// Copyright (C) 2021 Storj Labs, Inc.
// See LICENSE for copying information.

package metabase

import (
	"context"
	"database/sql"
	"errors"

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

// BeginMoveObjectResult holds data needed to begin move object.
type BeginMoveObjectResult BeginMoveCopyResults

// EncryptedKeyAndNonce holds single segment position, encrypted key and nonce.
type EncryptedKeyAndNonce struct {
	Position          SegmentPosition
	EncryptedKeyNonce []byte
	EncryptedKey      []byte
}

// BeginMoveObject holds all data needed begin move object method.
type BeginMoveObject struct {
	ObjectLocation
}

// BeginMoveCopyResults holds all data needed to begin move and copy object methods.
type BeginMoveCopyResults struct {
	StreamID                  uuid.UUID
	Version                   Version
	EncryptedMetadata         []byte
	EncryptedMetadataKeyNonce []byte
	EncryptedMetadataKey      []byte
	EncryptedKeysNonces       []EncryptedKeyAndNonce
	EncryptionParameters      storj.EncryptionParameters
}

// BeginMoveObject collects all data needed to begin object move procedure.
func (db *DB) BeginMoveObject(ctx context.Context, opts BeginMoveObject) (_ BeginMoveObjectResult, err error) {
	result, err := db.beginMoveCopyObject(ctx, opts.ObjectLocation, MoveSegmentLimit, nil)
	if err != nil {
		return BeginMoveObjectResult{}, err
	}

	return BeginMoveObjectResult(result), nil
}

// beginMoveCopyObject collects all data needed to begin object move/copy procedure.
func (db *DB) beginMoveCopyObject(ctx context.Context, location ObjectLocation, segmentLimit int64, verifyLimits func(encryptedObjectSize int64, nSegments int64) error) (result BeginMoveCopyResults, err error) {
	defer mon.Task()(&ctx)(&err)

	if err := location.Verify(); err != nil {
		return BeginMoveCopyResults{}, err
	}

	object, err := db.GetObjectLastCommitted(ctx, GetObjectLastCommitted{
		ObjectLocation: ObjectLocation{
			ProjectID:  location.ProjectID,
			BucketName: location.BucketName,
			ObjectKey:  location.ObjectKey,
		},
	})
	if err != nil {
		return BeginMoveCopyResults{}, err
	}

	if int64(object.SegmentCount) > segmentLimit {
		return BeginMoveCopyResults{}, ErrInvalidRequest.New("object has too many segments (%d). Limit is %d.", object.SegmentCount, CopySegmentLimit)
	}

	if verifyLimits != nil {
		err = verifyLimits(object.TotalEncryptedSize, int64(object.SegmentCount))
		if err != nil {
			return BeginMoveCopyResults{}, err
		}
	}

	err = withRows(db.db.QueryContext(ctx, `
		SELECT
			position, encrypted_key_nonce, encrypted_key
		FROM segments
		WHERE stream_id = $1
		ORDER BY stream_id, position ASC
	`, object.StreamID))(func(rows tagsql.Rows) error {
		for rows.Next() {
			var keys EncryptedKeyAndNonce

			err = rows.Scan(&keys.Position, &keys.EncryptedKeyNonce, &keys.EncryptedKey)
			if err != nil {
				return Error.New("failed to scan segments: %w", err)
			}

			result.EncryptedKeysNonces = append(result.EncryptedKeysNonces, keys)
		}

		return nil
	})
	if err != nil && !errors.Is(err, sql.ErrNoRows) {
		return BeginMoveCopyResults{}, Error.New("unable to fetch object segments: %w", err)
	}

	result.StreamID = object.StreamID
	result.Version = object.Version
	result.EncryptionParameters = object.Encryption
	result.EncryptedMetadata = object.EncryptedMetadata
	result.EncryptedMetadataKey = object.EncryptedMetadataEncryptedKey
	result.EncryptedMetadataKeyNonce = object.EncryptedMetadataNonce

	return result, nil
}

// FinishMoveObject holds all data needed to finish object move.
type FinishMoveObject struct {
	ObjectStream

	NewBucket             string
	NewSegmentKeys        []EncryptedKeyAndNonce
	NewEncryptedObjectKey ObjectKey
	// Optional. Required if object has metadata.
	NewEncryptedMetadataKeyNonce storj.Nonce
	NewEncryptedMetadataKey      []byte

	// NewDisallowDelete indicates whether the user is allowed to delete an existing unversioned object.
	NewDisallowDelete bool

	// NewVersioned indicates that the object allows multiple versions.
	NewVersioned bool
}

// Verify verifies metabase.FinishMoveObject data.
func (finishMove FinishMoveObject) Verify() error {
	if err := finishMove.ObjectStream.Verify(); err != nil {
		return err
	}

	switch {
	case len(finishMove.NewBucket) == 0:
		return ErrInvalidRequest.New("NewBucket is missing")
	case len(finishMove.NewEncryptedObjectKey) == 0:
		return ErrInvalidRequest.New("NewEncryptedObjectKey is missing")
	}

	return nil
}

// FinishMoveObject accepts new encryption keys for moved object and updates the corresponding object ObjectKey and segments EncryptedKey.
func (db *DB) FinishMoveObject(ctx context.Context, opts FinishMoveObject) (err error) {
	defer mon.Task()(&ctx)(&err)

