import { NextResponse } from 'next/server';
import { db } from '@/db';
import { exchangeRatesHistory } from '@/db/schema';
import { ProxyAgent, setGlobalDispatcher } from 'undici';

export const dynamic = 'force-dynamic';
export const fetchCache = 'force-no-store';
export const runtime = 'nodejs';

const CURRENCIES = [
  { from: 'USD', to: 'CNY' },
  { from: 'HKD', to: 'CNY' },
];

const JISU_API_BASE = 'https://api.jisuapi.com/exchange/convert';

interface JisuResult {
  from: string;
  to: string;
  rate: string;
  updatetime: string;
}

interface JisuResponse {
  status: number;
  msg: string;
  result: JisuResult;
}

async function fetchRate(
  from: string,
  to: string,
  apikey: string
): Promise<{ from: string; to: string; rate: string; success: true } | { from: string; success: false; error: string }> {
  const url = `${JISU_API_BASE}?appkey=${apikey}&from=${from}&to=${to}&amount=1`;

  try {
    const res = await fetch(url, { cache: 'no-store' });

    if (!res.ok) {
      return { from, success: false, error: `HTTP ${res.status}` };
    }

    const data: JisuResponse = await res.json();

    if (data.status !== 0) {
      return { from, success: false, error: data.msg || `API status: ${data.status}` };
    }

    if (!data.result || !data.result.rate) {
      return { from, success: false, error: 'Missing result.rate in response' };
    }

    return {
      from,
      to: data.result.to,
      rate: data.result.rate,
      success: true,
    };
  } catch (err) {
    console.error(`[ExchangeRate] Fetch ${from}/${to} failed:`, err);
    return { from, success: false, error: (err as Error).message };
  }
}

export async function GET(req: Request) {
  const cronSecret = process.env.CRON_SECRET;
  const authHeader = req.headers.get('Authorization');

  if (!cronSecret) {
    return NextResponse.json(
      { error: 'CRON_SECRET not configured' },
      { status: 500 }
    );
  }

  if (authHeader !== `Bearer ${cronSecret}`) {
    return NextResponse.json(
      { error: 'Unauthorized' },
      { status: 401 }
    );
  }

  const jisuApiKey = process.env.JISU_API_KEY;
  if (!jisuApiKey) {
    return NextResponse.json(
      { error: 'JISU_API_KEY not configured' },
      { status: 500 }
    );
  }

  const proxyUrl = process.env.HTTPS_PROXY;
  if (proxyUrl) {
    const proxyAgent = new ProxyAgent(proxyUrl);
    setGlobalDispatcher(proxyAgent);
  }

  const fetchPromises = CURRENCIES.map(({ from, to }) =>
    fetchRate(from, to, jisuApiKey)
  );

  const results = await Promise.allSettled(fetchPromises);

  const inserted: Array<{ from: string; to: string; rate: string }> = [];
  const failed: Array<{ from: string; error: string }> = [];

  for (let i = 0; i < results.length; i++) {
    const result = results[i];
    const pair = CURRENCIES[i];

    if (result.status === 'fulfilled') {
      const res = result.value;
      if (res.success) {
        try {
          await db.insert(exchangeRatesHistory).values({
            fromCurrency: res.from,
            toCurrency: res.to,
            rate: res.rate,
            fetchTime: new Date(),
          });
          inserted.push({ from: res.from, to: res.to, rate: res.rate });
          console.log(`[ExchangeRate] ${res.from}/${res.to} = ${res.rate} -> saved`);
        } catch (dbErr) {
          failed.push({ from: res.from, error: `DB insert failed: ${(dbErr as Error).message}` });
          console.error(`[ExchangeRate] DB insert failed for ${res.from}:`, dbErr);
        }
      } else {
        const failRes = res as { from: string; success: false; error: string };
        failed.push({ from: failRes.from, error: failRes.error });
        console.error(`[ExchangeRate] API error for ${failRes.from}: ${failRes.error}`);
      }
    } else {
      failed.push({ from: pair.from, error: result.reason?.message || 'Unknown error' });
      console.error(`[ExchangeRate] Promise rejected for ${pair.from}:`, result.reason);
    }
  }

  return NextResponse.json({
    success: true,
    timestamp: new Date().toISOString(),
    inserted: inserted.length,
    failed: failed.length,
    details: {
      inserted,
      failed,
    },
  });
}