import * as cheerio from 'cheerio';

type ScrapeResult = {
  prices: number[];
  blocked: boolean;
  diagnostics?: { selectorHits: Record<string, number>; sampleTexts: string[]; samplePrices: number[] };
};

async function scrapeSoldPricesUSDPage(html: string, wantDiagnostics = false): Promise<ScrapeResult> {
  const $ = cheerio.load(html);
  const prices: number[] = [];
  const selectorHits: Record<string, number> = {};
  const sampleTexts: string[] = [];
  const samplePrices: number[] = [];

  const blocked = html.includes('To continue, please verify') || html.toLowerCase().includes('robot check');

  const priceSelectors = [
    '.s-item__price',
    '.s-item__detail--primary .s-item__price',
    'span[class*="s-item__price"]',
  ];

  $('li.s-item').each((_i, el) => {
    const $el = $(el);
    let text: string | null = null;
    for (const sel of priceSelectors) {
      const t = $el.find(sel).first().text().trim();
      if (t) {
        text = t; selectorHits[sel] = (selectorHits[sel] || 0) + 1; break;
      }
    }
    if (!text) {
      // regex fallback within this listing's HTML
      const htmlFrag = $el.html() || '';
      const m = htmlFrag.match(/\$\s*[0-9]{1,3}(?:,[0-9]{3})*(?:\.[0-9]{2})?/);
      if (m) text = m[0];
    }
    if (!text) return;
    if (wantDiagnostics && sampleTexts.length < 10) sampleTexts.push(text);
    if (!text.includes('$')) return;
    const single = text.split(' to ')[0];
    const num = single.replace(/[^0-9.]/g, '');
    if (!num) return;
    const value = Number(num);
    if (!Number.isFinite(value) || value <= 0) return;
    prices.push(value);
    if (wantDiagnostics && samplePrices.length < 10) samplePrices.push(value);
  });

  return { prices, blocked, diagnostics: wantDiagnostics ? { selectorHits, sampleTexts, samplePrices } : undefined };
}

async function fetchSoldSearchHtml(query: string, page = 1): Promise<{ ok: boolean; html: string }> {
  const url = `https://www.ebay.com/sch/i.html?_nkw=${encodeURIComponent(query)}&LH_Sold=1&LH_Complete=1&rt=nc&_ipg=200&_pgn=${page}`; 
  const res = await fetch(url, {
    headers: {
      'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36',
      'Accept-Language': 'en-US,en;q=0.9'
    } as any
  } as any);
  const html = await res.text();
  return { ok: res.ok, html };
}

export async function fetchMedianSoldPriceUSDForSku(sku: string): Promise<number | null> {
  // Try quoted exact search first
  const tryQueries = [
    `"${sku}"`,
    sku // fallback without quotes
  ];
  for (const q of tryQueries) {
    let all: number[] = [];
    for (let page = 1; page <= 2; page++) {
      const { ok, html } = await fetchSoldSearchHtml(q, page);
      if (!ok) continue;
      const { prices, blocked } = await scrapeSoldPricesUSDPage(html);
      if (blocked) return null;
      all = all.concat(prices);
      if (all.length === 0) {
        // small delay before next page to be gentle
        await new Promise(r => setTimeout(r, 600));
      }
    }
    if (all.length > 0) {
      all.sort((a, b) => a - b);
      const mid = Math.floor(all.length / 2);
      return Number((all.length % 2 === 0 ? (all[mid - 1] + all[mid]) / 2 : all[mid]).toFixed(2));
    }
  }
  return null;
}

export async function debugFetchSoldPricesUSDForSku(sku: string) {
  const sequences = [`"${sku}"`, sku];
  const attempts: any[] = [];
  for (const q of sequences) {
    let total = 0;
    let blocked = false;
    const diagnostics: any = { pages: [] };
    for (let page = 1; page <= 2; page++) {
      const { ok, html } = await fetchSoldSearchHtml(q, page);
      const diag = await scrapeSoldPricesUSDPage(html, true);
      diagnostics.pages.push({ page, ok, count: diag.prices.length, selectorHits: diag.diagnostics?.selectorHits, sampleTexts: diag.diagnostics?.sampleTexts, samplePrices: diag.diagnostics?.samplePrices });
      total += diag.prices.length;
      blocked = blocked || diag.blocked;
      if (diag.prices.length === 0 && page === 1) {
        await new Promise(r => setTimeout(r, 600));
      }
    }
    attempts.push({ query: q, totalCount: total, blocked, details: diagnostics });
    if (total > 0) break;
  }
  return { attempts };
}