package backup

import (
	"os"
	"path/filepath"
	"strings"
	"testing"

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

// R-403 Group B — the mirror guard, driven through the REAL RunTier2.
//
// The `tier2Mirror` seam records every (src,dst) the run asks for, so a skip is provable as an
// ABSENCE OF A CALL rather than inferred from a log line — and the destination's own bytes are
// compared before and after, which is the consequence the customer actually cares about.

// r403Recorder is a mirror seam that records its calls and then performs a REAL MIRROR — the
// destination is emptied first, so `rsync -a --delete`'s defining behaviour is present in the test.
//
// This matters more than it looks: `copyTree` (the additive helper next door) would let every
// assertion here pass while proving nothing, because the deletion IS the defect. A seam that is
// gentler than the thing it stands in for is a test that cannot see the bug.
type r403Recorder struct{ calls []string }

func (r *r403Recorder) mirror(src, dst string) error {
	r.calls = append(r.calls, dst)
	if err := os.RemoveAll(dst); err != nil {
		return err
	}
	return copyTree(src, dst)
}

func (r *r403Recorder) calledFor(sub string) bool {
	for _, c := range r.calls {
		if strings.Contains(c, sub) {
			return true
		}
	}
	return false
}

// r403Fixture builds a Manager with a source drive and a registered off-drive target, seeds the
// SOURCE unit and (optionally) a pre-existing DESTINATION unit, and returns the recorder.
func r403Fixture(t *testing.T, srcDB, srcVols []string, destDB, destVols []string, destExists bool) (
	m *Manager, rec *r403Recorder, src, destBase string) {
	t.Helper()
	m, src, target, prov := newTier2V2(t, "app")
	rec = &r403Recorder{}
	m.tier2Mirror = rec.mirror
	prov.has["app"] = false // legacy path, no classified binds → the unit leg is the only leg
	destBase = filepath.Join(target, "backups", "secondary", "app")

	// SOURCE unit — newTier2V2 already wrote a `{}` manifest; replace it with a real one.
	srcUnit := RecoveryUnitPath(src, "app")
	man := &RecoveryManifest{SchemaVersion: 2, AppName: "app", DBDumps: srcDB, VolumeDumps: srcVols}
	if err := writeManifest(UnitManifestFile(srcUnit), man); err != nil {
		t.Fatal(err)
	}
	for _, d := range srcDB {
		mustWrite(t, filepath.Join(UnitDBDumpDir(srcUnit), d), "SOURCE-"+d)
	}
	for _, v := range srcVols {
		mustWrite(t, filepath.Join(UnitVolumeDumpDir(srcUnit), v), "SOURCE-"+v)
	}

	// DESTINATION unit — the copy that must survive.
	if destExists {
		destUnit := filepath.Join(destBase, "recovery-unit")
		// atomicWrite needs the parent to exist — the real capture creates it before writing.
		if err := os.MkdirAll(destUnit, 0o755); err != nil {
			t.Fatal(err)
		}
		dman := &RecoveryManifest{SchemaVersion: 2, AppName: "app", DBDumps: destDB, VolumeDumps: destVols}
		if err := writeManifest(UnitManifestFile(destUnit), dman); err != nil {
			t.Fatal(err)
		}
		for _, d := range destDB {
			mustWrite(t, filepath.Join(UnitDBDumpDir(destUnit), d), "DEST-"+d)
		}
		for _, v := range destVols {
			mustWrite(t, filepath.Join(UnitVolumeDumpDir(destUnit), v), "DEST-"+v)
		}
		mustWrite(t, filepath.Join(destBase, tier2LayoutMarker), tier2LayoutVersion)
	}
	return m, rec, src, destBase
}

// B1 — TestR403_HollowSourceOverCompleteDestIsSkipped. THE ACCEPTANCE TEST.
//
// This is the state measured live on demo-hp 2026-08-31: a hollow primary unit and a complete
// secondary copy. On the shipped v0.229.0 the run deleted 4 database dumps and 3 volume tars —
// 120 082 104 B → 7 036 B — and reported success.
//
// Red-proof (recorded in REPORT.md): remove the guard and this fails on BOTH assertions — the seam
// is called for the unit leg, and the destination's fingerprint changes.
func TestR403_HollowSourceOverCompleteDestIsSkipped(t *testing.T) {
	m, rec, _, destBase := r403Fixture(t, nil, nil,
		[]string{"app-postgres.sql"}, []string{"app_data.tar", "app_cache.tar"}, true)
	destUnit := filepath.Join(destBase, "recovery-unit")

	before := fingerprintTree(t, destUnit)
	if err := m.RunTier2("app"); err != nil {
		t.Fatalf("RunTier2 must still succeed — the other legs are not held hostage: %v", err)
	}

