import * as cheerio from 'cheerio'

// ─── Types ───────────────────────────────────────────────────────────────────

export interface TechStack {
  cms: string | null
  framework: string | null
  ecommerce: string | null
  analytics: string[]
  hosting: string | null
}

export interface PerformanceMetrics {
  score: number
  fcp: number
  lcp: number
  cls: number
  tbt: number
  speedIndex: number
}

export interface SiteAnalysis {
  url: string
  fetchedAt: string
  title: string | null
  description: string | null
  themeColor: string | null
  primaryColors: string[]
  headingStructure: { h1: string[]; h2: string[] }
  navLinks: string[]
  hasForms: boolean
  techStack: TechStack | null
  performance: PerformanceMetrics | null
  fetchError: string | null
}

// ─── Internal result types ────────────────────────────────────────────────────

interface ParsedHtml {
  title: string | null
  description: string | null
  themeColor: string | null
  primaryColors: string[]
  headingStructure: { h1: string[]; h2: string[] }
  navLinks: string[]
  hasForms: boolean
}

// ─── HTML parser ─────────────────────────────────────────────────────────────

function parseHtml(html: string): ParsedHtml {
  const $ = cheerio.load(html)

  const title = $('title').first().text().trim() || null

  const description =
    $('meta[name="description"]').attr('content')?.trim() ?? null

  const themeColor =
    $('meta[name="theme-color"]').attr('content')?.trim() ?? null

  const colorPattern = /(#[0-9a-fA-F]{3,8})|rgb[a]?\(\s*\d[\d\s,./%]*\)/g
  const colorSet = new Set<string>()

  $('style').each((_, el) => {
    const text = $(el).text()
    const matches = text.match(colorPattern)
    if (matches) matches.forEach(c => colorSet.add(c))
  })

  $('[style]').each((_, el) => {
    const style = $(el).attr('style') ?? ''
    const matches = style.match(colorPattern)
    if (matches) matches.forEach(c => colorSet.add(c))
  })

  const primaryColors = [...colorSet].slice(0, 8)

  const h1: string[] = []
  $('h1').each((_, el) => {
    if (h1.length < 3) h1.push($(el).text().trim())
  })

  const h2: string[] = []
  $('h2').each((_, el) => {
    if (h2.length < 3) h2.push($(el).text().trim())
  })

  const navLinks: string[] = []
  $('nav').first().find('a').each((_, el) => {
    const text = $(el).text().trim()
    if (text && navLinks.length < 10) navLinks.push(text)
  })

  const hasForms = $('form').length > 0

  return { title, description, themeColor, primaryColors, headingStructure: { h1, h2 }, navLinks, hasForms }
}

// ─── Tech stack detector ──────────────────────────────────────────────────────

function detectStack(html: string, headers: Record<string, string>): TechStack {
  const h = html.toLowerCase()
  const headerLower: Record<string, string> = {}
  for (const [k, v] of Object.entries(headers)) {
    headerLower[k.toLowerCase()] = v.toLowerCase()
  }

  // CMS
  let cms: string | null = null

  if (
    h.includes('wp-content/') ||
    (headerLower['x-powered-by']?.includes('php') && h.includes('wp-json'))
  ) {
    cms = 'WordPress'
  } else if (h.includes('cdn.shopify.com') || h.includes('shopify.theme')) {
    cms = 'Shopify'
  } else if (
    h.includes('wixsite.com') ||
    Object.keys(headerLower).some(k => k.includes('x-wix'))
  ) {
    cms = 'Wix'
  } else if (h.includes('static1.squarespace.com') || h.includes('squarespace-cdn')) {
    cms = 'Squarespace'
  } else if (h.includes('webflow.io') || h.includes('data-wf-site')) {
    cms = 'Webflow'
  } else if (h.includes('/media/jui/') || h.includes('joomla')) {
    cms = 'Joomla'
  } else if (
    h.includes('/sites/default/files/') ||
    headerLower['x-generator']?.includes('drupal')
  ) {
    cms = 'Drupal'
  } else if (h.includes('ghost.io') || h.includes('content="ghost')) {
    cms = 'Ghost'
  }

  // Framework
  let framework: string | null = null

  if (h.includes('__next_data__') || h.includes('_next/static')) {
    framework = 'Next.js'
  } else if (h.includes('__nuxt__') || h.includes('_nuxt/')) {
    framework = 'Nuxt'
  } else if (!framework && (h.includes('data-reactroot') || h.includes('react-root'))) {
    framework = 'React'
  } else if (!framework && h.includes('data-v-')) {
    framework = 'Vue'
  } else if (h.includes('ng-version')) {
    framework = 'Angular'
  }

  // Ecommerce
  let ecommerce: string | null = null

  if (h.includes('woocommerce')) {
    ecommerce = 'WooCommerce'
  } else if (h.includes('prestashop')) {
    ecommerce = 'PrestaShop'
  } else if (h.includes('mage.cookies') || h.includes('skin/frontend')) {
    ecommerce = 'Magento'
  }

