feature(pager): add search functionality (#321)

* Added initial search functionality

 * Added a handler for the key presses
 * Added a searchbar at the bottom of the screen
 * Made search results cycleable by pressing n

* correct start pos and ignore keys while searching

* fix out of bound error when pressing n

* made the matching pattern relative to the current pos

* added p for searching for previous match

* added highlighting to search matches

* dynamically replaced all matches

* fixed string highlight issue

* fixed truncation issue

* small simplifaction in ypos logic

* made prev and next behave the same atBottom

* simplified logic and fixed linter errors

* updated help text

* style changes

* added comments

* fixed truncation issue

* fixes infinte loop on very long lines

* added simple lipgloss truncate function

* updated colors for better contrast

* lint fix

* initial commit for soft-wrap functionality

* linter corrections and added for pager with new model

* added generic functions to a utility package

* fix soft lint errors

* made N match previous as well as p

* replaced help text when search is active

* ran gofmt -w

* reimplemented search and next to enabled support for dynamic highlights

* made the highlight move as you progress through the search

* simplified highlighter

* improvements to the clean up of the highlight function

* semi working reverse search

* reverse search without highlight

* added semi working highlight for reverser search

* working version of previous match

* fixed issue with single letter matches in next

* added support for softwrapping

* respond to soft lint warnings

* removed unused function

* lint

* simplified matchers and fixed duplicate highlights

* optimisations and change in matching pattern

* fixed bug in lipglosspadding and allowed matching 1 etc.

* make highlight respect user settings

* fixed logic error in slice

* made prev match wrap around

* fix: show next/prev match help when active

* updated how view port line is set

* avoid crashes when regex doesn't compile

* fix: spelling previous

---------

Co-authored-by: Maas Lalani <maas@lalani.dev>

internal/utils/utils.go

@@ -0,0 +1,23 @@
+package utils
+
+import (
+	"strings"
+
+	"github.com/charmbracelet/lipgloss"
+)
+
+// LipglossTruncate truncates a given line based on its lipgloss width.
+func LipglossTruncate(s string, width int) string {
+	var i int
+	for i = 0; i < len(s) && lipgloss.Width(s[:i]) < width; i++ {
+	} //revive:disable-line:empty-block
+	return s[:i]
+}
+
+// LipglossLengthPadding calculated calculates how much padding a string is given by a style.
+func LipglossPadding(style lipgloss.Style) (int, int) {
+	render := style.Render(" ")
+	before := strings.Index(render, " ")
+	after := len(render) - len(" ") - before
+	return before, after
+}

pager/command.go

@@ -35,9 +35,12 @@ func (o Options) Run() error {
 		viewport:            vp,
 		helpStyle:           o.HelpStyle.ToLipgloss(),
 		content:             o.Content,
+		origContent:         o.Content,
 		showLineNumbers:     o.ShowLineNumbers,
 		lineNumberStyle:     o.LineNumberStyle.ToLipgloss(),
 		softWrap:            o.SoftWrap,
+		matchStyle:          o.MatchStyle.ToLipgloss(),
+		matchHighlightStyle: o.MatchHighlightStyle.ToLipgloss(),
 	}
 	_, err := tea.NewProgram(model, tea.WithAltScreen()).Run()
 	if err != nil {

pager/options.go

@@ -11,4 +11,6 @@ type Options struct {
 	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"`
+	MatchStyle      style.Styles `embed:"" prefix:"match." help:"Style the matched text" set:"defaultForeground=212" set:"defaultBold=true" envprefix:"GUM_PAGER_MATCH_"` //nolint:staticcheck
+	MatchHighlightStyle      style.Styles `embed:"" prefix:"match-highlight." help:"Style the matched highlight text" set:"defaultForeground=235" set:"defaultBackground=225" set:"defaultBold=true" envprefix:"GUM_PAGER_MATCH_HIGH_"` //nolint:staticcheck
 }

pager/pager.go

@@ -9,17 +9,22 @@ import (
 
 	"github.com/charmbracelet/bubbles/viewport"
 	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/gum/internal/utils"
 	"github.com/charmbracelet/lipgloss"
-	"github.com/mattn/go-runewidth"
 )
 
 type model struct {
 	content             string
+	origContent         string
 	viewport            viewport.Model
 	helpStyle           lipgloss.Style
 	showLineNumbers     bool
 	lineNumberStyle     lipgloss.Style
 	softWrap            bool
+	search              search
+	matchStyle          lipgloss.Style
+	matchHighlightStyle lipgloss.Style
+	maxWidth            int
 }
 
