import { HTMLElement, parse } from "node-html-parser";

import { parseMoney, parseRating, parseReviewCount, parseStarBreakdown } from "./parsers.js";
import type { DeliverySummary, ProductSearchResult, ProductSpec } from "./types.js";

function textOf(node: HTMLElement | null | undefined): string {
  return cleanText(node?.textContent ?? "");
}

function attrOf(node: HTMLElement | null | undefined, name: string): string {
  return cleanText(node?.getAttribute(name) ?? "");
}

function cleanText(text: string): string {
  return text
    .replace(/\s+/g, " ")
    .replace(/\s*\{".*$/g, "")
    .trim();
}

function isScriptLike(text: string): boolean {
  return /\(function\s*\(|window\.|P\.when|ue\.count|tracking\(\)|logShoppableMetrics|buying options|add to cart/i.test(text);
}

function firstText(root: HTMLElement, selectors: string[]): string {
  for (const selector of selectors) {
    const text = textOf(root.querySelector(selector));
    if (text) {
      return text;
    }
  }
  return "";
}

function extractBullets(root: HTMLElement): string[] {
  const spanBullets = root.querySelectorAll("#feature-bullets li span")
    .map((node) => textOf(node))
    .filter((text) => text && !/make sure this fits/i.test(text));
  if (spanBullets.length > 0) {
    return spanBullets;
  }
  return root.querySelectorAll("#feature-bullets li")
    .map((node) => textOf(node))
    .filter((text) => text && !/make sure this fits/i.test(text));
}

function extractSpecs(root: HTMLElement): ProductSpec[] {
  const specs: ProductSpec[] = [];
  const seen = new Set<string>();
  const excludedNames = new Set(["customer reviews"]);
  for (const row of root.querySelectorAll("tr")) {
    const cells = row.querySelectorAll("th,td").map((cell) => textOf(cell)).filter(Boolean);
    if (cells.length >= 2) {
      const name = cells[0];
      const value = cells.slice(1).join(" ");
      const key = name.toLowerCase();
      if (seen.has(key) || excludedNames.has(key) || isScriptLike(name) || isScriptLike(value)) {
        continue;
      }
      seen.add(key);
      specs.push({ name, value });
    }
  }
  return specs;
}

function extractHistogramText(root: HTMLElement): string {
  const rows = root.querySelectorAll("#histogramTable tr, [aria-label*='star'] tr");
  const parts: string[] = [];
  for (const row of rows) {
    const cells = row.querySelectorAll("th,td").map((cell) => textOf(cell)).filter(Boolean);
    if (cells.length >= 2) {
      parts.push(`${cells[0]} ${cells[1]}`);
    }
  }
  return parts.join(" ");
}

function deliveryFromText(text: string, primeSignal = false): DeliverySummary | undefined {
  const display = text.replace(/\s+/g, " ").trim();
  if (!display) {
    return primeSignal ? { display: "Prime delivery available", prime: true } : undefined;
  }
  return {
    display,
    free: /\bfree\b/i.test(display),
    prime: primeSignal || /\bprime\b/i.test(display)
  };
}

function hasPrimeSignal(root: HTMLElement): boolean {
  const attributeText = root.querySelectorAll("[id], [class], [aria-label], img[alt]")
    .map((node) => [
      attrOf(node, "id"),
      attrOf(node, "class"),
      attrOf(node, "aria-label"),
      attrOf(node, "alt")
    ].join(" "))
    .join(" ");
  return /a-icon-prime|prime-logo|primeExclusive|primePopover|amazon\s+prime|\bprime\b/i.test(attributeText);
}

function mergeDelivery(detail: DeliverySummary | undefined, base: DeliverySummary | undefined): DeliverySummary | undefined {
  if (!detail) {
    return base;
  }
  if (!base) {
    return detail;
  }
  return {
    display: detail.display || base.display,
    free: Boolean(detail.free || base.free),
    prime: Boolean(detail.prime || base.prime),
    fastestDate: detail.fastestDate ?? base.fastestDate
  };
}

export function extractDetailPage(html: string, base: ProductSearchResult): ProductSearchResult {
  const root = parse(html);
  const title = firstText(root, ["#productTitle", "h1"]) || base.title;
  const priceText = firstText(root, [
    "#corePriceDisplay_desktop_feature_div .a-offscreen",
    ".a-price .a-offscreen",
    ".a-price"
  ]);
  const deliveryText = firstText(root, [
    "#mir-layout-DELIVERY_BLOCK-slot-PRIMARY_DELIVERY_MESSAGE_LARGE",
    "#deliveryBlockMessage",
    "[data-csa-c-delivery-price]"
  ]);
  const availability = firstText(root, ["#availability", "#availabilityInsideBuyBox_feature_div"]);
  const seller = firstText(root, ["#merchant-info", "#sellerProfileTriggerId"]);
  const ratingText = attrOf(root.querySelector("#acrPopover"), "title") || textOf(root.querySelector("#acrPopover"));
  const reviewText = textOf(root.querySelector("#acrCustomerReviewText"));
  const histogram = parseStarBreakdown(extractHistogramText(root));

  const product: ProductSearchResult = {
    ...base,
    title,
    price: parseMoney(priceText) ?? base.price,
    rating: parseRating(ratingText) ?? base.rating,
    reviewCount: parseReviewCount(reviewText) ?? base.reviewCount,
    delivery: mergeDelivery(deliveryFromText(deliveryText, hasPrimeSignal(root)), base.delivery),
    availability: availability || base.availability,
    seller: seller || base.seller,
    bullets: extractBullets(root),
    specs: extractSpecs(root),
    starBreakdown: histogram ?? base.starBreakdown,
    missingFields: [...base.missingFields],
    extractionNotes: [...base.extractionNotes]
  };

  for (const field of ["price", "delivery", "rating", "reviewCount", "starBreakdown"] as const) {
    if (product[field] === undefined && !product.missingFields.includes(field)) {
      product.missingFields.push(field);
    }
  }

  return product;
}