feat: improve textbox editor behaviour

tui.go

@@ -148,12 +148,14 @@ type App struct {
 	pendingZ              bool
 	searching             bool
 	searchQuery           string
+	searchEditor          textEditor
 	searchOrigin          int
 	helpVisible           bool
 	helpScroll            int
 	writeMode             writeMode
 	writeThreadID         string
 	replyDraft            string
+	replyEditor           textEditor
 	resolveTarget         bool
 	autoMergeTarget       bool
 	mergeMethod           string
@@ -197,6 +199,7 @@ type App struct {
 	aiMode                 aiMode
 	aiMenuIndex            int
 	aiInput                string
+	aiInputEditor          textEditor
 	aiPreview              AIPreview
 	aiCancel               context.CancelFunc
 	aiStatus               AIProviderStatus
@@ -298,6 +301,18 @@ func (m App) Init() tea.Cmd {
 	return tea.Batch(commands...)
 }
 
+func (m *App) resetInputEditor(editor *textEditor, text string) {
+	*editor = newTextEditor(text, m.editorMode == "vim")
+	editor.keys = m.keybindings
+	editor.hardwareCursor = m.cursorOutput != nil
+}
+
+func (m *App) resetSearchEditor(text string) {
+	m.searchEditor = newTextEditor(text, false)
+	m.searchEditor.keys = m.keybindings
+	m.searchEditor.hardwareCursor = m.cursorOutput != nil
+}
+
 func (m App) nextTick() tea.Cmd {
 	return tea.Tick(m.adaptivePollInterval(time.Now()), func(t time.Time) tea.Msg { return tickMsg(t) })
 }
@@ -416,6 +431,7 @@ func (m *App) startReply() {
 	}
 	m.writeMode, m.writeThreadID, m.replyDraft, m.err = writeReply, thread.ID, "", nil
 	m.restoreReplyDraft(thread.ID)
+	m.resetInputEditor(&m.replyEditor, m.replyDraft)
 	m.folded[thread.ID] = false
 	m.focusThreadDetail()
 	m.scroll = m.detailMaxScroll()
@@ -583,30 +599,28 @@ func (m App) updateWriteInput(key tea.KeyMsg) (tea.Model, tea.Cmd) {
 	case writeReply:
 		switch k {
 		case "esc":
-			m.writeMode, m.replyDraft, m.writeThreadID = writeNone, "", ""
-			m.scroll = min(m.scroll, m.detailMaxScroll())
+			if m.replyEditor.Modal && m.replyEditor.Mode != textEditorNormal {
+				m.replyEditor.handleKeyAtWidth(key, true, m.threadInputWidth())
+				m.replyDraft = m.replyEditor.Text
+			} else {
+				m.writeMode, m.replyDraft, m.replyEditor, m.writeThreadID =
+					writeNone, "", textEditor{}, ""
+				m.scroll = min(m.scroll, m.detailMaxScroll())
+			}
 		case "ctrl+s":
 			if strings.TrimSpace(m.replyDraft) == "" {
 				m.err = errors.New("reply cannot be empty")
 			} else {
 				m.writeMode, m.err = writeReplyConfirm, nil
 			}
-		case "enter":
-			m.replyDraft += "\n"
-		case "backspace":
-			runes := []rune(m.replyDraft)
-			if len(runes) > 0 {
-				m.replyDraft = string(runes[:len(runes)-1])
-			}
-			m.err = nil
 		default:
-			if key.Type == tea.KeyRunes || key.Type == tea.KeySpace {
-				m.replyDraft += textInputKeyValue(key)
+			if m.replyEditor.handleKeyAtWidth(key, true, m.threadInputWidth()) {
+				m.replyDraft = m.replyEditor.Text
 				m.err = nil
 			}
 		}
 		if m.writeMode == writeReply {
-			m.scroll = m.detailMaxScroll()
+			m.ensureThreadInputCursorVisible()
 			return m, m.queueReplyDraft()
 		}
 	case writeReplyConfirm:
@@ -997,7 +1011,7 @@ func (m App) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		if err := m.drafts.delete(draftKey); err != nil {
 			m.recordHealth("draft persistence", healthWarning, err.Error())
 		}
-		m.replyDraft, m.writeThreadID = "", ""
