// Copyright (C) 2020 Storj Labs, Inc.
// See LICENSE for copying information.

package metabase

import (
	"bytes"
	"context"
	"sort"

	"github.com/zeebo/errs"

	"storj.io/common/storj"
	"storj.io/private/dbutil"
	"storj.io/private/dbutil/pgutil"
	"storj.io/private/tagsql"
)

// DeleteObjectExactVersion contains arguments necessary for deleting an exact version of object.
type DeleteObjectExactVersion struct {
	Version Version
	ObjectLocation
}

// Verify delete object fields.
func (obj *DeleteObjectExactVersion) Verify() error {
	if err := obj.ObjectLocation.Verify(); err != nil {
		return err
	}
	if obj.Version <= 0 {
		return ErrInvalidRequest.New("Version invalid: %v", obj.Version)
	}
	return nil
}

// DeleteObjectResult result of deleting object.
type DeleteObjectResult struct {
	Objects  []Object
	Segments []DeletedSegmentInfo
}

// DeletedSegmentInfo info about deleted segment.
type DeletedSegmentInfo struct {
	RootPieceID storj.PieceID
	Pieces      Pieces
}

// DeleteObjectAnyStatusAllVersions contains arguments necessary for deleting all object versions.
type DeleteObjectAnyStatusAllVersions struct {
	ObjectLocation
}

// DeleteObjectsAllVersions contains arguments necessary for deleting all versions of multiple objects from the same bucket.
type DeleteObjectsAllVersions struct {
	Locations []ObjectLocation
}

// Verify delete objects fields.
func (delete *DeleteObjectsAllVersions) Verify() error {
	if len(delete.Locations) == 0 {
		return nil
	}

	if len(delete.Locations) > 1000 {
		return ErrInvalidRequest.New("cannot delete more than 1000 objects in a single request")
	}

	var errGroup errs.Group
	for _, location := range delete.Locations {
		errGroup.Add(location.Verify())
	}

	err := errGroup.Err()
	if err != nil {
		return err
	}

	// Verify if all locations are in the same bucket
	first := delete.Locations[0]
	for _, item := range delete.Locations[1:] {
		if first.ProjectID != item.ProjectID || first.BucketName != item.BucketName {
			return ErrInvalidRequest.New("all objects must be in the same bucket")
		}
	}

	return nil
}

// DeleteObjectLatestVersion contains arguments necessary for deleting latest object version.
type DeleteObjectLatestVersion struct {
	ObjectLocation
}

// DeleteObjectExactVersion deletes an exact object version.
func (db *DB) DeleteObjectExactVersion(ctx context.Context, opts DeleteObjectExactVersion) (result DeleteObjectResult, err error) {
	defer mon.Task()(&ctx)(&err)

	if err := opts.Verify(); err != nil {
		return DeleteObjectResult{}, err
	}
	err = withRows(db.db.Query(ctx, `
			WITH deleted_objects AS (
				DELETE FROM objects
				WHERE
					project_id   = $1 AND
					bucket_name  = $2 AND
					object_key   = $3 AND
					version      = $4 AND
					status       = `+committedStatus+`
				RETURNING
					version, stream_id,
					created_at, expires_at,
					status, segment_count,
					encrypted_metadata_nonce, encrypted_metadata, encrypted_metadata_encrypted_key,
					total_plain_size, total_encrypted_size, fixed_segment_size,
					encryption
			), deleted_segments AS (
				DELETE FROM segments
				WHERE segments.stream_id in (SELECT deleted_objects.stream_id FROM deleted_objects)
				RETURNING segments.stream_id,segments.root_piece_id, segments.remote_alias_pieces
			)
			SELECT
				deleted_objects.version, deleted_objects.stream_id,
				deleted_objects.created_at, deleted_objects.expires_at,
				deleted_objects.status, deleted_objects.segment_count,
				deleted_objects.encrypted_metadata_nonce, deleted_objects.encrypted_metadata, deleted_objects.encrypted_metadata_encrypted_key,
				deleted_objects.total_plain_size, deleted_objects.total_encrypted_size, deleted_objects.fixed_segment_size,
				deleted_objects.encryption,
				deleted_segments.root_piece_id, deleted_segments.remote_alias_pieces
			FROM deleted_objects
			LEFT JOIN deleted_segments ON deleted_objects.stream_id = deleted_segments.stream_id
		`, opts.ProjectID, []byte(opts.BucketName), []byte(opts.ObjectKey), opts.Version))(func(rows tagsql.Rows) error {
		result.Objects, result.Segments, err = db.scanObjectDeletion(ctx, opts.ObjectLocation, rows)
		return err
	})
	if err != nil {
		return DeleteObjectResult{}, err
	}

