Refactor code to remove duplicates and improve structure

cmd/internal/migrations/v3/cache_config.go

@@ -35,17 +35,10 @@ func MigrateCacheConfig(cmd *cobra.Command, cwd string, _, _ *semver.Version) er
 			s = strings.ReplaceAll(s, "Store:", "Storage:")
 			s = strings.ReplaceAll(s, "Key:", "KeyGenerator:")
 			s = reCacheControl.ReplaceAllStringFunc(s, func(match string) string {
-				value := strings.TrimPrefix(match, "CacheControl:")
-				value = strings.TrimSpace(value)
+				rawValue := strings.TrimPrefix(match, "CacheControl:")
+				rawValue = strings.TrimSpace(rawValue)
 
-				comment := ""
-				if idx := strings.Index(value, "//"); idx != -1 {
-					comment = strings.TrimSpace(value[idx:])
-					value = value[:idx]
-				} else if idx := strings.Index(value, "/*"); idx != -1 {
-					comment = strings.TrimSpace(value[idx:])
-					value = value[:idx]
-				}
+				value, comment := ExtractCommentAndValue(rawValue)
 
 				hasComma := strings.HasSuffix(strings.TrimRight(value, " \t"), ",")
 				if hasComma {

cmd/internal/migrations/v3/common.go

@@ -2,6 +2,7 @@ package v3
 
 import (
 	"fmt"
+	"go/ast"
 	"regexp"
 	"sort"
 	"strconv"
@@ -480,3 +481,89 @@ func addImport(content, path string) string {
 
 	return content
 }
+
+// GetBaseIdent recursively resolves an expression to its base identifier.
+// It handles selector expressions, call expressions, and identifiers.
+// Returns nil if the expression cannot be resolved to a simple identifier.
+func GetBaseIdent(expr ast.Expr) *ast.Ident {
+	for {
+		switch e := expr.(type) {
+		case *ast.Ident:
+			return e
+		case *ast.SelectorExpr:
+			expr = e.X
+		case *ast.CallExpr:
+			expr = e.Fun
+		default:
+			return nil
+		}
+	}
+}
+
+// ExtractCommentAndValue separates a value from its trailing comment.
+// It handles both line comments (//) and block comments (/* */).
+// Returns the value (trimmed) and the comment (with original delimiters).
+func ExtractCommentAndValue(line string) (value, comment string) {
+	value = line
+	if idx := strings.Index(line, "//"); idx >= 0 {
+		comment = strings.TrimSpace(line[idx:])
+		value = strings.TrimSpace(line[:idx])
+	} else if idx := strings.Index(line, "/*"); idx >= 0 {
+		comment = strings.TrimSpace(line[idx:])
+		value = strings.TrimSpace(line[:idx])
+	}
+	return value, comment
+}
+
+// FormatFieldWithComment formats a field assignment with consistent spacing
+// for indentation, value, comma, comment, and newline.
+func FormatFieldWithComment(indent, fieldName, value, comma, comment, newline string) string {
+	if comment != "" {
+		comment = " " + comment
+	}
+	return fmt.Sprintf("%s%s: %s%s%s%s", indent, fieldName, value, comma, comment, newline)
+}
+
+// IterateConfigBlocks finds all occurrences matching the given regex pattern,
+// extracts their config blocks using braces, processes each block with the
+// provided function, and reconstructs the content.
+func IterateConfigBlocks(content string, pattern *regexp.Regexp, processor func(string) string) string {
+	matches := pattern.FindAllStringIndex(content, -1)
+	if len(matches) == 0 {
+		return content
+	}
+
+	var b strings.Builder
+	last := 0
+	for _, m := range matches {
+		if m[0] < last {
+			// Skip matches that fall inside a block we've already processed.
+			continue
+		}
+		b.WriteString(content[last:m[0]]) //nolint:errcheck // WriteString never returns an error
+		start := m[0]
+		end := extractBlock(content, m[1], '{', '}')
+		cfg := content[start:end]
+
+		// Process the config block
+		cfg = processor(cfg)
+
+		b.WriteString(cfg) //nolint:errcheck // WriteString never returns an error
+		last = end
+	}
+	b.WriteString(content[last:]) //nolint:errcheck // WriteString never returns an error
+	return b.String()
+}
+
+// BuildExtractorChain builds an extractor expression from a slice of extractors.
+// Returns a single extractor for one element, Chain() for multiple, or empty for none.
+func BuildExtractorChain(extractors []string) string {
+	switch len(extractors) {
+	case 0:
+		return ""
+	case 1:
+		return extractors[0]
+	default:
+		return fmt.Sprintf("extractors.Chain(%s)", strings.Join(extractors, ", "))
+	}
+}

