refactor: extract migration logic into internal/migrate package (task q6)

Move all geheim→KeePass migration business logic from internal/cli/migrate_kdbx.go
into a new internal/migrate package (migrator.go, kdbx_store.go). The CLI layer
is now a thin orchestrator: parse flags, open KDBX, call migrate.Run, save, report.

Key design decisions:
- migrate.Run accepts separate logFn (stdout info) and warnFn (stderr errors)
  so per-entry errors correctly route to stderr via warn(), not stdout via logMsg()
- migrate.Options contains only DryRun; DBPath/BinaryOutDir removed (CLI-only concerns)
- StoreWalker interface is narrow, avoiding a direct dependency on backend.Backend
- cli_paths.go extracts readPasswordFile/resolveHomeDir/expandHome shared within cli
- kdbx_store.go deleted from cli (moved to internal/migrate)
- Duplicate TestExtractPasswordFromContent removed from kdbx_store_test.go
- Custom contains/containsStr helpers replaced with strings.Contains in tests
- Dry-run test now asserts logged message content

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

3 files changed, 488 insertions, 0 deletions

diff --git a/internal/migrate/kdbx_store.go b/internal/migrate/kdbx_store.go
new file mode 100644
index 0000000..d2ad900
--- /dev/null
+++ b/internal/migrate/kdbx_store.go
@@ -0,0 +1,105 @@
+// Package migrate provides the geheim→KeePass migration logic for foostore.
+// The CLI layer (internal/cli) is responsible only for flag parsing and exit
+// codes; all migration business logic lives here.
+package migrate
+
+import (
+	"fmt"
+	"os"
+
+	gokeepasslib "github.com/tobischo/gokeepasslib/v3"
+
+	"codeberg.org/snonux/foostore/internal/keepass"
+)
+
+// KDBXStore is the minimal interface needed by the migrator to write entries
+// into a KeePass database. Keeping it small satisfies the Interface Segregation
+// Principle and allows easy substitution in tests.
+type KDBXStore interface {
+	UpsertTextEntry(groupPath []string, title, password, notes string) (overwrote bool, err error)
+	UpsertBinaryEntry(groupPath []string, title, filename string, content []byte) (overwrote bool, err error)
+	Save() error
+}
+
+// kdbxStore wraps an in-memory gokeepasslib.Database and the file path it will
+// be written to on Save().
+type kdbxStore struct {
+	path string
+	db   *gokeepasslib.Database
+}
+
+// OpenKDBXStore opens an existing KDBX database using password credentials,
+// decodes and unlocks protected entries, and returns a ready-to-use KDBXStore.
+func OpenKDBXStore(dbPath, password string) (KDBXStore, error) {
+	f, err := os.Open(dbPath)
+	if err != nil {
+		return nil, fmt.Errorf("opening kdbx %q: %w", dbPath, err)
+	}
+	defer f.Close()
+
+	db := gokeepasslib.NewDatabase()
+	db.Credentials = gokeepasslib.NewPasswordCredentials(password)
+	if err := gokeepasslib.NewDecoder(f).Decode(db); err != nil {
+		return nil, fmt.Errorf("decoding kdbx %q: %w", dbPath, err)
+	}
+	if err := db.UnlockProtectedEntries(); err != nil {
+		return nil, fmt.Errorf("unlocking kdbx %q: %w", dbPath, err)
+	}
+
+	ensureRootGroup(db)
+	return &kdbxStore{path: dbPath, db: db}, nil
+}
+
+// ensureRootGroup guarantees that the database has a valid Content, Root, and
+// at least one top-level Group so callers never have to nil-check these fields.
+func ensureRootGroup(db *gokeepasslib.Database) {
+	if db.Content == nil {
+		db.Content = gokeepasslib.NewContent()
+	}
+	if db.Content.Root == nil {
+		db.Content.Root = gokeepasslib.NewRootData()
+	}
+	if len(db.Content.Root.Groups) == 0 {
+		root := gokeepasslib.NewGroup()
+		root.Name = "Root"
+		db.Content.Root.Groups = append(db.Content.Root.Groups, root)
+	}
+}
+
+// UpsertTextEntry creates or updates a text entry in groupPath with the given
+// title, password, and notes. Delegates field manipulation to keepass.SetEntryField
+// and group navigation to keepass.EnsureGroup.
