pc_builder/app/services/merchant_price_service.ts

import * as cheerio from 'cheerio'
import logger from '@adonisjs/core/services/logger'
import { withPage } from '#services/headless_browser_service'

const USER_AGENT =
  'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36'

export interface MerchantOffer {
  merchant:
    | 'Amazon'
    | 'LDLC'
    | 'Grosbill'
    | 'TopAchat'
    | 'Materiel.net'
    | 'Cdiscount'
    | 'PCComponentes'
  price: number
  url: string
}

async function fetchHtml(url: string): Promise<string | null> {
  try {
    const response = await fetch(url, {
      headers: {
        'User-Agent': USER_AGENT,
        'Accept-Language': 'fr-FR,fr;q=0.9',
      },
    })
    if (!response.ok) return null
    return await response.text()
  } catch (error) {
    logger.warn({ url, err: error }, 'Failed to fetch merchant page')
    return null
  }
}

/**
 * Parses a price from plain text like "64,95 €" or "413.59 €*".
 */
function parsePriceText(text: string): number | null {
  const normalized = text
    .replace(/\u00a0/g, ' ')
    .replace(/[^\d,.\s]/g, '')
    .trim()
    .replace(/\s/g, '')
    .replace(',', '.')
  const value = Number.parseFloat(normalized)
  return Number.isNaN(value) ? null : value
}

/**
 * Some merchants (LDLC, Grosbill, Materiel.net) render prices split across
 * sibling/child elements instead of plain text, e.g.
 * `<div class="price">64€<sup>95</sup></div>` renders as "64€95" once
 * flattened to text, which parsePriceText would misread as 6495 (or, worse,
 * "2 049€95" as 204995). This detects that "<whole>€<cents>" shape in
 * flattened text and recombines it as <whole>.<cents> instead.
 */
function parseFlattenedFragmentedPriceText(text: string): number | null {
  const match = text
    .replace(/\u00a0/g, ' ')
    .trim()
    .match(/^([\d\s]+)\s*€\s*(\d{1,2})$/)
  if (!match) return null
  const whole = match[1].replace(/\s/g, '')
  const cents = match[2].padEnd(2, '0').slice(0, 2)
  const value = Number.parseFloat(`${whole}.${cents}`)
  return Number.isNaN(value) ? null : value
}

/**
 * Same fragmented-price shape as parseFlattenedFragmentedPriceText, but
 * operating on a Cheerio element with a real `<sup>` child instead of
 * already-flattened text — used when scraping static HTML with cheerio
 * (LDLC, Grosbill) rather than reading `.innerText()` from a live browser
 * page (Materiel.net).
 *
 * LDLC additionally nests a duplicate `.price` wrapper
 * (`<div class="price"><div class="price">64€<sup>95</sup></div></div>`),
 * so this always resolves to the innermost element actually containing a
 * `<sup>`, rather than assuming $el itself is the leaf node.
 */
function parseFragmentedPrice($el: cheerio.Cheerio<any>): number | null {
  const sup = $el.find('sup').first()
  if (sup.length > 0) {
    // The element that directly holds both the whole-part text node and
    // the <sup> cents — not necessarily $el itself if it's a wrapper.
    const leaf = sup.parent()
    const cents = sup.text().replace(/\D/g, '')
    const wholePart = leaf.clone().children().remove().end().text().replace(/\D/g, '')
    if (wholePart) {
      const value = Number.parseFloat(`${wholePart}.${cents.padEnd(2, '0').slice(0, 2)}`)
      return Number.isNaN(value) ? null : value
    }
  }
  return parsePriceText($el.text())
}

/**
 * Builds a short, merchant-search-friendly query from a full pc-builder.io
 * product name. These sites' search engines are strict/exact-match and
 * choke on the long, spec-heavy names pc-builder.io uses (e.g. "AMD Ryzen 3
 * 3200G 3.6 GHz Quad-Core Processor" returns zero results everywhere, but
 * "AMD Ryzen 3" does). We search on the first few tokens (brand + series),
 * then use extractModelToken() to pick out the right result from the list.
 */
function shortSearchQuery(name: string): string {
  const tokens = name
    .replace(/\([^)]*\)/g, ' ')
    .split(/\s+/)
    .filter(Boolean)
  return tokens.slice(0, 3).join(' ')
}