 func (m model) Init() tea.Cmd {
@@ -29,18 +34,27 @@ func (m model) Init() tea.Cmd {
 func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	switch msg := msg.(type) {
 	case tea.WindowSizeMsg:
+		m.ProcessText(msg)
+	case tea.KeyMsg:
+		return m.KeyHandler(msg)
+	}
+
+	return m, nil
+}
+
+func (m *model) ProcessText(msg tea.WindowSizeMsg) {
 	m.viewport.Height = msg.Height - lipgloss.Height(m.helpStyle.Render("?")) - 1
 	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
+	// Determine max width of a line.
+	m.maxWidth = m.viewport.Width
 	if m.softWrap {
 		vpStyle := m.viewport.Style
-			maxLineWidth -= vpStyle.GetHorizontalBorderSize() + vpStyle.GetHorizontalMargins() + vpStyle.GetHorizontalPadding()
+		m.maxWidth -= vpStyle.GetHorizontalBorderSize() + vpStyle.GetHorizontalMargins() + vpStyle.GetHorizontalPadding()
 		if m.showLineNumbers {
-				maxLineWidth -= len("     │ ")
+			m.maxWidth -= lipgloss.Width("     │ ")
 		}
 	}
 
@@ -49,8 +63,8 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		if m.showLineNumbers {
 			text.WriteString(m.lineNumberStyle.Render(fmt.Sprintf("%4d │ ", i+1)))
 		}
-			for m.softWrap && len(line) > maxLineWidth {
-				truncatedLine := runewidth.Truncate(line, maxLineWidth, "")
+		for m.softWrap && lipgloss.Width(line) > m.maxWidth {
+			truncatedLine := utils.LipglossTruncate(line, m.maxWidth)
 			text.WriteString(textStyle.Render(truncatedLine))
 			text.WriteString("\n")
 			if m.showLineNumbers {
@@ -58,7 +72,7 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			}
 			line = strings.Replace(line, truncatedLine, "", 1)
 		}
-			text.WriteString(textStyle.Render(runewidth.Truncate(line, maxLineWidth, "")))
+		text.WriteString(textStyle.Render(utils.LipglossTruncate(line, m.maxWidth)))
 		text.WriteString("\n")
 	}
 
@@ -68,21 +82,60 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		text.WriteString(m.lineNumberStyle.Render(remainingLines))
 	}
 	m.viewport.SetContent(text.String())
-	case tea.KeyMsg:
-		switch msg.String() {
+}
+
+func (m model) KeyHandler(key tea.KeyMsg) (model, func() tea.Msg) {
+	var cmd tea.Cmd
+	if m.search.active {
+		switch key.String() {
+		case "enter":
+			if m.search.input.Value() != "" {
+				m.content = m.origContent
+				m.search.Execute(&m)
+
+				// Trigger a view update to highlight the found matches.
+				m.search.NextMatch(&m)
+				m.ProcessText(tea.WindowSizeMsg{Height: m.viewport.Height + 2, Width: m.viewport.Width})
+			} else {
+				m.search.Done()
+			}
+		case "ctrl+d", "ctrl+c", "esc":
+			m.search.Done()
+		default:
+			m.search.input, cmd = m.search.input.Update(key)
+		}
+	} else {
+		switch key.String() {
 		case "g":
 			m.viewport.GotoTop()
 		case "G":
 			m.viewport.GotoBottom()
+		case "/":
+			m.search.Begin()
+		case "p", "N":
+			m.search.PrevMatch(&m)
+			m.ProcessText(tea.WindowSizeMsg{Height: m.viewport.Height + 2, Width: m.viewport.Width})
+		case "n":
+			m.search.NextMatch(&m)
+			m.ProcessText(tea.WindowSizeMsg{Height: m.viewport.Height + 2, Width: m.viewport.Width})
 		case "q", "ctrl+c", "esc":
 			return m, tea.Quit
 		}
+		m.viewport, cmd = m.viewport.Update(key)
 	}
-	var cmd tea.Cmd
-	m.viewport, cmd = m.viewport.Update(msg)
+
 	return m, cmd
 }
 
 func (m model) View() string {
-	return m.viewport.View() + m.helpStyle.Render("\n ↑/↓: Navigate • q: Quit")
+	helpMsg := "\n ↑/↓: Navigate • q: Quit • /: Search "
+	if m.search.query != nil {
+		helpMsg += "• n: Next Match "
+		helpMsg += "• N: Prev Match "
+	}
+	if m.search.active {
+		return m.viewport.View() + "\n " + m.search.input.View()
+	}
+
+	return m.viewport.View() + m.helpStyle.Render(helpMsg)
 }

