add user service

internal/user/repository/postgres/repository.go

@@ -0,0 +1,38 @@
+package postgres
+
+import (
+	"context"
+
+	"datarush/pkg/api/user"
+	"github.com/jmoiron/sqlx"
+)
+
+type UserRepository struct {
+	db *sqlx.DB
+}
+
+func NewUserRepository(db *sqlx.DB) *UserRepository {
+	return &UserRepository{db: db}
+}
+
+func (r *UserRepository) GetProfile(ctx context.Context, userID string) (*user.User, error) {
+	var u user.User
+	err := r.db.GetContext(ctx, &u, "SELECT id, username, email, full_name, avatar_url FROM users WHERE id = $1", userID)
+	return &u, err
+}
+
+func (r *UserRepository) RegisterForCompetition(ctx context.Context, userID, competitionID string) error {
+	_, err := r.db.ExecContext(ctx, "INSERT INTO user_competitions (user_id, competition_id) VALUES ($1, $2)", userID, competitionID)
+	return err
+}
+
+func (r *UserRepository) UnregisterFromCompetition(ctx context.Context, userID, competitionID string) error {
+	_, err := r.db.ExecContext(ctx, "DELETE FROM user_competitions WHERE user_id = $1 AND competition_id = $2", userID, competitionID)
+	return err
+}
+
+func (r *UserRepository) ListUserCompetitions(ctx context.Context, userID string) ([]string, error) {
+	var competitionIDs []string
+	err := r.db.SelectContext(ctx, &competitionIDs, "SELECT competition_id FROM user_competitions WHERE user_id = $1", userID)
+	return competitionIDs, err
+}