fix(viewport): viewport may not scroll down to the end when content exceed the viewport.Width

viewport/viewport.go

@@ -103,6 +103,10 @@ func (m *Model) SetContent(s string) {
 	s = strings.ReplaceAll(s, "\r\n", "\n") // normalize line endings
 	m.lines = strings.Split(s, "\n")
 
+	joinedLines := strings.Join(m.lines, "\n")
+	wrapContents := m.wrapContent(joinedLines, false)
+	m.lines = strings.Split(wrapContents, "\n")
+
 	if m.YOffset > len(m.lines)-1 {
 		m.GotoBottom()
 	}
@@ -353,16 +357,14 @@ func (m Model) updateAsModel(msg tea.Msg) (Model, tea.Cmd) {
 	return m, cmd
 }
 
-// View renders the viewport into a string.
-func (m Model) View() string {
-	if m.HighPerformanceRendering {
-		// Just send newlines since we're going to be rendering the actual
-		// content separately. We still need to send something that equals the
-		// height of this view so that the Bubble Tea standard renderer can
-		// position anything below this view properly.
-		return strings.Repeat("\n", max(0, m.Height-1))
-	}
-
+// wrapContent wraps the given content within the viewport's dimensions.
+// It applies padding and truncation to ensure the content fits within the
+// viewport's dimensions.
+//
+// The `trimHeight` parameter determines whether the content should be trimmed
+// to the viewport's height. If `true`, the content will be truncated to the
+// viewport's height if it is taller than the viewport.
+func (m Model) wrapContent(content string, trimHeight bool) string {
 	w, h := m.Width, m.Height
 	if sw := m.Style.GetWidth(); sw != 0 {
 		w = min(w, sw)
@@ -373,11 +375,28 @@ func (m Model) View() string {
 	contentWidth := w - m.Style.GetHorizontalFrameSize()
 	contentHeight := h - m.Style.GetVerticalFrameSize()
 	contents := lipgloss.NewStyle().
-		Width(contentWidth).      // pad to width.
-		Height(contentHeight).    // pad to height.
-		MaxHeight(contentHeight). // truncate height if taller.
-		MaxWidth(contentWidth).   // truncate width if wider.
-		Render(strings.Join(m.visibleLines(), "\n"))
+		Width(contentWidth).   // pad to width.
+		MaxWidth(contentWidth) // truncate width if wider.
+	if trimHeight {
+		contents = contents.
+			Height(contentHeight).   // pad to height.
+			MaxHeight(contentHeight) // truncate height if taller.
+	}
+	return contents.Render(content)
+}
+
+// View renders the viewport into a string.
+func (m Model) View() string {
+	if m.HighPerformanceRendering {
+		// Just send newlines since we're going to be rendering the actual
+		// content separately. We still need to send something that equals the
+		// height of this view so that the Bubble Tea standard renderer can
+		// position anything below this view properly.
+		return strings.Repeat("\n", max(0, m.Height-1))
+	}
+
+	visibleLines := strings.Join(m.visibleLines(), "\n")
+	contents := m.wrapContent(visibleLines, true)
 	return m.Style.
 		UnsetWidth().UnsetHeight(). // Style size already applied in contents.
 		Render(contents)

