//go:build linux

package authconfig

import (
	"context"
	"errors"
	"os"
	"path/filepath"
	"sync/atomic"
	"testing"
	"time"

	"github.com/aritmolab/thothii/tools/tht/internal/authprojection"
	"github.com/aritmolab/thothii/tools/tht/internal/safeio"
	"github.com/aritmolab/thothii/tools/tht/internal/testsupport"
)

func TestBeginExternalTransactionReleasesOuterLockAfterRuntimeCancellation(t *testing.T) {
	canonicalRoot := writeAuthFiles(t, defaultAuthYAML, registryYAML(adminUserYAML("admin", "Admin", true, "admin")))
	spec := testProjectionSpec(t)
	raw, err := authprojection.Begin(toRuntimeSpec(spec), nil, false)
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		if raw != nil {
			_ = raw.Close()
		}
	}()

	admitted := make(chan struct{})
	restore := setRuntimeProjectionBeginForTest(func(ctx context.Context, runtimeSpec authprojection.Spec, before *authprojection.Snapshot, requireReadyMatch bool) (*authprojection.Transaction, error) {
		close(admitted)
		return authprojection.BeginContext(ctx, runtimeSpec, before, requireReadyMatch)
	})
	t.Cleanup(restore)
	ctx, cancel := context.WithCancel(context.Background())
	result := make(chan error, 1)
	go func() {
		transaction, err := BeginExternalProjectionTransaction(ctx, canonicalRoot, spec)
		if err == nil {
			err = transaction.Close()
		}
		result <- err
	}()
	<-admitted
	cancel()
	select {
	case err := <-result:
		if err == nil {
			t.Fatal("BeginExternalProjectionTransaction() unexpectedly succeeded after cancellation")
		}
	case <-time.After(2 * time.Second):
		t.Fatal("BeginExternalProjectionTransaction() did not return after runtime cancellation")
	}
	restore()

	if err := raw.Close(); err != nil {
		t.Fatal(err)
	}
	raw = nil
	next, err := BeginExternalProjectionTransaction(context.Background(), canonicalRoot, spec)
	if err != nil {
		t.Fatalf("outer lock remained held after runtime cancellation: %v", err)
	}
	if err := next.Close(); err != nil {
		t.Fatal(err)
	}
}

func TestExternalPublishContextReturnsWhenCanonicalLockIsHeld(t *testing.T) {
	canonicalRoot := writeAuthFiles(t, defaultAuthYAML, registryYAML(adminUserYAML("admin", "Admin", true, "admin")))
	ctx, cancel := context.WithCancel(context.Background())
	transaction, err := BeginExternalProjectionTransaction(ctx, canonicalRoot, testProjectionSpec(t))
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = transaction.Close() })
	canonicalLock, err := acquireLock(canonicalRoot)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = canonicalLock.Unlock() })
	contended := make(chan struct{}, 1)
	reblocked := make(chan struct{}, 1)
	restore := setProjectionCoordinatorHooksForTest(projectionCoordinatorHooks{
		onCanonicalLockContention: func() { contended <- struct{}{} },
		beforeProjectionBegin:     func() { reblocked <- struct{}{} },
	})
	t.Cleanup(restore)
	result := make(chan error, 1)
	go func() {
		_, err := transaction.PublishCanonical()
		result <- err
	}()
	<-contended
	if _, err := authprojection.Inspect(toRuntimeSpec(testProjectionSpecFromTransaction(transaction))); !errors.Is(err, authprojection.ErrBlocked) {
		t.Fatalf("Inspect() error = %v, want blocked while waiting for canonical lock", err)
	}
	cancel()
	select {
	case <-reblocked:
		t.Fatal("publishCanonicalContext() re-blocked even though Commit was never reached")
	case err := <-result:
		if !errors.Is(err, errProjectionPublish) {
			t.Fatalf("publishCanonicalContext() error = %v, want sanitized publish failure", err)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("publishCanonicalContext() did not return after cancellation")
	}
}

func TestExternalRestoreContextReturnsWhenCanonicalLockIsHeld(t *testing.T) {
	canonicalRoot := writeAuthFiles(t, defaultAuthYAML, registryYAML(adminUserYAML("admin", "Admin", true, "admin")))
	spec := testProjectionSpec(t)
	publishCanonical(t, canonicalRoot, spec)
	ctx, cancel := context.WithCancel(context.Background())
	transaction, err := BeginExternalProjectionTransaction(ctx, canonicalRoot, spec)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = transaction.Close() })
	canonicalLock, err := acquireLock(canonicalRoot)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = canonicalLock.Unlock() })
	contended := make(chan struct{}, 1)
	restoreHooks := setProjectionCoordinatorHooksForTest(projectionCoordinatorHooks{
		onCanonicalLockContention: func() { contended <- struct{}{} },
	})
	t.Cleanup(restoreHooks)
	result := make(chan error, 1)
	go func() { result <- transaction.RestorePriorIfCanonicalUnchanged() }()
	<-contended
	if _, err := authprojection.Inspect(toRuntimeSpec(spec)); !errors.Is(err, authprojection.ErrBlocked) {
		t.Fatalf("Inspect() error = %v, want blocked while waiting for canonical lock", err)
	}
	cancel()
	select {
	case err := <-result:
		if !errors.Is(err, errProjectionIntegrity) {
			t.Fatalf("RestorePriorIfCanonicalUnchanged() error = %v, want sanitized integrity failure", err)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("RestorePriorIfCanonicalUnchanged() did not return after cancellation")
	}
}

