import fs from "node:fs/promises";
import path from "node:path";
import { createRequire } from "node:module";
import {
  AssetInliner,
  DEFAULT_USER_AGENT,
  defaultArchivePath,
  findEffectiveBase,
  htmlEscape,
  inputToUrl,
  isFileUrl,
  isHttpUrl,
  slugForUrl,
  stripArchiveShell
} from "./asset-inliner.mjs";

const require = createRequire(import.meta.url);

export { DEFAULT_USER_AGENT, defaultArchivePath };

const AD_SELECTORS = [
  "[data-ad-status]",
  "[data-ad-type]",
  "[aria-label*='advertisement' i]",
  "[id^='leaderboard']",
  "[class*='LeaderboardAd_']",
  "[class*='FullWidthAd_']",
  "[class*='BaseAd_']",
  ".adWrapper",
  ".dvz-v0-ad",
  "amp-ad",
  "iframe[src*='doubleclick']",
  "iframe[src*='googletagmanager']",
  "iframe[src*='googlesyndication']"
];

const TRACKER_HOST_PATTERNS = [
  "doubleclick.net",
  "googletagmanager.com",
  "googlesyndication.com",
  "google-analytics.com",
  "pub.doubleverify.com",
  "securepubads.g.doubleclick.net",
  "s10.histats.com",
  "sstatic1.histats.com"
];

export async function archivePage(input, options = {}) {
  const sourceUrl = inputToUrl(input);
  const archivePath = options.archivePath || defaultArchivePath();
  const id = options.id || slugForUrl(sourceUrl);
  const filePath = path.join(archivePath, `${id}.html`);
  await fs.mkdir(archivePath, { recursive: true });

  const rawHtml = await readInputHtml(sourceUrl, options);
  const baseUrl = rawHtml ? findEffectiveBase(rawHtml, sourceUrl) : sourceUrl;
  const useStatic = options.static || (isFileUrl(sourceUrl) && options.stripArchiveShell && options.render !== true);
  const renderedHtml = useStatic
    ? prepareStaticHtml(rawHtml, options)
    : await renderPage(sourceUrl, { ...options, rawHtml, baseUrl });

  const inliner = new AssetInliner({
    userAgent: options.userAgent || DEFAULT_USER_AGENT,
    referer: isHttpUrl(sourceUrl) ? sourceUrl : undefined,
    maxAssetBytes: options.maxAssetBytes
  });
  const inlined = await inliner.inlineHtml(renderedHtml, baseUrl);
  const finalHtml = addArchiveComment(inlined, sourceUrl, options);
  await fs.writeFile(filePath, finalHtml, "utf8");

  return {
    id,
    filePath,
    sourceUrl,
    archivePath,
    warnings: inliner.warnings,
    externalAssets: findExternalAssetRefs(finalHtml)
  };
}

export async function readInputHtml(sourceUrl, options = {}) {
  if (isFileUrl(sourceUrl)) {
    return fs.readFile(new URL(sourceUrl), "utf8");
  }
  if (!isHttpUrl(sourceUrl) || !options.static) {
    return null;
  }
  const response = await fetch(sourceUrl, {
    headers: {
      "user-agent": options.userAgent || DEFAULT_USER_AGENT,
      accept: "text/html,application/xhtml+xml"
    },
    redirect: "follow"
  });
  if (!response.ok) {
    throw new Error(`Failed to fetch ${sourceUrl}: HTTP ${response.status}`);
  }
  return response.text();
}

function prepareStaticHtml(rawHtml, options = {}) {
  if (!rawHtml) {
    throw new Error("Static mode requires an HTML input file or fetched HTML document.");
  }
  return options.stripArchiveShell ? stripArchiveShell(rawHtml) : rawHtml;
}