/**
 * Extracts the most specific "model number" token from a product name, to
 * disambiguate between multiple search results (e.g. "3200G" out of "AMD
 * Ryzen 3 3200G ...", or "970" out of "Samsung 970 Evo Plus ..."). Prefers
 * alphanumeric tokens that mix letters and digits (typical of CPU/GPU model
 * numbers), falling back to a bare 3-4 digit number.
 */
function extractModelToken(name: string): string | null {
  const tokens = name
    .replace(/\([^)]*\)/g, ' ')
    .split(/\s+/)
    .filter(Boolean)
  const mixed = tokens.find(
    (t) => /[a-zA-Z]/.test(t) && /\d/.test(t) && !/^\d+(\.\d+)?ghz$/i.test(t)
  )
  if (mixed) return mixed
  return tokens.find((t) => /^\d{3,4}$/.test(t)) ?? null
}

/**
 * Reads the price directly from a known Amazon.fr product page
 * (https://www.amazon.fr/dp/{ASIN}?...). Only works for direct product
 * links; Amazon search-result links (https://www.amazon.fr/s?k=...) can't
 * be resolved to a single price this way.
 */
async function fetchAmazonPrice(amazonUrl: string): Promise<MerchantOffer | null> {
  if (!amazonUrl.includes('/dp/')) return null

  const html = await fetchHtml(amazonUrl)
  if (!html) return null

  const $ = cheerio.load(html)
  const priceText = $('.a-price .a-offscreen').first().text().trim()
  const price = parsePriceText(priceText)
  if (price === null) return null

  return { merchant: 'Amazon', price, url: amazonUrl }
}

/**
 * Searches LDLC by product name and reads the price of the result whose
 * label contains the extracted model token (e.g. "3200G"). Only falls back
 * to the first result when there is no model token to disambiguate with
 * (rare); otherwise a search that returns unrelated products (LDLC simply
 * doesn't carry this exact model) correctly yields no offer instead of a
 * misleading price for the wrong product.
 */
async function fetchLdlcPrice(productName: string): Promise<MerchantOffer | null> {
  const query = shortSearchQuery(productName)
  const modelToken = extractModelToken(productName)
  const url = `https://www.ldlc.com/recherche/${encodeURIComponent(query)}/`
  const html = await fetchHtml(url)
  if (!html) return null

  const $ = cheerio.load(html)
  const items = $('.listing-product li.pdt-item')
  if (!items.length) return null

  let best: cheerio.Cheerio<any> | null = modelToken ? null : items.first()
  if (modelToken) {
    items.each((_, el) => {
      const label = $(el).find('.pdt-desc a').first().text()
      if (label.toLowerCase().includes(modelToken.toLowerCase())) {
        best = $(el)
        return false
      }
    })
  }
  if (!best) return null

  const link = (best as cheerio.Cheerio<any>).find('.pdt-desc a').first().attr('href')
  const priceEl = (best as cheerio.Cheerio<any>).find('.price').first()
  const price = parseFragmentedPrice(priceEl)
  if (price === null || !link) return null

  return { merchant: 'LDLC', price, url: new URL(link, 'https://www.ldlc.com').toString() }
}

/**
 * Searches Grosbill by product name and reads the price of the result
 * whose label contains the extracted model token. Same rationale as
 * fetchLdlcPrice: without a model token match, we return null rather than
 * risk quoting the price of an unrelated product.
 */
async function fetchGrosbillPrice(productName: string): Promise<MerchantOffer | null> {
  const query = shortSearchQuery(productName)
  const modelToken = extractModelToken(productName)
  const url = `https://www.grosbill.com/produit.aspx?q=${encodeURIComponent(query)}/`
  const html = await fetchHtml(url)
  if (!html) return null

  const $ = cheerio.load(html)
  const items = $('[class*="la_liste_des_produits"]')
  if (!items.length) return null

  let best: cheerio.Cheerio<any> | null = modelToken ? null : items.first()
  if (modelToken) {
    items.each((_, el) => {
      const label = $(el)
        .find('.grb__liste-produit__liste__produit__information__libelle')
        .text()
        .replace(/\s+/g, ' ')
      if (label.toLowerCase().includes(modelToken.toLowerCase())) {
        best = $(el)
        return false
      }
    })
  }
  if (!best) return null

  const priceEl = (best as cheerio.Cheerio<any>).find('.price-main').first()
  const price = parseFragmentedPrice(priceEl)
  if (price === null) return null

  const link = (best as cheerio.Cheerio<any>).find('a[href]').first().attr('href')
  return { merchant: 'Grosbill', price, url: link ? new URL(link, url).toString() : url }
}

