refactor(outputters): implement Dependency Inversion Principle for formatters

Introduced Formatter interface and FormatterFactory abstraction to decouple
Outputter from concrete formatter implementations:

- Formatter interface: abstracts Format(summary) behavior
- FormatterFactory interface: abstracts formatter creation
- DefaultFormatterFactory: creates output.* formatters
- NewOutputterWithFactory: enables dependency injection for testing

Outputter now depends on FormatterFactory abstraction rather than directly
on output package implementations (DIP compliance).

Author: Test User

internal/outputters/outputter.go

@@ -4,24 +4,87 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/dotcommander/cclint/internal/config"
 	"github.com/dotcommander/cclint/internal/cli"
+	"github.com/dotcommander/cclint/internal/config"
 	"github.com/dotcommander/cclint/internal/output"
 )
 
-// Outputter handles output formatting
+// =============================================================================
+// Dependency Inversion: Formatter interface for output formatters
+// =============================================================================
+
+// Formatter defines the interface for output formatters.
+// This allows the Outputter to depend on an abstraction rather than
+// concrete formatter implementations (DIP compliance).
+type Formatter interface {
+	// Format formats the lint summary and outputs it
+	Format(summary *cli.LintSummary) error
+}
+
+// FormatterFactory creates formatters based on format type.
+// This follows the Factory pattern for DIP compliance.
+type FormatterFactory interface {
+	// CreateFormatter creates a formatter for the given format type
+	CreateFormatter(format string) (Formatter, error)
+}
+
+// =============================================================================
+// Default FormatterFactory implementation
+// =============================================================================
+
+// DefaultFormatterFactory creates formatters using the output package.
+type DefaultFormatterFactory struct {
+	cfg *config.Config
+}
+
+// NewDefaultFormatterFactory creates a new DefaultFormatterFactory.
+func NewDefaultFormatterFactory(cfg *config.Config) *DefaultFormatterFactory {
+	return &DefaultFormatterFactory{cfg: cfg}
+}
+
+// CreateFormatter implements FormatterFactory interface.
+func (f *DefaultFormatterFactory) CreateFormatter(format string) (Formatter, error) {
+	switch format {
+	case "console":
+		return output.NewConsoleFormatter(f.cfg.Quiet, f.cfg.Verbose, f.cfg.ShowScores, f.cfg.ShowImprovements), nil
+	case "json":
+		return output.NewJSONFormatter(f.cfg.Quiet, true, f.cfg.Output), nil
+	case "markdown":
+		return output.NewMarkdownFormatter(f.cfg.Quiet, f.cfg.Verbose, f.cfg.Output), nil
+	default:
+		return nil, fmt.Errorf("unsupported format: %s", format)
+	}
+}
+
+// =============================================================================
+// Outputter with DIP-compliant design
+// =============================================================================
+
+// Outputter handles output formatting using injected formatter factory.
+// It depends on the FormatterFactory abstraction, not concrete formatters.
 type Outputter struct {
-	config *config.Config
+	config  *config.Config
+	factory FormatterFactory
 }
 
-// NewOutputter creates a new Outputter
+// NewOutputter creates a new Outputter with the default formatter factory.
 func NewOutputter(config *config.Config) *Outputter {
 	return &Outputter{
-		config: config,
+		config:  config,
+		factory: NewDefaultFormatterFactory(config),
 	}
 }
 
-// Format formats the lint summary using the configured format
+// NewOutputterWithFactory creates a new Outputter with a custom formatter factory.
+// This allows for dependency injection and easier testing.
+func NewOutputterWithFactory(config *config.Config, factory FormatterFactory) *Outputter {
+	return &Outputter{
+		config:  config,
+		factory: factory,
+	}
+}
+
+// Format formats the lint summary using the configured format.
 func (o *Outputter) Format(summary *cli.LintSummary, format string) error {
 	// Set start time if not set
 	if summary.StartTime.IsZero() {
@@ -31,18 +94,11 @@ func (o *Outputter) Format(summary *cli.LintSummary, format string) error {
 	// Set project root in summary for display
 	summary.ProjectRoot = o.config.Root
 
-	// Create appropriate formatter based on format
-	switch format {
-	case "console":
-		formatter := output.NewConsoleFormatter(o.config.Quiet, o.config.Verbose, o.config.ShowScores, o.config.ShowImprovements)
-		return formatter.Format(summary)
-	case "json":
-		formatter := output.NewJSONFormatter(o.config.Quiet, true, o.config.Output)
-		return formatter.Format(summary)
-	case "markdown":
-		formatter := output.NewMarkdownFormatter(o.config.Quiet, o.config.Verbose, o.config.Output)
-		return formatter.Format(summary)
-	default:
-		return fmt.Errorf("unsupported format: %s", format)
+	// Create formatter via factory (DIP compliance)
+	formatter, err := o.factory.CreateFormatter(format)
+	if err != nil {
+		return err
 	}
+
+	return formatter.Format(summary)
 }