viewport/viewport_test.go

@@ -0,0 +1,291 @@
+package viewport
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/charmbracelet/lipgloss"
+)
+
+func TestSetContent(t *testing.T) {
+	// Normal case
+	m := New(10, 10) // Create a new Model with width 10 and height 10
+	m.SetContent("This is a test string")
+	if len(m.lines) != 3 {
+		t.Errorf("Expected 3 line, but got %d", len(m.lines))
+	}
+
+	// Edge case: empty string
+	m.SetContent("")
+	if len(m.lines) != 1 {
+		t.Errorf("Expected 1 lines, but got %d", len(m.lines))
+	}
+
+	// Edge case: single newline
+	m.SetContent("\n")
+	if len(m.lines) != 2 {
+		t.Errorf("Expected 2 line, but got %d", len(m.lines))
+	}
+
+	// Edge case: multiple newlines
+	m.SetContent("\n\n\n")
+	if len(m.lines) != 4 {
+		t.Errorf("Expected 4 lines, but got %d", len(m.lines))
+	}
+
+	// Extreme case: very long string
+	longString := strings.Repeat("This is a test string ", 1000)
+	m.SetContent(longString)
+	if len(m.lines) != (3 * 1000) { // Depending on the width of the Model, this might wrap to multiple lines
+		t.Errorf("Expected 3000 lines, but got %d", len(m.lines))
+	}
+
+	// Extreme case: string with ANSI escape codes
+	ansiString := "\x1b[31mThis is a test string\x1b[0m"
+	m.SetContent(ansiString)
+	if len(m.lines) != 3 {
+		t.Errorf("Expected 3 line, but got %d", len(m.lines))
+	}
+
+	// Extreme case: 2-width characters (Japanese characters)
+	japaneseString :=
+		"this is a really long text that should wrap around the viewport\n" +
+			"これはビューポートを囲む必要がある非常に長い日本語のテキストです"
+	m.SetContent(japaneseString)
+	if len(m.lines) != 15 {
+		t.Errorf("Expected 15 line, but got %d", len(m.lines))
+	}
+}
+
+func escapeString(s string) string {
+	s = strings.ReplaceAll(s, "\n", "\\n")
+	s = strings.ReplaceAll(s, "\r", "\\r")
+	s = strings.ReplaceAll(s, "\t", "\\t")
+	s = strings.ReplaceAll(s, " ", "\\s")
+	return s
+}
+
+func TestView(t *testing.T) {
+	// Normal case
+	m := New(10, 10) // Create a new Model with width 10 and height 10
+	m.SetContent("This is a test string")
+	view := m.View()
+	expected := "" +
+		"This is a \n" +
+		"test      \n" +
+		"string    "
+	if !strings.HasPrefix(view, expected) {
+		t.Errorf("Expected view to start with a newline, but got %s", escapeString(view))
+	}
+
+	// Edge case: empty content
+	m.SetContent("")
+	view = m.View()
+	expected = "" +
+		"          \n"
+	if !strings.HasPrefix(view, expected) {
+		t.Errorf("Expected empty view, but got %s", escapeString(view))
+	}
+
+	// Edge case: single newline
+	m.SetContent("\n")
+	view = m.View()
+	expected = "" +
+		"          \n"
+	if !strings.HasPrefix(view, expected) {
+		t.Errorf("Expected view to be a single newline, but got %s", escapeString(view))
+	}
+
+	// Edge case: multiple newlines
+	m.SetContent("\n\n\n")
+	view = m.View()
+	expected = "" +
+		"          \n"
+	if !strings.HasPrefix(view, expected) {
+		t.Errorf("Expected view to contain multiple newlines, but got %s", escapeString(view))
+	}
+
+	// Extreme case: very long content
+	longString := strings.Repeat("This is a test string ", 1000)
+	m.SetContent(longString)
+	view = m.View()
+	if len(view) < (10 * 10) { // Depending on the width of the Model, this might wrap to multiple lines
+		t.Errorf("Expected view to be at least 100 characters long, but got %s", escapeString(view))
+	}
+
+	// Extreme case: content with ANSI escape codes
+	ansiString := "\x1b[31mThis is a test string\x1b[0m"
+	m.SetContent(ansiString)
+	expected = "" +
+		"\x1b[31mThis is a \n" +
+		"test      \n" +
+		"string\x1b[0m    "
+	view = m.View()
+	if !strings.HasPrefix(view, expected) {
+		t.Errorf("Expected view to contain ANSI escape codes, but got %s", escapeString(view))
+	}
+
+	// Test case: 2-width characters (Japanese characters)
+	japaneseString :=
+		"this is a really long text that should wrap around the viewport\n" +
+			"これはビューポートを囲む必要がある非常に長い日本語のテキストです"
+	m.SetContent(japaneseString)
+	view = m.View()
+	expected = "" +
+		"this is a \n" +
+		"really    \n" +
+		"long text \n" +
+		"that      \n" +
+		"should    \n" +
+		"wrap      \n" +
+		"around the\n" +
+		"viewport  \n" +
+		"これはビュ\n" +
+		"ーポートを"
