package db

import (
	"database/sql"
)

// PersistExcalidrawIDs writes the assignments returned by the exporter
// back onto the corresponding rows. Idempotent: only updates rows whose
// excalidraw_id is currently NULL (the first export "owns" the id; later
// exports reuse it so mxdrw's collab cursors / undo history survive).
//
// Caller passes one map per kind; keys are the in-project row ids,
// values are the 21-char Excalidraw element ids the exporter minted.
func (s *Store) PersistExcalidrawIDs(projectID int64,
	frames, devices, ports, ios, cables, clamps map[int64]string,
) error {
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	if err := updateExIDs(tx, "frames", projectID, frames); err != nil {
		return err
	}
	if err := updateExIDs(tx, "devices", projectID, devices); err != nil {
		return err
	}
	if err := updateExIDs(tx, "ports", projectID, ports); err != nil {
		return err
	}
	if err := updateExIDs(tx, "io_markers", projectID, ios); err != nil {
		return err
	}
	if err := updateExIDs(tx, "cables", projectID, cables); err != nil {
		return err
	}
	if err := updateExIDs(tx, "clamps", projectID, clamps); err != nil {
		return err
	}
	return tx.Commit()
}

func updateExIDs(tx *sql.Tx, table string, projectID int64, m map[int64]string) error {
	if len(m) == 0 {
		return nil
	}
	stmt, err := tx.Prepare(
		`UPDATE ` + table + `
		 SET excalidraw_id = ?
		 WHERE id = ? AND project_id = ? AND excalidraw_id IS NULL`,
	)
	if err != nil {
		return err
	}
	defer stmt.Close()
	for id, exID := range m {
		if _, err := stmt.Exec(exID, id, projectID); err != nil {
			return err
		}
	}
	return nil
}