	if len(result.Objects) == 0 {
		return DeleteObjectResult{}, storj.ErrObjectNotFound.Wrap(Error.New("no rows deleted"))
	}

	mon.Meter("object_delete").Mark(len(result.Objects))
	mon.Meter("segment_delete").Mark(len(result.Segments))

	return result, nil
}

// DeletePendingObject contains arguments necessary for deleting a pending object.
type DeletePendingObject struct {
	ObjectStream
}

// Verify verifies delete pending object fields validity.
func (opts *DeletePendingObject) Verify() error {
	if err := opts.ObjectStream.Verify(); err != nil {
		return err
	}
	return nil
}

// DeletePendingObject deletes a pending object with specified version and streamID.
func (db *DB) DeletePendingObject(ctx context.Context, opts DeletePendingObject) (result DeleteObjectResult, err error) {
	defer mon.Task()(&ctx)(&err)

	if err := opts.Verify(); err != nil {
		return DeleteObjectResult{}, err
	}

	err = withRows(db.db.Query(ctx, `
			WITH deleted_objects AS (
				DELETE FROM objects
				WHERE
					project_id   = $1 AND
					bucket_name  = $2 AND
					object_key   = $3 AND
					version      = $4 AND
					stream_id    = $5 AND
					status       = `+pendingStatus+`
				RETURNING
					version, stream_id,
					created_at, expires_at,
					status, segment_count,
					encrypted_metadata_nonce, encrypted_metadata, encrypted_metadata_encrypted_key,
					total_plain_size, total_encrypted_size, fixed_segment_size,
					encryption
			), deleted_segments AS (
				DELETE FROM segments
				WHERE segments.stream_id in (SELECT deleted_objects.stream_id FROM deleted_objects)
				RETURNING segments.stream_id,segments.root_piece_id, segments.remote_alias_pieces
			)
			SELECT
				deleted_objects.version, deleted_objects.stream_id,
				deleted_objects.created_at, deleted_objects.expires_at,
				deleted_objects.status, deleted_objects.segment_count,
				deleted_objects.encrypted_metadata_nonce, deleted_objects.encrypted_metadata, deleted_objects.encrypted_metadata_encrypted_key,
				deleted_objects.total_plain_size, deleted_objects.total_encrypted_size, deleted_objects.fixed_segment_size,
				deleted_objects.encryption,
				deleted_segments.root_piece_id, deleted_segments.remote_alias_pieces
			FROM deleted_objects
			LEFT JOIN deleted_segments ON deleted_objects.stream_id = deleted_segments.stream_id
		`, opts.ProjectID, []byte(opts.BucketName), []byte(opts.ObjectKey), opts.Version, opts.StreamID))(func(rows tagsql.Rows) error {
		result.Objects, result.Segments, err = db.scanObjectDeletion(ctx, opts.Location(), rows)
		return err
	})

	if err != nil {
		return DeleteObjectResult{}, err
	}

	if len(result.Objects) == 0 {
		return DeleteObjectResult{}, storj.ErrObjectNotFound.Wrap(Error.New("no rows deleted"))
	}

	mon.Meter("object_delete").Mark(len(result.Objects))
	mon.Meter("segment_delete").Mark(len(result.Segments))

	return result, nil
}

// DeleteObjectLatestVersion deletes latest object version.
func (db *DB) DeleteObjectLatestVersion(ctx context.Context, opts DeleteObjectLatestVersion) (result DeleteObjectResult, err error) {
	defer mon.Task()(&ctx)(&err)