cmd/internal/migrations/v3/context_methods.go

@@ -26,20 +26,6 @@ func MigrateContextMethods(cmd *cobra.Command, cwd string, _, _ *semver.Version)
 			file, err := parser.ParseFile(fset, "", content, parser.ParseComments)
 			if err == nil {
 				modified := false
-				baseIdent := func(expr ast.Expr) *ast.Ident {
-					for {
-						switch e := expr.(type) {
-						case *ast.Ident:
-							return e
-						case *ast.SelectorExpr:
-							expr = e.X
-						case *ast.CallExpr:
-							expr = e.Fun
-						default:
-							return nil
-						}
-					}
-				}
 				ast.Inspect(file, func(n ast.Node) bool {
 					call, ok := n.(*ast.CallExpr)
 					if !ok {
@@ -49,7 +35,7 @@ func MigrateContextMethods(cmd *cobra.Command, cwd string, _, _ *semver.Version)
 					if !ok || sel.Sel.Name != "Context" || len(call.Args) != 0 {
 						return true
 					}
-					if ident := baseIdent(sel.X); ident != nil && isFiberCtx(orig, ident.Name) {
+					if ident := GetBaseIdent(sel.X); ident != nil && isFiberCtx(orig, ident.Name) {
 						sel.Sel.Name = "RequestCtx"
 						modified = true
 					}

cmd/internal/migrations/v3/csrfconfig.go

@@ -15,55 +15,27 @@ func MigrateCSRFConfig(cmd *cobra.Command, cwd string, _, _ *semver.Version) err
 	reConfig := regexp.MustCompile(`csrf\.Config{`)
 	reSession := regexp.MustCompile(`(?m)\s*SessionKey:\s*[^,\n]+,?\s*(//[^\n]*)?\n`)
 	changed, err := internal.ChangeFileContent(cwd, func(content string) string {
-		matches := reConfig.FindAllStringIndex(content, -1)
-		if len(matches) == 0 {
-			return content
-		}
-
-		var b strings.Builder
-		last := 0
-		for _, m := range matches {
-			if _, err := b.WriteString(content[last:m[0]]); err != nil {
-				return content
-			}
-			start := m[0]
-			end := extractBlock(content, m[1], '{', '}')
-			cfg := content[start:end]
+		updated := IterateConfigBlocks(content, reConfig, func(cfg string) string {
 			cfg = strings.ReplaceAll(cfg, "Expiration:", "IdleTimeout:")
 			cfg = reSession.ReplaceAllString(cfg, "")
 
-			cfg = replaceKeyLookup(cfg, func(indent, val, comma, comment, newline string) string {
+			return replaceKeyLookup(cfg, func(indent, val, comma, comment, newline string) string {
 				var extractor string
 				switch {
 				case strings.HasPrefix(val, "header:"):
-					extractor = fmt.Sprintf("Extractor: extractors.FromHeader(%q)", strings.TrimPrefix(val, "header:"))
+					extractor = fmt.Sprintf("extractors.FromHeader(%q)", strings.TrimPrefix(val, "header:"))
 				case strings.HasPrefix(val, "form:"):
-					extractor = fmt.Sprintf("Extractor: extractors.FromForm(%q)", strings.TrimPrefix(val, "form:"))
+					extractor = fmt.Sprintf("extractors.FromForm(%q)", strings.TrimPrefix(val, "form:"))
 				case strings.HasPrefix(val, "query:"):
-					extractor = fmt.Sprintf("Extractor: extractors.FromQuery(%q)", strings.TrimPrefix(val, "query:"))
+					extractor = fmt.Sprintf("extractors.FromQuery(%q)", strings.TrimPrefix(val, "query:"))
 				default:
-					if comment != "" {
-						comment = " " + comment
-					}
-					return fmt.Sprintf("%s// TODO: migrate KeyLookup: %s%s%s", indent, val, comment, newline)
+					return FormatFieldWithComment(indent, "// TODO: migrate KeyLookup", val, "", comment, newline)
 				}
 
