package vaultik_test

import (
	"bytes"
	"context"
	"fmt"
	"os"
	"path/filepath"
	"testing"
	"time"

	"github.com/spf13/afero"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"sneak.berlin/go/vaultik/internal/config"
	"sneak.berlin/go/vaultik/internal/database"
	"sneak.berlin/go/vaultik/internal/log"
	"sneak.berlin/go/vaultik/internal/storage"
	"sneak.berlin/go/vaultik/internal/ui"
	"sneak.berlin/go/vaultik/internal/vaultik"
)

// These tests cover https://git.eeqj.de/sneak/vaultik/issues/304: a
// backup counts a file as deleted only when the previous snapshot of
// the same name had it and it is gone, and never counts an excluded
// file.

// deletedCountEnv is a backup setup over the source directory src whose
// user-facing output is kept in out. Each test configures its snapshots
// with setSnapshot.
type deletedCountEnv struct {
	v   *vaultik.Vaultik
	out *bytes.Buffer
	src string
}

// newDeletedCountEnv writes files, keyed by path relative to src.
func newDeletedCountEnv(t *testing.T, files map[string][]byte) *deletedCountEnv {
	t.Helper()

	ctx := context.Background()
	fs := afero.NewOsFs()
	tempDir := t.TempDir()
	srcDir := filepath.Join(tempDir, "src")

	for rel, content := range files {
		path := filepath.Join(srcDir, rel)
		require.NoError(t, fs.MkdirAll(filepath.Dir(path), 0o755))
		require.NoError(t, afero.WriteFile(fs, path, content, 0o644))
	}

	cfg := faultTestConfig()
	cfg.IndexPath = filepath.Join(tempDir, "index.sqlite")
	cfg.Snapshots = map[string]config.SnapshotConfig{}

	store, err := storage.NewFileStorer(t.TempDir())
	require.NoError(t, err)

	db, err := database.New(ctx, cfg.IndexPath)
	require.NoError(t, err)
	t.Cleanup(func() { _ = db.Close() })

	repos := database.NewRepositories(db)
	out := &bytes.Buffer{}
	v := newBackupVaultik(ctx, cfg, store, repos, db, fs)
	v.UI = ui.NewWithColor(out, false)

	return &deletedCountEnv{v: v, out: out, src: srcDir}
}

// setSnapshot configures the snapshot name to back up the path rel
// beneath src, with the given excludes.
func (e *deletedCountEnv) setSnapshot(name, rel string, exclude ...string) {
	e.v.Config.Snapshots[name] = config.SnapshotConfig{
		Paths:   []string{filepath.Join(e.src, rel)},
		Exclude: exclude,
	}
}

// backUp runs a backup of the named snapshot and returns its output.
func (e *deletedCountEnv) backUp(t *testing.T, name string) string {
	t.Helper()

	e.out.Reset()
	require.NoError(t, e.v.CreateSnapshot(&vaultik.SnapshotCreateOptions{
		Snapshots: []string{name},
	}))

	return e.out.String()
}

// A file this snapshot excludes is not counted as deleted: neither one
// that another snapshot backs up, nor one that the previous snapshot of
// this name had before the exclude was added.
func TestBackupDoesNotCountExcludedFileAsDeleted(t *testing.T) {
	log.Initialize(log.Config{})
	t.Parallel()

	env := newDeletedCountEnv(t, map[string][]byte{
		"top.txt":       []byte("top"),
		"cache/tmp.bin": []byte("cache"),
		"photos/a.jpg":  []byte("photo a"),
		"photos/b.jpg":  []byte("photo b"),
		"photos/c.jpg":  []byte("photo c"),
	})
	env.setSnapshot("photos", "photos")
	env.setSnapshot("home", "", "/photos")

	env.backUp(t, "photos")
	assert.Contains(t, env.backUp(t, "home"), filesLine(2, 2, 0))

	env.setSnapshot("home", "", "/photos", "/cache")
	assert.Contains(t, env.backUp(t, "home"), filesLine(1, 0, 1))
}

// A file inside a directory that an exclude added after a backup
// matches is not counted as deleted, though the pattern matches only the
// directory and the directory is gone from disk.
func TestBackupDoesNotCountFileInExcludedDirectoryAsDeleted(t *testing.T) {
	log.Initialize(log.Config{})
	t.Parallel()

	env := newDeletedCountEnv(t, map[string][]byte{
		"top.txt":                         []byte("top"),
		"user/.local/share/Trash/old.txt": []byte("old"),
	})
	env.setSnapshot("home", "")

	assert.Contains(t, env.backUp(t, "home"), filesLine(2, 2, 0))

	require.NoError(t, os.RemoveAll(
		filepath.Join(env.src, "user/.local/share/Trash")))

	env.setSnapshot("home", "", "*/.local/share/Trash")
	assert.Contains(t, env.backUp(t, "home"), filesLine(1, 0, 1))
}