export async function renderPage(sourceUrl, options = {}) {
  const playwright = loadPlaywright();
  const browser = await playwright.chromium.launch({
    headless: true
  });
  try {
    const context = await browser.newContext({
      javaScriptEnabled: options.javaScriptEnabled ?? !(options.rawHtml && isFileUrl(sourceUrl)),
      userAgent: options.userAgent || DEFAULT_USER_AGENT,
      viewport: {
        width: options.viewportWidth || 1024,
        height: options.viewportHeight || 768
      }
    });
    const page = await context.newPage();

    if (options.stripAds !== false) {
      await page.route("**/*", (route) => {
        const url = route.request().url();
        if (isTrackerUrl(url)) {
          return route.abort();
        }
        return route.continue();
      });
    }

    if (options.rawHtml && isFileUrl(sourceUrl)) {
      const content = prepareRenderInputHtml(options.rawHtml, options);
      await page.setContent(content, { waitUntil: "domcontentloaded", timeout: options.timeoutMs || 60000 });
    } else {
      await page.goto(sourceUrl, { waitUntil: "domcontentloaded", timeout: options.timeoutMs || 60000 });
    }

    await settlePage(page, options);
    await cleanupAndFreezePage(page, options);
    return await page.content();
  } finally {
    await browser.close();
  }
}

async function settlePage(page, options) {
  try {
    await page.waitForLoadState("networkidle", { timeout: options.networkIdleTimeoutMs || 15000 });
  } catch {
    // Dynamic pages often keep long-lived connections open; DOM capture can still proceed.
  }

  if (options.scroll !== false) {
    await page.evaluate(async () => {
      await new Promise((resolve) => {
        let total = 0;
        const step = Math.max(400, Math.floor(window.innerHeight * 0.8));
        const timer = setInterval(() => {
          const previous = document.scrollingElement?.scrollTop || window.scrollY;
          window.scrollBy(0, step);
          total += step;
          const current = document.scrollingElement?.scrollTop || window.scrollY;
          if (current === previous || total > Math.max(document.body.scrollHeight, 20000)) {
            clearInterval(timer);
            window.scrollTo(0, 0);
            resolve();
          }
        }, 120);
      });
    });
  }
}

async function cleanupAndFreezePage(page, options) {
  await page.evaluate(
    ({
      adSelectors,
      freezeStyles,
      maxFreezeElements,
      maxSanitizeElements,
      stripAds,
      stripArchiveShell: shouldStripArchiveShell
    }) => {
      function removeAll(selector) {
        document.querySelectorAll(selector).forEach((node) => node.remove());
      }

      if (shouldStripArchiveShell) {
        const content = document.querySelector("#CONTENT .html1") || document.querySelector("#CONTENT");
        if (content) {
          document.body.innerHTML = "";
          document.body.appendChild(content.cloneNode(true));
          document.documentElement.removeAttribute("prefix");
          document.documentElement.removeAttribute("itemscope");
          document.documentElement.removeAttribute("itemtype");
        }
      }

      removeAll("script");
      removeAll("noscript");
      removeAll("link[rel='preconnect'],link[rel='dns-prefetch'],link[rel='modulepreload']");
      removeAll("meta[name='next-head-count']");

      if (stripAds) {
        for (const selector of adSelectors) {
          try {
            removeAll(selector);
          } catch {
            // Ignore unsupported selectors in older browser engines.
          }
        }
      }

      document.querySelectorAll("img").forEach((img) => {
        if (img.currentSrc) {
          img.setAttribute("data-original-src", img.getAttribute("src") || "");
          img.setAttribute("src", img.currentSrc);
        }
        img.removeAttribute("srcset");
        img.removeAttribute("sizes");
        img.setAttribute("loading", "lazy");
      });

      document.querySelectorAll("source").forEach((source) => {
        source.removeAttribute("srcset");
      });

      document.querySelectorAll("video,audio").forEach((media) => {
        if (media.currentSrc) {
          media.setAttribute("src", media.currentSrc);
        }
      });

