feat(textarea) Add multiline placeholder

Add the capability to show a multiline placeholder. Some refactoring was
required to improve readability and improve logic.

End of line buffer character was only shown when line numbers were
displayed which requires some verification whether this is the intended
outcome. This change resolves this issue.

go.mod

@@ -3,6 +3,7 @@ module github.com/charmbracelet/bubbles
 go 1.18
 
 require (
+	github.com/acarl005/stripansi v0.0.0-20180116102854-5a71ef0e047d
 	github.com/atotto/clipboard v0.1.4
 	github.com/charmbracelet/bubbletea v0.25.0
 	github.com/charmbracelet/harmonica v0.2.0

go.sum

@@ -1,3 +1,5 @@
+github.com/acarl005/stripansi v0.0.0-20180116102854-5a71ef0e047d h1:licZJFw2RwpHMqeKTCYkitsPqHNxTmd4SNR5r94FGM8=
+github.com/acarl005/stripansi v0.0.0-20180116102854-5a71ef0e047d/go.mod h1:asat636LX7Bqt5lYEZ27JNDcqxfjdBQuJ/MM4CN/Lzo=
 github.com/atotto/clipboard v0.1.4 h1:EH0zSVneZPSuFR11BlR9YppQTVDbh5+16AmcJi4g1z4=
 github.com/atotto/clipboard v0.1.4/go.mod h1:ZY9tmq7sm5xIbd9bOK4onWV4S6X0u6GY7Vn0Yu86PYI=
 github.com/aymanbagabas/go-osc52/v2 v2.0.1 h1:HwpRHbFMcZLEVr42D4p7XBqjyuxQH5SMiErDT4WkJ2k=

textarea/textarea.go

@@ -3,6 +3,7 @@ package textarea
 import (
 	"crypto/sha256"
 	"fmt"
+	"strconv"
 	"strings"
 	"unicode"
 
@@ -1166,36 +1167,67 @@ func (m Model) getPromptString(displayLine int) (prompt string) {
 func (m Model) placeholderView() string {
 	var (
 		s     strings.Builder
-		p     = rw.Truncate(m.Placeholder, m.width, "...")
+		p     = m.Placeholder
 		style = m.style.Placeholder.Inline(true)
 	)
 
-	prompt := m.getPromptString(0)
-	prompt = m.style.Prompt.Render(prompt)
-	s.WriteString(m.style.CursorLine.Render(prompt))
+	// split string by new lines
+	plines := strings.Split(strings.TrimSpace(p), "\n")
 
-	if m.ShowLineNumbers {
-		s.WriteString(m.style.CursorLine.Render(m.style.CursorLineNumber.Render((fmt.Sprintf(m.lineNumberFormat, 1)))))
-	}
-
-	m.Cursor.TextStyle = m.style.Placeholder
-	m.Cursor.SetChar(string(p[0]))
-	s.WriteString(m.style.CursorLine.Render(m.Cursor.View()))
-
-	// The rest of the placeholder text
-	s.WriteString(m.style.CursorLine.Render(style.Render(p[1:] + strings.Repeat(" ", max(0, m.width-uniseg.StringWidth(p))))))
+	for i := 0; i < m.height; i++ {
+		lineStyle := m.style.Base
+		lineNumberStyle := m.style.LineNumber
+		if i == 0 {
+			lineStyle = m.style.CursorLine
+			lineNumberStyle = m.style.CursorLineNumber
+		}
 
-	// The rest of the new lines
-	for i := 1; i < m.height; i++ {
-		s.WriteRune('\n')
+		// render prompt
 		prompt := m.getPromptString(i)
 		prompt = m.style.Prompt.Render(prompt)
-		s.WriteString(prompt)
+		s.WriteString(lineStyle.Render(prompt))
 
+		// when show line numbers enabled:
+		// - render line number for only the cursor line
+		// - indent other placeholder lines
+		// this is consistent with vim with line numbers enabled
 		if m.ShowLineNumbers {
-			eob := m.style.EndOfBuffer.Render((fmt.Sprintf(m.lineNumberFormat, string(m.EndOfBufferCharacter))))
+			var ln string
+
+			switch {
+			case i == 0:
+				ln = strconv.Itoa(i + 1)
+				fallthrough
+			case len(plines) > i:
+				s.WriteString(lineStyle.Render(lineNumberStyle.Render(fmt.Sprintf(m.lineNumberFormat, ln))))
+			default:
+			}
+		}
+
+		switch {
+		// first line
+		case i == 0:
+			// first character of first line as cursor with character
+			m.Cursor.TextStyle = m.style.Placeholder
+			m.Cursor.SetChar(string(plines[0][0]))
+			s.WriteString(lineStyle.Render(m.Cursor.View()))
+
+			// the rest of the first line
+			s.WriteString(lineStyle.Render(style.Render(plines[0][1:] + strings.Repeat(" ", max(0, m.width-uniseg.StringWidth(plines[0]))))))
+		// remaining lines
+		case len(plines) > i:
+			// current line placeholder text
+			if len(plines) > i {
+				s.WriteString(lineStyle.Render(style.Render(plines[i] + strings.Repeat(" ", max(0, m.width-rw.StringWidth(plines[i]))))))
+			}
+		default:
+			// end of line buffer character
+			eob := m.style.EndOfBuffer.Render(string(m.EndOfBufferCharacter))
 			s.WriteString(eob)
 		}
+
+		// terminate with new line
+		s.WriteRune('\n')
 	}
 
 	m.viewport.SetContent(s.String())

textarea/textarea_test.go

@@ -3,7 +3,9 @@ package textarea
 import (
 	"strings"
 	"testing"
+	"unicode"
 