// A file whose directory was replaced by a regular file of the same name
// is counted as deleted.
func TestBackupCountsFileInDirectoryReplacedByFileAsDeleted(t *testing.T) {
	log.Initialize(log.Config{})
	t.Parallel()

	env := newDeletedCountEnv(t, map[string][]byte{
		"dir/inside.txt": []byte("inside"),
	})
	env.setSnapshot("home", "")

	assert.Contains(t, env.backUp(t, "home"), filesLine(1, 1, 0))

	dir := filepath.Join(env.src, "dir")
	require.NoError(t, os.RemoveAll(dir))
	require.NoError(t, os.WriteFile(dir, []byte("now a file"), 0o600))

	assert.Contains(t, env.backUp(t, "home"),
		"Files: 1 examined, 1 backed up, 0 unchanged, 1 deleted.")
}

// Under --skip-errors a file inside a directory that the walk cannot
// open is not counted as deleted: it is still on disk.
func TestBackupDoesNotCountFileInUnopenableDirectoryAsDeleted(t *testing.T) {
	log.Initialize(log.Config{})
	t.Parallel()

	env := newDeletedCountEnv(t, map[string][]byte{
		"open.txt":          []byte("open"),
		"locked/inside.txt": []byte("inside"),
	})
	env.setSnapshot("work", "")

	assert.Contains(t, env.backUp(t, "work"), filesLine(2, 2, 0))

	// A directory's mode does not lock out root, who runs the tests, so
	// opening the directory is made to fail instead.
	env.v.Fs = &openFailFs{
		path: filepath.Join(env.src, "locked"),
		err:  os.ErrPermission,
	}

	env.out.Reset()
	err := env.v.CreateSnapshot(&vaultik.SnapshotCreateOptions{
		SkipErrors: true,
		Snapshots:  []string{"work"},
	})
	require.ErrorIs(t, err, vaultik.ErrFilesUnreadable)
	assert.Contains(t, env.out.String(),
		"Files: 2 examined, 0 backed up, 1 unchanged, 1 failed.")
}

// A backup counts only files that the previous snapshot of its own name
// had, not one that a later snapshot of another name over the same path
// had and that is since removed.
func TestBackupIgnoresSnapshotOfAnotherName(t *testing.T) {
	log.Initialize(log.Config{})
	t.Parallel()

	env := newDeletedCountEnv(t, map[string][]byte{
		"kept.txt": []byte("kept"),
	})
	env.setSnapshot("home", "")
	env.setSnapshot("other", "")

	env.backUp(t, "home")

	// Snapshot start times are kept in whole seconds: wait so that other's
	// snapshot is strictly the most recent.
	time.Sleep(time.Second)

	extra := filepath.Join(env.src, "extra.txt")
	require.NoError(t, os.WriteFile(extra, []byte("extra"), 0o600))
	env.backUp(t, "other")
	require.NoError(t, os.Remove(extra))

	assert.Contains(t, env.backUp(t, "home"), filesLine(1, 0, 1))
}

// A file removed from disk is counted as deleted by the next backup of
// the snapshot that had it, and not by any later backup of that
// snapshot, nor by the first backup of another name over the same path.
func TestBackupCountsDeletedFileOnce(t *testing.T) {
	log.Initialize(log.Config{})
	t.Parallel()

	aContent := bytes.Repeat([]byte("a"), 1000)
	bContent := bytes.Repeat([]byte("b"), 2000)
	keptContent := bytes.Repeat([]byte("k"), 500)

	env := newDeletedCountEnv(t, map[string][]byte{
		"a.txt":    aContent,
		"b.txt":    bContent,
		"kept.txt": keptContent,
	})
	env.setSnapshot("home", "")
	env.setSnapshot("other", "")

	assert.Contains(t, env.backUp(t, "home"), filesLine(3, 3, 0))

	require.NoError(t, os.Remove(filepath.Join(env.src, "a.txt")))
	require.NoError(t, os.Remove(filepath.Join(env.src, "b.txt")))

	summary := env.backUp(t, "home")
	assert.Contains(t, summary,
		"Files: 1 examined, 0 backed up, 1 unchanged, 2 deleted.")
	assert.Contains(t, summary,
		fmt.Sprintf("Data: %s total (%s backed up), %s deleted.",
			env.v.UI.Size(int64(len(keptContent))), env.v.UI.Size(0),
			env.v.UI.Size(int64(len(aContent)+len(bContent)))))

	assert.Contains(t, env.backUp(t, "home"), filesLine(1, 0, 1))
	assert.Contains(t, env.backUp(t, "other"), filesLine(1, 0, 1))
}