func TestAcquireTransactionLockRejectsSwapBetweenOpenAndRevalidation(t *testing.T) {
	canonicalRoot := writeAuthFiles(t, defaultAuthYAML, registryYAML(adminUserYAML("admin", "Admin", true, "admin")))
	opened := make(chan struct{})
	release := make(chan struct{})
	var firstOpen atomic.Bool
	restore := setProjectionLockHooksForTest(projectionLockHooks{afterOpen: func() {
		if firstOpen.CompareAndSwap(false, true) {
			close(opened)
			<-release
		}
	}})
	t.Cleanup(restore)
	first := make(chan struct {
		lock *transactionLock
		err  error
	}, 1)
	go func() {
		lock, err := acquireTransactionLock(context.Background(), canonicalRoot)
		first <- struct {
			lock *transactionLock
			err  error
		}{lock, err}
	}()
	<-opened
	replacement := filepath.Join(canonicalRoot, ".replacement-lock")
	if err := safeio.WriteCanonicalNewFile(replacement, nil, 0o600); err != nil {
		t.Fatal(err)
	}
	if err := os.Rename(replacement, filepath.Join(canonicalRoot, transactionLockFileName)); err != nil {
		t.Fatal(err)
	}
	second, err := acquireTransactionLock(context.Background(), canonicalRoot)
	if err != nil {
		t.Fatalf("replacement-domain acquisition error = %v", err)
	}
	t.Cleanup(func() { _ = second.Close() })
	close(release)
	firstResult := <-first
	if firstResult.lock != nil || !errors.Is(firstResult.err, errProjectionIntegrity) {
		t.Fatalf("swapped original acquisition = %#v, %v; want no old-domain lock", firstResult.lock, firstResult.err)
	}
}

func TestAcquireTransactionLockRejectsUnsafeMetadata(t *testing.T) {
	for _, fixture := range []struct {
		name    string
		arrange func(*testing.T, string)
	}{
		{
			name: "symlink",
			arrange: func(t *testing.T, path string) {
				target := path + ".target"
				if err := safeio.WriteCanonicalNewFile(target, nil, 0o600); err != nil {
					t.Fatal(err)
				}
				testsupport.SymlinkOrSkip(t, target, path)
			},
		},
		{
			name: "hardlink",
			arrange: func(t *testing.T, path string) {
				if err := safeio.WriteCanonicalNewFile(path, nil, 0o600); err != nil {
					t.Fatal(err)
				}
				if err := os.Link(path, path+".linked"); err != nil {
					t.Fatal(err)
				}
			},
		},
		{
			name: "non-0600 mode",
			arrange: func(t *testing.T, path string) {
				if err := safeio.WriteCanonicalNewFile(path, nil, 0o600); err != nil {
					t.Fatal(err)
				}
				if err := os.Chmod(path, 0o640); err != nil {
					t.Fatal(err)
				}
			},
		},
		{
			name: "wrong owner",
			arrange: func(t *testing.T, path string) {
				if os.Geteuid() != 0 {
					t.Skip("requires root to create a wrong numeric owner")
				}
				if err := safeio.WriteCanonicalNewFile(path, nil, 0o600); err != nil {
					t.Fatal(err)
				}
				if err := os.Chown(path, 10001, 10001); err != nil {
					t.Fatal(err)
				}
			},
		},
	} {
		t.Run(fixture.name, func(t *testing.T) {
			canonicalRoot := writeAuthFiles(t, defaultAuthYAML, registryYAML(adminUserYAML("admin", "Admin", true, "admin")))
			fixture.arrange(t, filepath.Join(canonicalRoot, transactionLockFileName))
			lock, err := acquireTransactionLock(context.Background(), canonicalRoot)
			if lock != nil || !errors.Is(err, errProjectionIntegrity) {
				t.Fatalf("acquireTransactionLock() = %#v, %v; want unsafe metadata rejection", lock, err)
			}
		})
	}
}

func TestAcquireTransactionLockAcceptsSafeCreatorRace(t *testing.T) {
	canonicalRoot := writeAuthFiles(t, defaultAuthYAML, registryYAML(adminUserYAML("admin", "Admin", true, "admin")))
	paused := make(chan struct{})
	release := make(chan struct{})
	var firstCreate atomic.Bool
	restore := setProjectionLockHooksForTest(projectionLockHooks{beforeCreate: func() {
		if firstCreate.CompareAndSwap(false, true) {
			close(paused)
			<-release
		}
	}})
	t.Cleanup(restore)
	first := make(chan struct {
		lock *transactionLock
		err  error
	}, 1)
	go func() {
		lock, err := acquireTransactionLock(context.Background(), canonicalRoot)
		first <- struct {
			lock *transactionLock
			err  error
		}{lock, err}
	}()
	<-paused
	second, err := acquireTransactionLock(context.Background(), canonicalRoot)
	if err != nil {
		t.Fatalf("creator-race winner error = %v", err)
	}
	if err := second.Close(); err != nil {
		t.Fatal(err)
	}
	close(release)
	result := <-first
	if result.err != nil || result.lock == nil {
		t.Fatalf("creator-race loser = %#v, %v; want same validated lock domain", result.lock, result.err)
	}
	if err := result.lock.Close(); err != nil {
		t.Fatal(err)
	}
}

func testProjectionSpecFromTransaction(transaction *ExternalProjectionTransaction) ProjectionSpec {
	return ProjectionSpec{RuntimeRoot: transaction.spec.RuntimeRoot, UID: transaction.spec.UID, GID: transaction.spec.GID}
}