Add extension normalization command

internal/extension/request.go

@@ -0,0 +1,100 @@
+package extension
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/rogeecn/renamer/internal/listing"
+)
+
+// ExtensionRequest captures all inputs required to evaluate an extension normalization run.
+type ExtensionRequest struct {
+	WorkingDir              string
+	SourceExtensions        []string
+	DisplaySourceExtensions []string
+	TargetExtension         string
+	DuplicateSources        []string
+	NoOpSources             []string
+
+	IncludeDirs   bool
+	Recursive     bool
+	IncludeHidden bool
+
+	ExtensionFilter []string
+
+	DryRun      bool
+	AutoConfirm bool
+
+	Timestamp time.Time
+}
+
+// NewRequest seeds an ExtensionRequest using the shared listing scope settings.
+func NewRequest(scope *listing.ListingRequest) *ExtensionRequest {
+	if scope == nil {
+		return &ExtensionRequest{}
+	}
+
+	filterCopy := append([]string(nil), scope.Extensions...)
+
+	return &ExtensionRequest{
+		WorkingDir:      scope.WorkingDir,
+		IncludeDirs:     scope.IncludeDirectories,
+		Recursive:       scope.Recursive,
+		IncludeHidden:   scope.IncludeHidden,
+		ExtensionFilter: filterCopy,
+	}
+}
+
+// SetExecutionMode records dry-run/auto-apply preferences inherited from CLI flags.
+func (r *ExtensionRequest) SetExecutionMode(dryRun, autoConfirm bool) {
+	r.DryRun = dryRun
+	r.AutoConfirm = autoConfirm
+}
+
+// SetExtensions stores source and target extensions before normalization.
+func (r *ExtensionRequest) SetExtensions(canonical []string, display []string, target string) {
+	r.SourceExtensions = append(r.SourceExtensions[:0], canonical...)
+	r.DisplaySourceExtensions = append(r.DisplaySourceExtensions[:0], display...)
+	r.TargetExtension = target
+}
+
+// SetWarnings captures duplicate or no-op tokens for later surfacing in preview output.
+func (r *ExtensionRequest) SetWarnings(dupes, noOps []string) {
+	r.DuplicateSources = append(r.DuplicateSources[:0], dupes...)
+	r.NoOpSources = append(r.NoOpSources[:0], noOps...)
+}
+
+// Normalize ensures working directory and timestamp fields are ready for execution.
+func (r *ExtensionRequest) Normalize() error {
+	if r.WorkingDir == "" {
+		cwd, err := os.Getwd()
+		if err != nil {
+			return fmt.Errorf("determine working directory: %w", err)
+		}
+		r.WorkingDir = cwd
+	}
+
+	if !filepath.IsAbs(r.WorkingDir) {
+		abs, err := filepath.Abs(r.WorkingDir)
+		if err != nil {
+			return fmt.Errorf("resolve working directory: %w", err)
+		}
+		r.WorkingDir = abs
+	}
+
+	info, err := os.Stat(r.WorkingDir)
+	if err != nil {
+		return fmt.Errorf("stat working directory: %w", err)
+	}
+	if !info.IsDir() {
+		return fmt.Errorf("working directory %q is not a directory", r.WorkingDir)
+	}
+
+	if r.Timestamp.IsZero() {
+		r.Timestamp = time.Now().UTC()
+	}
+
+	return nil
+}