+		m.replyDraft, m.replyEditor, m.writeThreadID = "", textEditor{}, ""
 		m.err = nil
 		m.lastRefresh = time.Now()
 		return m, m.difflet.setState(diffletSuccess)
@@ -1130,29 +1144,34 @@ func (m App) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		case "ctrl+c":
 			return m, tea.Quit
 		case "esc":
-			m.searching, m.searchQuery = false, ""
-			m.threadIndex = clamp(m.searchOrigin, 0, len(m.details.Threads)-1)
-			m.scroll = 0
+			if m.searchEditor.Modal && m.searchEditor.Mode != textEditorNormal {
+				m.searchEditor.handleKey(key, false)
+				m.searchQuery = m.searchEditor.Text
+			} else {
+				m.searching, m.searchQuery, m.searchEditor = false, "", textEditor{}
+				m.threadIndex = clamp(m.searchOrigin, 0, len(m.details.Threads)-1)
+				m.scroll = 0
+			}
 		case "enter":
 			m.searching = false
 		case "up":
 			m.moveSearch(-1)
 		case "down", "tab":
 			m.moveSearch(1)
-		case "backspace":
-			runes := []rune(m.searchQuery)
-			if len(runes) > 0 {
-				m.searchQuery = string(runes[:len(runes)-1])
-				m.selectBestSearchMatch()
-			}
 		case "ctrl+u":
-			m.searchQuery = ""
-			m.threadIndex = clamp(m.searchOrigin, 0, len(m.details.Threads)-1)
-			m.scroll = 0
+			if !m.searchEditor.Modal || m.searchEditor.Mode == textEditorInsert {
+				m.resetSearchEditor("")
+				m.searchQuery = ""
+				m.threadIndex = clamp(m.searchOrigin, 0, len(m.details.Threads)-1)
+				m.scroll = 0
+			}
 		default:
-			if key.Type == tea.KeyRunes || key.Type == tea.KeySpace {
-				m.searchQuery += textInputKeyValue(key)
-				m.selectBestSearchMatch()
+			before := m.searchEditor.Text
+			if m.searchEditor.handleKey(key, false) {
+				m.searchQuery = m.searchEditor.Text
+				if m.searchQuery != before {
+					m.selectBestSearchMatch()
+				}
 			}
 		}
 		return m, nil
@@ -1205,12 +1224,13 @@ func (m App) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		}
 	case "F":
 		if m.screen == threadScreen {
-			m.searchQuery = ""
+			m.searchQuery, m.searchEditor = "", textEditor{}
 			m.threadIndex = clamp(m.threadIndex, 0, len(m.details.Threads)-1)
 		}
 	case "/":
 		if m.screen == threadScreen {
 			m.searching, m.searchQuery, m.searchOrigin = true, "", m.threadIndex
+			m.resetSearchEditor("")
 			m.focus, m.listHidden, m.scroll = threadListPane, false, 0
 		}
 	case "r":
@@ -2168,17 +2188,20 @@ func (m App) viewWritePopup() string {
 			"",
 		}
 		lines = append(lines, renderTextInput(
-			m.replyDraft, width-2, m.cursorOutput != nil,
+			m.replyEditor, width-2, m.cursorOutput != nil,
 		)...)
 		if m.err != nil {
 			lines = append(lines, "", badStyle.Render(m.err.Error()))
 		}
-		lines = append(lines, "", dimStyle.Render(fmt.Sprintf(
-			"%s newline  •  %s review  •  %s cancel",
-			primaryKeyLabel(m.keybindings.Input.Newline),
-			primaryKeyLabel(m.keybindings.Input.Submit),
-			primaryKeyLabel(m.keybindings.Input.Cancel),
-		)))
+		if m.editorMode != "vim" {
+			lines = append(lines, "", dimStyle.Render(fmt.Sprintf(
+				"%s newline  •  %s review  •  %s %s",
+				primaryKeyLabel(m.keybindings.Input.Newline),
+				primaryKeyLabel(m.keybindings.Input.Submit),
+				primaryKeyLabel(m.keybindings.Input.Cancel),
+				m.inputCancelAction(),
+			)))
+		}
 	case writeReplyConfirm:
 		lines = []string{titleStyle.Render("Submit this reply to " + location + "?"), ""}
 		lines = append(lines, renderCommentMarkdown(m.replyDraft, width-2)...)
