semi working reverse search

pager/search.go

@@ -68,7 +68,7 @@ func (s *search) NextMatch(m *model) {
 	if nextMatch == "" {
 		// Start the search from the beginning of the document.
 		s.lastMatchLoc = 0
-		m.viewport.SetYOffset(0)
+		m.viewport.GotoTop()
 		return
 	}
 	m.content = m.content[:s.lastMatchLoc] + strings.Replace(m.content[s.lastMatchLoc:], nextMatch, m.matchHighlightStyle.Render(nextMatch), 1)
@@ -95,4 +95,59 @@ func (s *search) NextMatch(m *model) {
 }
 
 func (s *search) PrevMatch(m *model) {
+	// Check that we are within bounds.
+	if s.query == nil {
+		return
+	}
+
+	// Removed last highlight.
+	if s.prevMatch != "" {
+		leftPadding, rightPadding := utils.LipglossLengthPadding(s.prevMatch, m.matchHighlightStyle)
+		metastring := regexp.QuoteMeta(m.matchHighlightStyle.Render(s.query.String()))
+		query := regexp.MustCompile("(" + metastring[:leftPadding+1] + ")(" + s.query.String() + ")(" + metastring[len(metastring)-rightPadding-1:] + ")")
+		m.content = query.ReplaceAllString(m.content, "$2")
+	}
+	// Find the string to highlight.
+	var i int
+	var nextMatch string
+	for i = 0; s.query.FindString(m.content[i:s.lastMatchLoc]) != ""; i++ {
+		nextMatch = s.query.FindString(m.content[:s.lastMatchLoc])
+	}
+	s.prevMatch = nextMatch
+	if nextMatch == "" {
+		// Start the search from the beginning of the document.
+		s.lastMatchLoc = m.viewport.TotalLineCount()
+		m.viewport.GotoTop()
+		return
+	}
+	// m.content = strings.Replace(m.content[:i], nextMatch, m.matchHighlightStyle.Render(nextMatch), 1) + m.content[i:]
+
+	// Update the postion of the last found match.
+	for i = 0; s.query.FindString(m.content[i:s.lastMatchLoc]) != ""; i++ {
+	}
+
+	s.lastMatchLoc = i
+
+	// Update the viewport position.
+	line := 0
+	for i, c := range m.content {
+		if c == '\n' {
+			line++
+		}
+		if i == s.lastMatchLoc {
+			break
+		}
+	}
+
+	// Only update if the match is not within the viewport
+	if line > m.viewport.YOffset+m.viewport.VisibleLineCount()-1 || line < m.viewport.YOffset {
+		m.viewport.SetYOffset(line)
+	}
+}
+
+func Reverse(s string) (result string) {
+	for _, v := range s {
+		result = string(v) + result
+	}
+	return
 }