+func (s *kdbxStore) UpsertTextEntry(groupPath []string, title, password, notes string) (bool, error) {
+	g := keepass.EnsureGroup(&s.db.Content.Root.Groups[0], groupPath)
+	entry, overwrote := keepass.UpsertEntryByTitle(g, title)
+	keepass.SetEntryField(entry, "Title", title)
+	keepass.SetEntryField(entry, "Password", password)
+	keepass.SetEntryField(entry, "Notes", notes)
+	return overwrote, nil
+}
+
+// UpsertBinaryEntry creates or updates a binary attachment entry in groupPath.
+// Delegates field manipulation to keepass.SetEntryField and group navigation
+// to keepass.EnsureGroup.
+func (s *kdbxStore) UpsertBinaryEntry(groupPath []string, title, filename string, content []byte) (bool, error) {
+	g := keepass.EnsureGroup(&s.db.Content.Root.Groups[0], groupPath)
+	entry, overwrote := keepass.UpsertEntryByTitle(g, title)
+	keepass.SetEntryField(entry, "Title", title)
+	keepass.SetEntryField(entry, "Password", "")
+
+	b := s.db.AddBinary(content)
+	entry.Binaries = []gokeepasslib.BinaryReference{b.CreateReference(filename)}
+	// Keep notes concise for binary-only entries.
+	keepass.SetEntryField(entry, "Notes", fmt.Sprintf("Migrated binary attachment: %s", filename))
+	return overwrote, nil
+}
+
+// Save locks protected entries and atomically writes the database to disk.
+// Delegates the tmp→encode→rename sequence to keepass.AtomicSave to avoid
+// duplicating that logic here.
+func (s *kdbxStore) Save() error {
+	if err := s.db.LockProtectedEntries(); err != nil {
+		return fmt.Errorf("locking kdbx entries: %w", err)
+	}
+	return keepass.AtomicSave(s.db, s.path)
+}
diff --git a/internal/migrate/migrator.go b/internal/migrate/migrator.go
new file mode 100644
index 0000000..7ff0e30
--- /dev/null
+++ b/internal/migrate/migrator.go
@@ -0,0 +1,181 @@
+package migrate
+
+import (
+	"context"
+	"fmt"
+	"regexp"
+	"sort"
+	"strings"
+
+	"codeberg.org/snonux/foostore/internal/keepass"
+	"codeberg.org/snonux/foostore/internal/store"
+)
+
+// Options holds the resolved parameters for a geheim→KeePass migration run.
+type Options struct {
+	DryRun bool
+}
+
+// Stats accumulates counters for a migration run so callers can report progress.
+type Stats struct {
+	Total           int
+	TextMigrated    int
+	BinaryMigrated  int
+	OverwrittenText int
+	OverwrittenBin  int
+	Errors          int
+}
+
+// StoreWalker is the subset of backend.Backend needed by the migrator. Using a
+// narrow interface here avoids importing the full backend package and makes
+// testing straightforward.
+type StoreWalker interface {
+	WalkIndexes(ctx context.Context, prefix string, fn func(*store.Index) error) error
+	LoadData(ctx context.Context, idx *store.Index) (*store.Data, error)
+}
+
+// Run walks all index entries in src, migrating each one into kdbx.
+// It returns aggregated Stats. When opts.DryRun is true, no writes are made
+// to kdbx (kdbx may be nil in that case). logFn receives informational
+// messages; warnFn receives per-entry error messages (should write to stderr).
+// Neither may be nil.
