databaseUserStore.go

package rbac

import (
	"context"
	"fmt"

	"code.fbi.h-da.de/danet/gosdn/controller/customerrs"
	"code.fbi.h-da.de/danet/gosdn/controller/interfaces/rbac"
	"code.fbi.h-da.de/danet/gosdn/controller/store"
	"github.com/google/uuid"
	log "github.com/sirupsen/logrus"
	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"go.mongodb.org/mongo-driver/mongo/writeconcern"
)

const storeName = "user.json"

// DatabaseUserStore is used to store users in database.
type DatabaseUserStore struct {
	collection *mongo.Collection
}

func NewDatabaseUserStore(db *mongo.Database) *DatabaseUserStore {
	collection := db.Collection(storeName)

	return &DatabaseUserStore{
		collection: collection,
	}
}

// Add adds an User.
func (s *DatabaseUserStore) Add(ctx context.Context, userToAdd rbac.User) (err error) {
	_, err = s.collection.InsertOne(ctx, userToAdd)
	if err != nil {
		if mongo.IsDuplicateKeyError(err) {
			return nil
		}

		return customerrs.CouldNotCreateError{Identifier: userToAdd.ID(), Type: userToAdd, Err: err}
	}

	return nil
}

// Delete deletes an User.
func (s *DatabaseUserStore) Delete(ctx context.Context, userToDelete rbac.User) (err error) {
	_, err = s.collection.DeleteOne(ctx, bson.D{primitive.E{Key: "_id", Value: userToDelete.ID().String()}})
	if err != nil {
		return customerrs.CouldNotDeleteError{Identifier: userToDelete.ID(), Type: userToDelete, Err: err}
	}

	return nil
}

// Get takes a User's UUID or name and returns the User. If the requested
// User does not exist an error is returned.
func (s *DatabaseUserStore) Get(ctx context.Context, query store.Query) (rbac.LoadedUser, error) {
	var loadedUser rbac.LoadedUser

	if query.ID != uuid.Nil {
		loadedUser, err := s.getByID(ctx, query.ID)
		if err != nil {
			return loadedUser, err
		}

		return loadedUser, nil
	}

	loadedUser, err := s.getByName(ctx, query.Name)
	if err != nil {
		return loadedUser, err
	}

	return loadedUser, nil
}

func (s *DatabaseUserStore) getByID(ctx context.Context, idOfUser uuid.UUID) (loadedUser rbac.LoadedUser, err error) {
	result := s.collection.FindOne(ctx, bson.D{primitive.E{Key: "_id", Value: idOfUser.String()}})
	if result == nil {
		return loadedUser, customerrs.CouldNotFindError{ID: idOfUser}
	}

	err = result.Decode(&loadedUser)
	if err != nil {
		log.Printf("Failed marshalling %v", err)
		return loadedUser, customerrs.CouldNotMarshallError{Identifier: idOfUser, Type: loadedUser, Err: err}
	}

	return loadedUser, nil
}

func (s *DatabaseUserStore) getByName(ctx context.Context, nameOfUser string) (loadedUser rbac.LoadedUser, err error) {
	result := s.collection.FindOne(ctx, bson.D{primitive.E{Key: "username", Value: nameOfUser}})
	if result == nil {
		return loadedUser, customerrs.CouldNotFindError{Name: nameOfUser}
	}

	err = result.Decode(&loadedUser)
	if err != nil {
		log.Printf("Failed marshalling %v", err)
		return loadedUser, customerrs.CouldNotMarshallError{Identifier: nameOfUser, Type: loadedUser, Err: err}
	}

	return loadedUser, nil
}

// GetAll returns all Users.
func (s *DatabaseUserStore) GetAll(ctx context.Context) (loadedUsers []rbac.LoadedUser, err error) {
	cursor, err := s.collection.Find(ctx, bson.D{})
	if err != nil {
		return nil, err
	}
	defer func() {
		if ferr := cursor.Close(ctx); ferr != nil {
			fErrString := ferr.Error()
			err = fmt.Errorf("InternalError=%w DeferError=%+s", err, fErrString)
		}
	}()

	err = cursor.All(ctx, &loadedUsers)
	if err != nil {
		log.Printf("Failed marshalling %v", err)

		return nil, customerrs.CouldNotMarshallError{Type: loadedUsers, Err: err}
	}
	return loadedUsers, nil
}

// Update updates the User.
func (s *DatabaseUserStore) Update(ctx context.Context, userToUpdate rbac.User) (err error) {
	var updatedLoadedUser rbac.LoadedUser

	wc := writeconcern.Majority()
	txnOptions := options.Transaction().SetWriteConcern(wc)
	// Starts a session on the client
	session, err := s.collection.Database().Client().StartSession()
	if err != nil {
		return err
	}
	// Defers ending the session after the transaction is committed or ended
	defer session.EndSession(ctx)

	// 3.2.1 If yes -> Update entity in callback
	callback := func(sessCtx mongo.SessionContext) (interface{}, error) {
		// 2. Fetch exisiting Entity
		existingUser, err := s.getByID(ctx, userToUpdate.ID())
		if err != nil {
			return nil, err
		}

		// 3. Check if Entity.Metadata.ResourceVersion == UpdatedEntity.Metadata.ResourceVersion
		if userToUpdate.GetMetadata().ResourceVersion != existingUser.Metadata.ResourceVersion {
			// 3.1.1 End transaction
			// 3.1.2 If no -> return error

			return nil, fmt.Errorf(
				"resource version %d of provided user %s is older or newer than %d in the store",
				userToUpdate.GetMetadata().ResourceVersion,
				userToUpdate.ID().String(), existingUser.Metadata.ResourceVersion,
			)
		}

		// Important: You must pass sessCtx as the Context parameter to the operations for them to be executed in the
		// transaction.

		u, _ := userToUpdate.(*User)
		u.Metadata.ResourceVersion = u.Metadata.ResourceVersion + 1

		update := bson.D{primitive.E{Key: "$set", Value: u}}

		upsert := false
		after := options.After
		opt := options.FindOneAndUpdateOptions{
			Upsert:         &upsert,
			ReturnDocument: &after,
		}

		err = s.collection.FindOneAndUpdate(
			ctx, bson.M{"_id": userToUpdate.ID().String()}, update, &opt).
			Decode(&updatedLoadedUser)
		if err != nil {
			log.Printf("Could not update User: %v", err)

			return nil, customerrs.CouldNotUpdateError{Identifier: userToUpdate.ID(), Type: userToUpdate, Err: err}
		}

		// 3.2.2 End transaction
		return "", nil
	}

	_, err = session.WithTransaction(ctx, callback, txnOptions)
	if err != nil {
		return err
	}

	return nil
}