fix(display): integrate helpers and fix scrolling at screen bottom

- Re-integrated hint and completion rendering into the new Refresh cycle.
- Implemented robust terminal height probing to handle scrolling at the screen bottom.
- Cleaned up unused legacy display methods from the engine.
- Exported and standardized default multiline indicator styles.

Author: maxlandon

internal/display/engine.go

@@ -66,43 +66,6 @@ func Init(e *Engine, highlighter func([]rune) string) {
 	e.highlighter = highlighter
 }
 
-// refreshOld recomputes and redisplays the entire readline interface, except
-// the first lines of the primary prompt when the latter is a multiline one.
-func (e *Engine) refreshOld() {
-	fmt.Print(term.HideCursor)
-
-	// Go back to the first column, and if the primary prompt
-	// was not printed yet, back up to the line's beginning row.
-	term.MoveCursorBackwards(term.GetWidth())
-
-	if !e.primaryPrinted {
-		term.MoveCursorUp(e.cursorRow)
-	}
-
-	// Print either all or the last line of the prompt.
-	e.prompt.LastPrint()
-
-	// Get all positions required for the redisplay to come:
-	// prompt end (thus indentation), cursor positions, etc.
-	e.computeCoordinates(true)
-
-	// Print the line, and any of the secondary and right prompts.
-	e.displayLine()
-	e.displayMultilinePrompts()
-
-	// Display hints and completions, go back
-	// to the start of the line, then to cursor.
-	helpersMoved := e.displayHelpers()
-	if helpersMoved {
-		e.cursorHintToLineStart()
-		e.lineStartToCursorPos()
-	} else {
-		e.lineEndToCursorPos()
-	}
-
-	fmt.Print(term.ShowCursor)
-}
-
 // PrintPrimaryPrompt redraws the primary prompt.
 // There are relatively few cases where you want to use this.
 // It is currently only used when using clear-screen commands.
@@ -275,71 +238,6 @@ func (e *Engine) displayLine() {
 	}
 }
 
-func (e *Engine) displayMultilinePrompts() {
-	// If we have more than one line, write the columns.
-	if e.line.Lines() > 1 {
-		term.MoveCursorUp(e.lineRows)
-		term.MoveCursorBackwards(term.GetWidth())
-		e.prompt.MultilineColumnPrint()
-	}
-
-	// Then if we have a line at all, rewrite the last column
-	// character with any secondary prompt available.
-	if e.line.Lines() > 0 {
-		term.MoveCursorBackwards(term.GetWidth())
-		e.prompt.SecondaryPrint()
-		term.MoveCursorBackwards(term.GetWidth())
-		term.MoveCursorForwards(e.lineCol)
-	}
-
-	// Then prompt the right-sided prompt if possible.
-	e.prompt.RightPrint(e.lineCol, true)
-}
-
-// displayHelpers renders the hint and completion sections.
-// It assumes that the cursor is on the last line of input,
-// and goes back to this same line after displaying this.
-func (e *Engine) displayHelpers() bool {
-	// Recompute completions and hints if autocompletion is on.
-	e.completer.Autocomplete()
-
-	hintRows := ui.CoordinatesHint(e.hint)
-	compMatches := e.completer.Matches()
-	compSkip := e.completer.DisplaySkipped()
-
-	if e.hintRows == 0 && e.compRows == 0 && hintRows == 0 && (compMatches == 0 || compSkip) {
-		return false
-	}
-
-	fmt.Print(term.NewlineReturn)
-
-	prevHintRows := e.hintRows
-	prevCompRows := e.compRows
-
-	// Display hint and completions.
-	ui.DisplayHint(e.hint)
-
-	e.hintRows = ui.CoordinatesHint(e.hint)
-	if compMatches > 0 && !compSkip {
-		completion.Display(e.completer, e.AvailableHelperLines())
-		e.compRows = completion.Coordinates(e.completer)
-	} else {
-		e.completer.ResetUsedRows()
-		e.compRows = 0
-	}
-
-	if e.hintRows+e.compRows < prevHintRows+prevCompRows {
-		fmt.Print(term.ClearScreenBelow)
-	}
-
-	// Go back to the first line below the input line.
-	term.MoveCursorBackwards(term.GetWidth())
-	term.MoveCursorUp(e.compRows)
-	term.MoveCursorUp(e.hintRows)
-
-	return true
-}
-
 // lineEndToCursorPos moves the cursor from the end of the input line
 // to the current cursor position.
 func (e *Engine) lineEndToCursorPos() {

internal/display/refresh.go

@@ -5,9 +5,11 @@ import (
 	"strconv"
 
 	"github.com/reeflective/readline/internal/color"
+	"github.com/reeflective/readline/internal/completion"
 	"github.com/reeflective/readline/internal/core"
 	"github.com/reeflective/readline/internal/strutil"
 	"github.com/reeflective/readline/internal/term"
+	"github.com/reeflective/readline/internal/ui"
 )
 
