feat: use postgres

mail/internal/adapters/postgres/mailstore/helpers.go

@@ -0,0 +1,64 @@
+package mailstore
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgconn"
+)
+
+// pgUniqueViolationCode identifies the SQLSTATE returned by PostgreSQL when
+// a UNIQUE constraint is violated by INSERT or UPDATE.
+const pgUniqueViolationCode = "23505"
+
+// isUniqueViolation reports whether err is a PostgreSQL unique-violation,
+// regardless of constraint name.
+func isUniqueViolation(err error) bool {
+	var pgErr *pgconn.PgError
+	if !errors.As(err, &pgErr) {
+		return false
+	}
+	return pgErr.Code == pgUniqueViolationCode
+}
+
+// nullableTime returns t.UTC() when non-nil, otherwise nil for NULL columns.
+func nullableTime(t *time.Time) any {
+	if t == nil {
+		return nil
+	}
+	return t.UTC()
+}
+
+// isNoRows reports whether err is sql.ErrNoRows.
+func isNoRows(err error) bool {
+	return errors.Is(err, sql.ErrNoRows)
+}
+
+// timeFromNullable copies an optional *time.Time read from Postgres into a
+// new pointer normalised to UTC.
+func timeFromNullable(value *time.Time) *time.Time {
+	if value == nil {
+		return nil
+	}
+	utc := value.UTC()
+	return &utc
+}
+
+// withTimeout derives a child context bounded by timeout and prefixes context
+// errors with operation. Callers must always invoke the returned cancel.
+func withTimeout(ctx context.Context, operation string, timeout time.Duration) (context.Context, context.CancelFunc, error) {
+	if ctx == nil {
+		return nil, nil, fmt.Errorf("%s: nil context", operation)
+	}
+	if err := ctx.Err(); err != nil {
+		return nil, nil, fmt.Errorf("%s: %w", operation, err)
+	}
+	if timeout <= 0 {
+		return nil, nil, fmt.Errorf("%s: operation timeout must be positive", operation)
+	}
+	bounded, cancel := context.WithTimeout(ctx, timeout)
+	return bounded, cancel, nil
+}