pager/search.go

@@ -0,0 +1,163 @@
+package pager
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+
+	"github.com/charmbracelet/bubbles/textinput"
+	"github.com/charmbracelet/gum/internal/utils"
+	"github.com/charmbracelet/lipgloss"
+)
+
+type search struct {
+	active           bool
+	input            textinput.Model
+	query            *regexp.Regexp
+	matchIndex       int
+	matchLipglossStr string
+	matchString      string
+}
+
+func (s *search) new() {
+	input := textinput.New()
+	input.Placeholder = "search"
+	input.Prompt = "/"
+	input.PromptStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("240"))
+	s.input = input
+}
+
+func (s *search) Begin() {
+	s.new()
+	s.active = true
+	s.input.Focus()
+}
+
+// Execute find all lines in the model with a match.
+func (s *search) Execute(m *model) {
+	defer s.Done()
+	if s.input.Value() == "" {
+		s.query = nil
+		return
+	}
+
+	var err error
+	s.query, err = regexp.Compile(s.input.Value())
+	if err != nil {
+		s.query = nil
+		return
+	}
+	query := regexp.MustCompile(fmt.Sprintf("(%s)", s.query.String()))
+	m.content = query.ReplaceAllString(m.content, m.matchStyle.Render("$1"))
+
+	// Recompile the regex to match the an replace the highlights.
+	leftPad, _ := utils.LipglossPadding(m.matchStyle)
+	matchingString := regexp.QuoteMeta(m.matchStyle.Render()[:leftPad]) + s.query.String() + regexp.QuoteMeta(m.matchStyle.Render()[leftPad:])
+	s.query, err = regexp.Compile(matchingString)
+	if err != nil {
+		s.query = nil
+	}
+}
+
+func (s *search) Done() {
+	s.active = false
+
+	// To account for the first match is always executed.
+	s.matchIndex = -1
+}
+
+func (s *search) NextMatch(m *model) {
+	// Check that we are within bounds.
+	if s.query == nil {
+		return
+	}
+
+	// Remove previous highlight.
+	m.content = strings.Replace(m.content, s.matchLipglossStr, s.matchString, 1)
+
+	// Highlight the next match.
+	allMatches := s.query.FindAllStringIndex(m.content, -1)
+	if len(allMatches) == 0 {
+		return
+	}
+
+	leftPad, rightPad := utils.LipglossPadding(m.matchStyle)
+	s.matchIndex = (s.matchIndex + 1) % len(allMatches)
+	match := allMatches[s.matchIndex]
+	lhs := m.content[:match[0]]
+	rhs := m.content[match[0]:]
+	s.matchString = m.content[match[0]:match[1]]
+	s.matchLipglossStr = m.matchHighlightStyle.Render(s.matchString[leftPad : len(s.matchString)-rightPad])
+	m.content = lhs + strings.Replace(rhs, m.content[match[0]:match[1]], s.matchLipglossStr, 1)
+
+	// Update the viewport position.
+	var line int
+	formatStr := softWrapEm(m.content, m.maxWidth, m.softWrap)
+	index := strings.Index(formatStr, s.matchLipglossStr)
+	if index != -1 {
+		line = strings.Count(formatStr[:index], "\n")
+	}
+
+	// Only update if the match is not within the viewport.
+	if index != -1 && (line > m.viewport.YOffset-1+m.viewport.VisibleLineCount()-1 || line < m.viewport.YOffset) {
+		m.viewport.SetYOffset(line)
+	}
+}
+
+func (s *search) PrevMatch(m *model) {
+	// Check that we are within bounds.
+	if s.query == nil {
+		return
+	}
+
+	// Remove previous highlight.
+	m.content = strings.Replace(m.content, s.matchLipglossStr, s.matchString, 1)
+
+	// Highlight the previous match.
+	allMatches := s.query.FindAllStringIndex(m.content, -1)
+	if len(allMatches) == 0 {
+		return
+	}
+
+	s.matchIndex = (s.matchIndex - 1) % len(allMatches)
+	if s.matchIndex < 0 {
+		s.matchIndex = len(allMatches) - 1
+	}
+
+	leftPad, rightPad := utils.LipglossPadding(m.matchStyle)
+	match := allMatches[s.matchIndex]
+	lhs := m.content[:match[0]]
+	rhs := m.content[match[0]:]
+	s.matchString = m.content[match[0]:match[1]]
+	s.matchLipglossStr = m.matchHighlightStyle.Render(s.matchString[leftPad : len(s.matchString)-rightPad])
+	m.content = lhs + strings.Replace(rhs, m.content[match[0]:match[1]], s.matchLipglossStr, 1)
+
+	// Update the viewport position.
+	var line int
+	formatStr := softWrapEm(m.content, m.maxWidth, m.softWrap)
+	index := strings.Index(formatStr, s.matchLipglossStr)
+	if index != -1 {
+		line = strings.Count(formatStr[:index], "\n")
+	}
+
+	// Only update if the match is not within the viewport.
+	if index != -1 && (line > m.viewport.YOffset-1+m.viewport.VisibleLineCount()-1 || line < m.viewport.YOffset) {
+		m.viewport.SetYOffset(line)
+	}
+}
+
+func softWrapEm(str string, maxWidth int, softWrap bool) string {
+	var text strings.Builder
+	for _, line := range strings.Split(str, "\n") {
+		for softWrap && lipgloss.Width(line) > maxWidth {
+			truncatedLine := utils.LipglossTruncate(line, maxWidth)
+			text.WriteString(truncatedLine)
+			text.WriteString("\n")
+			line = strings.Replace(line, truncatedLine, "", 1)
+		}
+		text.WriteString(utils.LipglossTruncate(line, maxWidth))
+		text.WriteString("\n")
+	}
+
+	return text.String()
+}