 // Refresh recomputes and redisplays the entire readline interface, except
@@ -43,9 +45,9 @@ func (e *Engine) Refresh() {
 	if e.prompt.LastUsed() == 0 && e.line.Lines() > 0 {
 		var indicator string
 		if e.opts.GetBool("multiline-column-numbered") {
-			indicator = fmt.Sprintf("\x1b[1;30m%d\x1b[0m ", 1)
+			indicator = fmt.Sprintf(color.FgBlackBright+"%d"+color.Reset+" ", 1)
 		} else {
-			indicator = "\x1b[1;30m\U00002502 \x1b[0m"
+			indicator = ui.DefaultMultilineColumn
 		}
 
 		e.startCols += indicatorWidth
@@ -67,10 +69,53 @@ func (e *Engine) Refresh() {
 		e.lineCol, e.lineRows = core.CoordinatesLine(e.line, e.startCols)
 	}
 
-	// 3. Input Area Rendering
+	// Ensure that we have enough space to print the line.
+	// We probe the terminal to verify that we are not at the bottom of the screen.
+	// If we are, we scroll the screen to make space for the line.
+	if e.lineRows > 1 {
+		// 1. Probe the terminal height.
+		// We move the cursor down to the last line of the input line,
+		// and check if the cursor is at the expected position.
+		term.MoveCursorDown(e.lineRows - 1)
+		_, actualRow := e.keys.GetCursorPos()
+		term.MoveCursorUp(e.lineRows - 1)
+
+		// 2. Calculate the overshoot.
+		expectedRow := e.startRows + e.lineRows - 1
+		overshoot := expectedRow - actualRow
+
+		// 3. Scroll the screen if needed.
+		if overshoot > 0 {
+			// Move to the bottom of the terminal.
+			term.MoveCursorDown(actualRow - e.startRows)
+
+			// Scroll the screen by printing newlines.
+			for i := 0; i < overshoot; i++ {
+				fmt.Print("\n")
+			}
+
+			// Update the start row to reflect the scrolling.
+			e.startRows -= overshoot
+
+			// Move the cursor back up to the new start position.
+			term.MoveCursorUp(e.lineRows - 1)
+			term.MoveCursorForwards(e.startCols)
+		}
+	}
 
+	// 3. Input Area Rendering
 	e.renderInputArea()
+
 	// 4. Helpers Rendering
+	// We clear everything below the input area to ensure that no artifacts
+	// from previous renders (like longer lines or helpers) remain visible.
+	term.MoveCursorDown(1)
+	term.MoveCursorBackwards(term.GetWidth())
+	fmt.Print(term.ClearScreenBelow)
+	term.MoveCursorUp(1)
+	term.MoveCursorForwards(e.lineCol)
+
+	e.renderHelpers()
 
 	// 5. Final Cursor Positioning
 	// The cursor is currently at the end of the input line (lineRows, lineCol).
@@ -88,6 +133,68 @@ func (e *Engine) Refresh() {
 func (e *Engine) renderInputArea() {
 	e.displayLineRefactored()
 	e.renderMultilineIndicators()
+	e.renderRightPrompt()
+}
+
+func (e *Engine) renderHelpers() {
+	e.completer.Autocomplete()
+
+	// 1. Check if we have anything to print.
+	hintRows := ui.CoordinatesHint(e.hint)
+	compMatches := e.completer.Matches()
+	compSkip := e.completer.DisplaySkipped()
+
+	// 2. Clear below the input line to remove artifacts,
+	// unless we are at the bottom of the screen.
+	termHeight := term.GetLength()
+	if (e.startRows + e.lineRows) < termHeight {
+		term.MoveCursorDown(1)
+		term.MoveCursorBackwards(term.GetWidth())
+		fmt.Print(term.ClearScreenBelow)
+		term.MoveCursorUp(1)
+		term.MoveCursorForwards(e.lineCol)
+	}
+
+	if hintRows == 0 && (compMatches == 0 || compSkip) {
+		e.hintRows = 0
+		e.compRows = 0
+
+		return
+	}
+
+	fmt.Print(term.NewlineReturn)
+
+	// 3. Display Hints
+	ui.DisplayHint(e.hint)
+	e.hintRows = ui.CoordinatesHint(e.hint)
+
+	// 4. Display Completions
+	if compMatches > 0 && !compSkip {
+		completion.Display(e.completer, e.AvailableHelperLines())
+		e.compRows = completion.Coordinates(e.completer)
+	} else {
+		e.completer.ResetUsedRows()
+		e.compRows = 0
+	}
+
+	// 5. Restore Cursor to the "bottom of input area"
+	// The cursor is currently at the bottom of the helpers.
+	// We need to move it back up to the line just below the input text.
+	term.MoveCursorUp(e.compRows)
+	term.MoveCursorUp(e.hintRows)
+	term.MoveCursorUp(1)
+
+	// We are now on the same row as the end of the input line,
+	// but at column 0. We need to move to e.lineCol.
+	term.MoveCursorForwards(e.lineCol)
+}
+
+func (e *Engine) renderRightPrompt() {
+	e.prompt.RightPrint(e.lineCol, true)
+
+	// Restore cursor to the end of the input line.
+	term.MoveCursorBackwards(term.GetWidth())
+	term.MoveCursorForwards(e.lineCol)
 }
 
