package repository

import (
	"context"

	"github.com/alcionai/clues"
	"github.com/kopia/kopia/repo/manifest"
	"github.com/pkg/errors"

	"github.com/alcionai/corso/src/internal/common/idname"
	"github.com/alcionai/corso/src/internal/data"
	"github.com/alcionai/corso/src/internal/kopia"
	"github.com/alcionai/corso/src/internal/m365/collection/drive/metadata"
	"github.com/alcionai/corso/src/internal/model"
	"github.com/alcionai/corso/src/internal/operations"
	"github.com/alcionai/corso/src/internal/streamstore"
	"github.com/alcionai/corso/src/internal/version"
	"github.com/alcionai/corso/src/pkg/backup"
	"github.com/alcionai/corso/src/pkg/backup/details"
	"github.com/alcionai/corso/src/pkg/fault"
	"github.com/alcionai/corso/src/pkg/selectors"
	"github.com/alcionai/corso/src/pkg/store"
)

// BackupGetter deals with retrieving metadata about backups from the
// repository.
type BackupGetter interface {
	Backup(ctx context.Context, id string) (*backup.Backup, error)
	Backups(ctx context.Context, ids []string) ([]*backup.Backup, *fault.Bus)
	BackupsByTag(ctx context.Context, fs ...store.FilterOption) ([]*backup.Backup, error)
	GetBackupDetails(
		ctx context.Context,
		backupID string,
	) (*details.Details, *backup.Backup, *fault.Bus)
	GetBackupErrors(
		ctx context.Context,
		backupID string,
	) (*fault.Errors, *backup.Backup, *fault.Bus)
}

type Backuper interface {
	NewBackup(
		ctx context.Context,
		self selectors.Selector,
	) (operations.BackupOperation, error)
	NewBackupWithLookup(
		ctx context.Context,
		self selectors.Selector,
		ins idname.Cacher,
	) (operations.BackupOperation, error)
	DeleteBackups(
		ctx context.Context,
		failOnMissing bool,
		ids ...string,
	) error
}

// NewBackup generates a BackupOperation runner.
func (r repository) NewBackup(
	ctx context.Context,
	sel selectors.Selector,
) (operations.BackupOperation, error) {
	return r.NewBackupWithLookup(ctx, sel, nil)
}

// NewBackupWithLookup generates a BackupOperation runner.
// ownerIDToName and ownerNameToID are optional populations, in case the caller has
// already generated those values.
func (r repository) NewBackupWithLookup(
	ctx context.Context,
	sel selectors.Selector,
	ins idname.Cacher,
) (operations.BackupOperation, error) {
	err := r.ConnectDataProvider(ctx, sel.PathService())
	if err != nil {
		return operations.BackupOperation{}, clues.Wrap(err, "connecting to m365")
	}

	resource, err := r.Provider.PopulateProtectedResourceIDAndName(ctx, sel.DiscreteOwner, ins)
	if err != nil {
		return operations.BackupOperation{}, clues.Wrap(err, "resolving resource owner details")
	}

	// TODO: retrieve display name from gc
	sel = sel.SetDiscreteOwnerIDName(resource.ID(), resource.Name())

	return operations.NewBackupOperation(
		ctx,
		r.Opts,
		r.dataLayer,
		store.NewWrapper(r.modelStore),
		r.Provider,
		r.Account,
		sel,
		sel, // the selector acts as an IDNamer for its discrete resource owner.
		r.Bus,
		r.counter)
}

// Backup retrieves a backup by id.
func (r repository) Backup(ctx context.Context, id string) (*backup.Backup, error) {
	return getBackup(ctx, id, store.NewWrapper(r.modelStore))
}

// getBackup handles the processing for Backup.
func getBackup(
	ctx context.Context,
	id string,
	sw store.BackupGetter,
) (*backup.Backup, error) {
	b, err := sw.GetBackup(ctx, model.StableID(id))
	if err != nil {
		return nil, errWrapper(err)
	}

	return b, nil
}

// Backups lists backups by ID. Returns as many backups as possible with
// errors for the backups it was unable to retrieve.
func (r repository) Backups(ctx context.Context, ids []string) ([]*backup.Backup, *fault.Bus) {
	var (
		bups []*backup.Backup
		errs = fault.New(false)
		sw   = store.NewWrapper(r.modelStore)
	)

	for _, id := range ids {
		ictx := clues.Add(ctx, "backup_id", id)

		b, err := sw.GetBackup(ictx, model.StableID(id))
		if err != nil {
			errs.AddRecoverable(ctx, errWrapper(err))
		}

		bups = append(bups, b)
	}

	return bups, errs
}

// BackupsByTag lists all backups in a repository that contain all the tags
// specified.
func (r repository) BackupsByTag(ctx context.Context, fs ...store.FilterOption) ([]*backup.Backup, error) {
	sw := store.NewWrapper(r.modelStore)
	return backupsByTag(ctx, sw, fs)
}

// backupsByTag returns all backups matching all provided tags.
//
// TODO(ashmrtn): This exists mostly for testing, but we could restructure the
// code in this file so there's a more elegant mocking solution.
func backupsByTag(
	ctx context.Context,
	sw store.BackupWrapper,
	fs []store.FilterOption,
) ([]*backup.Backup, error) {
	bs, err := sw.GetBackups(ctx, fs...)
	if err != nil {
		return nil, clues.Stack(err)
	}