/**
 * Searches TopAchat by product name. When the search resolves to a single
 * matching product, TopAchat redirects straight to the product page
 * (label-product / offer-price__price). List-page matching by model token
 * is attempted first for queries with multiple hits.
 */
async function fetchTopAchatPrice(productName: string): Promise<MerchantOffer | null> {
  const query = shortSearchQuery(productName)
  const modelToken = extractModelToken(productName)
  const url = `https://www.topachat.com/search/${encodeURIComponent(query)}`
  const html = await fetchHtml(url)
  if (!html) return null

  const $ = cheerio.load(html)

  // Case 1: redirected straight to a single product page.
  const singlePrice = $('.offer-price__price').first()
  if (singlePrice.length) {
    const label = $('.label-product').first().text()
    if (!modelToken || label.toLowerCase().includes(modelToken.toLowerCase())) {
      const priceText = singlePrice.clone().children().remove().end().text().trim()
      const price = parsePriceText(priceText)
      if (price !== null) {
        const canonical = $('link[rel="canonical"]').attr('href')
        return { merchant: 'TopAchat', price, url: canonical || url }
      }
    }
  }

  // Case 2: a list of results (product__price / product__label cards).
  const cards = $('article.product, [class*="product__"]').filter(
    (_, el) => $(el).find('.product__price').length > 0
  )
  let best: cheerio.Cheerio<any> | null = null
  cards.each((_, el) => {
    const label = $(el).find('.product__label').text()
    if (!modelToken || label.toLowerCase().includes(modelToken.toLowerCase())) {
      best = $(el)
      return false
    }
  })
  if (!best) return null

  const priceText = (best as cheerio.Cheerio<any>).find('.product__price').first().text().trim()
  const price = parsePriceText(priceText)
  if (price === null) return null

  const link = (best as cheerio.Cheerio<any>).closest('a[href]').attr('href')
  return { merchant: 'TopAchat', price, url: link ? new URL(link, url).toString() : url }
}

/**
 * Searches Materiel.net by simulating the real search form submission in a
 * headless browser. A plain GET on /recherche/?query=... always returns an
 * empty "no results" template — the search only actually runs client-side
 * (Stimulus/Turbo), so this is one of three merchants where a real browser
 * is required rather than a plain HTTP fetch.
 *
 * When there's a single match, Materiel.net redirects straight to the
 * product page. Otherwise it lists cards matched by model token.
 */
async function fetchMaterielNetPrice(productName: string): Promise<MerchantOffer | null> {
  const query = shortSearchQuery(productName)
  const modelToken = extractModelToken(productName)

  return withPage(async (page) => {
    await page.goto('https://www.materiel.net/', { waitUntil: 'networkidle', timeout: 20000 })
    await page.fill('#search_search_text', query)
    await page.click('button[type="submit"]')
    await page.waitForLoadState('networkidle', { timeout: 20000 })

    // Case 1: redirected straight to a single product page (URL pattern
    // distinguishes this from Case 2 — a list page also has
    // .o-product__price elements, once per card, so checking for its mere
    // presence isn't enough to tell the two cases apart).
    if (/\/produit\//.test(page.url())) {
      const title = await page.title()
      if (!modelToken || title.toLowerCase().includes(modelToken.toLowerCase())) {
        const text = await page
          .locator('.o-product__price')
          .first()
          .innerText()
          .catch(() => '')
        const price = parseFlattenedFragmentedPriceText(text) ?? parsePriceText(text)
        if (price !== null) {
          return { merchant: 'Materiel.net' as const, price, url: page.url() }
        }
      }
      return null
    }

    // Case 2: a list of results.
    const cards = page.locator('li.c-products-list__item[data-id]')
    const count = await cards.count()
    for (let i = 0; i < count; i++) {
      const card = cards.nth(i)
      const label = await card
        .locator('.c-product__meta h2.c-product__title')
        .innerText()
        .catch(() => '')
      if (modelToken && !label.toLowerCase().includes(modelToken.toLowerCase())) continue

      const priceText = await card
        .locator('.o-product__price')
        .first()
        .innerText()
        .catch(() => '')
      const price = parseFlattenedFragmentedPriceText(priceText) ?? parsePriceText(priceText)
      if (price === null) continue

      const link = await card
        .locator('.c-product__meta a.c-product__link')
        .first()
        .getAttribute('href')
      return { merchant: 'Materiel.net' as const, price, url: link ?? page.url() }
    }

