import type { PlayRunLedgerEventSource } from './run-ledger';

const PLAY_RUN_LEDGER_EVENT_SOURCES: readonly PlayRunLedgerEventSource[] = [
  'worker',
  'convex',
  'coordinator',
  'system',
];

/**
 * Run terminal source state machine.
 *
 * Coordinator terminals are transport heals from a live cache and stay
 * provisional. Producer terminals are authoritative and must win over heals.
 */
export function normalizePlayRunLedgerTerminalSource(
  value: unknown,
): PlayRunLedgerEventSource | null {
  return PLAY_RUN_LEDGER_EVENT_SOURCES.includes(
    value as PlayRunLedgerEventSource,
  )
    ? (value as PlayRunLedgerEventSource)
    : null;
}

export function isAuthoritativePlayRunTerminalSource(
  value: unknown,
): value is Exclude<PlayRunLedgerEventSource, 'coordinator'> {
  const source = normalizePlayRunLedgerTerminalSource(value);
  return source !== null && source !== 'coordinator';
}

export function nextPlayRunLedgerTerminalSource(input: {
  currentSource: unknown;
  eventSource: PlayRunLedgerEventSource;
}): PlayRunLedgerEventSource {
  if (input.eventSource !== 'coordinator') {
    return input.eventSource;
  }
  const current = normalizePlayRunLedgerTerminalSource(input.currentSource);
  return isAuthoritativePlayRunTerminalSource(current)
    ? current
    : 'coordinator';
}