import express from 'express';
import { fileURLToPath } from 'url';
import { dirname, join } from 'path';

const __dirname = dirname(fileURLToPath(import.meta.url));
const app = express();

const cache = new Map();
const TTL = 60 * 60 * 1000; // 1 hour

async function cachedFetch(url) {
  const entry = cache.get(url);
  if (entry && Date.now() - entry.ts < TTL) return entry.data;
  const response = await fetch(url);
  const data = await response.json();
  cache.set(url, { data, ts: Date.now() });
  return data;
}

app.use(express.static(join(__dirname, 'public')));

app.get('/api/holidays', async (req, res) => {
  const { year } = req.query;
  try {
    const data = await cachedFetch(`https://api.dagsmart.se/holidays?year=${year}&weekends=false`);
    res.json(data);
  } catch (err) {
    res.status(500).json({ error: String(err) });
  }
});

app.get('/api/bridge-days', async (req, res) => {
  const { year } = req.query;
  try {
    const data = await cachedFetch(`https://api.dagsmart.se/bridge-days?year=${year}`);
    res.json(data);
  } catch (err) {
    res.status(500).json({ error: String(err) });
  }
});

// ─────────────────────────────────────────────────────────────────────────────
// /shouldibeworking — same work-time rules as public/app.js (see isWorkDay /
// isCurrentlyWorkTime there), ported so it can be evaluated server-side.
// ─────────────────────────────────────────────────────────────────────────────

const WORK_START = 8 * 60;   // 08:00
const LUNCH_START = 12 * 60; // 12:00
const LUNCH_END = 13 * 60;   // 13:00
const WORK_END = 17 * 60;    // 17:00

function formatDate(date) {
  const y = date.getFullYear();
  const m = String(date.getMonth() + 1).padStart(2, '0');
  const d = String(date.getDate()).padStart(2, '0');
  return `${y}-${m}-${d}`;
}

function isWeekend(date) {
  const d = date.getDay();
  return d === 0 || d === 6;
}

// Matches app.js: all of July counts as non-work (Swedish summer holidays).
function isJuly(date) {
  return date.getMonth() === 6;
}

async function isWorkDay(date, includeBridgeDays) {
  if (isWeekend(date)) return false;
  if (isJuly(date)) return false;
  const year = date.getFullYear();
  const ds = formatDate(date);
  const holidays = await cachedFetch(`https://api.dagsmart.se/holidays?year=${year}&weekends=false`);
  if (holidays.some(h => h.date === ds)) return false;
  if (includeBridgeDays) {
    const bridgeDays = await cachedFetch(`https://api.dagsmart.se/bridge-days?year=${year}`);
    if (bridgeDays.some(h => h.date === ds)) return false;
  }
  return true;
}

async function isCurrentlyWorkTime(date, includeBridgeDays) {
  if (!(await isWorkDay(date, includeBridgeDays))) return false;
  const mins = date.getHours() * 60 + date.getMinutes();
  if (mins < WORK_START || mins >= WORK_END) return false;
  if (mins >= LUNCH_START && mins < LUNCH_END) return false;
  return true;
}

// Minutes from `now` until the working/not-working state next flips —
// the next of WORK_START/LUNCH_START/LUNCH_END/WORK_END today, or WORK_START
// on the next work day if none of those are left today. Rounded up, so it
// never reads 0 while a change is still seconds away.
async function minutesUntilNextShift(now, includeBridgeDays) {
  const nowMins = now.getHours() * 60 + now.getMinutes() + now.getSeconds() / 60;

  if (await isWorkDay(now, includeBridgeDays)) {
    for (const boundary of [WORK_START, LUNCH_START, LUNCH_END, WORK_END]) {
      if (boundary > nowMins) return Math.ceil(boundary - nowMins);
    }
  }

  const cursor = new Date(now);
  cursor.setHours(0, 0, 0, 0);
  cursor.setDate(cursor.getDate() + 1);
  for (let i = 0; i < 60; i++) {
    if (await isWorkDay(cursor, includeBridgeDays)) {
      const target = new Date(cursor);
      target.setMinutes(WORK_START);
      return Math.ceil((target - now) / 60000);
    }
    cursor.setDate(cursor.getDate() + 1);
  }
  return null; // no work day found within 60 days — shouldn't happen
}

// Fixed-window rate limiter: N requests per IP per window, no dependencies.
function rateLimit({ windowMs, max }) {
  const hits = new Map(); // ip -> { count, resetAt }
  return (req, res, next) => {
    const now = Date.now();
    const entry = hits.get(req.ip);
    if (!entry || now > entry.resetAt) {
      hits.set(req.ip, { count: 1, resetAt: now + windowMs });
      return next();
    }
    if (entry.count >= max) {
      res.set('Retry-After', String(Math.ceil((entry.resetAt - now) / 1000)));
      return res.status(429).json({ error: 'rate limited' });
    }
    entry.count++;
    next();
  };
}

app.get(
  '/shouldibeworking',
  rateLimit({ windowMs: 60 * 1000, max: 20 }),
  async (req, res) => {
    try {
      const includeBridgeDays = req.query.bridgeDays === 'true';
      const now = new Date();
      const working = await isCurrentlyWorkTime(now, includeBridgeDays);
      const minutesUntilChange = await minutesUntilNextShift(now, includeBridgeDays);
      res.json({ working, includeBridgeDays, minutesUntilChange });
    } catch (err) {
      res.status(500).json({ error: String(err) });
    }
  }
);

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => console.log(`Aftersummer → http://localhost:${PORT}`));