package vaultik_test

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

	"filippo.io/age"
	"github.com/spf13/afero"
	"github.com/stretchr/testify/require"
	"sneak.berlin/go/vaultik/internal/log"
	"sneak.berlin/go/vaultik/internal/snapshot"
	"sneak.berlin/go/vaultik/internal/ui"
	"sneak.berlin/go/vaultik/internal/vaultik"
)

// TestRestoreRejectsTruncatedMetadataDB backs up a real tree, then replaces
// the snapshot's db.zst.age with a stream cut right after the age header and
// its 16-byte nonce. age.Decrypt still accepts such an object and the zstd
// decoder turns the truncated read into a clean EOF, so before the fix restore
// built a fresh empty schema and reported success. Restore must now fail with
// io.ErrUnexpectedEOF, the error the reader raises for a truncated object.
// Asserting that specific error pins the reader fix: without it the truncation
// yields an empty database, which the identity check rejects for an unrelated
// reason, and this test would pass anyway.
func TestRestoreRejectsTruncatedMetadataDB(t *testing.T) {
	log.Initialize(log.Config{})
	t.Parallel()

	fs := afero.NewOsFs()
	tempDir := t.TempDir()

	dataDir := filepath.Join(tempDir, "source")
	storeDir := filepath.Join(tempDir, "remote")
	restoreDir := filepath.Join(tempDir, "restored")
	dbPath := filepath.Join(tempDir, "index.sqlite")

	chunkSize := int64(64 * 1024)
	maxBlobSize := int64(512 * 1024)

	setupE2ESourceTree(t, fs, dataDir, chunkSize)

	ctx := context.Background()

	cfg, storer, snapshotID := runFileStorageBackup(
		ctx, t, fs, dataDir, storeDir, dbPath, chunkSize, maxBlobSize)

	// Encrypting empty plaintext to the snapshot recipient yields
	// header + nonce(16) + a single 16-byte final chunk tag. Dropping the
	// trailing tag leaves exactly the age header plus its nonce — the
	// truncation an attacker can write over metadata without any key.
	recipient, err := age.ParseX25519Recipient(testAgePublicKey)
	require.NoError(t, err)

	var full bytes.Buffer

	w, err := age.Encrypt(&full, recipient)
	require.NoError(t, err)
	require.NoError(t, w.Close())

	truncated := full.Bytes()[:full.Len()-16]

	dbKeyPath := filepath.Join(storeDir, "metadata",
		snapshot.RemoteSnapshotKey(snapshotID), "db.zst.age")
	require.NoError(t, afero.WriteFile(fs, dbKeyPath, truncated, 0o644))

	restoreVaultik := &vaultik.Vaultik{
		Config:  cfg,
		Storage: storer,
		Fs:      fs,
		Stdout:  io.Discard,
		Stderr:  io.Discard,
		UI:      ui.NewWithColor(io.Discard, false),
	}
	restoreVaultik.SetContext(ctx)

	err = restoreVaultik.Restore(&vaultik.RestoreOptions{
		SnapshotID: snapshotID,
		TargetDir:  restoreDir,
		Verify:     true,
	})
	require.ErrorIs(t, err, io.ErrUnexpectedEOF)
}