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

	err = txutil.WithTx(ctx, db.db, nil, func(ctx context.Context, tx tagsql.Tx) (err error) {
		var highestVersion Version

		if !opts.NewVersioned {
			// TODO(ver): this logic can probably merged into update query
			//
			// Note, we are prematurely deleting the object without permissions
			// and then rolling the action back, if we were not allowed to.
			deleted, err := db.deleteObjectUnversionedCommitted(ctx, ObjectLocation{
				ProjectID:  opts.ProjectID,
				BucketName: opts.NewBucket,
				ObjectKey:  opts.NewEncryptedObjectKey,
			}, tx)
			if err != nil {
				return Error.New("unable to delete object at target location: %w", err)
			}
			if deleted.DeletedObjectCount > 0 && opts.NewDisallowDelete {
				return ErrPermissionDenied.New("no permissions to delete existing object")
			}

			highestVersion = deleted.MaxVersion
		} else {
			highestVersion, err = db.queryHighestVersion(ctx, ObjectLocation{
				ProjectID:  opts.ProjectID,
				BucketName: opts.NewBucket,
				ObjectKey:  opts.NewEncryptedObjectKey,
			}, tx)
			if err != nil {
				return Error.New("unable to query highest version: %w", err)
			}
		}

		var segmentsCount int
		var hasMetadata bool
		var streamID uuid.UUID

		newStatus := committedWhereVersioned(opts.NewVersioned)

		err = tx.QueryRowContext(ctx, `
			UPDATE objects SET
				bucket_name = $1,
				object_key = $2,
				version = $10,
				status = $9,
				encrypted_metadata_encrypted_key =
					CASE WHEN objects.encrypted_metadata IS NOT NULL
						THEN $3
						ELSE objects.encrypted_metadata_encrypted_key
					END,
				encrypted_metadata_nonce =
					CASE WHEN objects.encrypted_metadata IS NOT NULL
						THEN $4
						ELSE objects.encrypted_metadata_nonce
					END
			WHERE
				(project_id, bucket_name, object_key, version) = ($5, $6, $7, $8)
			RETURNING
				segment_count,
				objects.encrypted_metadata IS NOT NULL AND LENGTH(objects.encrypted_metadata) > 0 AS has_metadata,
				stream_id
		`, []byte(opts.NewBucket), opts.NewEncryptedObjectKey, opts.NewEncryptedMetadataKey,
			opts.NewEncryptedMetadataKeyNonce, opts.ProjectID, []byte(opts.BucketName),
			opts.ObjectKey, opts.Version, newStatus, highestVersion+1).
			Scan(&segmentsCount, &hasMetadata, &streamID)

		if err != nil {
			if errors.Is(err, sql.ErrNoRows) {
				return ErrObjectNotFound.New("object not found")
			}
			return Error.New("unable to update object: %w", err)
		}
		if streamID != opts.StreamID {
			return ErrObjectNotFound.New("object was changed during move")
		}
		if segmentsCount != len(opts.NewSegmentKeys) {
			return ErrInvalidRequest.New("wrong number of segments keys received")
		}
		if hasMetadata {
			switch {
			case opts.NewEncryptedMetadataKeyNonce.IsZero() && len(opts.NewEncryptedMetadataKey) != 0:
				return ErrInvalidRequest.New("EncryptedMetadataKeyNonce is missing")
			case len(opts.NewEncryptedMetadataKey) == 0 && !opts.NewEncryptedMetadataKeyNonce.IsZero():
				return ErrInvalidRequest.New("EncryptedMetadataKey is missing")
			}
		}

		var newSegmentKeys struct {
			Positions          []int64
			EncryptedKeys      [][]byte
			EncryptedKeyNonces [][]byte
		}

		for _, u := range opts.NewSegmentKeys {
			newSegmentKeys.EncryptedKeys = append(newSegmentKeys.EncryptedKeys, u.EncryptedKey)
			newSegmentKeys.EncryptedKeyNonces = append(newSegmentKeys.EncryptedKeyNonces, u.EncryptedKeyNonce)
			newSegmentKeys.Positions = append(newSegmentKeys.Positions, int64(u.Position.Encode()))
		}

		updateResult, err := tx.ExecContext(ctx, `
			UPDATE segments SET
				encrypted_key_nonce = P.encrypted_key_nonce,
				encrypted_key = P.encrypted_key
			FROM (SELECT unnest($2::INT8[]), unnest($3::BYTEA[]), unnest($4::BYTEA[])) as P(position, encrypted_key_nonce, encrypted_key)
			WHERE
				stream_id = $1 AND
				segments.position = P.position
		`, opts.StreamID, pgutil.Int8Array(newSegmentKeys.Positions), pgutil.ByteaArray(newSegmentKeys.EncryptedKeyNonces), pgutil.ByteaArray(newSegmentKeys.EncryptedKeys))
		if err != nil {
			return Error.Wrap(err)
		}

		affected, err := updateResult.RowsAffected()
		if err != nil {
			return Error.New("failed to get rows affected: %w", err)
		}

		if affected != int64(len(newSegmentKeys.Positions)) {
			return Error.New("segment is missing")
		}
		return nil
	})
	if err != nil {
		return err
	}

	mon.Meter("finish_move_object").Mark(1)

	return nil
}