	if err := opts.Verify(); err != nil {
		return DeleteObjectResult{}, err
	}

	var query string
	switch db.impl {
	case dbutil.Cockroach:
		query = `
			WITH deleted_objects AS (
				DELETE FROM objects
				WHERE
					project_id   = $1 AND
					bucket_name  = $2 AND
					object_key   = $3 AND
					status       = ` + committedStatus + `
				ORDER BY version DESC
				LIMIT 1
				RETURNING
					version, stream_id,
					created_at, expires_at,
					status, segment_count,
					encrypted_metadata_nonce, encrypted_metadata, encrypted_metadata_encrypted_key,
					total_plain_size, total_encrypted_size, fixed_segment_size,
					encryption
			), deleted_segments AS (
				DELETE FROM segments
				WHERE segments.stream_id in (SELECT deleted_objects.stream_id FROM deleted_objects)
				RETURNING segments.stream_id,segments.root_piece_id, segments.remote_alias_pieces
			)
			SELECT
				deleted_objects.version, deleted_objects.stream_id,
				deleted_objects.created_at, deleted_objects.expires_at,
				deleted_objects.status, deleted_objects.segment_count,
				deleted_objects.encrypted_metadata_nonce, deleted_objects.encrypted_metadata, deleted_objects.encrypted_metadata_encrypted_key,
				deleted_objects.total_plain_size, deleted_objects.total_encrypted_size, deleted_objects.fixed_segment_size,
				deleted_objects.encryption,
				deleted_segments.root_piece_id, deleted_segments.remote_alias_pieces
			FROM deleted_objects
			LEFT JOIN deleted_segments ON deleted_objects.stream_id = deleted_segments.stream_id
		`
	case dbutil.Postgres:
		query = `
			WITH deleted_objects AS (
				DELETE FROM objects
				WHERE
					project_id   = $1 AND
					bucket_name  = $2 AND
					object_key   = $3 AND
					version IN (
						SELECT version FROM objects
						WHERE
							project_id   = $1 AND
							bucket_name  = $2 AND
							object_key   = $3 AND
							status       = ` + committedStatus + `
						ORDER BY version DESC LIMIT 1
					) AND
					status       = ` + committedStatus + `
				RETURNING
					version, stream_id,
					created_at, expires_at,
					status, segment_count,
					encrypted_metadata_nonce, encrypted_metadata, encrypted_metadata_encrypted_key,
					total_plain_size, total_encrypted_size, fixed_segment_size,
					encryption
			), deleted_segments AS (
				DELETE FROM segments
				WHERE segments.stream_id in (SELECT deleted_objects.stream_id FROM deleted_objects)
				RETURNING segments.stream_id,segments.root_piece_id, segments.remote_alias_pieces
			)
			SELECT
				deleted_objects.version, deleted_objects.stream_id,
				deleted_objects.created_at, deleted_objects.expires_at,
				deleted_objects.status, deleted_objects.segment_count,
				deleted_objects.encrypted_metadata_nonce, deleted_objects.encrypted_metadata, deleted_objects.encrypted_metadata_encrypted_key,
				deleted_objects.total_plain_size, deleted_objects.total_encrypted_size, deleted_objects.fixed_segment_size,
				deleted_objects.encryption,
				deleted_segments.root_piece_id, deleted_segments.remote_alias_pieces
			FROM deleted_objects
			LEFT JOIN deleted_segments ON deleted_objects.stream_id = deleted_segments.stream_id
		`
	default:
		return DeleteObjectResult{}, Error.New("unhandled database: %v", db.impl)
	}
	err = withRows(db.db.Query(ctx, query, opts.ProjectID, []byte(opts.BucketName), []byte(opts.ObjectKey)))(func(rows tagsql.Rows) error {
		result.Objects, result.Segments, err = db.scanObjectDeletion(ctx, opts.ObjectLocation, rows)
		return err
	})

	if err != nil {
		return DeleteObjectResult{}, err
	}

	if len(result.Objects) == 0 {
		return DeleteObjectResult{}, storj.ErrObjectNotFound.Wrap(Error.New("no rows deleted"))
	}

	mon.Meter("object_delete").Mark(len(result.Objects))
	mon.Meter("segment_delete").Mark(len(result.Segments))

	return result, nil
}

// DeleteObjectAnyStatusAllVersions deletes all object versions.
func (db *DB) DeleteObjectAnyStatusAllVersions(ctx context.Context, opts DeleteObjectAnyStatusAllVersions) (result DeleteObjectResult, err error) {
	defer mon.Task()(&ctx)(&err)