@@ -2293,9 +2316,9 @@ func (m App) helpBindings() []helpBinding {
 			{keyLabel(m.keybindings.Input.Cancel), "Return to Normal mode or cancel the editor"},
 			{combinedKeyLabel(m.keybindings.Navigation.PageDown, m.keybindings.Navigation.PageUp), "Move through the description by half a page"},
 			{combinedKeyLabel(m.keybindings.Input.PreviousCompletion, m.keybindings.Input.NextCompletion), "Select the previous / next branch or user completion"},
-			{combinedKeyLabel(m.keybindings.Input.NextField, m.keybindings.Input.Newline), "Complete the selected branch or user"},
+			{keyLabel(m.keybindings.Input.Newline), "Complete the selected branch or user"},
 		}
-		if m.prEditEditors[prEditBodyField].Modal {
+		if m.editorMode == "vim" {
 			bindings = append(bindings,
 				helpBinding{combinedKeyLabel(
 					m.keybindings.Navigation.Left, m.keybindings.Navigation.Down,
@@ -2312,7 +2335,7 @@ func (m App) helpBindings() []helpBinding {
 				), "Move to the line start, first non-blank, or line end"},
 				helpBinding{combinedKeyLabel(
 					m.keybindings.Vim.GoPrefix, m.keybindings.Navigation.Last,
-				), "Move to the start / end of the description"},
+				), "Move to the start / end of the active field"},
 				helpBinding{combinedKeyLabel(
 					m.keybindings.Vim.Insert, m.keybindings.Vim.Append,
 					m.keybindings.Vim.InsertLineStart, m.keybindings.Vim.AppendLineEnd,
@@ -2320,7 +2343,7 @@ func (m App) helpBindings() []helpBinding {
 				), "Enter Insert mode"},
 				helpBinding{combinedKeyLabel(
 					m.keybindings.Vim.OpenBelow, m.keybindings.Vim.OpenAbove,
-				), "Open a line below / above"},
+				), "Open a description line below / above"},
 				helpBinding{combinedKeyLabel(
 					m.keybindings.Vim.Visual, m.keybindings.Vim.VisualLine,
 				), "Start character-wise / line-wise Visual mode"},
@@ -2343,7 +2366,7 @@ func (m App) helpBindings() []helpBinding {
 				helpBinding{combinedKeyLabel(
 					m.keybindings.Navigation.Left, m.keybindings.Navigation.Down,
 					m.keybindings.Navigation.Up, m.keybindings.Navigation.Right,
-				), "Move the description cursor"},
+				), "Move the active field cursor"},
 				helpBinding{combinedKeyLabel(
 					m.keybindings.Input.LineStart, m.keybindings.Input.LineEnd,
 				), "Move to the start / end of the current visual line"},
@@ -2695,6 +2718,34 @@ func (m App) viewDashboardWithLines(lines []string) string {
 	return view
 }
 
+func (m App) activeInputEditor() (textEditor, string, bool) {
+	if m.helpVisible {
+		return textEditor{}, "", false
+	}
+	switch {
+	case m.writeMode == writeReply:
+		return m.replyEditor, "REPLY", m.replyEditor.Modal
+	case m.aiMode == aiDiscussion:
+		return m.aiInputEditor, "AI DISCUSSION", m.aiInputEditor.Modal
+	case m.writeMode == writePREdit:
+		contexts := [...]string{
+			"EDIT TITLE", "EDIT TARGET BRANCH", "EDIT REVIEWERS",
