package postgres

import (
	"errors"

	"github.com/jackc/pgerrcode"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgconn"

	"code.nochebuena.dev/einherjar/core/xerrors"
)

// HandleError maps pgx and PostgreSQL errors to typed [xerrors] values.
// Returns nil when err is nil. Also available as [Provider.HandleError].
//
// Mapped codes:
//   - UniqueViolation     → ErrAlreadyExists
//   - ForeignKeyViolation → ErrInvalidInput
//   - CheckViolation      → ErrInvalidInput
//   - pgx.ErrNoRows       → ErrNotFound
//   - all others          → ErrInternal
func HandleError(err error) error {
	if err == nil {
		return nil
	}
	var pgErr *pgconn.PgError
	if errors.As(err, &pgErr) {
		switch pgErr.Code {
		case pgerrcode.UniqueViolation:
			return xerrors.New(xerrors.ErrAlreadyExists, "record already exists").
				WithContext("constraint", pgErr.ConstraintName).WithError(err)
		case pgerrcode.ForeignKeyViolation:
			return xerrors.New(xerrors.ErrInvalidInput, "data integrity violation").
				WithContext("table", pgErr.TableName).WithError(err)
		case pgerrcode.CheckViolation:
			return xerrors.New(xerrors.ErrInvalidInput, "data constraint violation").
				WithContext("table", pgErr.TableName).
				WithContext("column", pgErr.ColumnName).WithError(err)
		}
	}
	if errors.Is(err, pgx.ErrNoRows) {
		return xerrors.New(xerrors.ErrNotFound, "record not found").WithError(err)
	}
	return xerrors.New(xerrors.ErrInternal, "unexpected database error").WithError(err)
}