	if err := opts.Verify(); err != nil {
		return DeleteObjectResult{}, err
	}

	err = withRows(db.db.Query(ctx, `
			WITH deleted_objects AS (
				DELETE FROM objects
				WHERE
				project_id   = $1 AND
				bucket_name  = $2 AND
				object_key   = $3
				RETURNING
					version, stream_id,
					created_at, expires_at,
					status, segment_count,
					encrypted_metadata_nonce, encrypted_metadata, encrypted_metadata_encrypted_key,
					total_plain_size, total_encrypted_size, fixed_segment_size,
					encryption
			), deleted_segments AS (
				DELETE FROM segments
				WHERE segments.stream_id in (SELECT deleted_objects.stream_id FROM deleted_objects)
				RETURNING segments.stream_id,segments.root_piece_id, segments.remote_alias_pieces
			)
			SELECT
				deleted_objects.version, deleted_objects.stream_id,
				deleted_objects.created_at, deleted_objects.expires_at,
				deleted_objects.status, deleted_objects.segment_count,
				deleted_objects.encrypted_metadata_nonce, deleted_objects.encrypted_metadata, deleted_objects.encrypted_metadata_encrypted_key,
				deleted_objects.total_plain_size, deleted_objects.total_encrypted_size, deleted_objects.fixed_segment_size,
				deleted_objects.encryption,
				deleted_segments.root_piece_id, deleted_segments.remote_alias_pieces
			FROM deleted_objects
			LEFT JOIN deleted_segments ON deleted_objects.stream_id = deleted_segments.stream_id
		`, opts.ProjectID, []byte(opts.BucketName), []byte(opts.ObjectKey)))(func(rows tagsql.Rows) error {
		result.Objects, result.Segments, err = db.scanObjectDeletion(ctx, opts.ObjectLocation, rows)
		return err
	})

	if err != nil {
		return DeleteObjectResult{}, err
	}

	if len(result.Objects) == 0 {
		return DeleteObjectResult{}, storj.ErrObjectNotFound.Wrap(Error.New("no rows deleted"))
	}

	mon.Meter("object_delete").Mark(len(result.Objects))
	mon.Meter("segment_delete").Mark(len(result.Segments))

	return result, nil
}

// DeleteObjectsAllVersions deletes all versions of multiple objects from the same bucket.
func (db *DB) DeleteObjectsAllVersions(ctx context.Context, opts DeleteObjectsAllVersions) (result DeleteObjectResult, err error) {
	defer mon.Task()(&ctx)(&err)

	if len(opts.Locations) == 0 {
		// nothing to delete, no error
		return DeleteObjectResult{}, nil
	}

	if err := opts.Verify(); err != nil {
		return DeleteObjectResult{}, err
	}

	// It is aleady verified that all object locations are in the same bucket
	projectID := opts.Locations[0].ProjectID
	bucketName := opts.Locations[0].BucketName

	objectKeys := make([][]byte, len(opts.Locations))
	for i := range opts.Locations {
		objectKeys[i] = []byte(opts.Locations[i].ObjectKey)
	}

	// Sorting the object keys just in case.
	// TODO: Check if this is really necessary for the SQL query.
	sort.Slice(objectKeys, func(i, j int) bool {
		return bytes.Compare(objectKeys[i], objectKeys[j]) < 0
	})
	err = withRows(db.db.Query(ctx, `
				WITH deleted_objects AS (
					DELETE FROM objects
					WHERE
					project_id   = $1 AND
					bucket_name  = $2 AND
					object_key   = ANY ($3) AND
					status       = `+committedStatus+`
					RETURNING
						project_id, bucket_name,
						object_key, version, stream_id,
						created_at, expires_at,
						status, segment_count,
						encrypted_metadata_nonce, encrypted_metadata, encrypted_metadata_encrypted_key,
						total_plain_size, total_encrypted_size, fixed_segment_size,
						encryption
				), deleted_segments AS (
					DELETE FROM segments
					WHERE segments.stream_id in (SELECT deleted_objects.stream_id FROM deleted_objects)
					RETURNING segments.stream_id,segments.root_piece_id, segments.remote_alias_pieces
				)
				SELECT
					deleted_objects.project_id, deleted_objects.bucket_name,
					deleted_objects.object_key,deleted_objects.version, deleted_objects.stream_id,
					deleted_objects.created_at, deleted_objects.expires_at,
					deleted_objects.status, deleted_objects.segment_count,
					deleted_objects.encrypted_metadata_nonce, deleted_objects.encrypted_metadata, deleted_objects.encrypted_metadata_encrypted_key,
					deleted_objects.total_plain_size, deleted_objects.total_encrypted_size, deleted_objects.fixed_segment_size,
					deleted_objects.encryption,
					deleted_segments.root_piece_id, deleted_segments.remote_alias_pieces
				FROM deleted_objects
				LEFT JOIN deleted_segments ON deleted_objects.stream_id = deleted_segments.stream_id
			`, projectID, []byte(bucketName), pgutil.ByteaArray(objectKeys)))(func(rows tagsql.Rows) error {
		result.Objects, result.Segments, err = db.scanMultipleObjectsDeletion(ctx, rows)
		return err
	})

