storage.go

package storage

import (
	"context"
	"strings"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"

	"code.vereign.com/gaiax/tsa/golib/errors"
	"code.vereign.com/gaiax/tsa/task/internal/service/task"
)

const (
	taskDB        = "task"
	taskTemplates = "taskTemplates"
	taskQueue     = "tasks"
	tasksHistory  = "tasksHistory"
)

type Storage struct {
	templates    *mongo.Collection
	tasks        *mongo.Collection
	tasksHistory *mongo.Collection
}

func New(db *mongo.Client) *Storage {
	return &Storage{
		templates:    db.Database(taskDB).Collection(taskTemplates),
		tasks:        db.Database(taskDB).Collection(taskQueue),
		tasksHistory: db.Database(taskDB).Collection(tasksHistory),
	}
}

func (s *Storage) TaskTemplate(ctx context.Context, taskName string) (*task.Task, error) {
	result := s.templates.FindOne(ctx, bson.M{
		"name": taskName,
	})

	if result.Err() != nil {
		if strings.Contains(result.Err().Error(), "no documents in result") {
			return nil, errors.New(errors.NotFound, "task template not found")
		}
		return nil, result.Err()
	}

	var task task.Task
	if err := result.Decode(&task); err != nil {
		return nil, err
	}

	return &task, nil
}

func (s *Storage) Add(ctx context.Context, task *task.Task) error {
	_, err := s.tasks.InsertOne(ctx, task)
	return err
}

// Poll retrieves one task from the tasks collection with the
// older ones being retrieved first (FIFO). It updates the state
// of the task to "pending", so that consequent calls to Poll would
// not retrieve the same task.
func (s *Storage) Poll(ctx context.Context) (*task.Task, error) {
	opts := options.
		FindOneAndUpdate().
		SetSort(bson.M{"createdAt": 1}).
		SetReturnDocument(options.After)

	filter := bson.M{"state": task.Created}
	update := bson.M{"$set": bson.M{"state": task.Pending}}
	result := s.tasks.FindOneAndUpdate(
		ctx,
		filter,
		update,
		opts,
	)

	if result.Err() != nil {
		if strings.Contains(result.Err().Error(), "no documents in result") {
			return nil, errors.New(errors.NotFound, "task not found")
		}
		return nil, result.Err()
	}

	var task task.Task
	if err := result.Decode(&task); err != nil {
		return nil, err
	}

	return &task, nil
}

// Ack removes a task from the `tasks` collection.
func (s *Storage) Ack(ctx context.Context, task *task.Task) error {
	_, err := s.tasks.DeleteOne(ctx, bson.M{"id": task.ID})
	return err
}

// Unack changes the "pending" state of a task to "created", so that
// it can be retrieved for processing again.
func (s *Storage) Unack(ctx context.Context, t *task.Task) error {
	filter := bson.M{"id": t.ID}
	update := bson.M{"$set": bson.M{"state": task.Created}}
	_, err := s.tasks.UpdateOne(ctx, filter, update)
	return err
}