package backup

import (
	"bytes"
	"errors"
	"io"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"testing"

	"gitea.dooplex.hu/admin/felhom-controller/internal/settings"
)

// t2rFakeProvider records the lifecycle calls RestoreTier2Files makes — the refusal tests assert
// the NON-effect (never stopped) and the happy path asserts the stop→copy→start order.
type t2rFakeProvider struct {
	hdd     string
	mounts  []string // F-S2: configurable compose-derived HDD mounts (drives appdata dir-name resolution)
	stopped []string
	started []string
	order   []string // interleaved event log: "stop", "copy" (appended by the copier seam), "start"
}

func (f *t2rFakeProvider) GetStackComposePath(string) (string, bool) { return "", false }
func (f *t2rFakeProvider) ListDeployedStacks() []StackSummary        { return nil }
func (f *t2rFakeProvider) GetStackHDDMounts(string) []string         { return f.mounts }
func (f *t2rFakeProvider) GetStackHDDPath(string) string             { return f.hdd }
func (f *t2rFakeProvider) GetDockerVolumes(string) []string          { return nil }
func (f *t2rFakeProvider) StopStack(name string) error {
	f.stopped = append(f.stopped, name)
	f.order = append(f.order, "stop")
	return nil
}
func (f *t2rFakeProvider) StartStack(name string) error {
	f.started = append(f.started, name)
	f.order = append(f.order, "start")
	return nil
}
func (f *t2rFakeProvider) RefreshAndIsRunning(string) bool { return true }
func (f *t2rFakeProvider) GetStackRecoveryInfo(string) (RecoveryInfo, bool) {
	return RecoveryInfo{}, false
}
func (f *t2rFakeProvider) GetStackClassifiedBinds(string) ([]ClassifiedBind, bool) { return nil, false }
func (f *t2rFakeProvider) RecoverStackSecrets(string, []string) map[string]string  { return nil }
func (f *t2rFakeProvider) RecreateStackFromUnit(string, string, map[string]string) error {
	return nil
}

// newT2RManager builds a Manager with a RECORDED Tier-2 copy for "app": live drive + a populated
// <dest>/backups/secondary/app/appdata dir, and a CrossDriveBackup entry pointing at dest.
func newT2RManager(t *testing.T) (m *Manager, fake *t2rFakeProvider, liveDrive, destDrive string) {
	t.Helper()
	tmp := t.TempDir()
	liveDrive = filepath.Join(tmp, "usb")
	destDrive = filepath.Join(tmp, "flash")
	sett, err := settings.Load(filepath.Join(tmp, "settings.json"), log.New(io.Discard, "", 0))
	if err != nil {
		t.Fatal(err)
	}
	for _, p := range []string{liveDrive, destDrive} {
		if err := sett.AddStoragePath(settings.StoragePath{Path: p, Label: filepath.Base(p)}); err != nil {
			t.Fatal(err)
		}
	}
	if err := sett.SetCrossDriveConfig("app", &settings.CrossDriveBackup{
		Enabled: true, Method: "rsync", DestinationPath: destDrive,
		LastRun: "2026-07-05T03:30:00Z", LastStatus: "ok",
	}); err != nil {
		t.Fatal(err)
	}
	// v2 layout: marker + an hdd/ leg with content.
	destBase := filepath.Join(destDrive, "backups", "secondary", "app")
	mustWrite(t, filepath.Join(destBase, "hdd", "appdata", "photos", "a.jpg"), "JPEGDATA")
	mustWrite(t, filepath.Join(destBase, tier2LayoutMarker), tier2LayoutVersion)

	fake = &t2rFakeProvider{hdd: liveDrive}
	m = &Manager{
		logger:         log.New(io.Discard, "", 0),
		settings:       sett,
		systemDataPath: filepath.Join(tmp, "sys"),
		stackProvider:  fake,
	}
	return m, fake, liveDrive, destDrive
}

// TestRestoreTier2Files_Orchestration proves the stop → copy → start order, the src/dst the copier
// receives (recorded Tier-2 layout → live AppDataDir), and the returned count.
func TestRestoreTier2Files_Orchestration(t *testing.T) {
	m, fake, liveDrive, destDrive := newT2RManager(t)
	var gotSrc, gotDst string
	m.restoreFilesCopier = func(src, dst string) (int, error) {
		gotSrc, gotDst = src, dst
		fake.order = append(fake.order, "copy")
		return 3, nil
	}

