tsk-18: Create service user (#22)

Closes #18

Reviewed-on: phoenix/textsender-auth#22
Co-authored-by: phoenix <kundeng00@pm.me>
Co-committed-by: phoenix <kundeng00@pm.me>

internal/store/service.go

@@ -0,0 +1,50 @@
+package store
+
+import (
+	"context"
+	"fmt"
+
+	"git.kundeng.us/phoenix/textsender-models/pkg/user"
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+type ServiceStore interface {
+	CheckWithUsername(ctx context.Context, username string) (bool, error)
+	Create(ctx context.Context, serviceUser *user.ServiceUser) error
+}
+
+type PGServiceStore struct {
+	db *pgxpool.Pool
+}
+
+func NewServiceStore(db *pgxpool.Pool) *PGServiceStore {
+	return &PGServiceStore{db: db}
+}
+
+func (s *PGServiceStore) CheckWithUsername(ctx context.Context, username string) (bool, error) {
+	var exists bool
+	query := `SELECT EXISTS(SELECT 1 FROM service_users WHERE Username = $1)`
+
+	if err := s.db.QueryRow(ctx, query, username).Scan(&exists); err != nil {
+		if err == pgx.ErrNoRows {
+			return exists, nil
+		} else {
+			return exists, fmt.Errorf("Error querying row: %v", err)
+		}
+	} else {
+		return exists, nil
+	}
+}
+
+func (s *PGServiceStore) Create(ctx context.Context, serviceUser *user.ServiceUser) error {
+	query := `
+		INSERT INTO service_users (username, passphrase)
+		VALUES ($1, $2)
+		RETURNING id, created
+	`
+
+	return s.db.QueryRow(ctx, query, serviceUser.Username, serviceUser.Passphrase).Scan(
+		&serviceUser.Id, &serviceUser.Created,
+	)
+}