import { existsSync, mkdirSync, writeFileSync } from 'fs'
import { resolve, dirname } from 'path'
import { fileURLToPath } from 'url'

const DIR = resolve(dirname(fileURLToPath(import.meta.url)), 'public', 'icons')

export const WMO = {
  0:  { label: 'Clear Sky',                icon: '01d' },
  1:  { label: 'Mainly Clear',             icon: '01d' },
  2:  { label: 'Partly Cloudy',            icon: '02d' },
  3:  { label: 'Overcast',                 icon: '04d' },
  45: { label: 'Fog',                      icon: '50d' },
  48: { label: 'Icy Fog',                  icon: '50d' },
  51: { label: 'Light Drizzle',            icon: '09d' },
  53: { label: 'Drizzle',                  icon: '09d' },
  55: { label: 'Heavy Drizzle',            icon: '09d' },
  61: { label: 'Light Rain',               icon: '10d' },
  63: { label: 'Rain',                     icon: '10d' },
  65: { label: 'Heavy Rain',               icon: '10d' },
  71: { label: 'Light Snow',               icon: '13d' },
  73: { label: 'Snow',                     icon: '13d' },
  75: { label: 'Heavy Snow',               icon: '13d' },
  77: { label: 'Snow Grains',              icon: '13d' },
  80: { label: 'Light Showers',            icon: '09d' },
  81: { label: 'Showers',                  icon: '09d' },
  82: { label: 'Heavy Showers',            icon: '09d' },
  85: { label: 'Snow Showers',             icon: '13d' },
  86: { label: 'Heavy Snow Showers',       icon: '13d' },
  95: { label: 'Thunderstorm',             icon: '11d' },
  96: { label: 'Thunderstorm w/ Hail',     icon: '11d' },
  99: { label: 'Thunderstorm w/ Hail',     icon: '11d' },
}

export function weatherFromCode(code, isDay = true) {
  const w    = WMO[code] ?? { label: 'Unknown', icon: '01d' }
  const icon = isDay ? w.icon : w.icon.replace('d', 'n')
  return { weather_code: code, weather_label: w.label, weather_icon: `/icons/${icon}.png` }
}

export async function downloadIcons() {
  if (!existsSync(DIR)) mkdirSync(DIR, { recursive: true })
  const icons = new Set(Object.values(WMO).map(w => [w.icon, w.icon.replace('d','n')]).flat())
  await Promise.all([...icons].map(async icon => {
    const path = resolve(DIR, `${icon}.png`)
    if (existsSync(path)) return
    const res  = await fetch(`https://openweathermap.org/img/wn/${icon}@2x.png`)
    const buf  = Buffer.from(await res.arrayBuffer())
    writeFileSync(path, buf)
    console.log(`  📥 Downloaded icon: ${icon}.png`)
  }))
  console.log('✅ Weather icons ready')
}