Comprehensive Security, Code Quality, and Accessibility Improvements

internal/processor/strategy/after-first.go

@@ -1,86 +1,20 @@
 package strategy
 
-import (
-	"bufio"
-	"fmt"
-	"os"
-)
-
 // AfterFirstAppearStrategy finds the first appearance of markers
 type AfterFirstAppearStrategy struct{}
 
 func (s *AfterFirstAppearStrategy) FindInitSectionPosition(filePath string, markers []string) (int64, int64, error) {
-	file, err := os.Open(filePath)
+	scanner, err := NewFileScanner(filePath)
 	if err != nil {
 		return 0, 0, err
 	}
-	defer file.Close()
-
-	scanner := bufio.NewScanner(file)
-	lineNum := int64(0)
-
-	// Sliding window for multiline marker detection
-	window := make([]string, 0, len(markers)+10)
-
-	for scanner.Scan() {
-		line := scanner.Text()
-		window = append(window, line)
-
-		// Keep window size reasonable
-		maxWindowSize := len(markers) + 10
-		if len(window) > maxWindowSize {
-			window = window[1:] // Remove oldest line
-		}
-
-		// Try to find start marker pattern in current window
-		if matchPos := findStartMarkerInWindow(window, markers, lineNum-int64(len(window))+1); matchPos != nil {
-			return matchPos.begin, matchPos.end, nil
-		}
-
-		lineNum++
-	}
-
-	return 0, 0, fmt.Errorf("start marker not found: %v", markers)
+	return scanner.FindFirstMarkerFromStart(markers)
 }
 
 func (s *AfterFirstAppearStrategy) FindPrintSectionPosition(filePath string, markers []string, searchFromLine int64) (int64, int64, error) {
-	file, err := os.Open(filePath)
+	scanner, err := NewFileScanner(filePath)
 	if err != nil {
 		return 0, 0, err
 	}
-	defer file.Close()
-
-	scanner := bufio.NewScanner(file)
-	lineNum := int64(0)
-
-	// Skip to the search start position
-	for lineNum <= searchFromLine && scanner.Scan() {
-		lineNum++
-	}
-
-	// Sliding window for multiline marker detection
-	window := make([]string, 0, len(markers)+10)
-
-	for scanner.Scan() {
-		line := scanner.Text()
-		window = append(window, line)
-
-		// Keep window size reasonable
-		maxWindowSize := len(markers) + 10
-		if len(window) > maxWindowSize {
-			window = window[1:] // Remove oldest line
-		}
-
-		// Calculate the correct window start line position for this iteration
-		currentWindowStart := lineNum - int64(len(window)) + 1
-
-		// Try to find marker pattern in current window
-		if matchPos := findStartMarkerInWindow(window, markers, currentWindowStart); matchPos != nil {
-			return matchPos.begin, matchPos.end, nil
-		}
-
-		lineNum++
-	}
-
-	return 0, 0, fmt.Errorf("end marker not found after line %d: %v", searchFromLine, markers)
+	return scanner.FindFirstMarkerFromLine(markers, searchFromLine+1)
 }

internal/processor/strategy/before-first.go

@@ -1,86 +1,20 @@
 package strategy
 
-import (
-	"bufio"
-	"fmt"
-	"os"
-)
-
 // BeforeCommandStrategy finds markers that appear before specific commands
 type BeforeCommandStrategy struct{}
 
 func (s *BeforeCommandStrategy) FindInitSectionPosition(filePath string, markers []string) (int64, int64, error) {
-	file, err := os.Open(filePath)
+	scanner, err := NewFileScanner(filePath)
 	if err != nil {
 		return 0, 0, err
 	}
-	defer file.Close()
-
-	scanner := bufio.NewScanner(file)
-	lineNum := int64(0)
-
-	// Sliding window for multiline marker detection
-	window := make([]string, 0, len(markers)+10)
-
-	for scanner.Scan() {
-		line := scanner.Text()
-		window = append(window, line)
-
-		// Keep window size reasonable
-		maxWindowSize := len(markers) + 10
-		if len(window) > maxWindowSize {
-			window = window[1:] // Remove oldest line
-		}
-
-		// Try to find start marker pattern in current window
-		if matchPos := findStartMarkerInWindow(window, markers, lineNum-int64(len(window))+1); matchPos != nil {
-			return matchPos.begin, matchPos.end, nil
-		}
-
-		lineNum++
-	}
-
-	return 0, 0, fmt.Errorf("start marker not found before commands: %v", markers)
+	return scanner.FindFirstMarkerFromStart(markers)
 }
 