+	"github.com/acarl005/stripansi"
 	tea "github.com/charmbracelet/bubbletea"
 )
 
@@ -428,6 +430,208 @@ func TestRendersEndOfLineBuffer(t *testing.T) {
 	}
 }
 
+func TestRendersPlaceholder(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name                 string
+		lines                []string
+		showLineNumbers      bool
+		endOfBufferCharacter rune
+		expected             []string
+	}{
+		{
+			name: "single line",
+			lines: []string{
+				"the first line",
+			},
+			expected: []string{
+				"> the first line",
+				"> ~",
+				"> ~",
+				"> ~",
+				"> ~",
+				"> ~",
+			},
+		},
+		{
+			name: "single line with show line numbers",
+			lines: []string{
+				"the first line",
+			},
+			showLineNumbers: true,
+			expected: []string{
+				">   1 the first line",
+				"> ~",
+				"> ~",
+				"> ~",
+				"> ~",
+				"> ~",
+			},
+		},
+		{
+			name: "single line with end of buffer character",
+			lines: []string{
+				"the first line",
+			},
+			endOfBufferCharacter: '*',
+			expected: []string{
+				"> the first line",
+				"> *",
+				"> *",
+				"> *",
+				"> *",
+				"> *",
+			},
+		},
+		{
+			name: "single line with show line numbers and end of buffer character",
+			lines: []string{
+				"the first line",
+			},
+			showLineNumbers:      true,
+			endOfBufferCharacter: '*',
+			expected: []string{
+				">   1 the first line",
+				"> *",
+				"> *",
+				"> *",
+				"> *",
+				"> *",
+			},
+		},
+		{
+			name: "multiple lines",
+			lines: []string{
+				"the first line",
+				"the second line",
+				"the third line",
+			},
+			expected: []string{
+				"> the first line",
+				"> the second line",
+				"> the third line",
+				"> ~",
+				"> ~",
+				"> ~",
+			},
+		},
+		{
+			name: "multiple lines with show line numbers",
+			lines: []string{
+				"the first line",
+				"the second line",
+				"the third line",
+			},
+			showLineNumbers: true,
+			expected: []string{
+				">   1 the first line",
+				">     the second line",
+				">     the third line",
+				"> ~",
+				"> ~",
+				"> ~",
+			},
+		},
+		{
+			name: "multiple lines with end of buffer character",
+			lines: []string{
+				"the first line",
+				"the second line",
+				"the third line",
+			},
+			endOfBufferCharacter: '*',
+			expected: []string{
+				"> the first line",
+				"> the second line",
+				"> the third line",
+				"> *",
+				"> *",
+				"> *",
+			},
+		},
+		{
+			name: "multiple lines with show line numbers and end of buffer character",
+			lines: []string{
+				"the first line",
+				"the second line",
+				"the third line",
+			},
+			showLineNumbers:      true,
+			endOfBufferCharacter: '*',
+			expected: []string{
+				">   1 the first line",
+				">     the second line",
+				">     the third line",
+				"> *",
+				"> *",
+				"> *",
+			},
+		},
+		{
+			name: "multiple lines (equal to default textarea height)",
+			lines: []string{
+				"the first line",
+				"the second line",
+				"the third line",
+				"the forth line",
+				"the fifth line",
+				"the sixth line",
+			},
+			expected: []string{
+				"> the first line",
+				"> the second line",
+				"> the third line",
+				"> the forth line",
+				"> the fifth line",
+				"> the sixth line",
+			},
+		},
+		{
+			name: "multiple lines (greater than default textarea height)",
+			lines: []string{
+				"the first line",
+				"the second line",
+				"the third line",
+				"the forth line",
+				"the fifth line",
+				"the sixth line",
+				"the seventh line",
+			},
+			expected: []string{
+				"> the first line",
+				"> the second line",
+				"> the third line",
+				"> the forth line",
+				"> the fifth line",
+				"> the sixth line",
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			textarea := newTextArea()
+			textarea.Placeholder = strings.Join(tt.lines, "\n")
+			textarea.ShowLineNumbers = tt.showLineNumbers
+			if tt.endOfBufferCharacter != 0 {
+				textarea.EndOfBufferCharacter = tt.endOfBufferCharacter
+			}
+			view := stripString(textarea.View())
+
+			expected := strings.Join(tt.expected, "\n")
+
+			if expected != view {
+				t.Errorf("\nExpected:\n---\n%v\n---\n\nGot:\n---\n%v\n---\n\n", expected, view)
+			}
+		})
+	}
+}
+
 func newTextArea() Model {
 	textarea := New()
 
@@ -444,3 +648,16 @@ func newTextArea() Model {
 func keyPress(key rune) tea.Msg {
 	return tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune{key}, Alt: false}
 }
+
+func stripString(str string) string {
+	s := stripansi.Strip(str)
+	ss := strings.Split(s, "\n")
+
+	var lines []string
+	for _, l := range ss {
+		trim := strings.TrimRightFunc(l, unicode.IsSpace)
+		lines = append(lines, trim)
+	}
+
+	return strings.Join(lines, "\n")
+}