+func Run(ctx context.Context, src StoreWalker, kdbx KDBXStore, opts Options, logFn, warnFn func(string)) (Stats, error) {
+	var indexes store.IndexSlice
+	if err := src.WalkIndexes(ctx, "", func(idx *store.Index) error {
+		indexes = append(indexes, idx)
+		return nil
+	}); err != nil {
+		return Stats{}, fmt.Errorf("listing store entries: %w", err)
+	}
+	sort.Sort(indexes)
+
+	var stats Stats
+	for _, idx := range indexes {
+		stats.Total++
+		if err := migrateOneEntry(ctx, src, idx, opts, kdbx, &stats, logFn); err != nil {
+			stats.Errors++
+			// Per-entry errors go through warnFn so the caller can route them
+			// to stderr, keeping informational log and error output separate.
+			warnFn(err.Error())
+		}
+	}
+	return stats, nil
+}
+
+// migrateOneEntry migrates a single index entry from src into kdbx (or logs
+// the action when dry-run is active). Errors are returned so the caller can
+// increment the error counter and continue.
+func migrateOneEntry(
+	ctx context.Context,
+	src StoreWalker,
+	idx *store.Index,
+	opts Options,
+	kdbx KDBXStore,
+	stats *Stats,
+	logFn func(string),
+) error {
+	safePath, err := keepass.SanitizeRelativePath(idx.Description)
+	if err != nil {
+		return fmt.Errorf("entry %q: %w", idx.Description, err)
+	}
+
+	d, err := src.LoadData(ctx, idx)
+	if err != nil {
+		return fmt.Errorf("loading data for %q: %w", idx.Description, err)
+	}
+
+	if idx.IsBinary() {
+		return migrateBinaryEntry(idx, safePath, d.Content, opts, kdbx, stats, logFn)
+	}
+	return migrateTextEntry(idx, safePath, d.Content, opts, kdbx, stats, logFn)
+}
+
+// migrateBinaryEntry handles a binary (non-text) store entry.
+func migrateBinaryEntry(
+	idx *store.Index,
+	safePath string,
+	content []byte,
+	opts Options,
+	kdbx KDBXStore,
+	stats *Stats,
+	logFn func(string),
+) error {
+	groupPath, title, err := keepass.SplitDescriptionPath(safePath)
+	if err != nil {
+		return fmt.Errorf("mapping binary entry %q: %w", idx.Description, err)
+	}
+	if opts.DryRun {
+		logFn(fmt.Sprintf("DRY-RUN binary migrate: %s -> attachment=%s", idx.Description, title))
+		stats.BinaryMigrated++
+		return nil
+	}
+	overwrote, err := kdbx.UpsertBinaryEntry(groupPath, title, title, content)
+	if err != nil {
+		return fmt.Errorf("upserting binary entry %q: %w", idx.Description, err)
+	}
+	if overwrote {
+		stats.OverwrittenBin++
+	}
+	stats.BinaryMigrated++
+	return nil
+}
+
+// migrateTextEntry handles a text (non-binary) store entry.
+func migrateTextEntry(
+	idx *store.Index,
+	safePath string,
+	content []byte,
+	opts Options,
+	kdbx KDBXStore,
+	stats *Stats,
+	logFn func(string),
+) error {
+	groupPath, title, err := keepass.SplitDescriptionPath(safePath)
+	if err != nil {
+		return fmt.Errorf("mapping text entry %q: %w", idx.Description, err)
+	}
+	if opts.DryRun {
+		logFn(fmt.Sprintf("DRY-RUN text migrate: %s -> group=%q title=%q",
+			idx.Description, strings.Join(groupPath, "/"), title))
+		stats.TextMigrated++
+		return nil
+	}
+	entryPassword, entryNotes := ExtractPasswordFromContent(string(content))
+	overwrote, err := kdbx.UpsertTextEntry(groupPath, title, entryPassword, entryNotes)
+	if err != nil {
+		return fmt.Errorf("upserting text entry %q: %w", idx.Description, err)
+	}
+	if overwrote {
+		stats.OverwrittenText++
+	}
+	stats.TextMigrated++
+	return nil
+}
+
+// passwordLinePattern matches lines like "password: s3cr3t" or "pass: s3cr3t"
+// (case-insensitive) so that the password field can be extracted from entry content.
