feat(story-1.3): add user registration API with Argon2 password hashing

internal/repository/user.go

@@ -0,0 +1,123 @@
+// Package repository implements data access for domain entities.
+package repository
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/google/uuid"
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+	"github.com/michael/flowreader/internal/domain"
+)
+
+// UserRepository implements domain.UserRepository using PostgreSQL.
+type UserRepository struct {
+	pool *pgxpool.Pool
+}
+
+// NewUserRepository creates a new user repository.
+func NewUserRepository(pool *pgxpool.Pool) *UserRepository {
+	return &UserRepository{pool: pool}
+}
+
+// Create inserts a new user into the database.
+func (r *UserRepository) Create(user *domain.User) error {
+	ctx := context.Background()
+
+	query := `
+		INSERT INTO users (id, email, password_hash, is_admin, created_at, updated_at)
+		VALUES ($1, $2, $3, $4, $5, $6)
+	`
+
+	_, err := r.pool.Exec(ctx, query,
+		user.ID,
+		user.Email,
+		user.PasswordHash,
+		user.IsAdmin,
+		user.CreatedAt,
+		user.UpdatedAt,
+	)
+
+	if err != nil {
+		return fmt.Errorf("creating user: %w", err)
+	}
+
+	return nil
+}
+
+// GetByEmail retrieves a user by their email address.
+func (r *UserRepository) GetByEmail(email string) (*domain.User, error) {
+	ctx := context.Background()
+
+	query := `
+		SELECT id, email, password_hash, is_admin, created_at, updated_at
+		FROM users
+		WHERE email = $1
+	`
+
+	var user domain.User
+	err := r.pool.QueryRow(ctx, query, email).Scan(
+		&user.ID,
+		&user.Email,
+		&user.PasswordHash,
+		&user.IsAdmin,
+		&user.CreatedAt,
+		&user.UpdatedAt,
+	)
+
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, nil // User not found
+		}
+		return nil, fmt.Errorf("getting user by email: %w", err)
+	}
+
+	return &user, nil
+}
+
+// GetByID retrieves a user by their ID.
+func (r *UserRepository) GetByID(id uuid.UUID) (*domain.User, error) {
+	ctx := context.Background()
+
+	query := `
+		SELECT id, email, password_hash, is_admin, created_at, updated_at
+		FROM users
+		WHERE id = $1
+	`
+
+	var user domain.User
+	err := r.pool.QueryRow(ctx, query, id).Scan(
+		&user.ID,
+		&user.Email,
+		&user.PasswordHash,
+		&user.IsAdmin,
+		&user.CreatedAt,
+		&user.UpdatedAt,
+	)
+
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, nil // User not found
+		}
+		return nil, fmt.Errorf("getting user by ID: %w", err)
+	}
+
+	return &user, nil
+}
+
+// Exists checks if a user with the given email exists.
+func (r *UserRepository) Exists(email string) (bool, error) {
+	ctx := context.Background()
+
+	query := `SELECT EXISTS(SELECT 1 FROM users WHERE email = $1)`
+
+	var exists bool
+	err := r.pool.QueryRow(ctx, query, email).Scan(&exists)
+	if err != nil {
+		return false, fmt.Errorf("checking user exists: %w", err)
+	}
+
+	return exists, nil
+}