *testing.T) {
 			newText:  "abc",
 			expected: nil,
 		},
+		{
+			oldText: "abc",
+			newText: "ghij",
+			expected: &TextDiff{
+				start:        0,
+				end:          2,
+				previousText: "abc",
+				newText:      "ghij",
+				operation:    textOperationReplace,
+			},
+		},
+		{
+			oldText: "abc",
+			newText: "babcd",
+			expected: &TextDiff{
+				start:        0,
+				end:          2,
+				previousText: "abc",
+				newText:      "babcd",
+				operation:    textOperationReplace,
+			},
+		},
+		{
+			oldText: "abc",
+			newText: "baebcd",
+			expected: &TextDiff{
+				start:        0,
+				end:          2,
+				previousText: "abc",
+				newText:      "baebcd",
+				operation:    textOperationReplace,
+			},
+		},
+		{
+			oldText: "abc",
+			newText: "aefc",
+			expected: &TextDiff{
+				start:        1,
+				end:          1,
+				previousText: "abc",
+				newText:      "ef",
+				operation:    textOperationReplace,
+			},
+		},
+		{
+			oldText: "abc",
+			newText: "adc",
+			expected: &TextDiff{
+				start:        1,
+				end:          1,
+				previousText: "abc",
+				newText:      "d",
+				operation:    textOperationReplace,
+			},
+		},
+		{
+			oldText: "abc",
+			newText: "abd",
+			expected: &TextDiff{
+				start:        2,
+				end:          2,
+				previousText: "abc",
+				newText:      "d",
+				operation:    textOperationReplace,
+			},
+		},
+		{
+			oldText: "abc",
+			newText: "cbc",
+			expected: &TextDiff{
+				start:        0,
+				end:          0,
+				previousText: "abc",
+				newText:      "c",
+				operation:    textOperationReplace,
+			},
+		},
+		{
+			oldText: "abc",
+			newText: "ffbc",
+			expected: &TextDiff{
+				start:        0,
+				end:          0,
+				previousText: "abc",
+				newText:      "ff",
+				operation:    textOperationReplace,
+			},
+		},
 	}
 	for i, tc := range testCases {
 		t.Run(fmt.Sprintf("%d", i+1), func(t *testing.T) {
@@ -641,16 +795,19 @@ func TestMentionSuggestionCases(t *testing.T) {
 		{"@u2", 1},
 		{"@u23", 0},
 		{"@u2", 1},
+		{"@u2 abc", 0},
+		{"@u2 abc @u3", 1},
+		{"@u2 abc@u3", 0},
+		{"@u2 abc@u3 ", 0},
+		{"@u2 abc @u3", 1},
 	}
 
 	for i, tc := range testCases {
 		t.Run(fmt.Sprintf("%d", i+1), func(t *testing.T) {
-			_, err := mentionManager.OnChangeText(chatID, tc.inputText)
+			ctx, err := mentionManager.OnChangeText(chatID, tc.inputText)
 			require.NoError(t, err)
-			ctx, err := mentionManager.CalculateSuggestions(chatID, tc.inputText)
-			require.NoError(t, err)
-			require.Equal(t, tc.expectedSize, len(ctx.MentionSuggestions))
 			t.Logf("Input: %+v, MentionState:%+v, InputSegments:%+v\n", tc.inputText, ctx.MentionState, ctx.InputSegments)
+			require.Equal(t, tc.expectedSize, len(ctx.MentionSuggestions))
 		})
 	}
 }
@@ -693,22 +850,17 @@ func TestMentionSuggestionSpecialChars(t *testing.T) {
 	testCases := []struct {
 		inputText    string
 		expectedSize int
-		calculateSuggestion bool
 	}{
-		{"'", 0, false},
+		{"'", 0},
-		{"‘", 0, true},
+		{"‘", 0},
-		{"‘@", len(mentionableUserMap), true},
+		{"‘@", len(mentionableUserMap)},
 	}
 
 	for _, tc := range testCases {
 		ctx, err := mentionManager.OnChangeText(chatID, tc.inputText)
 		require.NoError(t, err)
-		if tc.calculateSuggestion {
-			ctx, err = mentionManager.CalculateSuggestions(chatID, tc.inputText)
-			require.NoError(t, err)
-			require.Equal(t, tc.expectedSize, len(ctx.MentionSuggestions))
-		}
 		t.Logf("Input: %+v, MentionState:%+v, InputSegments:%+v\n", tc.inputText, ctx.MentionState, ctx.InputSegments)
+		require.Equal(t, tc.expectedSize, len(ctx.MentionSuggestions))
 	}
 }
 
@@ -725,11 +877,10 @@ func TestMentionSuggestionAtSignSpaceCases(t *testing.T) {
 	testCases := []struct {
 		inputText    string
 		expectedSize int
-		calculateSuggestion bool
 	}{
-		{"@", len(mentionableUserMap), true},
+		{"@", len(mentionableUserMap)},
-		{"@ ", 0, true},
+		{"@ ", 0},
-		{"@ @", len(mentionableUserMap), true},
+		{"@ @", len(mentionableUserMap)},
 	}
 
 	var ctx *ChatMentionContext
@@ -738,12 +889,7 @@ func TestMentionSuggestionAtSignSpaceCases(t *testing.T) {
 		ctx, err = mentionManager.OnChangeText(chatID, tc.inputText)
 		require.NoError(t, err)
 		t.Logf("After OnChangeText, Input: %+v, MentionState:%+v, InputSegments:%+v\n", tc.inputText, ctx.MentionState, ctx.InputSegments)
-		if tc.calculateSuggestion {
-			ctx, err = mentionManager.CalculateSuggestions(chatID, tc.inputText)
-			require.NoError(t, err)
 		require.Equal(t, tc.expectedSize, len(ctx.MentionSuggestions))
-			t.Logf("After CalculateSuggestions, Input: %+v, MentionState:%+v, InputSegments:%+v\n", tc.inputText, ctx.MentionState, ctx.InputSegments)
-		}
 	}
 	require.Len(t, ctx.InputSegments, 3)
 	require.Equal(t, Mention, ctx.InputSegments[0].Type)
@@ -754,6 +900,29 @@ func TestMentionSuggestionAtSignSpaceCases(t *testing.T) {
 	require.Equal(t, "@", ctx.InputSegments[2].Value)
 }
 
+func TestSelectMention(t *testing.T) {
+	_, chatID, mentionManager := setupMentionSuggestionTest(t, nil)
+
+	text := "@u2 abc"
+	ctx, err := mentionManager.OnChangeText(chatID, text)
+	require.NoError(t, err)
+	require.Equal(t, 0, len(ctx.MentionSuggestions))
+
+	ctx, err = mentionManager.OnChangeText(chatID, "@u abc")
+	require.NoError(t, err)
+	require.Equal(t, 3, len(ctx.MentionSuggestions))
+
+	ctx, err = mentionManager.SelectMention(chatID, "@u abc", "u2", "0xpk2")
+	require.NoError(t, err)
+	require.Equal(t, 0, len(ctx.MentionSuggestions))
+	require.Equal(t, text, ctx.NewText)
+	require.Equal(t, text, ctx.PreviousText)
+
+	ctx, err = mentionManager.OnChangeText(chatID, text)
+	require.NoError(t, err)
+	require.Equal(t, 0, len(ctx.MentionSuggestions))
+}
+
 func setupMentionSuggestionTest(t *testing.T, mentionableUserMapInput map[string]*MentionableUser) (map[string]*MentionableUser, string, *MentionManager) {
 	mentionableUserMap := mentionableUserMapInput
 	if mentionableUserMap == nil {