+			"EDIT ASSIGNEES", "EDIT DESCRIPTION",
+		}
+		editor := m.prEditEditors[m.prEditField]
+		return editor, contexts[m.prEditField], editor.Modal
+	default:
+		return textEditor{}, "", false
+	}
+}
+
+func (m App) inputCancelAction() string {
+	if m.editorMode == "vim" {
+		return "normal/cancel"
+	}
+	return "cancel"
+}
+
 func (m App) dashboardDisplayLines() []string {
 	mascot := m.difflet.frameLines()
 	if len(mascot) == diffletHeight && !m.diffletHiddenForCurrentView() {
@@ -3488,18 +3539,27 @@ func (m App) viewThreads() string {
 			primaryKeyLabel(m.keybindings.Input.Cancel),
 		)
 	} else if m.writeMode == writeReply {
-		help = fmt.Sprintf(
-			"reply inline • %s newline • %s review • %s cancel",
-			primaryKeyLabel(m.keybindings.Input.Newline),
-			primaryKeyLabel(m.keybindings.Input.Submit),
-			primaryKeyLabel(m.keybindings.Input.Cancel),
-		)
+		if m.editorMode == "vim" {
+			help = fmt.Sprintf(
+				"%s review • %s normal/cancel",
+				primaryKeyLabel(m.keybindings.Input.Submit),
+				primaryKeyLabel(m.keybindings.Input.Cancel),
+			)
+		} else {
+			help = fmt.Sprintf(
+				"reply inline • arrows move • %s newline • %s review • %s cancel",
+				primaryKeyLabel(m.keybindings.Input.Newline),
+				primaryKeyLabel(m.keybindings.Input.Submit),
+				primaryKeyLabel(m.keybindings.Input.Cancel),
+			)
+		}
 	} else if m.aiMode == aiDiscussion {
 		help = fmt.Sprintf(
-			"local AI discussion • %s newline • %s prepare • %s cancel",
+			"local AI discussion • arrows move • %s newline • %s prepare • %s %s",
 			primaryKeyLabel(m.keybindings.Input.Newline),
 			primaryKeyLabel(m.keybindings.Input.Submit),
 			primaryKeyLabel(m.keybindings.Input.Cancel),
+			m.inputCancelAction(),
 		)
 	}
 	m.positionThreadInputHardwareCursor()
@@ -3520,9 +3580,8 @@ func (m App) threadList(width, height int) string {
 	lines := []string{titleStyle.Render(fmt.Sprintf("Threads (%d/%d)", len(matches), len(m.details.Threads)))}
 	if m.searching {
 		queryWidth := max(1, innerWidth-len("Filter: ")-1)
-		query := ansi.Truncate(m.searchQuery, queryWidth, "…")
-		lines = append(lines, titleStyle.Render("Filter: ")+query+
-			inputCursorFallback(m.cursorOutput != nil))
+		query := renderSingleLineInput(m.searchEditor, queryWidth, m.cursorOutput != nil)
+		lines = append(lines, titleStyle.Render("Filter: ")+query)
 	}
 	if m.loading && len(m.details.Threads) == 0 {
 		lines = append(lines, "Loading…")
@@ -3839,7 +3898,9 @@ func (m App) inlineReplyLines(width int) []detailLine {
 	}
 	textWidth := max(1, width-5)
 	lineIndex := 0
-	for _, part := range renderTextInput(m.replyDraft, textWidth, m.cursorOutput != nil) {
+	for _, part := range renderTextInput(
+		m.replyEditor, textWidth, m.cursorOutput != nil,
+	) {
 		lines = append(lines, detailLine{
