Add insert command

internal/insert/apply.go

@@ -0,0 +1,85 @@
+package insert
+
+import (
+	"context"
+	"errors"
+	"os"
+	"path/filepath"
+	"sort"
+
+	"github.com/rogeecn/renamer/internal/history"
+)
+
+// Apply performs planned insert operations and records them in the ledger.
+func Apply(ctx context.Context, req *Request, planned []PlannedOperation, summary *Summary) (history.Entry, error) {
+	entry := history.Entry{Command: "insert"}
+
+	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: op.OriginalRelative,
+			To:   op.ProposedRelative,
+		})
+	}
+
+	if len(done) == 0 {
+		return entry, nil
+	}
+
+	entry.Operations = done
+	if summary != nil {
+		meta := make(map[string]any, len(summary.LedgerMetadata))
+		for k, v := range summary.LedgerMetadata {
+			meta[k] = v
+		}
+		meta["totalCandidates"] = summary.TotalCandidates
+		meta["totalChanged"] = summary.TotalChanged
+		meta["noChange"] = summary.NoChange
+		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
+}