import type { SyncMove, HistoryEntry } from './types';

/** Coordinate notation, e.g. "e2e4" or "e7e8q". */
export function toCoordinate(move: SyncMove): string {
  return `${move.from}${move.to}${move.promotion ?? ''}`;
}

export interface SavedGame {
  variant: 'duplicate-chess';
  version: 1;
  moves: HistoryEntry[];
}

export function serialize(history: HistoryEntry[]): string {
  const data: SavedGame = { variant: 'duplicate-chess', version: 1, moves: history };
  return JSON.stringify(data, null, 2);
}

export function deserialize(json: string): HistoryEntry[] {
  const data = JSON.parse(json) as Partial<SavedGame>;
  if (data.variant !== 'duplicate-chess' || !Array.isArray(data.moves)) {
    throw new Error('Not a duplicate-chess save file');
  }
  if (data.version !== 1) {
    throw new Error('Unsupported save version');
  }
  return data.moves;
}