+var passwordLinePattern = regexp.MustCompile(`(?i)^\s*(pass|password)\s*:\s*(.*)\s*$`)
+
+// ExtractPasswordFromContent splits entry text content into a password (from
+// the first "pass:" or "password:" line) and the remaining notes. The password
+// line itself is removed from the notes output. This is exported so the CLI
+// package can call it directly in tests without duplicating the logic.
+func ExtractPasswordFromContent(content string) (password, notes string) {
+	lines := strings.Split(content, "\n")
+	notesLines := make([]string, 0, len(lines))
+
+	for _, line := range lines {
+		m := passwordLinePattern.FindStringSubmatch(line)
+		if len(m) == 3 {
+			// Take only the first password line encountered.
+			if password == "" {
+				password = strings.TrimSpace(m[2])
+			}
+			continue
+		}
+		notesLines = append(notesLines, line)
+	}
+
+	notes = strings.TrimRight(strings.Join(notesLines, "\n"), "\n")
+	return password, notes
+}
diff --git a/internal/migrate/migrator_test.go b/internal/migrate/migrator_test.go
new file mode 100644
index 0000000..b8a11a2
--- /dev/null
+++ b/internal/migrate/migrator_test.go
@@ -0,0 +1,202 @@
+package migrate_test
+
+import (
+	"context"
+	"strings"
+	"testing"
+
+	"codeberg.org/snonux/foostore/internal/migrate"
+	"codeberg.org/snonux/foostore/internal/store"
+)
+
+// ---- ExtractPasswordFromContent tests ----------------------------------------
+
+func TestExtractPasswordFromContent(t *testing.T) {
+	cases := []struct {
+		name          string
+		input         string
+		wantPassword  string
+		wantNotesHas  string
+		wantNotesMiss string
+	}{
+		{
+			name:          "password line extracted",
+			input:         "user: alice\npassword: s3cr3t\nurl: example.com\n",
+			wantPassword:  "s3cr3t",
+			wantNotesHas:  "user: alice",
+			wantNotesMiss: "password: s3cr3t",
+		},
+		{
+			name:          "pass shorthand extracted",
+			input:         "pass: abc123\nhost: db.local",
+			wantPassword:  "abc123",
+			wantNotesHas:  "host: db.local",
+			wantNotesMiss: "pass: abc123",
+		},
+		{
+			name:          "case insensitive",
+			input:         "PASSWORD: hidden\nother: line",
+			wantPassword:  "hidden",
+			wantNotesHas:  "other: line",
+			wantNotesMiss: "PASSWORD",
+		},
+		{
+			name:          "no password line",
+			input:         "just notes\nno password here",
+			wantPassword:  "",
+			wantNotesHas:  "just notes",
+			wantNotesMiss: "",
+		},
+		{
+			name:          "only first password line taken",
+			input:         "password: first\npassword: second",
+			wantPassword:  "first",
+			wantNotesMiss: "first",
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			pw, notes := migrate.ExtractPasswordFromContent(tc.input)
+			if pw != tc.wantPassword {
+				t.Errorf("password = %q; want %q", pw, tc.wantPassword)
+			}
+			if tc.wantNotesHas != "" && !strings.Contains(notes, tc.wantNotesHas) {
+				t.Errorf("notes %q should contain %q", notes, tc.wantNotesHas)
+			}
+			if tc.wantNotesMiss != "" && strings.Contains(notes, tc.wantNotesMiss) {
+				t.Errorf("notes %q should NOT contain %q", notes, tc.wantNotesMiss)
+			}
+		})
+	}
+}
+
+// ---- Run tests with fakes ----------------------------------------------------
+
+// fakeWalker implements StoreWalker using an in-memory list of entries.
+type fakeWalker struct {
+	indexes []*store.Index
+	// dataByDesc maps description to raw content bytes.