-				if comment != "" {
-					comment = " " + comment
-				}
-				return fmt.Sprintf("%s%s%s%s%s", indent, extractor, comma, comment, newline)
+				return FormatFieldWithComment(indent, "Extractor", extractor, comma, comment, newline)
 			})
+		})
 
-			if _, err := b.WriteString(cfg); err != nil {
-				return content
-			}
-			last = end
-		}
-		if _, err := b.WriteString(content[last:]); err != nil {
-			return content
-		}
-
-		updated := b.String()
 		if updated != content {
 			updated = addImport(updated, "github.com/gofiber/fiber/v3/extractors")
 		}

cmd/internal/migrations/v3/encryptcookie_config.go

@@ -15,34 +15,11 @@ func MigrateEncryptcookieConfig(cmd *cobra.Command, cwd string, _, _ *semver.Ver
 	reConfig := regexp.MustCompile(`encryptcookie\.Config{`)
 
 	changed, err := internal.ChangeFileContent(cwd, func(content string) string {
-		matches := reConfig.FindAllStringIndex(content, -1)
-		if len(matches) == 0 {
-			return content
-		}
-
-		var b strings.Builder
-		last := 0
-		for _, m := range matches {
-			if _, err := b.WriteString(content[last:m[0]]); err != nil {
-				return content
-			}
-
-			start := m[0]
-			end := extractBlock(content, m[1], '{', '}')
-			cfg := content[start:end]
+		return IterateConfigBlocks(content, reConfig, func(cfg string) string {
 			cfg = addEncryptcookieParam(cfg, "Encryptor")
 			cfg = addEncryptcookieParam(cfg, "Decryptor")
-
-			if _, err := b.WriteString(cfg); err != nil {
-				return content
-			}
-			last = end
-		}
-
-		if _, err := b.WriteString(content[last:]); err != nil {
-			return content
-		}
-		return b.String()
+			return cfg
+		})
 	})
 	if err != nil {
 		return fmt.Errorf("failed to migrate encryptcookie configs: %w", err)

cmd/internal/migrations/v3/jwt_extractor.go

@@ -60,33 +60,16 @@ func MigrateJWTExtractor(cmd *cobra.Command, cwd string, _, _ *semver.Version) e
 						case strings.HasPrefix(p, "form:"):
 							extractors = append(extractors, fmt.Sprintf("extractors.FromForm(%q)", strings.TrimPrefix(p, "form:")))
 						default:
-							if comment != "" {
-								comment = " " + comment
-							}
-							return fmt.Sprintf("%s// TODO: migrate TokenLookup: %s%s%s", indent, val, comment, newline)
+							return FormatFieldWithComment(indent, "// TODO: migrate TokenLookup", val, "", comment, newline)
 						}
 					}
 
-					extractor := ""
-					switch len(extractors) {
-					case 1:
-						extractor = extractors[0]
-					case 0:
-					default:
-						extractor = fmt.Sprintf("extractors.Chain(%s)", strings.Join(extractors, ", "))
-					}
-
+					extractor := BuildExtractorChain(extractors)
 					if extractor == "" {
-						if comment != "" {
-							comment = " " + comment
-						}
-						return fmt.Sprintf("%s// TODO: migrate TokenLookup: %s%s%s", indent, val, comment, newline)
+						return FormatFieldWithComment(indent, "// TODO: migrate TokenLookup", val, "", comment, newline)
 					}
 