	// Filter out assist backup bases as they're considered incomplete and we
	// haven't been displaying them before now.
	res := make([]*backup.Backup, 0, len(bs))

	for _, b := range bs {
		if t := b.Tags[model.BackupTypeTag]; t != model.AssistBackup {
			res = append(res, b)
		}
	}

	return res, nil
}

// BackupDetails returns the specified backup.Details
func (r repository) GetBackupDetails(
	ctx context.Context,
	backupID string,
) (*details.Details, *backup.Backup, *fault.Bus) {
	errs := fault.New(false)

	deets, bup, err := getBackupDetails(
		ctx,
		backupID,
		r.Account.ID(),
		r.dataLayer,
		store.NewWrapper(r.modelStore),
		errs)

	return deets, bup, errs.Fail(err)
}

// getBackupDetails handles the processing for GetBackupDetails.
func getBackupDetails(
	ctx context.Context,
	backupID, tenantID string,
	kw *kopia.Wrapper,
	sw store.BackupGetter,
	errs *fault.Bus,
) (*details.Details, *backup.Backup, error) {
	b, err := sw.GetBackup(ctx, model.StableID(backupID))
	if err != nil {
		return nil, nil, errWrapper(err)
	}

	ssid := b.StreamStoreID
	if len(ssid) == 0 {
		ssid = b.DetailsID
	}

	if len(ssid) == 0 {
		return nil, b, clues.New("no streamstore id in backup").WithClues(ctx)
	}

	var (
		sstore = streamstore.NewStreamer(kw, tenantID, b.Selector.PathService())
		deets  details.Details
	)

	err = sstore.Read(
		ctx,
		ssid,
		streamstore.DetailsReader(details.UnmarshalTo(&deets)),
		errs)
	if err != nil {
		return nil, nil, err
	}

	// Retroactively fill in isMeta information for items in older
	// backup versions without that info
	// version.Restore2 introduces the IsMeta flag, so only v1 needs a check.
	if b.Version >= version.OneDrive1DataAndMetaFiles && b.Version < version.OneDrive3IsMetaMarker {
		for _, d := range deets.Entries {
			if d.OneDrive != nil {
				d.OneDrive.IsMeta = metadata.HasMetaSuffix(d.RepoRef)
			}
		}
	}

	deets.DetailsModel = deets.FilterMetaFiles()

	return &deets, b, nil
}

// BackupErrors returns the specified backup's fault.Errors
func (r repository) GetBackupErrors(
	ctx context.Context,
	backupID string,
) (*fault.Errors, *backup.Backup, *fault.Bus) {
	errs := fault.New(false)

	fe, bup, err := getBackupErrors(
		ctx,
		backupID,
		r.Account.ID(),
		r.dataLayer,
		store.NewWrapper(r.modelStore),
		errs)

	return fe, bup, errs.Fail(err)
}

// getBackupErrors handles the processing for GetBackupErrors.
func getBackupErrors(
	ctx context.Context,
	backupID, tenantID string,
	kw *kopia.Wrapper,
	sw store.BackupGetter,
	errs *fault.Bus,
) (*fault.Errors, *backup.Backup, error) {
	b, err := sw.GetBackup(ctx, model.StableID(backupID))
	if err != nil {
		return nil, nil, errWrapper(err)
	}

	ssid := b.StreamStoreID
	if len(ssid) == 0 {
		return nil, b, clues.New("missing streamstore id in backup").WithClues(ctx)
	}

	var (
		sstore = streamstore.NewStreamer(kw, tenantID, b.Selector.PathService())
		fe     fault.Errors
	)

	err = sstore.Read(
		ctx,
		ssid,
		streamstore.FaultErrorsReader(fault.UnmarshalErrorsTo(&fe)),
		errs)
	if err != nil {
		return nil, nil, err
	}

	return &fe, b, nil
}

// DeleteBackups removes the backups from both the model store and the backup
// storage.
//
// If failOnMissing is true then returns an error if a backup model can't be
// found. Otherwise ignores missing backup models.
//
// Missing models or snapshots during the actual deletion do not cause errors.
//
// All backups are delete as an atomic unit so any failures will result in no
// deletions.
func (r repository) DeleteBackups(
	ctx context.Context,
	failOnMissing bool,
	ids ...string,
) error {
	return deleteBackups(ctx, store.NewWrapper(r.modelStore), failOnMissing, ids...)
}

// deleteBackup handles the processing for backup deletion.
func deleteBackups(
	ctx context.Context,
	sw store.BackupGetterModelDeleter,
	failOnMissing bool,
	ids ...string,
) error {
	// Although we haven't explicitly stated it, snapshots are technically
	// manifests in kopia. This means we can use the same delete API to remove
	// them and backup models. Deleting all of them together gives us both
	// atomicity guarantees (around when data will be flushed) and helps reduce
	// the number of manifest blobs that kopia will create.
	var toDelete []manifest.ID

	for _, id := range ids {
		b, err := sw.GetBackup(ctx, model.StableID(id))
		if err != nil {
			if !failOnMissing && errors.Is(err, data.ErrNotFound) {
				continue
			}

			return clues.Stack(errWrapper(err)).
				WithClues(ctx).
				With("delete_backup_id", id)
		}

		toDelete = append(toDelete, b.ModelStoreID)

		if len(b.SnapshotID) > 0 {
			toDelete = append(toDelete, manifest.ID(b.SnapshotID))
		}

		ssid := b.StreamStoreID
		if len(ssid) == 0 {
			ssid = b.DetailsID
		}

		if len(ssid) > 0 {
			toDelete = append(toDelete, manifest.ID(ssid))
		}
	}

	return sw.DeleteWithModelStoreIDs(ctx, toDelete...)
}