+	dataByDesc map[string][]byte
+}
+
+func (w *fakeWalker) WalkIndexes(_ context.Context, _ string, fn func(*store.Index) error) error {
+	for _, idx := range w.indexes {
+		if err := fn(idx); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (w *fakeWalker) LoadData(_ context.Context, idx *store.Index) (*store.Data, error) {
+	content := w.dataByDesc[idx.Description]
+	return &store.Data{Content: content}, nil
+}
+
+// fakeKDBX records calls to UpsertTextEntry and UpsertBinaryEntry.
+type fakeKDBX struct {
+	texts    []string
+	binaries []string
+	saved    bool
+}
+
+func (k *fakeKDBX) UpsertTextEntry(groupPath []string, title, password, notes string) (bool, error) {
+	k.texts = append(k.texts, title+"|"+password)
+	return false, nil
+}
+
+func (k *fakeKDBX) UpsertBinaryEntry(groupPath []string, title, filename string, content []byte) (bool, error) {
+	k.binaries = append(k.binaries, title)
+	return false, nil
+}
+
+func (k *fakeKDBX) Save() error {
+	k.saved = true
+	return nil
+}
+
+func makeIndex(description string) *store.Index {
+	return &store.Index{Description: description}
+}
+
+func TestRun_dryRun(t *testing.T) {
+	walker := &fakeWalker{
+		indexes: []*store.Index{
+			makeIndex("work/notes"),
+			makeIndex("images/logo.png"),
+		},
+		dataByDesc: map[string][]byte{
+			"work/notes":      []byte("password: secret\nsome notes"),
+			"images/logo.png": {0, 1, 2},
+		},
+	}
+
+	var logged []string
+	logFn := func(msg string) { logged = append(logged, msg) }
+	warnFn := func(string) {}
+
+	opts := migrate.Options{DryRun: true}
+	stats, err := migrate.Run(context.Background(), walker, nil, opts, logFn, warnFn)
+	if err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	if stats.Total != 2 {
+		t.Errorf("Total = %d; want 2", stats.Total)
+	}
+	if stats.TextMigrated != 1 {
+		t.Errorf("TextMigrated = %d; want 1", stats.TextMigrated)
+	}
+	if stats.BinaryMigrated != 1 {
+		t.Errorf("BinaryMigrated = %d; want 1", stats.BinaryMigrated)
+	}
+	if stats.Errors != 0 {
+		t.Errorf("Errors = %d; want 0", stats.Errors)
+	}
+	// Verify dry-run log messages are emitted for both entry types.
+	foundText := false
+	foundBinary := false
+	for _, msg := range logged {
+		if strings.Contains(msg, "DRY-RUN text migrate") {
+			foundText = true
+		}
+		if strings.Contains(msg, "DRY-RUN binary migrate") {
+			foundBinary = true
+		}
+	}
+	if !foundText {
+		t.Errorf("no 'DRY-RUN text migrate' message in logged: %v", logged)
+	}
+	if !foundBinary {
+		t.Errorf("no 'DRY-RUN binary migrate' message in logged: %v", logged)
+	}
+}
+
+func TestRun_liveWrites(t *testing.T) {
+	walker := &fakeWalker{
+		indexes: []*store.Index{
+			makeIndex("finance/budget"),
+			makeIndex("attachments/report.pdf"),
+		},
+		dataByDesc: map[string][]byte{
+			"finance/budget":         []byte("password: money\nnotes line"),
+			"attachments/report.pdf": {5, 6, 7},
+		},
+	}
+
+	kdbx := &fakeKDBX{}
+	opts := migrate.Options{DryRun: false}
+	stats, err := migrate.Run(context.Background(), walker, kdbx, opts, func(string) {}, func(string) {})
+	if err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	if stats.TextMigrated != 1 || stats.BinaryMigrated != 1 {
+		t.Errorf("stats = %+v; want text=1 binary=1", stats)
+	}
+	if len(kdbx.texts) != 1 || !strings.Contains(kdbx.texts[0], "money") {
+		t.Errorf("texts = %v; want password field 'money'", kdbx.texts)
+	}
+	if len(kdbx.binaries) != 1 {
+		t.Errorf("binaries = %v; want 1 entry", kdbx.binaries)
+	}
+}