import 'server-only';
import type {
  PointAccount,
  PointHistoryEntry,
} from '@/lib/domain/point-account';
import type { PointAccountQuery } from '@/lib/domain/point-account-query';

// TODO(백엔드): 누적포인트 API가 아직 없다. 아래 mock 생성기를 지우고 다른 Repository처럼
// backendFetch + getSessionAccessToken으로 교체한다.
// 이슈: 구분(사이트)은 기획대로 FOX PAY App. 하나뿐이다 — 확장은 백엔드가 사이트를 실어 준 뒤다.

const TOTAL_ACCOUNTS = 3290;
const SITE_NAME = 'FOX PAY App.';
const SCHOOL_NAMES = [
  '폭스고등학교',
  '여우고등학교',
  '한빛고등학교',
  '새롬고등학교',
];
const EVENT_TITLES = ['EVENT-1', 'EVENT-2', 'EVENT-3'];
const BASE_DATE = Date.UTC(2026, 1, 5);
const DAY_MS = 24 * 60 * 60 * 1000;

function dateAt(offsetDays: number): string {
  return new Date(BASE_DATE - offsetDays * DAY_MS).toISOString().slice(0, 10);
}

function timestampAt(index: number): string {
  const hour = 9 + (index % 9);
  const minute = (index * 7) % 60;
  const pad = (value: number) => String(value).padStart(2, '0');
  return `${dateAt(index % 400)} ${pad(hour)}:${pad(minute)}`;
}

/** 인덱스로만 만든다 — 난수를 쓰면 새로고침마다 목록이 흔들린다. */
function buildAccount(index: number): PointAccount {
  const serial = TOTAL_ACCOUNTS - index;
  const totalPoint = 120 + ((index * 37) % 880);
  const deductedPoint = (index * 13) % 60;
  const usedPoint = (index * 29) % 300;

  return {
    id: `PA-${String(serial).padStart(5, '0')}`,
    memberNo: `NO_${String(10000 + serial)}`,
    loginId: `user_${String(serial).padStart(4, '0')}`,
    studentName: `학생${serial}`,
    schoolName: SCHOOL_NAMES[index % SCHOOL_NAMES.length],
    grade: (index % 3) + 1,
    classNo: (index % 10) + 1,
    studentNo: (index % 30) + 1,
    totalPoint,
    deductedPoint,
    usedPoint,
    currentPoint: totalPoint - deductedPoint - usedPoint,
    updatedAt: timestampAt(index),
    siteName: SITE_NAME,
  };
}

const ACCOUNTS: PointAccount[] = Array.from(
  { length: TOTAL_ACCOUNTS },
  (_, index) => buildAccount(index)
);

function matchesQuery(account: PointAccount, query: PointAccountQuery): boolean {
  if (
    query.schoolName &&
    !account.schoolName.toLowerCase().includes(query.schoolName.toLowerCase())
  ) {
    return false;
  }
  if (query.grade !== null && account.grade !== query.grade) {
    return false;
  }
  if (query.classNo !== null && account.classNo !== query.classNo) {
    return false;
  }
  if (query.studentNo !== null && account.studentNo !== query.studentNo) {
    return false;
  }
  if (query.keyword) {
    const needle = query.keyword.toLowerCase();
    const haystack =
      query.searchField === 'loginId' ? account.loginId : account.studentName;
    if (!haystack.toLowerCase().includes(needle)) {
      return false;
    }
  }
  return true;
}

/** 기획 PTS10200001 ② — 최근 수정일시로 정렬. */
function byUpdatedAtDesc(a: PointAccount, b: PointAccount): number {
  return b.updatedAt.localeCompare(a.updatedAt);
}

export async function fetchPointAccounts(
  query: PointAccountQuery
): Promise<{ items: PointAccount[]; totalCount: number }> {
  const filtered = ACCOUNTS.filter((account) => matchesQuery(account, query));
  filtered.sort(byUpdatedAtDesc);

  const start = (query.page - 1) * query.pageSize;
  return {
    items: filtered.slice(start, start + query.pageSize),
    totalCount: filtered.length,
  };
}

export async function fetchPointAccount(
  id: string
): Promise<PointAccount | null> {
  return ACCOUNTS.find((account) => account.id === id) ?? null;
}

function buildHistory(account: PointAccount): PointHistoryEntry[] {
  const seed = Number(account.id.slice(3));
  const length = 12 + (seed % 9);

  return Array.from({ length }, (_, index) => {
    const isPurchase = (seed + index) % 4 === 3;
    return {
      id: `${account.id}-H${String(index + 1).padStart(3, '0')}`,
      title: isPurchase
        ? `배지 이미지 구입 - BADGE_${String(((seed + index) % 20) + 1).padStart(3, '0')}`
        : EVENT_TITLES[(seed + index) % EVENT_TITLES.length],
      point: isPurchase ? -100 : 10,
      siteName: SITE_NAME,
      date: dateAt(index),
    };
  });
}

/** 기획 PTS10300001 ② — 최근 날짜순 정렬. */
export async function fetchPointHistory(
  accountId: string,
  page: number,
  pageSize: number
): Promise<{ items: PointHistoryEntry[]; totalCount: number }> {
  const account = await fetchPointAccount(accountId);
  if (!account) {
    return { items: [], totalCount: 0 };
  }

  const entries = buildHistory(account);
  entries.sort((a, b) => b.date.localeCompare(a.date));

  const start = (page - 1) * pageSize;
  return {
    items: entries.slice(start, start + pageSize),
    totalCount: entries.length,
  };
}