export type EventState = 'running' | 'countdown' | 'stopped' | 'unconfigured';

export interface EventStatePayload {
  state: EventState;
  serverNowUtc: string;
  eventStartUtc: string | null;
  eventEndUtc: string | null;
  secondsToStart: number | null;
  secondsToEnd: number | null;
}

export interface EventSourceLike {
  addEventListener(
    type: 'open' | 'message' | 'error' | 'unauthorized',
    listener: (ev: MessageEvent | Event) => void,
  ): void;
  close(): void;
}

export function formatDdHhMm(totalSeconds: number): string {
  if (!Number.isFinite(totalSeconds) || totalSeconds < 0) return '00:00:00';
  const s = Math.floor(totalSeconds);
  const days = Math.floor(s / 86400);
  const hours = Math.floor((s % 86400) / 3600);
  const minutes = Math.floor((s % 3600) / 60);
  const pad = (n: number) => n.toString().padStart(2, '0');
  return `${pad(days)}:${pad(hours)}:${pad(minutes)}`;
}

export function deriveCountdownText(
  state: EventState,
  secondsToStart: number | null,
  secondsToEnd: number | null,
): string {
  if (state === 'unconfigured') return '';
  if (state === 'stopped') return 'Event ended';
  if (state === 'countdown') {
    return secondsToStart == null ? '00:00:00' : formatDdHhMm(secondsToStart);
  }
  return secondsToEnd == null ? '00:00:00' : formatDdHhMm(secondsToEnd);
}

export const LED_COLOR_BY_STATE: Readonly<Record<EventState, string>> = {
  running: 'var(--color-success)',
  countdown: 'var(--color-warning)',
  stopped: 'var(--color-danger)',
  unconfigured: 'var(--color-secondary)',
};

export function ledBackgroundColor(state: EventState): string {
  return LED_COLOR_BY_STATE[state];
}