 func (s *BeforeCommandStrategy) FindPrintSectionPosition(filePath string, markers []string, searchFromLine int64) (int64, int64, error) {
-	file, err := os.Open(filePath)
+	scanner, err := NewFileScanner(filePath)
 	if err != nil {
 		return 0, 0, err
 	}
-	defer file.Close()
-
-	scanner := bufio.NewScanner(file)
-	lineNum := int64(0)
-
-	// Skip to the search start position
-	for lineNum <= searchFromLine && scanner.Scan() {
-		lineNum++
-	}
-
-	// Sliding window for multiline marker detection
-	window := make([]string, 0, len(markers)+10)
-
-	for scanner.Scan() {
-		line := scanner.Text()
-		window = append(window, line)
-
-		// Keep window size reasonable
-		maxWindowSize := len(markers) + 10
-		if len(window) > maxWindowSize {
-			window = window[1:] // Remove oldest line
-		}
-
-		// Calculate the correct window start line position for this iteration
-		currentWindowStart := lineNum - int64(len(window)) + 1
-
-		// Try to find marker pattern in current window
-		if matchPos := findStartMarkerInWindow(window, markers, currentWindowStart); matchPos != nil {
-			return matchPos.begin, matchPos.end, nil
-		}
-
-		lineNum++
-	}
-
-	return 0, 0, fmt.Errorf("end marker not found before commands after line %d: %v", searchFromLine, markers)
+	return scanner.FindFirstMarkerFromLine(markers, searchFromLine+1)
 }

internal/processor/strategy/common.go

@@ -1,12 +1,132 @@
 package strategy
 
-import "strings"
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
 
 type startMarkerMatch struct {
 	begin int64
 	end   int64
 }
 
+// FileScanner provides common file scanning functionality for strategies
+type FileScanner struct {
+	filePath string
+	lines    []string
+}
+
+// NewFileScanner creates a new file scanner
+func NewFileScanner(filePath string) (*FileScanner, error) {
+	lines, err := readAllLines(filePath)
+	if err != nil {
+		return nil, err
+	}
+	return &FileScanner{
+		filePath: filePath,
+		lines:    lines,
+	}, nil
+}
+
+// FindFirstMarkerFromStart finds the first occurrence of markers from the beginning
+func (fs *FileScanner) FindFirstMarkerFromStart(markers []string) (int64, int64, error) {
+	return fs.findMarkerWithSlidingWindow(markers, 0, len(fs.lines)-1, true)
+}
+
+// FindFirstMarkerFromLine finds the first occurrence of markers starting from a specific line
+func (fs *FileScanner) FindFirstMarkerFromLine(markers []string, startLine int64) (int64, int64, error) {
+	if startLine < 0 || int(startLine) >= len(fs.lines) {
+		return 0, 0, fmt.Errorf("start line %d out of bounds", startLine)
+	}
+	return fs.findMarkerWithSlidingWindow(markers, int(startLine), len(fs.lines)-1, true)
+}
+
+// FindLastMarkerFromStart finds the last occurrence of markers from the beginning
+func (fs *FileScanner) FindLastMarkerFromStart(markers []string) (int64, int64, error) {
+	return fs.findMarkerWithSlidingWindow(markers, 0, len(fs.lines)-1, false)
+}
+
+// FindLastMarkerFromLine finds the last occurrence of markers starting from a specific line
+func (fs *FileScanner) FindLastMarkerFromLine(markers []string, startLine int64) (int64, int64, error) {
+	if startLine < 0 || int(startLine) >= len(fs.lines) {
+		return 0, 0, fmt.Errorf("start line %d out of bounds", startLine)
+	}
+	return fs.findMarkerWithSlidingWindow(markers, int(startLine), len(fs.lines)-1, false)
+}
+
+// findMarkerWithSlidingWindow implements the sliding window search algorithm
+func (fs *FileScanner) findMarkerWithSlidingWindow(markers []string, startIdx, endIdx int, returnFirst bool) (int64, int64, error) {
+	if len(markers) == 0 {
+		return 0, 0, fmt.Errorf("no markers provided")
+	}
+
+	var lastFoundBegin, lastFoundEnd int64 = -1, -1
+
+	if len(markers) == 1 {
+		// Single line marker - simple search
+		for i := startIdx; i <= endIdx; i++ {
+			if strings.Contains(strings.TrimSpace(fs.lines[i]), strings.TrimSpace(markers[0])) {
+				if returnFirst {
+					return int64(i), int64(i), nil
+				}
+				lastFoundBegin = int64(i)
+				lastFoundEnd = int64(i)
+			}
+		}
+	} else {
+		// Multiline marker - sliding window approach
+		window := make([]string, 0, len(markers)+10)
+
+		for i := startIdx; i <= endIdx; i++ {
+			line := fs.lines[i]
+			window = append(window, line)
+
+			// Keep window size reasonable
+			maxWindowSize := len(markers) + 10
+			if len(window) > maxWindowSize {
+				window = window[1:] // Remove oldest line
+			}
+
+			// Calculate the correct window start line position
+			currentWindowStart := int64(i) - int64(len(window)) + 1
+
+			// Try to find marker pattern in current window
+			if matchPos := findStartMarkerInWindow(window, markers, currentWindowStart); matchPos != nil {
+				if returnFirst {
+					return matchPos.begin, matchPos.end, nil
+				}
+				lastFoundBegin = matchPos.begin
+				lastFoundEnd = matchPos.end
+			}
+		}
+	}
+
+	if lastFoundBegin == -1 {
+		return 0, 0, fmt.Errorf("marker not found: %v", markers)
+	}
+
+	return lastFoundBegin, lastFoundEnd, nil
+}
+
+// readAllLines reads all lines from a file into memory
+func readAllLines(filePath string) ([]string, error) {
+	file, err := os.Open(filePath)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	var lines []string
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+
+	return lines, scanner.Err()
+}
+
 // findStartMarkerInWindow searches for start marker pattern in the sliding window
 func findStartMarkerInWindow(window []string, markers []string, windowStartLine int64) *startMarkerMatch {
 	if len(markers) == 1 {