    return null
  })
}

/**
 * Searches Cdiscount by product name via a headless browser. Cdiscount's
 * search-results page returns an empty body to plain HTTP fetches (no
 * error, just nothing), which is consistent with the listing being
 * rendered client-side and/or gated behind bot-detection that only lets
 * real browsers through.
 */
async function fetchCdiscountPrice(productName: string): Promise<MerchantOffer | null> {
  const query = shortSearchQuery(productName)
  const modelToken = extractModelToken(productName)
  const url = `https://www.cdiscount.com/search/10/${encodeURIComponent(query)}.html`

  return withPage(async (page) => {
    await page.goto(url, { waitUntil: 'networkidle', timeout: 20000 })

    const cards = page.locator('div[data-e2e="offer-wrapper"]')
    const count = await cards.count()
    for (let i = 0; i < count; i++) {
      const card = cards.nth(i)
      const label = await card
        .locator('[data-e2e="lplr-title"]')
        .innerText()
        .catch(() => '')
      if (modelToken && !label.toLowerCase().includes(modelToken.toLowerCase())) continue

      const priceText = await card
        .locator('[data-e2e="lplr-price"]')
        .first()
        .innerText()
        .catch(() => '')
      const price = parsePriceText(priceText)
      if (price === null) continue

      const link = await card.locator('a').first().getAttribute('href')
      const offerUrl = link ? new URL(link, 'https://www.cdiscount.com').toString() : url
      return { merchant: 'Cdiscount' as const, price, url: offerUrl }
    }

    return null
  })
}

/**
 * Searches PCComponentes.com by product name via a headless browser
 * (blocked with a plain HTTP 403 otherwise). Product cards expose clean,
 * pre-parsed data on the <a> element itself (data-product-price as a plain
 * number, data-product-category to distinguish standalone components from
 * full "Sobremesa" pre-built PCs), so full-PC listings that happen to
 * mention the same CPU are excluded rather than misreported as its price.
 */
async function fetchPcComponentesPrice(productName: string): Promise<MerchantOffer | null> {
  const query = shortSearchQuery(productName)
  const modelToken = extractModelToken(productName)
  const url = `https://www.pccomponentes.com/buscar/?query=${encodeURIComponent(query)}`

  return withPage(async (page) => {
    await page.goto(url, { waitUntil: 'networkidle', timeout: 20000 })

    const cards = page.locator('#search-results-product-grid > a[data-product-id]')
    const count = await cards.count()
    for (let i = 0; i < count; i++) {
      const card = cards.nth(i)
      const category = await card.getAttribute('data-product-category')
      if (category === 'Sobremesa') continue // full pre-built PC, not the component itself

      const name = (await card.getAttribute('data-product-name')) ?? ''
      if (modelToken && !name.toLowerCase().includes(modelToken.toLowerCase())) continue

      const priceAttr = await card.getAttribute('data-product-price')
      const price = priceAttr ? Number.parseFloat(priceAttr) : null
      if (price === null || Number.isNaN(price)) continue

      const href = await card.getAttribute('href')
      const offerUrl = href ? new URL(href, 'https://www.pccomponentes.com').toString() : url
      return { merchant: 'PCComponentes' as const, price, url: offerUrl }
    }

    return null
  })
}

/**
 * Fetches offers from every supported merchant in parallel and returns
 * them sorted by ascending price. Merchants that fail (blocked, no match,
 * network error) are silently skipped rather than failing the whole
 * comparison.
 */
async function findCheapestOffers(
  productName: string,
  amazonUrl: string | null
): Promise<MerchantOffer[]> {
  const lookups: Promise<MerchantOffer | null>[] = [
    amazonUrl ? fetchAmazonPrice(amazonUrl) : Promise.resolve(null),
    fetchLdlcPrice(productName),
    fetchGrosbillPrice(productName),
    fetchTopAchatPrice(productName),
    fetchMaterielNetPrice(productName),
    fetchCdiscountPrice(productName),
    fetchPcComponentesPrice(productName),
  ]

  const results = await Promise.allSettled(lookups)
  const offers = results
    .filter(
      (result): result is PromiseFulfilledResult<MerchantOffer | null> =>
        result.status === 'fulfilled'
    )
    .map((result) => result.value)
    .filter((offer): offer is MerchantOffer => offer !== null)

  return offers.sort((a, b) => a.price - b.price)
}

export {
  findCheapestOffers,
  fetchAmazonPrice,
  fetchLdlcPrice,
  fetchGrosbillPrice,
  fetchTopAchatPrice,
  fetchMaterielNetPrice,
  fetchCdiscountPrice,
  fetchPcComponentesPrice,
}