export type MatchStatusKind = 'live' | 'upcoming' | 'finished' | 'postponed' | 'unknown';

type MatchStatusInput = {
  kickoff_utc?: string | null;
  match_time_utc?: string | null;
  match_time?: string | null;
  status?: string | null;
  home_score?: number | null;
  away_score?: number | null;
};

const LIVE_WINDOW_MS = 150 * 60 * 1000;
const RESULT_BACKFILL_GRACE_MS = 240 * 60 * 1000;

function kickoffTimestamp(match: MatchStatusInput): number | null {
  const raw = match.kickoff_utc || match.match_time_utc || match.match_time;
  if (!raw) {
    return null;
  }
  const timestamp = Date.parse(raw);
  return Number.isNaN(timestamp) ? null : timestamp;
}

function normalizedStatus(match: MatchStatusInput): string {
  return (match.status || '').trim().toLowerCase().replace(/_/g, '-');
}

function hasScore(match: MatchStatusInput): boolean {
  return typeof match.home_score === 'number' && typeof match.away_score === 'number';
}

export function matchStatusKind(match: MatchStatusInput, now: Date = new Date()): MatchStatusKind {
  const status = normalizedStatus(match);
  const kickoff = kickoffTimestamp(match);
  const nowMs = now.getTime();

  if (/postponed|delayed|suspended|cancelled|canceled|abandoned/.test(status)) {
    return 'postponed';
  }

  if (/finished|final|full-time|fulltime|ft|completed|closed/.test(status)) {
    return 'finished';
  }

  if (/live|in-play|inplay|playing|ongoing|1st|2nd|first-half|second-half|halftime|half-time/.test(status)) {
    return 'live';
  }

  if (kickoff === null) {
    return hasScore(match) ? 'finished' : 'unknown';
  }

  if (kickoff > nowMs) {
    return 'upcoming';
  }

  const elapsed = nowMs - kickoff;
  if (elapsed <= LIVE_WINDOW_MS) {
    return 'live';
  }

  if (hasScore(match) || elapsed > RESULT_BACKFILL_GRACE_MS) {
    return hasScore(match) ? 'finished' : 'unknown';
  }

  return 'unknown';
}

export function matchStatusLabel(match: MatchStatusInput, now: Date = new Date()): string {
  const kind = matchStatusKind(match, now);
  const score = hasScore(match) ? `${match.home_score}-${match.away_score}` : null;

  if (kind === 'live') {
    return score ? `進行中 ${score}` : '進行中';
  }
  if (kind === 'finished') {
    return score ? `已完賽 ${score}` : '已完賽';
  }
  if (kind === 'postponed') {
    return '延期/中止';
  }
  if (kind === 'upcoming') {
    return '未開賽';
  }
  return '結果待回填';
}

export function sortMatchesForProfessionalDisplay<T extends MatchStatusInput>(matches: T[], now: Date = new Date()): T[] {
  const rank: Record<MatchStatusKind, number> = {
    live: 0,
    upcoming: 1,
    unknown: 2,
    postponed: 3,
    finished: 4,
  };

  return [...matches].sort((a, b) => {
    const kindA = matchStatusKind(a, now);
    const kindB = matchStatusKind(b, now);
    if (kindA !== kindB) {
      return rank[kindA] - rank[kindB];
    }

    const timeA = kickoffTimestamp(a) ?? 0;
    const timeB = kickoffTimestamp(b) ?? 0;
    if (kindA === 'finished') {
      return timeB - timeA;
    }
    return timeA - timeB;
  });
}