import fs from 'fs'
import path from 'path'
import { fileURLToPath } from 'url'

const __dirname = path.dirname(fileURLToPath(import.meta.url))
const FONTS_DIR = path.join(__dirname, '..', 'fonts')
const FONT_FILE = path.join(FONTS_DIR, 'NotoSansSC-Regular.otf')

const CDN_URLS = [
  'https://cdn.jsdelivr.net/gh/googlefonts/noto-cjk@main/Sans/SubsetOTF/SC/NotoSansSC-Regular.otf',
  'https://raw.githubusercontent.com/googlefonts/noto-cjk/main/Sans/SubsetOTF/SC/NotoSansSC-Regular.otf',
]

let fontReady: string | null = null

export async function ensureChineseFont(): Promise<string> {
  if (fontReady) return fontReady

  // Check if already downloaded
  if (fs.existsSync(FONT_FILE) && fs.statSync(FONT_FILE).size > 100000) {
    fontReady = FONT_FILE
    return FONT_FILE
  }

  // Ensure directory exists
  if (!fs.existsSync(FONTS_DIR)) fs.mkdirSync(FONTS_DIR, { recursive: true })

  // Try each CDN URL
  for (const url of CDN_URLS) {
    try {
      console.log(`Downloading Chinese font from ${url.split('/')[2]}...`)
      const res = await fetch(url, { signal: AbortSignal.timeout(60000) })
      if (!res.ok) continue
      const buf = Buffer.from(await res.arrayBuffer())
      if (buf.length < 100000) continue // too small, probably error page
      fs.writeFileSync(FONT_FILE, buf)
      console.log(`Chinese font downloaded (${(buf.length / 1024 / 1024).toFixed(1)} MB)`)
      fontReady = FONT_FILE
      return FONT_FILE
    } catch (e: any) {
      console.warn(`Font download failed from ${url.split('/')[2]}: ${e.message}`)
    }
  }

  // Fallback: try local system fonts
  const fallbacks = [
    'C:\\Windows\\Fonts\\simhei.ttf',
    'C:\\Windows\\Fonts\\msyh.ttf',
    '/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc',
    '/System/Library/Fonts/PingFang.ttc',
  ]
  for (const f of fallbacks) {
    if (fs.existsSync(f)) {
      console.log(`Using fallback system font: ${f}`)
      fontReady = f
      return f
    }
  }

  throw new Error('No Chinese font available. Set PDF_FONT_PATH env variable to a TTF/OTF font path.')
}

export function getChineseFont(): string {
  if (!fontReady) throw new Error('Font not initialized. Call ensureChineseFont() first.')
  return fontReady
}