recipes2/internal/storage/postgresql/postgresql.go

package postgresql

import (
	"context"
	"fmt"
	"recipes/internal/domain/models"

	"github.com/jackc/pgx/v5/pgxpool"
)

type Storage struct {
	db *pgxpool.Pool
}

func New(user, password, addr, dbname string) (*Storage, error) {
	const op = "storage.postgresql.New"

	pool, err := pgxpool.New(context.Background(), fmt.Sprintf("postgres://%s:%s@%s/%s?sslmode=disable", user, password, addr, dbname))
	if err != nil {
		return nil, fmt.Errorf("%s: %w", op, err)
	}

	return &Storage{db: pool}, nil
}

// AddRecipe adds recipe to db.
func (s *Storage) AddRecipe(ctx context.Context, recipe models.Recipe) error {
	const op = "storage.postgresql.AddRecipe"

	// open transaction
	tx, err := s.db.Begin(ctx)
	if err != nil {
		return fmt.Errorf("%s: %w", op, err)
	}

	// refactor error handling
	// rollback transaction on return
	defer tx.Rollback(ctx)

	var id uint
	// insert recipe
	err = s.db.QueryRow(
		ctx,
		"insert into recipe (title, description, image, cooking_time, servings, cal) values ($1, $2, $3, $4, $5, $6) returning id",
		recipe.Title, recipe.Description, recipe.Image, recipe.CookingTime, recipe.ServingsNum, recipe.Calories,
	).Scan(&id)

	// insert ingredients
	for _, r := range recipe.Ingredients {
		var ing_id uint
		err = s.db.QueryRow(
			ctx,
			"insert into recipe_ingredients_group (recipe_id, title) values ($1, $2) returning id",
			id, r.Title,
		).Scan(&ing_id)
		if err != nil {
			return fmt.Errorf("%s: %w", op, err)
		}

		for _, i := range r.Ingredients {
			_, err = s.db.Exec(
				ctx,
				"insert into recipe_ingredients (recipe_ingredients_group_id, ingredient) values ($1, $2)",
				ing_id, i,
			)
			if err != nil {
				return fmt.Errorf("%s: %w", op, err)
			}
		}
	}

	// insert steps
	for i, step := range recipe.Recipe_steps {
		s.db.Exec(
			ctx,
			"insert into recipe_steps (recipe_id, step_num, step_text) values ($1, $2, $3)",
			id, i, step,
		)
	}

	// insert advices
	for _, a := range recipe.Advices {
		s.db.Exec(
			ctx,
			"insert into recipe_advices (recipe_id, advice) values ($1, $2)",
			id, a,
		)
	}

	// insert categories
	for _, c := range recipe.Categories {
		s.db.Exec(
			ctx,
			"insert into recipe_categories (recipe_id, category) values ($1, $2)",
			id, c,
		)
	}

	// commit transaction
	if err := tx.Commit(ctx); err != nil {
		return fmt.Errorf("%s: %w", op, err)
	}

	return nil
}

// RecipeExists returns true if recipe is exists.
func (s *Storage) RecipeExists(ctx context.Context, title string) (bool, error) {
	const op = "storage.postgresql.RecipeExists"

	var exists bool

	err := s.db.QueryRow(
		ctx,
		"select exists(select id from recipe where title = $1)",
		title,
	).Scan(&exists)
	if err != nil {
		return false, fmt.Errorf("%s: %w", op, err)
	}

	return exists, nil
}

// GetRecipes gets recipes by offset and limit.
func (s *Storage) GetRecipes(ctx context.Context, offset, limit int) ([]models.Recipe, error) {
	const op = "storage.postgresql.GetRecipes"

	rows, err := s.db.Query(
		ctx,
		"select id, title, image, cooking_time, cal from recipe order by id desc offset $1 limit $2",
		offset, limit,
	)
	if err != nil {
		return nil, fmt.Errorf("%s: %w", op, err)
	}

	defer rows.Close()

	var recipes []models.Recipe = make([]models.Recipe, 0, limit)

	for rows.Next() {
		var r models.Recipe

		err = rows.Scan(
			&r.ID,
			&r.Title,
			&r.Image,
			&r.CookingTime,
			&r.Calories,
		)
		if err != nil {
			return nil, fmt.Errorf("%s: %w", op, err)
		}

		recipes = append(recipes, r)
	}

	return recipes, nil
}

// GetRecipe gets recipe by id.
func (s *Storage) GetRecipe(ctx context.Context, r_id uint) (models.Recipe, error) {
	const op = "storage.postgresql.GetRecipe"

	var recipe models.Recipe

	err := s.db.QueryRow(
		ctx,
		"select title, description, image, cooking_time, servings, cal from recipe where id = $1",
		r_id,
	).Scan(&recipe)

	if err != nil {
		return models.Recipe{}, fmt.Errorf("%s: %w", op, err)
	}

	err = s.AddRecipeInformation(ctx, &recipe)
	if err != nil {
		return models.Recipe{}, fmt.Errorf("%s: %w", op, err)
	}

	return recipe, nil
}

// TODO
// handling special errors
// AddRecipeInformation

// AddRecipeInformation adds to recipe struct info about ingredients, steps, advices, categories.
func (s *Storage) AddRecipeInformation(ctx context.Context, r *models.Recipe) error {
	const op = "storage.postgresql.AddRecipeInformation"

	// select ingredients

	// select steps

	// select advices

	// select categories

	return nil
}

// GetRecipesByCategory gets recipes by category, offset and limit.
func (s *Storage) GetRecipesByCategory(ctx context.Context, offset, limit int, category string) ([]models.Recipe, error) {
	const op = "storage.postgresql.GetRecipesByCategory"

	rows, err := s.db.Query(
		ctx,
		"select r.id, r.title, r.image, r.cooking_time, r.cal from recipe r inner join recipe_categories c on r.id = c.recipe_id where c.category = $1 order by r.id limit $2 offset $3",
		category, limit, offset,
	)
	if err != nil {
		return nil, fmt.Errorf("%s: %w", op, err)
	}

	defer rows.Close()

	var recipes []models.Recipe = make([]models.Recipe, 0, limit)

	for rows.Next() {
		var r models.Recipe

		err = rows.Scan(
			&r.ID,
			&r.Title,
			&r.Image,
			&r.CookingTime,
			&r.Calories,
		)
		if err != nil {
			return nil, fmt.Errorf("%s: %w", op, err)
		}

		s.AddRecipeInformation(ctx, &r)

		recipes = append(recipes, r)
	}

	return recipes, nil
}