-					if comment != "" {
-						comment = " " + comment
-					}
-					return fmt.Sprintf("%sExtractor: %s%s%s%s", indent, extractor, comma, comment, newline)
+					return FormatFieldWithComment(indent, "Extractor", extractor, comma, comment, newline)
 				})
 
 				cfg = reAuthLine.ReplaceAllString(cfg, "")

cmd/internal/migrations/v3/key_auth_config.go

@@ -48,30 +48,16 @@ func MigrateKeyAuthConfig(cmd *cobra.Command, cwd string, _, _ *semver.Version)
 					case strings.HasPrefix(p, "cookie:"):
 						extractors = append(extractors, fmt.Sprintf("extractors.FromCookie(%q)", strings.TrimPrefix(p, "cookie:")))
 					default:
-						if comment != "" {
-							comment = " " + comment
-						}
-						return fmt.Sprintf("%s// TODO: migrate KeyLookup: %s%s%s", indent, val, comment, newline)
+						return FormatFieldWithComment(indent, "// TODO: migrate KeyLookup", val, "", comment, newline)
 					}
 				}
 
-				extractor := ""
-				if len(extractors) == 1 {
-					extractor = extractors[0]
-				} else if len(extractors) > 1 {
-					extractor = fmt.Sprintf("extractors.Chain(%s)", strings.Join(extractors, ", "))
-				}
+				extractor := BuildExtractorChain(extractors)
 				if extractor == "" {
-					if comment != "" {
-						comment = " " + comment
-					}
-					return fmt.Sprintf("%s// TODO: migrate KeyLookup: %s%s%s", indent, val, comment, newline)
+					return FormatFieldWithComment(indent, "// TODO: migrate KeyLookup", val, "", comment, newline)
 				}
 
-				if comment != "" {
-					comment = " " + comment
-				}
-				return fmt.Sprintf("%sExtractor: %s%s%s%s", indent, extractor, comma, comment, newline)
+				return FormatFieldWithComment(indent, "Extractor", extractor, comma, comment, newline)
 			})
 
 			cfg = removeConfigField(cfg, "AuthScheme")

cmd/internal/migrations/v3/paseto_extractor.go

@@ -45,10 +45,7 @@ func MigratePasetoExtractor(cmd *cobra.Command, cwd string, _, _ *semver.Version
 					lookup = strings.TrimSuffix(lookup, "}")
 					parts := splitArgs(lookup)
 					if len(parts) < 2 {
-						if comment != "" {
-							comment = " " + comment
-						}
-						return fmt.Sprintf("%s// TODO: migrate TokenLookup: %s%s%s", indent, val, comment, newline)
+						return FormatFieldWithComment(indent, "// TODO: migrate TokenLookup", val, "", comment, newline)
 					}
 
 					source := strings.TrimSpace(parts[0])
@@ -99,16 +96,10 @@ func MigratePasetoExtractor(cmd *cobra.Command, cwd string, _, _ *semver.Version
 					}
 
 					if extractor == "" {
-						if comment != "" {
-							comment = " " + comment
-						}
-						return fmt.Sprintf("%s// TODO: migrate TokenLookup: %s%s%s", indent, val, comment, newline)
+						return FormatFieldWithComment(indent, "// TODO: migrate TokenLookup", val, "", comment, newline)
 					}
 
-					if comment != "" {
-						comment = " " + comment
-					}
-					return fmt.Sprintf("%sExtractor: %s%s%s%s", indent, extractor, comma, comment, newline)
+					return FormatFieldWithComment(indent, "Extractor", extractor, comma, comment, newline)
 				})
 
 				cfg = removeConfigField(cfg, "TokenPrefix")

cmd/internal/migrations/v3/redirect_methods.go

@@ -27,21 +27,6 @@ func MigrateRedirectMethods(cmd *cobra.Command, cwd string, _, _ *semver.Version
 
 		modified := false
 
-		baseIdent := func(expr ast.Expr) *ast.Ident {
-			for {
-				switch e := expr.(type) {
-				case *ast.Ident:
-					return e
-				case *ast.SelectorExpr:
-					expr = e.X
-				case *ast.CallExpr:
-					expr = e.Fun
-				default:
-					return nil
-				}
-			}
-		}
-
 		ast.Inspect(file, func(n ast.Node) bool {
 			call, ok := n.(*ast.CallExpr)
 			if !ok {
@@ -53,7 +38,7 @@ func MigrateRedirectMethods(cmd *cobra.Command, cwd string, _, _ *semver.Version
 				return true
 			}
 
-			ident := baseIdent(sel.X)
+			ident := GetBaseIdent(sel.X)
 			if ident == nil || !isFiberCtx(orig, ident.Name) {
 				return true
 			}