	n, err := m.RestoreTier2Files("app")
	if err != nil {
		t.Fatalf("restore: %v", err)
	}
	if n != 3 {
		t.Errorf("filesRestored = %d, want 3", n)
	}
	// v2: the hdd/ subtree merges whole into the live namespace root (relpath-mirroring).
	if want := filepath.Join(destDrive, "backups", "secondary", "app", "hdd"); gotSrc != want {
		t.Errorf("copier src = %q, want the v2 hdd/ subtree %q", gotSrc, want)
	}
	if gotDst != liveDrive {
		t.Errorf("copier dst = %q, want the live namespace root %q", gotDst, liveDrive)
	}
	if len(fake.order) != 3 || fake.order[0] != "stop" || fake.order[1] != "copy" || fake.order[2] != "start" {
		t.Errorf("order = %v, want [stop copy start]", fake.order)
	}
}

// TestRestoreTier2Files_Refusals proves every refusal happens BEFORE any side effect: the app is
// never stopped and the copier is never invoked (Scenario C1–C5).
func TestRestoreTier2Files_Refusals(t *testing.T) {
	assertNoEffect := func(t *testing.T, m *Manager, fake *t2rFakeProvider, copierCalled *bool, wantErr error) {
		t.Helper()
		n, err := m.RestoreTier2Files("app")
		if err == nil {
			t.Fatal("expected refusal, got nil")
		}
		if wantErr != nil && !errors.Is(err, wantErr) {
			t.Errorf("err = %v, want %v", err, wantErr)
		}
		if n != 0 {
			t.Errorf("filesRestored = %d, want 0", n)
		}
		if len(fake.stopped) != 0 {
			t.Errorf("app was STOPPED on a refusal: %v", fake.stopped)
		}
		if *copierCalled {
			t.Error("copier was invoked on a refusal")
		}
	}
	wire := func(m *Manager) *bool {
		called := false
		m.restoreFilesCopier = func(string, string) (int, error) { called = true; return 0, nil }
		return &called
	}

	t.Run("C1 no Tier-2 record", func(t *testing.T) {
		m, fake, _, _ := newT2RManager(t)
		called := wire(m)
		if err := m.settings.SetCrossDriveConfig("app", nil); err != nil {
			t.Fatal(err)
		}
		assertNoEffect(t, m, fake, called, errNoTier2Copy)
	})

	t.Run("C1b LastRun empty", func(t *testing.T) {
		m, fake, _, destDrive := newT2RManager(t)
		called := wire(m)
		if err := m.settings.SetCrossDriveConfig("app", &settings.CrossDriveBackup{
			Enabled: true, DestinationPath: destDrive, // no LastRun — never actually ran
		}); err != nil {
			t.Fatal(err)
		}
		assertNoEffect(t, m, fake, called, errNoTier2Copy)
	})

	t.Run("C2 copy dir absent on target", func(t *testing.T) {
		m, fake, _, destDrive := newT2RManager(t)
		called := wire(m)
		if err := os.RemoveAll(filepath.Join(destDrive, "backups")); err != nil {
			t.Fatal(err)
		}
		assertNoEffect(t, m, fake, called, errNoTier2Copy)
	})

	t.Run("C3 Tier-2 drive disconnected", func(t *testing.T) {
		m, fake, _, destDrive := newT2RManager(t)
		called := wire(m)
		if err := m.settings.SetDisconnected(destDrive, true, nil); err != nil {
			t.Fatal(err)
		}
		assertNoEffect(t, m, fake, called, errTier2DriveGone)
	})

	t.Run("C4 live drive disconnected", func(t *testing.T) {
		m, fake, liveDrive, _ := newT2RManager(t)
		called := wire(m)
		if err := m.settings.SetDisconnected(liveDrive, true, nil); err != nil {
			t.Fatal(err)
		}
		assertNoEffect(t, m, fake, called, errLiveDriveGone)
	})

	t.Run("C4b live drive decommissioned", func(t *testing.T) {
		m, fake, liveDrive, _ := newT2RManager(t)
		called := wire(m)
		if err := m.settings.SetDecommissioned(liveDrive, ""); err != nil {
			t.Fatal(err)
		}
		assertNoEffect(t, m, fake, called, errLiveDriveDecommed)
	})

	t.Run("C5 backup already running", func(t *testing.T) {
		m, fake, _, _ := newT2RManager(t)
		called := wire(m)
		m.mu.Lock()
		m.running = true
		m.mu.Unlock()
		assertNoEffect(t, m, fake, called, nil) // acquireRunning's own error
		m.mu.Lock()
		m.running = false
		m.mu.Unlock()
	})
}