 func (e *Engine) displayLineRefactored() {
@@ -121,43 +228,49 @@ func (e *Engine) renderMultilineIndicators() {
 	if e.line.Lines() == 0 {
 		return
 	}
+
 	// 1. Determine if we need to print columns.
 	columns := e.opts.GetBool("multiline-column") ||
 		e.opts.GetBool("multiline-column-numbered") ||
 		e.opts.GetString("multiline-column-custom") != ""
 	promptEmpty := e.prompt.LastUsed() == 0
+
 	// If no columns are requested and the prompt is not empty, we have nothing to do.
 	if !columns && !promptEmpty {
 		return
 	}
+
 	// 2. Move to the top of the input area (first line).
 	term.MoveCursorUp(e.lineRows)
 	term.MoveCursorBackwards(term.GetWidth())
+
 	// 3. Print the indicators for subsequent lines (1..N).
 	printedLines := 0
 	numbered := e.opts.GetBool("multiline-column-numbered")
-	pipe := "\x1b[1;30m\U00002502 \x1b[0m"
-	angle := "\x1b[1;30m\U00002514 \x1b[0m"
+
+	// Indicators
+	pipe := ui.DefaultMultilineColumn
 
 	for i := 1; i <= e.line.Lines(); i++ {
-		var indicator string
+		fmt.Print("\n")
+
 		if numbered {
-			indicator = fmt.Sprintf("\x1b[1;30m%d\x1b[0m ", i+1)
+			fmt.Print(fmt.Sprintf(color.FgBlackBright+"%d"+color.Reset+" ", i+1))
 		} else if i == e.line.Lines() {
-			indicator = angle
+			e.prompt.SecondaryPrint()
 		} else {
-			indicator = pipe
+			fmt.Print(pipe)
 		}
 
-		fmt.Print("\n" + indicator)
-
 		printedLines++
 	}
+
 	// 4. Return cursor to the bottom of the input area.
 	correction := e.lineRows - printedLines
 	if correction > 0 {
 		term.MoveCursorDown(correction)
 	}
+
 	// 5. Restore horizontal position to the end of the input text.
 	term.MoveCursorBackwards(term.GetWidth())
 	term.MoveCursorForwards(e.lineCol)

internal/ui/prompt.go

@@ -6,15 +6,18 @@ import (
 	"strings"
 
 	"github.com/reeflective/readline/inputrc"
+	"github.com/reeflective/readline/internal/color"
 	"github.com/reeflective/readline/internal/core"
 	"github.com/reeflective/readline/internal/keymap"
 	"github.com/reeflective/readline/internal/strutil"
 	"github.com/reeflective/readline/internal/term"
 )
 
-const (
-	secondaryPromptDefault = "\x1b[1;30m\U00002514 \x1b[0m"
-	multilineColumnDefault = "\x1b[1;30m\U00002502 \x1b[0m"
+var (
+	// DefaultSecondaryPrompt is the default prompt to use for secondary lines.
+	DefaultSecondaryPrompt = color.FgBlackBright + "\U00002514 " + color.Reset
+	// DefaultMultilineColumn is the default prompt to use for multiline columns.
+	DefaultMultilineColumn = color.FgBlackBright + "\U00002502 " + color.Reset
 )
 
 // Prompt stores all prompt rendering/generation functions and is
@@ -181,7 +184,7 @@ func (p *Prompt) SecondaryPrint() {
 		return
 	}
 
-	fmt.Print(secondaryPromptDefault)
+	fmt.Print(DefaultSecondaryPrompt)
 }
 
 // MultilineColumnPrint prints the multiline editor column status indicator.
@@ -195,7 +198,7 @@ func (p *Prompt) MultilineColumnPrint() {
 	case numbered:
 		column := ""
 		for pos := range p.line.Lines() {
-			column += fmt.Sprintf("\n\x1b[1;30m%d\x1b[0m ", pos+2)
+			column += fmt.Sprintf("\n"+color.FgBlackBright+"%d"+color.Reset+" ", pos+2)
 		}
 		fmt.Print(column)
 	case len(custom) > 0:
@@ -207,7 +210,7 @@ func (p *Prompt) MultilineColumnPrint() {
 	case defaultCol:
 		column := ""
 		for range p.line.Lines() {
-			column += "\n" + multilineColumnDefault
+			column += "\n" + DefaultMultilineColumn
 		}
 		fmt.Print(column)
 	}