	if err != nil {
		return DeleteObjectResult{}, err
	}

	mon.Meter("object_delete").Mark(len(result.Objects))
	mon.Meter("segment_delete").Mark(len(result.Segments))

	return result, nil
}

func (db *DB) scanObjectDeletion(ctx context.Context, location ObjectLocation, rows tagsql.Rows) (objects []Object, segments []DeletedSegmentInfo, err error) {
	defer func() { err = errs.Combine(err, rows.Close()) }()

	objects = make([]Object, 0, 10)
	segments = make([]DeletedSegmentInfo, 0, 10)

	var rootPieceID *storj.PieceID
	var object Object
	var segment DeletedSegmentInfo
	var aliasPieces AliasPieces

	for rows.Next() {

		object.ProjectID = location.ProjectID
		object.BucketName = location.BucketName
		object.ObjectKey = location.ObjectKey

		err = rows.Scan(&object.Version, &object.StreamID,
			&object.CreatedAt, &object.ExpiresAt,
			&object.Status, &object.SegmentCount,
			&object.EncryptedMetadataNonce, &object.EncryptedMetadata, &object.EncryptedMetadataEncryptedKey,
			&object.TotalPlainSize, &object.TotalEncryptedSize, &object.FixedSegmentSize,
			encryptionParameters{&object.Encryption}, &rootPieceID, &aliasPieces)
		if err != nil {
			return nil, nil, Error.New("unable to delete object: %w", err)
		}
		if len(objects) == 0 || objects[len(objects)-1].StreamID != object.StreamID {
			objects = append(objects, object)
		}
		if rootPieceID != nil {
			segment.RootPieceID = *rootPieceID
			segment.Pieces, err = db.aliasCache.ConvertAliasesToPieces(ctx, aliasPieces)
			if err != nil {
				return nil, nil, Error.Wrap(err)
			}
			if len(segment.Pieces) > 0 {
				segments = append(segments, segment)
			}
		}
	}

	if err := rows.Err(); err != nil {
		return nil, nil, Error.New("unable to delete object: %w", err)
	}

	if len(segments) == 0 {
		return objects, nil, nil
	}
	return objects, segments, nil
}

func (db *DB) scanMultipleObjectsDeletion(ctx context.Context, rows tagsql.Rows) (objects []Object, segments []DeletedSegmentInfo, err error) {
	defer func() { err = errs.Combine(err, rows.Close()) }()

	objects = make([]Object, 0, 10)
	segments = make([]DeletedSegmentInfo, 0, 10)

	var rootPieceID *storj.PieceID
	var object Object
	var segment DeletedSegmentInfo
	var aliasPieces AliasPieces

	for rows.Next() {
		err = rows.Scan(&object.ProjectID, &object.BucketName,
			&object.ObjectKey, &object.Version, &object.StreamID,
			&object.CreatedAt, &object.ExpiresAt,
			&object.Status, &object.SegmentCount,
			&object.EncryptedMetadataNonce, &object.EncryptedMetadata, &object.EncryptedMetadataEncryptedKey,
			&object.TotalPlainSize, &object.TotalEncryptedSize, &object.FixedSegmentSize,
			encryptionParameters{&object.Encryption}, &rootPieceID, &aliasPieces)
		if err != nil {
			return nil, nil, Error.New("unable to delete object: %w", err)
		}

		if len(objects) == 0 || objects[len(objects)-1].StreamID != object.StreamID {
			objects = append(objects, object)
		}
		if rootPieceID != nil {
			segment.RootPieceID = *rootPieceID
			segment.Pieces, err = db.aliasCache.ConvertAliasesToPieces(ctx, aliasPieces)
			if err != nil {
				return nil, nil, Error.Wrap(err)
			}
			if len(segment.Pieces) > 0 {
				segments = append(segments, segment)
			}
		}
	}

	if err := rows.Err(); err != nil {
		return nil, nil, Error.New("unable to delete object: %w", err)
	}

	if len(objects) == 0 {
		objects = nil
	}
	if len(segments) == 0 {
		return objects, nil, nil
	}

	return objects, segments, nil
}