Add extension normalization command

internal/extension/apply.go

@@ -0,0 +1,109 @@
+package extension
+
+import (
+	"context"
+	"errors"
+	"os"
+	"path/filepath"
+	"sort"
+
+	"github.com/rogeecn/renamer/internal/history"
+)
+
+// Apply executes planned renames and records the operations in the ledger.
+func Apply(ctx context.Context, req *ExtensionRequest, planned []PlannedRename, summary *ExtensionSummary) (history.Entry, error) {
+	entry := history.Entry{Command: "extension"}
+
+	if len(planned) == 0 {
+		return entry, nil
+	}
+
+	sort.SliceStable(planned, func(i, j int) bool {
+		return planned[i].Depth > planned[j].Depth
+	})
+
+	done := make([]history.Operation, 0, len(planned))
+
+	revert := func() error {
+		for i := len(done) - 1; i >= 0; i-- {
+			op := done[i]
+			source := filepath.Join(req.WorkingDir, filepath.FromSlash(op.To))
+			destination := filepath.Join(req.WorkingDir, filepath.FromSlash(op.From))
+			if err := os.Rename(source, destination); err != nil && !errors.Is(err, os.ErrNotExist) {
+				return err
+			}
+		}
+		return nil
+	}
+
+	for _, op := range planned {
+		if err := ctx.Err(); err != nil {
+			_ = revert()
+			return history.Entry{}, err
+		}
+
+		if op.OriginalAbsolute == op.ProposedAbsolute {
+			continue
+		}
+
+		if err := os.Rename(op.OriginalAbsolute, op.ProposedAbsolute); err != nil {
+			_ = revert()
+			return history.Entry{}, err
+		}
+
+		done = append(done, history.Operation{
+			From: filepath.ToSlash(op.OriginalRelative),
+			To:   filepath.ToSlash(op.ProposedRelative),
+		})
+	}
+
+	if len(done) == 0 {
+		return entry, nil
+	}
+
+	entry.Operations = done
+
+	if summary != nil {
+		meta := make(map[string]any)
+		if len(req.DisplaySourceExtensions) > 0 {
+			meta["sourceExtensions"] = append([]string(nil), req.DisplaySourceExtensions...)
+		}
+		if req.TargetExtension != "" {
+			meta["targetExtension"] = req.TargetExtension
+		}
+		meta["totalCandidates"] = summary.TotalCandidates
+		meta["totalChanged"] = summary.TotalChanged
+		meta["noChange"] = summary.NoChange
+
+		if len(summary.PerExtensionCounts) > 0 {
+			counts := make(map[string]int, len(summary.PerExtensionCounts))
+			for ext, count := range summary.PerExtensionCounts {
+				counts[ext] = count
+			}
+			meta["perExtensionCounts"] = counts
+		}
+
+		scope := map[string]any{
+			"includeDirs":   req.IncludeDirs,
+			"recursive":     req.Recursive,
+			"includeHidden": req.IncludeHidden,
+		}
+		if len(req.ExtensionFilter) > 0 {
+			scope["extensionFilter"] = append([]string(nil), req.ExtensionFilter...)
+		}
+		meta["scope"] = scope
+
+		if len(summary.Warnings) > 0 {
+			meta["warnings"] = append([]string(nil), summary.Warnings...)
+		}
+
+		entry.Metadata = meta
+	}
+
+	if err := history.Append(req.WorkingDir, entry); err != nil {
+		_ = revert()
+		return history.Entry{}, err
+	}
+
+	return entry, nil
+}