import { api } from '../services/apiClient.ts';
import type { Cycle, KPI, Site } from '../types/api.ts';

export type KandangRankingRow = {
  rank: number;
  siteId: number;
  siteName: string;
  kandangId: number;
  kandangName: string;
  cycleId: number;
  startDate: string;
  endDate: string;
  totalDays: number;
  eef: number | null;
  fcr: number | null;
};

export type LoadKandangRankingArgs = {
  sites: Site[];
  months: number;
  /** Defaults to today (local). */
  now?: Date;
};

function toIsoDate(d: Date): string {
  const pad = (n: number) => String(n).padStart(2, '0');
  return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}`;
}

/** Inclusive lower bound: end_date >= (today − months). */
export function rankingWindowStart(months: number, now = new Date()): string {
  const start = new Date(now.getFullYear(), now.getMonth(), now.getDate());
  start.setMonth(start.getMonth() - months);
  return toIsoDate(start);
}

export function isEndDateInWindow(endDate: string | null | undefined, windowStart: string): boolean {
  if (!endDate) return false;
  return endDate >= windowStart;
}

/**
 * Latest valid FCR/EEF for a cycle.
 * Matches EefDashboardPage: sort by age/date ascending, then walk from the end.
 * (API KPI list is ordered `-date` / newest-first — do not assume array order.)
 */
export function latestValidRatios(kpis: KPI[]): { eef: number | null; fcr: number | null } {
  const sorted = [...kpis].sort((a, b) => a.age - b.age || a.date.localeCompare(b.date));
  let eef: number | null = null;
  let fcr: number | null = null;
  for (let i = sorted.length - 1; i >= 0; i--) {
    const row = sorted[i];
    if (!row) continue;
    if (eef == null && row.eef > 0) eef = row.eef;
    if (fcr == null && row.fcr > 0) fcr = row.fcr;
    if (eef != null && fcr != null) break;
  }
  return { eef, fcr };
}

function assignRanks(
  rows: Omit<KandangRankingRow, 'rank'>[]
): KandangRankingRow[] {
  const withEef = rows
    .filter((r) => r.eef != null)
    .sort((a, b) => (b.eef as number) - (a.eef as number));
  const withoutEef = rows.filter((r) => r.eef == null);

  const ranked: KandangRankingRow[] = withEef.map((row, index) => ({
    ...row,
    rank: index + 1,
  }));
  const unranked: KandangRankingRow[] = withoutEef.map((row) => ({
    ...row,
    rank: 0,
  }));
  return [...ranked, ...unranked];
}

/**
 * Load closed-cycle EEF rankings for the given sites within a months window.
 * Uses one closed-cycles list + per-site kandangs + per-cycle KPI fetches.
 */
export async function loadKandangRanking({
  sites,
  months,
  now = new Date(),
}: LoadKandangRankingArgs): Promise<KandangRankingRow[]> {
  if (sites.length === 0 || months < 1) return [];

  const windowStart = rankingWindowStart(months, now);
  const siteById = new Map(sites.map((s) => [s.id, s]));

  const kandangLists = await Promise.all(
    sites.map((site) => api.kandangs.list({ site_id: site.id }))
  );

  type KandangMeta = { siteId: number; siteName: string; kandangName: string };
  const kandangMeta = new Map<number, KandangMeta>();
  kandangLists.forEach((list, i) => {
    const site = sites[i];
    if (!site) return;
    for (const k of list) {
      kandangMeta.set(k.id, {
        siteId: site.id,
        siteName: site.site_name,
        kandangName: k.kandang_name,
      });
    }
  });

  if (kandangMeta.size === 0) return [];

  let closedCycles: Cycle[] = [];
  try {
    closedCycles = await api.cycles.list({ status: 'closed' });
  } catch {
    // Fallback: per-kandang if global closed list fails
    const perKandang = await Promise.all(
      [...kandangMeta.keys()].map(async (kandangId) => {
        try {
          return await api.cycles.list({ kandang_id: kandangId, status: 'closed' });
        } catch {
          return [] as Cycle[];
        }
      })
    );
    closedCycles = perKandang.flat();
  }

  const inScope = closedCycles.filter((cycle) => {
    if (!kandangMeta.has(cycle.kandang)) return false;
    return isEndDateInWindow(cycle.end_date, windowStart);
  });

  const metricRows = await Promise.all(
    inScope.map(async (cycle) => {
      const meta = kandangMeta.get(cycle.kandang);
      if (!meta || !cycle.end_date) return null;
      // Ensure site still in requested set (defensive)
      if (!siteById.has(meta.siteId)) return null;

      let eef: number | null = null;
      let fcr: number | null = null;
      try {
        const kpis = await api.kpis.list({ cycle_id: cycle.id });
        ({ eef, fcr } = latestValidRatios(kpis));
      } catch {
        // leave nulls
      }

      return {
        siteId: meta.siteId,
        siteName: meta.siteName,
        kandangId: cycle.kandang,
        kandangName: meta.kandangName || cycle.kandang_name,
        cycleId: cycle.id,
        startDate: cycle.start_date,
        endDate: cycle.end_date,
        totalDays: cycle.total_days || cycle.current_day || 0,
        eef,
        fcr,
      } satisfies Omit<KandangRankingRow, 'rank'>;
    })
  );

  return assignRanks(metricRows.filter((r): r is Omit<KandangRankingRow, 'rank'> => r != null));
}