 			rail: rail, anchor: fmt.Sprintf("reply:body:%d", lineIndex), text: part,
 		})
@@ -3848,48 +3909,72 @@ func (m App) inlineReplyLines(width int) []detailLine {
 	if m.err != nil {
 		lines = append(lines, detailLine{rail: rail, text: badStyle.Render(m.err.Error())})
 	}
-	lines = append(lines, detailLine{
-		rail: rail,
-		text: dimStyle.Render(fmt.Sprintf(
-			"%s newline  •  %s review  •  %s cancel",
-			primaryKeyLabel(m.keybindings.Input.Newline),
-			primaryKeyLabel(m.keybindings.Input.Submit),
-			primaryKeyLabel(m.keybindings.Input.Cancel),
-		)),
-	})
+	if m.editorMode != "vim" {
+		lines = append(lines, detailLine{
+			rail: rail,
+			text: dimStyle.Render(fmt.Sprintf(
+				"%s newline  •  %s review  •  %s %s",
+				primaryKeyLabel(m.keybindings.Input.Newline),
+				primaryKeyLabel(m.keybindings.Input.Submit),
+				primaryKeyLabel(m.keybindings.Input.Cancel),
+				m.inputCancelAction(),
+			)),
+		})
+	}
 	return lines
 }
 
-func inputCursorFallback(hardwareCursor bool) string {
-	if hardwareCursor {
-		return ""
+func renderTextInput(editor textEditor, width int, hardwareCursor bool) []string {
+	editor.hardwareCursor = hardwareCursor
+	rendered := renderTextEditor(editor, width, true)
+	lines := make([]string, 0, len(rendered))
+	for _, line := range rendered {
+		lines = append(lines, line.text)
 	}
-	return "\x1b[4m \x1b[24m"
+	return lines
 }
 
-func renderTextInput(value string, width int, hardwareCursor bool) []string {
-	const cursorSentinel = "\ue000"
-	if hardwareCursor {
-		value += cursorSentinel
-	} else {
-		value += inputCursorFallback(false)
+func renderSingleLineInput(editor textEditor, width int, hardwareCursor bool) string {
+	editor.hardwareCursor = hardwareCursor
+	rendered := renderTextEditor(editor, width, true)
+	return rendered[editorCursorVisualLine(editor, width)].text
+}
+
+func (m App) threadInputWidth() int {
+	width, _ := m.detailPaneSize()
+	return max(1, width-5)
+}
+
+func (m *App) ensureThreadInputCursorVisible() {
+	if m.writeMode != writeReply && m.aiMode != aiDiscussion {
+		return
 	}
-	var lines []string
-	for _, sourceLine := range strings.Split(value, "\n") {
-		wrapped := ansi.Hardwrap(ansi.Wordwrap(sourceLine, width, ""), width, false)
-		if hardwareCursor {
-			wrapped = strings.TrimSuffix(wrapped, cursorSentinel)
+	width, height := m.detailPaneSize()
+	editor, prefix := m.replyEditor, "reply:body:"
+	if m.aiMode == aiDiscussion {
+		editor, prefix = m.aiInputEditor, "ai-discussion:body:"
+	}
+	visualLine := editorCursorVisualLine(editor, m.threadInputWidth())
+	wantedAnchor := fmt.Sprintf("%s%d", prefix, visualLine)
+	lines := m.renderedDetailLines(width)
+	cursorLine := -1
+	for index := range lines {
+		if lines[index].anchor == wantedAnchor {
+			cursorLine = index
+			break
 		}
-		lines = append(lines, strings.Split(wrapped, "\n")...)