	// THE CONSEQUENCE, first: the customer's package is byte-identical.
	if after := fingerprintTree(t, destUnit); after != before {
		t.Error("the destination unit CHANGED — a hollow source was mirrored over a complete copy (R-403)")
	}
	for _, f := range []string{"db-dumps/app-postgres.sql", "volume-dumps/app_data.tar", "volume-dumps/app_cache.tar"} {
		if _, err := os.Stat(filepath.Join(destUnit, f)); err != nil {
			t.Errorf("%s was DELETED from the copy: %v", f, err)
		}
	}
	// And the mechanism: the mirror was never asked to touch the unit leg.
	if rec.calledFor("recovery-unit") {
		t.Errorf("the mirror seam WAS called for the unit leg: %v", rec.calls)
	}
}

// B2 — a complete source still mirrors. The guard must not become a general refusal.
func TestR403_CompleteSourceStillMirrors(t *testing.T) {
	m, rec, _, destBase := r403Fixture(t, []string{"app-postgres.sql"}, []string{"app_data.tar"},
		[]string{"old.sql"}, []string{"old.tar"}, true)
	if err := m.RunTier2("app"); err != nil {
		t.Fatalf("RunTier2: %v", err)
	}
	if !rec.calledFor("recovery-unit") {
		t.Fatalf("the unit leg did not run for a complete source: %v", rec.calls)
	}
	destUnit := filepath.Join(destBase, "recovery-unit")
	if _, err := os.Stat(filepath.Join(destUnit, "volume-dumps/app_data.tar")); err != nil {
		t.Errorf("the source's tar did not reach the copy: %v", err)
	}
	// --delete still works: the stale destination file is gone. The mirror is still a MIRROR.
	if _, err := os.Stat(filepath.Join(destUnit, "volume-dumps/old.tar")); err == nil {
		t.Error("the stale destination tar survived — --delete was neutered, which is NOT the fix")
	}
}

// B3 — hollow over hollow still mirrors. An app that genuinely has no database and no volumes is not
// a defect, and both sides agree, so nothing is at risk.
func TestR403_HollowOverHollowStillMirrors(t *testing.T) {
	m, rec, _, _ := r403Fixture(t, nil, nil, nil, nil, true)
	if err := m.RunTier2("app"); err != nil {
		t.Fatalf("RunTier2: %v", err)
	}
	if !rec.calledFor("recovery-unit") {
		t.Errorf("hollow→hollow was skipped; it must mirror: %v", rec.calls)
	}
}

// B3b — a first copy (no destination unit at all) still mirrors, hollow source or not.
func TestR403_FirstCopyStillMirrors(t *testing.T) {
	m, rec, _, _ := r403Fixture(t, nil, nil, nil, nil, false)
	if err := m.RunTier2("app"); err != nil {
		t.Fatalf("RunTier2: %v", err)
	}
	if !rec.calledFor("recovery-unit") {
		t.Errorf("the first copy was skipped: %v", rec.calls)
	}
}

// B4 — the other legs still run when the unit leg is skipped. A preserved package must not cost the
// customer their file legs.
func TestR403_OtherLegsStillRunWhenTheUnitLegIsSkipped(t *testing.T) {
	m, rec, src, _ := r403Fixture(t, nil, nil, []string{"a.sql"}, []string{"a.tar"}, true)
	// Give the app a classified file leg with real content.
	prov := m.stackProvider.(*t2v2Provider)
	prov.has["app"] = true
	prov.binds["app"] = []ClassifiedBind{mHDD("appdata/app")}
	mustWrite(t, filepath.Join(src, "appdata", "app", "user.txt"), "USERDATA")

	if err := m.RunTier2("app"); err != nil {
		t.Fatalf("RunTier2: %v", err)
	}
	if rec.calledFor("recovery-unit") {
		t.Error("the unit leg ran despite a hollow source over a complete destination")
	}
	if !rec.calledFor(filepath.Join("hdd", "appdata", "app")) {
		t.Errorf("the FILE leg was held hostage by the skipped unit leg: %v", rec.calls)
	}
}