// TestRestoreTier2Files_NothingToRestore proves Scenario D: zero files copied is a SUCCESS
// (0, nil), not an error — the "everything is already in place" answer.
func TestRestoreTier2Files_NothingToRestore(t *testing.T) {
	m, fake, _, _ := newT2RManager(t)
	m.restoreFilesCopier = func(string, string) (int, error) { return 0, nil }

	n, err := m.RestoreTier2Files("app")
	if err != nil {
		t.Fatalf("zero-copy restore must succeed: %v", err)
	}
	if n != 0 {
		t.Errorf("filesRestored = %d, want 0", n)
	}
	// The stop/start cycle still happened (acceptable per spec).
	if len(fake.stopped) != 1 || len(fake.started) != 1 {
		t.Errorf("stop/start: %v/%v", fake.stopped, fake.started)
	}
}

// TestRestoreTier2Files_CopyErrorSurfaces proves no-silent-failure: a copier error is returned
// (flash_error path) and the app is still restarted.
func TestRestoreTier2Files_CopyErrorSurfaces(t *testing.T) {
	m, fake, _, _ := newT2RManager(t)
	m.restoreFilesCopier = func(string, string) (int, error) { return 1, errors.New("disk full") }

	if _, err := m.RestoreTier2Files("app"); err == nil {
		t.Fatal("copier error must surface")
	}
	if len(fake.started) != 1 {
		t.Error("app must still be restarted after a failed copy")
	}
}

// TestCountRestoredFiles pins the itemize-changes parsing: only transferred regular files (">f")
// count — created dirs (cd), symlinks (cL) and untransferred lines do not.
func TestCountRestoredFiles(t *testing.T) {
	out := ">f+++++++++ photos/a.jpg\n" +
		"cd+++++++++ photos/\n" +
		"cL+++++++++ link -> target\n" +
		">f+++++++++ docs/b.pdf\n" +
		".d..t...... ./\n" +
		"\n"
	if n := countRestoredFiles(out); n != 2 {
		t.Errorf("count = %d, want 2", n)
	}
	if n := countRestoredFiles(""); n != 0 {
		t.Errorf("empty output count = %d, want 0", n)
	}
}

// TestRsyncRestoreMissing_Semantics is the FS-level proof of the additive-only contract (Scenarios
// A + B together), run against the REAL rsync (skipped where rsync is unavailable — it runs on the
// Linux build server and in the live validation):
//   - a file missing live is restored byte-identical (and counted);
//   - a live file with DIFFERENT content than the backup keeps its LIVE bytes;
//   - a live-only file survives.
//
// §10 COMPANION: swapping the helper's flags for rsyncMirror's (-a --delete, no --ignore-existing)
// makes this fail TWICE — b.txt gets clobbered AND c.txt gets deleted.
func TestRsyncRestoreMissing_Semantics(t *testing.T) {
	if _, err := exec.LookPath("rsync"); err != nil {
		t.Skip("rsync not available on this machine — runs on the Linux build server")
	}
	tmp := t.TempDir()
	src := filepath.Join(tmp, "tier2copy")
	dst := filepath.Join(tmp, "live")

	mustWrite(t, filepath.Join(src, "photos", "a.jpg"), "JPEG-FROM-BACKUP")
	mustWrite(t, filepath.Join(src, "b.txt"), "BACKUP-VERSION")
	mustWrite(t, filepath.Join(dst, "b.txt"), "LIVE-EDIT-AFTER-COPY")
	mustWrite(t, filepath.Join(dst, "c.txt"), "LIVE-ONLY-NEW-FILE")

	n, err := rsyncRestoreMissing(src, dst)
	if err != nil {
		t.Fatalf("rsyncRestoreMissing: %v", err)
	}
	if n != 1 {
		t.Errorf("filesRestored = %d, want 1 (only the missing a.jpg)", n)
	}
	// Scenario A: the deleted file is back, byte-identical.
	got, err := os.ReadFile(filepath.Join(dst, "photos", "a.jpg"))
	if err != nil || !bytes.Equal(got, []byte("JPEG-FROM-BACKUP")) {
		t.Errorf("a.jpg not restored byte-identical: %q %v", got, err)
	}
	// Scenario B core #1: the differing live file keeps its LIVE bytes (backup NOT restored).
	if got := mustRead(t, filepath.Join(dst, "b.txt")); got != "LIVE-EDIT-AFTER-COPY" {
		t.Errorf("live-edited b.txt was CLOBBERED: %q", got)
	}
	// Scenario B core #2: the live-only file was NOT deleted.
	if got := mustRead(t, filepath.Join(dst, "c.txt")); got != "LIVE-ONLY-NEW-FILE" {
		t.Errorf("live-only c.txt was harmed: %q", got)
	}
}