package vaultik_test

import (
	"bytes"
	"context"
	"encoding/json"
	"io"
	"os"
	"path/filepath"
	"testing"

	"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"
)

// TestShallowVerifyDetectsWrongBlobSize backs up a real snapshot, runs
// shallow verify (which passes and reports exactly the blobs it checked),
// then grows one stored blob so its size no longer matches the manifest.
// Shallow verify must then fail, count the grown blob as a size mismatch,
// and drop it from the verified count rather than continuing to report it
// as checked.
func TestShallowVerifyDetectsWrongBlobSize(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")
	dbPath := filepath.Join(tempDir, "index.sqlite")

	chunkSize := int64(32 * 1024)
	maxBlobSize := int64(128 * 1024)

	// Enough data to span several blobs, so the mismatch count and the
	// dropped verified count are both meaningful.
	require.NoError(t, fs.MkdirAll(dataDir, 0o755))
	require.NoError(t, afero.WriteFile(fs,
		filepath.Join(dataDir, "data.bin"),
		bytesPattern("shallow-", int(maxBlobSize*4)), 0o644))

	ctx := context.Background()

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

	newVerifier := func(out io.Writer) *vaultik.Vaultik {
		v := &vaultik.Vaultik{
			Config:  cfg,
			Storage: storer,
			Fs:      fs,
			Stdout:  out,
			Stderr:  io.Discard,
			UI:      ui.NewWithColor(io.Discard, false),
		}
		v.SetContext(ctx)

		return v
	}

	var out bytes.Buffer

	require.NoError(t,
		newVerifier(&out).VerifySnapshotWithOptions(
			snapshotID, &vaultik.VerifyOptions{JSON: true}),
		"shallow verify should pass on a healthy snapshot")

	healthy := decodeVerifyResult(t, out.Bytes())
	require.Equal(t, "ok", healthy.Status)
	require.Positive(t, healthy.BlobCount)
	require.Equal(t, healthy.BlobCount, healthy.Verified,
		"shallow verify must report exactly the blobs it checked")
	require.Zero(t, healthy.Mismatched)

	// Grow one stored blob so its size no longer matches the manifest.
	growOneBlob(t, fs, filepath.Join(storeDir, "blobs"))

	out.Reset()
	err := newVerifier(&out).VerifySnapshotWithOptions(
		snapshotID, &vaultik.VerifyOptions{JSON: true})
	require.Error(t, err,
		"shallow verify must fail when a blob's stored size differs from the manifest")

	bad := decodeVerifyResult(t, out.Bytes())
	require.Equal(t, "failed", bad.Status)
	require.Equal(t, 1, bad.Mismatched)
	require.Equal(t, healthy.BlobCount-1, bad.Verified,
		"the wrong-sized blob must not be counted as verified")
}

// TestShallowVerifyDetectsMissingDatabase backs up a real snapshot,
// confirms shallow verify passes, then deletes the snapshot's encrypted
// database. Shallow verify must fail: a snapshot without its database is
// not restorable, even when every blob is present.
func TestShallowVerifyDetectsMissingDatabase(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")
	dbPath := filepath.Join(tempDir, "index.sqlite")

	chunkSize := int64(32 * 1024)
	maxBlobSize := int64(128 * 1024)

	require.NoError(t, fs.MkdirAll(dataDir, 0o755))
	require.NoError(t, afero.WriteFile(fs,
		filepath.Join(dataDir, "data.bin"),
		bytesPattern("shallow-db-", int(maxBlobSize*2)), 0o644))

	ctx := context.Background()

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

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

		return v
	}

	require.NoError(t,
		newVerifier().VerifySnapshotWithOptions(
			snapshotID, &vaultik.VerifyOptions{}),
		"shallow verify should pass on a healthy snapshot")

	// The database lives under the hashed remote key, not the human ID.
	dbObject := filepath.Join(storeDir, "metadata",
		snapshot.RemoteSnapshotKey(snapshotID), "db.zst.age")
	require.NoError(t, os.Remove(dbObject))

	require.Error(t,
		newVerifier().VerifySnapshotWithOptions(
			snapshotID, &vaultik.VerifyOptions{}),
		"shallow verify must fail when db.zst.age is absent")
}

// growOneBlob appends bytes to the first blob file found under blobsDir,
// changing its on-disk size so it no longer matches the manifest.
func growOneBlob(t *testing.T, fs afero.Fs, blobsDir string) {
	t.Helper()

	var blobPath string

	err := afero.Walk(fs, blobsDir,
		func(path string, info os.FileInfo, err error) error {
			if err != nil {
				return err
			}

			if blobPath == "" && !info.IsDir() {
				blobPath = path
			}

			return nil
		})
	require.NoError(t, err)
	require.NotEmpty(t, blobPath, "expected at least one blob on disk")

	data, err := afero.ReadFile(fs, blobPath)
	require.NoError(t, err)

	data = append(data, []byte("extra")...)
	require.NoError(t, afero.WriteFile(fs, blobPath, data, 0o644))
}

func decodeVerifyResult(t *testing.T, b []byte) vaultik.VerifyResult {
	t.Helper()

	var result vaultik.VerifyResult

	require.NoError(t, json.Unmarshal(b, &result))

	return result
}