//nolint:testpackage // exercises unexported SnapshotManager internals
package snapshot

import (
	"bytes"
	"context"
	"database/sql"
	"io"
	"path/filepath"
	"testing"

	"github.com/spf13/afero"
	"sneak.berlin/go/vaultik/internal/config"
	"sneak.berlin/go/vaultik/internal/database"
	"sneak.berlin/go/vaultik/internal/log"
)

const (
	// Test age public key for encryption
	testAgeRecipient = "age1ezrjmfpwsc95svdg0y54mums3zevgzu0x0ecq2f7tp8a05gl0sjq9q9wjg"
)

// copyFile is a test helper to copy files using afero
func copyFile(fs afero.Fs, src, dst string) error {
	sourceFile, err := fs.Open(src)
	if err != nil {
		return err
	}

	defer func() { _ = sourceFile.Close() }()

	destFile, err := fs.Create(dst)
	if err != nil {
		return err
	}

	defer func() { _ = destFile.Close() }()

	_, err = io.Copy(destFile, sourceFile)

	return err
}

// verifyCleanedDB opens the cleaned database and checks that the kept
// snapshot survived while the orphan file and chunk were removed.
func verifyCleanedDB(
	ctx context.Context,
	t *testing.T,
	tempDBPath, snapshotID string,
	file *database.File,
	chunk *database.Chunk,
) {
	t.Helper()

	cleanedDB, err := database.New(ctx, tempDBPath)
	if err != nil {
		t.Fatalf("failed to open cleaned database: %v", err)
	}

	defer func() {
		err := cleanedDB.Close()
		if err != nil {
			t.Errorf("failed to close database: %v", err)
		}
	}()

	cleanedRepos := database.NewRepositories(cleanedDB)

	// Verify snapshot exists
	verifySnapshot, err := cleanedRepos.Snapshots.GetByID(ctx, snapshotID)
	if err != nil {
		t.Fatalf("failed to get snapshot: %v", err)
	}

	if verifySnapshot == nil {
		t.Error("snapshot should exist")
	}

	// Verify orphan file is gone
	f, err := cleanedRepos.Files.GetByPath(ctx, file.Path.String())
	if err != nil {
		t.Fatalf("failed to check file: %v", err)
	}

	if f != nil {
		t.Error("orphan file should not exist")
	}

	// Verify orphan chunk is gone
	c, err := cleanedRepos.Chunks.GetByHash(ctx, chunk.ChunkHash.String())
	if err != nil {
		t.Fatalf("failed to check chunk: %v", err)
	}

	if c != nil {
		t.Error("orphan chunk should not exist")
	}
}

// TestVacuumDatabaseRemovesDeletedData proves the export path uploads a
// compacted database: after rows carrying a recognizable marker are deleted
// and vacuumDatabase runs, no page holding that marker survives in the file
// on disk (the file compressFile later reads for upload).
func TestVacuumDatabaseRemovesDeletedData(t *testing.T) {
	log.Initialize(log.Config{})
	t.Parallel()

	ctx := context.Background()
	fs := afero.NewOsFs()

	tempDir := t.TempDir()
	dbPath := filepath.Join(tempDir, "snapshot.db")

	db, err := database.New(ctx, dbPath)
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}

	// A marker distinctive enough that its presence in the raw file can only
	// come from the rows inserted below.
	marker := []byte("VACUUM_PROBE_DEADBEEF_DELETED_ROW")
	payload := bytes.Repeat(marker, 128) // ~4 KiB per row

	_, err = db.Conn().ExecContext(ctx,
		"CREATE TABLE vacuum_probe (id INTEGER PRIMARY KEY, payload BLOB)")
	if err != nil {
		t.Fatalf("failed to create probe table: %v", err)
	}

	for range 512 {
		_, err = db.Conn().ExecContext(ctx,
			"INSERT INTO vacuum_probe (payload) VALUES (?)", payload)
		if err != nil {
			t.Fatalf("failed to insert probe row: %v", err)
		}
	}

	_, err = db.Conn().ExecContext(ctx, "DELETE FROM vacuum_probe")
	if err != nil {
		t.Fatalf("failed to delete probe rows: %v", err)
	}

