From e108bc46687a92c670166a9689913eb01f01f06d Mon Sep 17 00:00:00 2001
From: Leon Stam <leon@elephantcs.nl>
Date: Tue, 6 Dec 2022 17:40:53 +0100
Subject: [PATCH] feat(pager): add --soft-wrap option to gum pager

---
 pager/command.go |  1 +
 pager/options.go |  1 +
 pager/pager.go   | 23 ++++++++++++++++++++++-
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/pager/command.go b/pager/command.go
index 568d09a..0b4fd45 100644
--- a/pager/command.go
+++ b/pager/command.go
@@ -34,6 +34,7 @@ func (o Options) Run() error {
 		content:         o.Content,
 		showLineNumbers: o.ShowLineNumbers,
 		lineNumberStyle: o.LineNumberStyle.ToLipgloss(),
+		softWrap:        o.SoftWrap,
 	}
 	_, err := tea.NewProgram(model, tea.WithAltScreen()).Run()
 	if err != nil {
diff --git a/pager/options.go b/pager/options.go
index f8da7ce..210cadc 100644
--- a/pager/options.go
+++ b/pager/options.go
@@ -10,4 +10,5 @@ type Options struct {
 	Content         string       `arg:"" optional:"" help:"Display content to scroll"`
 	ShowLineNumbers bool         `help:"Show line numbers" default:"true"`
 	LineNumberStyle style.Styles `embed:"" prefix:"line-number." help:"Style the line numbers" set:"defaultForeground=237" envprefix:"GUM_PAGER_LINE_NUMBER_"`
+	SoftWrap        bool         `help:"Soft wrap lines" default:"false"`
 }
diff --git a/pager/pager.go b/pager/pager.go
index f920074..685de4f 100644
--- a/pager/pager.go
+++ b/pager/pager.go
@@ -19,6 +19,7 @@ type model struct {
 	helpStyle       lipgloss.Style
 	showLineNumbers bool
 	lineNumberStyle lipgloss.Style
+	softWrap        bool
 }
 
 func (m model) Init() tea.Cmd {
@@ -32,12 +33,32 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.viewport.Width = msg.Width
 		textStyle := lipgloss.NewStyle().Width(m.viewport.Width)
 		var text strings.Builder
+
+		// Determine max width of a line
+		maxLineWidth := m.viewport.Width
+		if m.softWrap {
+			vpStyle := m.viewport.Style
+			maxLineWidth -= vpStyle.GetHorizontalBorderSize() + vpStyle.GetHorizontalMargins() + vpStyle.GetHorizontalPadding()
+			if m.showLineNumbers {
+				maxLineWidth -= len("     │ ")
+			}
+		}
+
 		for i, line := range strings.Split(m.content, "\n") {
 			line = strings.ReplaceAll(line, "\t", "    ")
 			if m.showLineNumbers {
 				text.WriteString(m.lineNumberStyle.Render(fmt.Sprintf("%4d │ ", i+1)))
 			}
-			text.WriteString(textStyle.Render(runewidth.Truncate(line, m.viewport.Width, "")))
+			for m.softWrap && len(line) > maxLineWidth {
+				truncatedLine := runewidth.Truncate(line, maxLineWidth, "")
+				text.WriteString(textStyle.Render(truncatedLine))
+				text.WriteString("\n")
+				if m.showLineNumbers {
+					text.WriteString(m.lineNumberStyle.Render("     │ "))
+				}
+				line = strings.Replace(line, truncatedLine, "", 1)
+			}
+			text.WriteString(textStyle.Render(runewidth.Truncate(line, maxLineWidth, "")))
 			text.WriteString("\n")
 		}