/**
 * Distributor Lead Time & Stock Monitor
 *
 * Scrapes Mouser Electronics and Digi-Key for transceiver
 * availability, stock levels, and lead times.
 *
 * Lead time is a 2-4 month supply constraint indicator:
 *   Lead time > 12 weeks  → price increase likely in 6-8 weeks
 *   Lead time < 4 weeks   → excess supply, price pressure downward
 *   In Stock / large qty  → commodity phase
 *
 * No API keys required — uses public catalog search pages.
 */

import * as cheerio from "cheerio";
import { pool } from "../utils/db";
import { logger } from "../utils/logger";

const HEADERS = {
  "User-Agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
  "Accept": "text/html,application/xhtml+xml,application/xhtml",
  "Accept-Language": "en-US,en;q=0.9",
};

interface LeadEntry {
  distributor: string;
  formFactor: string;
  speedLabel: string;
  partNumber: string;
  productName: string;
  inStock: boolean;
  stockQty: number | null;
  leadTimeWeeks: number | null;
  priceUsd: number | null;
  productUrl: string;
}

// ─── Mouser ────────────────────────────────────────────────────────────────

const MOUSER_SEARCHES = [
  { url: "https://www.mouser.com/c/optoelectronics/fiber-optic-components/fiber-optic-transceivers-pluggable/?q=100G&instock=y", form: "QSFP28",  speed: "100G" },
  { url: "https://www.mouser.com/c/optoelectronics/fiber-optic-components/fiber-optic-transceivers-pluggable/?q=400G",           form: "QSFP-DD", speed: "400G" },
  { url: "https://www.mouser.com/c/optoelectronics/fiber-optic-components/fiber-optic-transceivers-pluggable/?q=800G",           form: "OSFP",    speed: "800G" },
  { url: "https://www.mouser.com/c/optoelectronics/fiber-optic-components/fiber-optic-transceivers-pluggable/?q=SFP+10G",        form: "SFP+",    speed: "10G"  },
];

async function scrapeMouser(entry: { url: string; form: string; speed: string }): Promise<LeadEntry[]> {
  const res = await fetch(entry.url, { headers: HEADERS, signal: AbortSignal.timeout(20000) });
  if (!res.ok) throw new Error(`Mouser ${res.status}`);
  const $ = cheerio.load(await res.text());

  const results: LeadEntry[] = [];

  $(".product-table tr[data-part-number]").each((_, el) => {
    const partNumber  = $(el).attr("data-part-number") ?? "";
    const productName = $(el).find(".part-description a").first().text().trim();
    const productUrl  = `https://www.mouser.com${$(el).find(".part-description a").first().attr("href") ?? ""}`;
    const priceText   = $(el).find(".pricing-buy-price").first().text().replace(/,/g, "").trim();
    const price       = parseFloat(priceText.replace(/[^0-9.]/g, "")) || null;
    const availText   = $(el).find(".avail-text").first().text().trim();
    const qtyMatch    = availText.match(/([\d,]+)\s*In Stock/i);
    const inStock     = qtyMatch != null || availText.toLowerCase().includes("in stock");
    const stockQty    = qtyMatch ? parseInt(qtyMatch[1].replace(/,/g, "")) : (inStock ? 1 : null);

    let leadTimeWeeks: number | null = null;
    const leadMatch = availText.match(/(\d+)\s*(?:week|wk)/i);
    if (leadMatch) leadTimeWeeks = parseInt(leadMatch[1]);
    else if (!inStock) leadTimeWeeks = null; // non-stocked

    if (!partNumber && !productName) return;

    results.push({
      distributor: "mouser",
      formFactor: entry.form,
      speedLabel: entry.speed,
      partNumber,
      productName: productName.substring(0, 200),
      inStock,
      stockQty,
      leadTimeWeeks,
      priceUsd: price,
      productUrl: productUrl.substring(0, 500),
    });
  });

  return results;
}

// ─── Digi-Key ──────────────────────────────────────────────────────────────

const DIGIKEY_SEARCHES = [
  { url: "https://www.digikey.com/en/products/filter/fiber-optic-transceivers-pluggable/814?q=100G&s=N4IgjCBcoA2oBhUBjEAzAhgGwM4FMBXAFwHsoBOABgDoA2AJgFYBOGoA", form: "QSFP28",  speed: "100G" },
  { url: "https://www.digikey.com/en/products/filter/fiber-optic-transceivers-pluggable/814?q=400G",                                                                        form: "QSFP-DD", speed: "400G" },
];

async function scrapeDigikey(entry: { url: string; form: string; speed: string }): Promise<LeadEntry[]> {
  const res = await fetch(entry.url, { headers: HEADERS, signal: AbortSignal.timeout(20000) });
  if (!res.ok) throw new Error(`Digi-Key ${res.status}`);
  const $ = cheerio.load(await res.text());

  const results: LeadEntry[] = [];