	// Close so the deletes reach the main file, mirroring the state
	// prepareExportDB hands to vacuumDatabase.
	err = db.Close()
	if err != nil {
		t.Fatalf("failed to close database: %v", err)
	}

	beforeInfo, err := fs.Stat(dbPath)
	if err != nil {
		t.Fatalf("failed to stat database before vacuum: %v", err)
	}

	beforeBytes, err := afero.ReadFile(fs, dbPath)
	if err != nil {
		t.Fatalf("failed to read database before vacuum: %v", err)
	}

	if !bytes.Contains(beforeBytes, marker) {
		t.Fatalf("expected deleted-row data to linger before vacuum")
	}

	sm := &SnapshotManager{fs: fs}

	err = sm.vacuumDatabase(ctx, dbPath)
	if err != nil {
		t.Fatalf("vacuumDatabase failed: %v", err)
	}

	afterBytes, err := afero.ReadFile(fs, dbPath)
	if err != nil {
		t.Fatalf("failed to read database after vacuum: %v", err)
	}

	if bytes.Contains(afterBytes, marker) {
		t.Fatalf("deleted-row data survived vacuum in the uploaded file")
	}

	afterInfo, err := fs.Stat(dbPath)
	if err != nil {
		t.Fatalf("failed to stat database after vacuum: %v", err)
	}

	if afterInfo.Size() >= beforeInfo.Size() {
		t.Fatalf("expected vacuum to shrink the file: before=%d after=%d",
			beforeInfo.Size(), afterInfo.Size())
	}
}

func TestCleanSnapshotDBEmptySnapshot(t *testing.T) {
	// Initialize logger
	log.Initialize(log.Config{})
	t.Parallel()

	ctx := context.Background()
	fs := afero.NewOsFs()

	// Create a test database
	tempDir := t.TempDir()
	dbPath := filepath.Join(tempDir, "test.db")

	db, err := database.New(ctx, dbPath)
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}

	repos := database.NewRepositories(db)

	// Create an empty snapshot
	snapshot := &database.Snapshot{
		ID:       "empty-snapshot",
		Hostname: "test-host",
	}

	err = repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
		return repos.Snapshots.Create(ctx, tx, snapshot)
	})
	if err != nil {
		t.Fatalf("failed to create snapshot: %v", err)
	}

	// Create some files and chunks not associated with any snapshot
	file := &database.File{Path: "/orphan/file.txt", Size: 1000}
	chunk := &database.Chunk{ChunkHash: "orphan-chunk", Size: 500}

	err = repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
		err := repos.Files.Create(ctx, tx, file)
		if err != nil {
			return err
		}

		return repos.Chunks.Create(ctx, tx, chunk)
	})
	if err != nil {
		t.Fatalf("failed to create orphan data: %v", err)
	}

	// Close the database
	err = db.Close()
	if err != nil {
		t.Fatalf("failed to close database: %v", err)
	}

	// Copy database
	tempDBPath := filepath.Join(tempDir, "temp.db")

	err = copyFile(fs, dbPath, tempDBPath)
	if err != nil {
		t.Fatalf("failed to copy database: %v", err)
	}

	// Create a mock config for testing
	cfg := &config.Config{
		CompressionLevel: 3,
		AgeRecipients:    []string{testAgeRecipient},
	}
	// Create SnapshotManager with filesystem
	sm := &SnapshotManager{
		config: cfg,
		fs:     fs,
	}

	_, err = sm.cleanSnapshotDB(ctx, tempDBPath, snapshot.ID.String())
	if err != nil {
		t.Fatalf("failed to clean snapshot database: %v", err)
	}

	// Verify the cleaned database
	verifyCleanedDB(ctx, t, tempDBPath, snapshot.ID.String(), file, chunk)
}

func TestCleanSnapshotDBNonExistentSnapshot(t *testing.T) {
	// Initialize logger
	log.Initialize(log.Config{})
	t.Parallel()

	ctx := context.Background()
	fs := afero.NewOsFs()

	// Create a test database
	tempDir := t.TempDir()
	dbPath := filepath.Join(tempDir, "test.db")

	db, err := database.New(ctx, dbPath)
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}

	// Close immediately
	err = db.Close()
	if err != nil {
		t.Fatalf("failed to close database: %v", err)
	}

	// Copy database
	tempDBPath := filepath.Join(tempDir, "temp.db")

	err = copyFile(fs, dbPath, tempDBPath)
	if err != nil {
		t.Fatalf("failed to copy database: %v", err)
	}

	// Create a mock config for testing
	cfg := &config.Config{
		CompressionLevel: 3,
		AgeRecipients:    []string{testAgeRecipient},
	}
	// Try to clean with non-existent snapshot
	sm := &SnapshotManager{config: cfg, fs: fs}
	_, err = sm.cleanSnapshotDB(ctx, tempDBPath, "non-existent-snapshot")

	// Should not error - it will just delete everything
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
}