+	if !strings.HasPrefix(view, expected) {
+		t.Errorf("Expected view to contain Japanese characters, but got %s", escapeString(view))
+	}
+}
+
+func TestSetContent_NormalCase(t *testing.T) {
+	vp := New(0, 0)
+	vp.SetContent("test")
+
+	actual := strings.Join(vp.lines, "\n")
+	expected := "test"
+
+	if actual != expected {
+		t.Errorf("Error: vp.lines = %q, want %q", actual, expected)
+	}
+}
+
+func assertArray(t *testing.T, actual, expected []string) {
+	if len(actual) != len(expected) {
+		t.Errorf("Error: actual = %d, want %d", len(actual), len(expected))
+	}
+
+	for i, actualLine := range actual {
+		if len(actualLine) != len(expected[i]) {
+			t.Errorf("Error: actual = %d, want %d", len(actualLine), len(expected[i]))
+		}
+	}
+
+	actualStr := strings.Join(actual, "\n")
+	expectedStr := strings.Join(expected, "\n")
+
+	if actualStr != expectedStr {
+		t.Errorf("Error: actual = %q, want %q", actualStr, expectedStr)
+	}
+}
+
+func TestSetContent_WithLargeText(t *testing.T) {
+	content := []string{
+		"this is a really long text that should wrap around the viewport",
+	}
+	vp := New(30, 5)
+	vp.SetContent(strings.Join(content, "\n"))
+
+	assertArray(t, vp.lines, []string{
+		"this is a really long text    ",
+		"that should wrap around the   ",
+		"viewport                      ",
+	})
+}
+
+func TestSetContent_WithMultipleLineLargeTest(t *testing.T) {
+	content := []string{
+		"this is a really long text that should wrap around the viewport",
+		"this is a really long text that should wrap around the viewport",
+	}
+	vp := New(30, 5)
+	vp.SetContent(strings.Join(content, "\n"))
+
+	assertArray(t, vp.lines, []string{
+		"this is a really long text    ",
+		"that should wrap around the   ",
+		"viewport                      ",
+		"this is a really long text    ",
+		"that should wrap around the   ",
+		"viewport                      ",
+	})
+}
+
+func TestSetContent_WithStyledLargeText(t *testing.T) {
+	content := []string{
+		lipgloss.NewStyle().Foreground(lipgloss.Color("1")).Render("this ") + "is a really long text that should wrap around the viewport",
+	}
+	vp := New(30, 5)
+	vp.SetContent(strings.Join(content, "\n"))
+
+	assertArray(t, vp.lines, []string{
+		"this is a really long text    ",
+		"that should wrap around the   ",
+		"viewport                      ",
+	})
+}
+
+func TestSetContent_WithLargeTextWithViewportPadding(t *testing.T) {
+	content := []string{
+		"this is a really long text that should wrap around the viewport",
+	}
+	vp := New(30, 5)
+	vp.Style = lipgloss.NewStyle().Padding(1)
+	vp.SetContent(strings.Join(content, "\n"))
+
+	assertArray(t, vp.lines, []string{
+		"this is a really long text  ",
+		"that should wrap around the ",
+		"viewport                    ",
+	})
+}
+
+func TestSetContent_WithLargeTextWithWideCharacter(t *testing.T) {
+	content := []string{
+		"this is a really long text that should wrap around the viewport",
+		"これはビューポートを囲む必要がある非常に長い日本語のテキストです",
+	}
+	vp := New(30, 5)
+	vp.SetContent(strings.Join(content, "\n"))
+
+	assertArray(t, vp.lines, []string{
+		"this is a really long text    ",
+		"that should wrap around the   ",
+		"viewport                      ",
+		"これはビューポートを囲む必要が",
+		"ある非常に長い日本語のテキスト",
+		"です                          ",
+	})
+}
+
+func TestWrapContent_WidthPaddingAndMaxWidth(t *testing.T) {
+	m := Model{
+		Width: 10,
+		Style: lipgloss.NewStyle(),
+	}
+
+	// Test case 1: Content width is less than model width
+	content := "Hello"
+	expected := "Hello     "
+	actual := m.wrapContent(content, false)
+	if actual != expected {
+		t.Errorf("Expected '%s' but got '%s'", expected, actual)
+	}
+
+	// Test case 2: Content width is equal to model width
+	content = "abcdefghij"
+	expected = "abcdefghij"
+	actual = m.wrapContent(content, false)
+	if actual != expected {
+		t.Errorf("Expected '%s' but got '%s'", expected, actual)
+	}
+
+	// Test case 3: Content width is greater than model width
+	content = "abcdefghijk"
+	expected = "" +
+		"abcdefghij\n" +
+		"k         "
+	actual = m.wrapContent(content, false)
+	if actual != expected {
+		t.Errorf("Expected '%s' but got '%s'", expected, actual)
+	}
+}