// B5 — TestR403_SkipIsRecordedForTheSurface. Not only logged.
//
// A refusal that lives only in a container log is a refusal the customer cannot see, and the whole
// point of preserving the copy is lost if the page then calls it fresh.
func TestR403_SkipIsRecordedForTheSurface(t *testing.T) {
	m, _, _, destBase := r403Fixture(t, nil, nil, []string{"a.sql"}, []string{"a.tar"}, true)
	// Stamp the destination manifest with a date so the surface has a package date to name.
	destUnit := filepath.Join(destBase, "recovery-unit")
	dman := &RecoveryManifest{SchemaVersion: 2, AppName: "app", CreatedAt: "2026-08-25T03:30:00Z",
		DBDumps: []string{"a.sql"}, VolumeDumps: []string{"a.tar"}}
	if err := os.MkdirAll(destUnit, 0o755); err != nil {
		t.Fatal(err)
	}
	if err := writeManifest(UnitManifestFile(destUnit), dman); err != nil {
		t.Fatal(err)
	}

	if err := m.RunTier2("app"); err != nil {
		t.Fatalf("RunTier2: %v", err)
	}
	cd := m.settings.GetCrossDriveConfig("app")
	if cd == nil {
		t.Fatal("no cross-drive record was written at all")
	}
	if !cd.UnitLegSkipped {
		t.Error("UnitLegSkipped is false — the surface cannot tell the package was preserved")
	}
	if cd.UnitPackageDate != "2026-08-25T03:30:00Z" {
		t.Errorf("UnitPackageDate = %q, want the DESTINATION manifest's own created_at", cd.UnitPackageDate)
	}
	if !strings.Contains(cd.LastWarning, "hi") { // ASCII fragment of "hiányos" (R-364)
		t.Errorf("LastWarning does not carry the preserved-copy notice: %q", cd.LastWarning)
	}
	if cd.LastWarning != tier2UnitPreservedWarning &&
		!strings.Contains(cd.LastWarning, tier2UnitPreservedWarning) {
		t.Errorf("LastWarning is not the named constant: %q", cd.LastWarning)
	}
	// And the coverage the restore surface reads agrees, from the ARTIFACT rather than the record.
	cov, err := m.Tier2RestoreCoverage("app")
	if err != nil {
		t.Fatalf("coverage: %v", err)
	}
	date, older := cov.UnitRestoreDate()
	if date != "2026-08-25T03:30:00Z" || !older {
		t.Errorf("UnitRestoreDate() = (%q,%v), want the package date and older-than-the-run", date, older)
	}
}

// B6 — TestR403_DataLegShrinkIsUnaffected. The guard is on the UNIT leg only.
//
// `07-backup-architecture.md` §8 row 5 records that the secondary is a derived copy, rebuilt on the
// next run, and tier2.go's header records that a classified app's copy legitimately shrinks as
// `export` drops out of its class set. Fencing that would be calling a decision a defect.
//
// Red-proof (recorded in REPORT.md): widen the guard to the data legs and this fails — the stale file
// survives in the copy.
func TestR403_DataLegShrinkIsUnaffected(t *testing.T) {
	m, _, src, destBase := r403Fixture(t, []string{"a.sql"}, []string{"a.tar"}, nil, nil, true)
	prov := m.stackProvider.(*t2v2Provider)
	prov.has["app"] = true
	prov.binds["app"] = []ClassifiedBind{mHDD("appdata/app")}
	mustWrite(t, filepath.Join(src, "appdata", "app", "kept.txt"), "KEPT")
	// A file that exists ONLY in the destination — the shrink case.
	mustWrite(t, filepath.Join(destBase, "hdd", "appdata", "app", "dropped.txt"), "SHOULD-GO")

	if err := m.RunTier2("app"); err != nil {
		t.Fatalf("RunTier2: %v", err)
	}
	if _, err := os.Stat(filepath.Join(destBase, "hdd", "appdata", "app", "kept.txt")); err != nil {
		t.Errorf("the live file did not reach the copy: %v", err)
	}
	if _, err := os.Stat(filepath.Join(destBase, "hdd", "appdata", "app", "dropped.txt")); err == nil {
		t.Error("a data leg stopped shrinking — the guard is TOO WIDE and is fencing a design decision")
	}
}

// A guard that quietly widened would also be caught by the class constant staying where it belongs.
func TestR403_GuardUsesTheSharedPredicate(t *testing.T) {
	// The predicate answers the same for the same directory whichever caller asks — one definition.
	dir := r403Unit(t, nil, []string{"v.tar"}, nil)
	if unitIsHollow(dir) != !unitCarriesData(dir) {
		t.Error("unitIsHollow is not the negation of unitCarriesData")
	}
	_ = appbackup.UnitManifestFile // the unit-dir-relative helper is what both callers resolve through
}