  // Analytics (collect all)
  const analytics: string[] = []

  if (h.includes('gtag') && /\/g-[a-z0-9]+\//i.test(html)) {
    analytics.push('Google Analytics 4')
  }
  if (h.includes('googletagmanager.com')) {
    analytics.push('Google Tag Manager')
  }
  if (h.includes('hotjar.com')) {
    analytics.push('Hotjar')
  }
  if (h.includes('matomo.js') || h.includes('piwik.js')) {
    analytics.push('Matomo')
  }
  if (h.includes('fbq(')) {
    analytics.push('Facebook Pixel')
  }

  // Hosting
  let hosting: string | null = null

  if ('cf-ray' in headerLower) {
    hosting = 'Cloudflare'
  } else if (Object.keys(headerLower).some(k => k.startsWith('x-vercel'))) {
    hosting = 'Vercel'
  } else if ('x-nf-request-id' in headerLower) {
    hosting = 'Netlify'
  } else if (
    'wpe-backend' in headerLower ||
    headerLower['server']?.includes('wpe')
  ) {
    hosting = 'WP Engine'
  }

  return { cms, framework, ecommerce, analytics, hosting }
}

// ─── PageSpeed fetcher ────────────────────────────────────────────────────────

async function fetchPageSpeed(url: string): Promise<PerformanceMetrics | null> {
  try {
    const apiUrl = `https://www.googleapis.com/pagespeedonline/v5/runPagespeed?url=${encodeURIComponent(url)}&strategy=mobile`
    const res = await fetch(apiUrl)
    const json = await res.json() as Record<string, unknown>

    const lr = json['lighthouseResult'] as Record<string, unknown>
    const categories = lr['categories'] as Record<string, Record<string, unknown>>
    const audits = lr['audits'] as Record<string, Record<string, unknown>>

    const score = Math.round((categories['performance']['score'] as number) * 100)
    const fcp = audits['first-contentful-paint']['numericValue'] as number
    const lcp = audits['largest-contentful-paint']['numericValue'] as number
    const cls = audits['cumulative-layout-shift']['numericValue'] as number
    const tbt = audits['total-blocking-time']['numericValue'] as number
    const speedIndex = audits['speed-index']['numericValue'] as number

    return { score, fcp, lcp, cls, tbt, speedIndex }
  } catch {
    return null
  }
}

// ─── URL validation ───────────────────────────────────────────────────────────

function normalizeUrl(input: string): string {
  const trimmed = input.trim()
  if (!/^https?:\/\//i.test(trimmed)) {
    return `https://${trimmed}`
  }
  return trimmed
}

function isHttpUrl(input: string): boolean {
  return /^https?:\/\//i.test(input)
}

// ─── Main export ──────────────────────────────────────────────────────────────

export async function analyzeSite(url: string): Promise<SiteAnalysis> {
  const normalizedUrl = normalizeUrl(url)
  const fetchedAt = new Date().toISOString()

  const base: SiteAnalysis = {
    url: normalizedUrl,
    fetchedAt,
    title: null,
    description: null,
    themeColor: null,
    primaryColors: [],
    headingStructure: { h1: [], h2: [] },
    navLinks: [],
    hasForms: false,
    techStack: null,
    performance: null,
    fetchError: null,
  }

  if (!isHttpUrl(normalizedUrl)) {
    return { ...base, fetchError: 'Invalid URL: only http and https schemes are supported.' }
  }

  let html: string
  let headers: Record<string, string>

  try {
    const controller = new AbortController()
    const timeout = setTimeout(() => controller.abort(), 5000)

    const response = await fetch(normalizedUrl, {
      signal: controller.signal,
      headers: { 'User-Agent': 'Mozilla/5.0 (compatible; SiteAnalyzer/1.0)' },
    })

    clearTimeout(timeout)

    html = await response.text()

    headers = {}
    response.headers.forEach((value, key) => {
      headers[key.toLowerCase()] = value
    })
  } catch (err) {
    const message = err instanceof Error ? err.message : String(err)
    return { ...base, fetchError: message }
  }

  const [htmlResult, stackResult, perfResult] = await Promise.allSettled([
    Promise.resolve(parseHtml(html)),
    Promise.resolve(detectStack(html, headers)),
    fetchPageSpeed(normalizedUrl),
  ])

  const parsed = htmlResult.status === 'fulfilled' ? htmlResult.value : null
  const stack = stackResult.status === 'fulfilled' ? stackResult.value : null
  const perf = perfResult.status === 'fulfilled' ? perfResult.value : null

  return {
    url: normalizedUrl,
    fetchedAt,
    title: parsed?.title ?? null,
    description: parsed?.description ?? null,
    themeColor: parsed?.themeColor ?? null,
    primaryColors: parsed?.primaryColors ?? [],
    headingStructure: parsed?.headingStructure ?? { h1: [], h2: [] },
    navLinks: parsed?.navLinks ?? [],
    hasForms: parsed?.hasForms ?? false,
    techStack: stack,
    performance: perf,
    fetchError: null,
  }
}