 	}
-	return lines
-}
-
-func textInputKeyValue(key tea.KeyMsg) string {
-	if key.Type == tea.KeySpace {
-		return " "
+	if cursorLine < 0 {
+		return
 	}
-	return string(key.Runes)
+	viewportHeight := max(1, height-2)
+	switch {
+	case cursorLine < m.scroll:
+		m.scroll = cursorLine
+	case cursorLine >= m.scroll+viewportHeight:
+		m.scroll = cursorLine - viewportHeight + 1
+	}
+	m.scroll = clamp(m.scroll, 0, max(0, len(lines)-viewportHeight))
 }
 
 func (m App) positionThreadInputHardwareCursor() {
@@ -3906,10 +3991,13 @@ func (m App) positionThreadInputHardwareCursor() {
 			paneWidth = m.threadListWidth()
 		}
 		queryWidth := max(1, max(1, paneWidth-2)-len("Filter: ")-1)
-		query := ansi.Truncate(m.searchQuery, queryWidth, "…")
+		if m.searchEditor.Mode != textEditorInsert {
+			return
+		}
+		_, column := editorCursorVisualPosition(m.searchEditor, queryWidth)
 		m.cursorOutput.SetCursor(
 			true,
-			2+ansi.StringWidth("Filter: ")+ansi.StringWidth(query),
+			2+ansi.StringWidth("Filter: ")+column,
 			m.contentTop+topLines+3,
 		)
 		return
@@ -3923,10 +4011,20 @@ func (m App) positionThreadInputHardwareCursor() {
 	if m.aiMode == aiDiscussion {
 		prefix = "ai-discussion:body:"
 	}
+	editor := m.replyEditor
+	if m.aiMode == aiDiscussion {
+		editor = m.aiInputEditor
+	}
+	if editor.Mode != textEditorInsert {
+		return
+	}
+	visualLine, column := editorCursorVisualPosition(editor, m.threadInputWidth())
 	cursorLine := -1
+	wantedAnchor := fmt.Sprintf("%s%d", prefix, visualLine)
 	for index := range lines {
-		if strings.HasPrefix(lines[index].anchor, prefix) {
+		if lines[index].anchor == wantedAnchor {
 			cursorLine = index
+			break
 		}
 	}
 	if cursorLine < 0 {
@@ -3945,7 +4043,7 @@ func (m App) positionThreadInputHardwareCursor() {
 	line := lines[cursorLine]
 	m.cursorOutput.SetCursor(
 		true,
-		paneStart+2+ansi.StringWidth(line.rail)+ansi.StringWidth(line.fixed+line.text),
+		paneStart+2+ansi.StringWidth(line.rail+line.fixed)+column,
 		m.contentTop+topLines+2+screenLine,
 	)
 }
@@ -4226,21 +4324,47 @@ func (m App) frame(lines []string, help string) string {
 	if status == "" && !m.lastRefresh.IsZero() {
 		status = dimStyle.Render("updated " + m.lastRefresh.Format("15:04:05"))
 	}
-	footer := truncate(help, m.width)
+	footerWidth := m.width
 	if status != "" {
-		footer = truncate(help, max(0, m.width-lipgloss.Width(status)-2)) + "  " + status
+		footerWidth = max(0, m.width-lipgloss.Width(status)-2)
+	}
+	footer := m.renderFooter(help, footerWidth)
+	if status != "" {
+		footer += "  " + status
 	}
 	bodyLines := strings.Split(body, "\n")
-	if len(bodyLines) > max(0, m.height-1) {
-		bodyLines = bodyLines[:max(0, m.height-1)]
+	bodyHeight := max(0, m.height-1)
+	if len(bodyLines) > bodyHeight {
+		bodyLines = bodyLines[:bodyHeight]
 	}
 	for i := range bodyLines {
 		bodyLines[i] = ansi.Truncate(bodyLines[i], m.width, "")
 	}
-	bodyLines = append(bodyLines, ansi.Truncate(dimStyle.Render(footer), m.width, ""))
+	for len(bodyLines) < bodyHeight {
+		bodyLines = append(bodyLines, "")
+	}
+	bodyLines = append(bodyLines, ansi.Truncate(footer, m.width, ""))
 	return lipgloss.NewStyle().Width(m.width).Height(m.height).Render(strings.Join(bodyLines, "\n"))
 }
 
+func (m App) renderFooter(help string, width int) string {
+	if width <= 0 {
+		return ""
+	}
+	editor, context, ok := m.activeInputEditor()
+	if !ok {
+		return dimStyle.Render(truncate(help, width))
+	}
+	mode := activeStyle.Render(" " + editor.modeLabel() + " ")
+	contextLabel := titleStyle.Render(context)
+	prefix := mode + " " + contextLabel
+	remaining := width - lipgloss.Width(prefix)
+	if remaining <= 2 {
+		return ansi.Truncate(prefix, width, "")
+	}
+	return prefix + "  " + dimStyle.Render(truncate(help, remaining-2))
+}
+
 func (m App) restingDiffletState() diffletState {
 	if m.err != nil {
 		return diffletSad