  // Digi-Key uses React-rendered tables — grab what's in the SSR HTML
  $("tr[data-partid], .product-table tbody tr").each((_, el) => {
    const cells = $(el).find("td");
    if (cells.length < 4) return;

    const partLink = $(cells[0]).find("a").first();
    const partNumber  = partLink.text().trim() || $(cells[0]).text().trim();
    const productName = $(cells[1]).text().trim();
    const priceText   = $(cells[2]).text().replace(/,/g, "").trim();
    const price       = parseFloat(priceText.replace(/[^0-9.]/g, "")) || null;
    const qtyText     = $(cells[3]).text().replace(/,/g, "").trim();
    const qty         = parseInt(qtyText.replace(/[^0-9]/g, "")) || 0;

    if (!partNumber || partNumber.length < 3) return;

    results.push({
      distributor: "digikey",
      formFactor: entry.form,
      speedLabel: entry.speed,
      partNumber: partNumber.substring(0, 100),
      productName: productName.substring(0, 200),
      inStock: qty > 0,
      stockQty: qty || null,
      leadTimeWeeks: qty === 0 ? null : 0,
      priceUsd: price,
      productUrl: `https://www.digikey.com${partLink.attr("href") ?? ""}`,
    });
  });

  return results;
}

// ─── RS Components ─────────────────────────────────────────────────────────

async function scrapeRsComponents(): Promise<LeadEntry[]> {
  const url = "https://uk.rs-online.com/web/c/optoelectronics/fibre-optic-components/fibre-optic-transceivers/?applied-dimensions=4294958026&sortby=P_PRICE&st=400G";
  const res = await fetch(url, { headers: HEADERS, signal: AbortSignal.timeout(20000) });
  if (!res.ok) throw new Error(`RS ${res.status}`);
  const $ = cheerio.load(await res.text());

  const results: LeadEntry[] = [];

  $(".product-info-wrap").each((_, el) => {
    const partNumber  = $(el).find(".product-number").first().text().trim().replace("RS Stock No.", "");
    const productName = $(el).find(".product-title a").first().text().trim();
    const productUrl  = `https://uk.rs-online.com${$(el).find(".product-title a").attr("href") ?? ""}`;
    const priceText   = $(el).find(".price-info .price").first().text().trim();
    const price       = parseFloat(priceText.replace(/[^0-9.]/g, "")) || null;
    const stockText   = $(el).find(".stock-status").first().text().trim();
    const inStock     = /in stock|available/i.test(stockText);

    if (!productName) return;

    results.push({
      distributor: "rs-components",
      formFactor: "QSFP-DD",
      speedLabel: "400G",
      partNumber: partNumber.trim(),
      productName: productName.substring(0, 200),
      inStock,
      stockQty: null,
      leadTimeWeeks: inStock ? 0 : null,
      priceUsd: price, // GBP, stored as-is — currency conversion handled in forecast
      productUrl: productUrl.substring(0, 500),
    });
  });

  return results;
}

export async function scrapeDistributorLeads(): Promise<void> {
  logger.info("Distributor lead time scraper starting");
  let recorded = 0;

  // Mouser
  for (const s of MOUSER_SEARCHES) {
    try {
      await new Promise(r => setTimeout(r, 3000));
      logger.info(`Mouser: ${s.speed} ${s.form}`);
      const entries = await scrapeMouser(s);
      for (const e of entries.slice(0, 50)) { // limit to 50 per search
        await pool.query(`
          INSERT INTO distributor_lead_times
            (distributor, form_factor, speed_label, part_number, product_name,
             in_stock, stock_qty, lead_time_weeks, price_usd, product_url)
          VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10)
        `, [e.distributor, e.formFactor, e.speedLabel, e.partNumber, e.productName,
            e.inStock, e.stockQty, e.leadTimeWeeks, e.priceUsd, e.productUrl]);
        recorded++;
      }
      logger.info(`Mouser ${s.speed}: ${entries.length} products`);
    } catch (err) {
      logger.warn(`Mouser scrape failed: ${s.speed}`, { err });
    }
  }

  // Digi-Key
  for (const s of DIGIKEY_SEARCHES) {
    try {
      await new Promise(r => setTimeout(r, 4000));
      logger.info(`Digi-Key: ${s.speed} ${s.form}`);
      const entries = await scrapeDigikey(s);
      for (const e of entries.slice(0, 30)) {
        await pool.query(`
          INSERT INTO distributor_lead_times
            (distributor, form_factor, speed_label, part_number, product_name,
             in_stock, stock_qty, lead_time_weeks, price_usd, product_url)
          VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10)
        `, [e.distributor, e.formFactor, e.speedLabel, e.partNumber, e.productName,
            e.inStock, e.stockQty, e.leadTimeWeeks, e.priceUsd, e.productUrl]);
        recorded++;
      }
      logger.info(`Digi-Key ${s.speed}: ${entries.length} products`);
    } catch (err) {
      logger.warn(`Digi-Key scrape failed: ${s.speed}`, { err });
    }
  }

  // RS Components
  try {
    await new Promise(r => setTimeout(r, 3000));
    const rsEntries = await scrapeRsComponents();
    for (const e of rsEntries.slice(0, 30)) {
      await pool.query(`
        INSERT INTO distributor_lead_times
          (distributor, form_factor, speed_label, part_number, product_name,
           in_stock, stock_qty, lead_time_weeks, price_usd, product_url)
        VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10)
      `, [e.distributor, e.formFactor, e.speedLabel, e.partNumber, e.productName,
          e.inStock, e.stockQty, e.leadTimeWeeks, e.priceUsd, e.productUrl]);
      recorded++;
    }
    logger.info(`RS Components: ${rsEntries.length} products`);
  } catch (err) {
    logger.warn("RS Components scrape failed", { err });
  }

  logger.info(`Distributor lead time scraper done — ${recorded} records`);
}