internal/webserver/errors.go

@@ -18,6 +18,7 @@ const (
 	ErrorTypeFileIO         ErrorType = "file_io"
 	ErrorTypeUpload         ErrorType = "upload"
 	ErrorTypeInternal       ErrorType = "internal"
+	ErrorTypeSecurity       ErrorType = "security"
 )
 
 // ErrorResponse represents a structured error response
@@ -50,6 +51,50 @@ func CategorizeErrorWithLang(err error, lang string) ErrorResponse {
 	errMsg := err.Error()
 	errMsgLower := strings.ToLower(errMsg)
 
+	// Security errors - handle these first as they're high priority
+	if strings.Contains(errMsgLower, "csrf") || strings.Contains(errMsgLower, "token") {
+		return ErrorResponse{
+			Type:        ErrorTypeSecurity,
+			Code:        "csrf_token_invalid",
+			Title:       GetTranslation(lang, "error_security_title"),
+			Description: GetTranslation(lang, "error_security_description"),
+			Details:     errMsg,
+			Suggestions: []string{
+				GetTranslation(lang, "error_security_suggestion_refresh"),
+				GetTranslation(lang, "error_security_suggestion_cookies"),
+			},
+		}
+	}
+
+	if strings.Contains(errMsgLower, "file validation") || strings.Contains(errMsgLower, "invalid file") {
+		return ErrorResponse{
+			Type:        ErrorTypeSecurity,
+			Code:        "file_validation_failed",
+			Title:       GetTranslation(lang, "error_file_validation_title"),
+			Description: GetTranslation(lang, "error_file_validation_description"),
+			Details:     errMsg,
+			Suggestions: []string{
+				GetTranslation(lang, "error_file_validation_suggestion_type"),
+				GetTranslation(lang, "error_file_validation_suggestion_size"),
+				GetTranslation(lang, "error_file_validation_suggestion_content"),
+			},
+		}
+	}
+
+	if strings.Contains(errMsgLower, "path traversal") || strings.Contains(errMsgLower, "dangerous") {
+		return ErrorResponse{
+			Type:        ErrorTypeSecurity,
+			Code:        "security_violation",
+			Title:       GetTranslation(lang, "error_security_title"),
+			Description: GetTranslation(lang, "error_security_description"),
+			Details:     errMsg,
+			Suggestions: []string{
+				GetTranslation(lang, "error_security_suggestion_filename"),
+				GetTranslation(lang, "error_security_suggestion_safe"),
+			},
+		}
+	}
+
 	// Template-related errors
 	if strings.Contains(errMsgLower, "template") || strings.Contains(errMsgLower, "parse") {
 		if strings.Contains(errMsgLower, "custom template") {