feat: Show context around keyword search matches

Author: RajeshkannanRamakrishnan

internal/ui/model.go

@@ -50,6 +50,13 @@ var (
 	matchStyle = lipgloss.NewStyle().Background(lipgloss.Color("#FFFF00")).Foreground(lipgloss.Color("#000000"))
 )
 
+const searchContextLineCount = 10
+
+type filteredCandidate struct {
+	line      string
+	textMatch bool
+}
+
 type Point struct {
 	X int
 	Y int
@@ -748,8 +755,10 @@ func splitIncomingContent(content string) []string {
 
 func (m *Model) applyFilters(resetView bool) {
 	var filtered []string
+	var candidates []filteredCandidate
 	// Directly iterate over originalLines
 	lines := m.originalLines
+	filterLower := strings.ToLower(m.filterText)
 
 	// Pre-compile regex if in regex mode
 	if m.filterText != "" {
@@ -795,23 +804,56 @@ func (m *Model) applyFilters(resetView bool) {
 		}
 
 		// 3. Text/Regex Filtering
+		textMatch := false
 		if m.filterText != "" {
 			if m.regexMode {
-				if m.regex != nil && !m.regex.MatchString(line) {
-					continue
+				if m.regex != nil {
+					textMatch = m.regex.MatchString(line)
 				}
 			} else {
 				// Case-insensitive contains (old robust behavior)
-				if !strings.Contains(strings.ToLower(line), strings.ToLower(m.filterText)) {
-					continue
-				}
+				textMatch = strings.Contains(strings.ToLower(line), filterLower)
 			}
 		}
 
 		// Tab Normalization (Fixes offset drift in selection)
 		line = strings.ReplaceAll(line, "\t", "    ")
 
-		filtered = append(filtered, line)
+		candidates = append(candidates, filteredCandidate{
+			line:      line,
+			textMatch: textMatch,
+		})
+	}
+
+	if m.filterText == "" || (m.regexMode && m.regex == nil) {
+		for _, candidate := range candidates {
+			filtered = append(filtered, candidate.line)
+		}
+	} else {
+		include := make([]bool, len(candidates))
+		for i, candidate := range candidates {
+			if !candidate.textMatch {
+				continue
+			}
+
+			start := i - searchContextLineCount
+			if start < 0 {
+				start = 0
+			}
+			end := i + searchContextLineCount
+			if end >= len(candidates) {
+				end = len(candidates) - 1
+			}
+			for j := start; j <= end; j++ {
+				include[j] = true
+			}
+		}
+
+		for i, candidate := range candidates {
+			if include[i] {
+				filtered = append(filtered, candidate.line)
+			}
+		}
 	}
 
 	// Stack Trace Folding Logic

internal/ui/model_test.go

@@ -1,6 +1,7 @@
 package ui
 
 import (
+	"fmt"
 	"testing"
 )
 
@@ -52,21 +53,21 @@ func TestApplyFilters(t *testing.T) {
 	}
 
 	m := InitialModel("test.log", lines, nil)
-	
+
 	// Test 1: No filters
 	m.applyFilters(true)
 	if len(m.filteredLines) != 4 {
 		t.Errorf("Expected 4 lines, got %d", len(m.filteredLines))
 	}
 
-	// Test 2: Filter Text
+	// Test 2: Filter Text includes matching lines with surrounding context
 	m.filterText = "Error"
 	m.applyFilters(true)
-	if len(m.filteredLines) != 1 {
-		t.Errorf("Expected 1 error line, got %d", len(m.filteredLines))
+	if len(m.filteredLines) != 4 {
+		t.Errorf("Expected 4 context lines, got %d", len(m.filteredLines))
 	}
-	if len(m.filteredLines) > 0 && m.filteredLines[0] != lines[2] {
-		t.Errorf("Expected line to be '%s', got '%s'", lines[2], m.filteredLines[0])
+	if len(m.filteredLines) > 2 && m.filteredLines[2] != lines[2] {
+		t.Errorf("Expected line to be '%s', got '%s'", lines[2], m.filteredLines[2])
 	}
 
 	// Test 3: Level Filtering (Toggle off INFO)
@@ -79,6 +80,54 @@ func TestApplyFilters(t *testing.T) {
 	}
 }
 
+func TestApplyFiltersAddsKeywordContext(t *testing.T) {
+	lines := make([]string, 35)
+	for i := range lines {
+		lines[i] = fmt.Sprintf("2023-01-01 10:00:%02d INFO line %02d", i, i)
+	}
+	lines[20] = "2023-01-01 10:00:20 ERROR target keyword"
+
+	m := InitialModel("test.log", lines, nil)
+	m.filterText = "keyword"
+	m.applyFilters(true)
+
+	if len(m.filteredLines) != 21 {
+		t.Fatalf("expected 21 lines with context, got %d", len(m.filteredLines))
+	}
+	if m.filteredLines[0] != lines[10] {
+		t.Fatalf("expected context to start at line 10, got %q", m.filteredLines[0])
+	}
+	if m.filteredLines[10] != lines[20] {
+		t.Fatalf("expected match at context index 10, got %q", m.filteredLines[10])
+	}
+	if m.filteredLines[20] != lines[30] {
+		t.Fatalf("expected context to end at line 30, got %q", m.filteredLines[20])
+	}
+}
+
+func TestApplyFiltersMergesOverlappingKeywordContext(t *testing.T) {
+	lines := make([]string, 40)
+	for i := range lines {
+		lines[i] = fmt.Sprintf("2023-01-01 10:00:%02d INFO line %02d", i, i)
+	}
+	lines[12] = "2023-01-01 10:00:12 ERROR target keyword"
+	lines[18] = "2023-01-01 10:00:18 ERROR another keyword"
+
+	m := InitialModel("test.log", lines, nil)
+	m.filterText = "keyword"
+	m.applyFilters(true)
+
+	if len(m.filteredLines) != 27 {
+		t.Fatalf("expected merged context range without duplicates, got %d lines", len(m.filteredLines))
+	}
+	if m.filteredLines[0] != lines[2] {
+		t.Fatalf("expected merged context to start at line 2, got %q", m.filteredLines[0])
+	}
+	if m.filteredLines[26] != lines[28] {
+		t.Fatalf("expected merged context to end at line 28, got %q", m.filteredLines[26])
+	}
+}
+
 func TestResolvePos(t *testing.T) {
     // Setup a model with forced width
     lines := []string{