      document.querySelectorAll("iframe").forEach((frame) => {
        const src = frame.getAttribute("src");
        if (src) {
          frame.setAttribute("data-archived-src", src);
        }
        try {
          const doc = frame.contentDocument;
          if (doc?.documentElement) {
            frame.setAttribute("srcdoc", "<!doctype html>" + doc.documentElement.outerHTML);
            frame.removeAttribute("src");
          }
        } catch {
          // Cross-origin iframe sources are handled in the Node-side inliner when possible.
        }
      });

      const walkedElements = [];
      const walker = document.createTreeWalker(document.documentElement, NodeFilter.SHOW_ELEMENT);
      let element = document.documentElement;
      let visited = 0;
      while (element && visited < maxSanitizeElements) {
        walkedElements.push(element);
        for (const attr of Array.from(element.attributes)) {
          if (/^on/i.test(attr.name) || attr.name === "integrity" || attr.name === "nonce") {
            element.removeAttribute(attr.name);
          }
        }
        visited += 1;
        element = walker.nextNode();
      }

      if (!freezeStyles || element || walkedElements.length > maxFreezeElements) {
        return;
      }

      for (const element of walkedElements) {
        if (element.tagName === "SCRIPT" || element.tagName === "STYLE") {
          continue;
        }
        const computed = window.getComputedStyle(element);
        const declarations = [];
        for (let i = 0; i < computed.length; i += 1) {
          const property = computed[i];
          const value = computed.getPropertyValue(property);
          if (value) {
            declarations.push(`${property}:${value}`);
          }
        }
        if (declarations.length) {
          element.setAttribute("style", declarations.join(";"));
        }
      }
    },
    {
      adSelectors: AD_SELECTORS,
      freezeStyles: options.freezeStyles !== false,
      maxFreezeElements: options.maxFreezeElements || 2500,
      maxSanitizeElements: options.maxSanitizeElements || 5000,
      stripAds: options.stripAds !== false,
      stripArchiveShell: Boolean(options.stripArchiveShell)
    }
  );
}

function prepareRenderInputHtml(rawHtml, options) {
  let html = options.stripArchiveShell ? stripArchiveShell(rawHtml) : rawHtml;
  html = html
    .replace(/<script\b[\s\S]*?<\/script>/gi, "")
    .replace(/<noscript\b[\s\S]*?<\/noscript>/gi, "");
  if (!options.baseUrl) {
    return html;
  }
  if (/<base\b/i.test(html)) {
    return html;
  }
  const baseTag = `<base href="${htmlEscape(options.baseUrl)}">`;
  if (/<head\b[^>]*>/i.test(html)) {
    return html.replace(/<head\b[^>]*>/i, (match) => `${match}${baseTag}`);
  }
  return `${baseTag}${html}`;
}

function loadPlaywright() {
  try {
    return require("playwright");
  } catch (error) {
    throw new Error(
      `Playwright is required for render mode. Run "npm install" and "npm run install-browsers", or use --static for HTML input files. Original error: ${error.message}`
    );
  }
}

function isTrackerUrl(rawUrl) {
  let host = "";
  try {
    host = new URL(rawUrl).hostname;
  } catch {
    return false;
  }
  return TRACKER_HOST_PATTERNS.some((pattern) => host === pattern || host.endsWith(`.${pattern}`));
}

function addArchiveComment(html, sourceUrl, options) {
  const comment = `<!-- Archived locally. Source: ${sourceUrl}. Created: ${new Date().toISOString()}. Paywall bypass filters were not executed. -->`;
  if (/<!doctype/i.test(html)) {
    return html.replace(/<!doctype[^>]*>/i, (doctype) => `${doctype}\n${comment}`);
  }
  return `<!doctype html>\n${comment}\n${html}`;
}

export function findExternalAssetRefs(html) {
  const refs = new Set();
  const attrPattern = /\b(?:src|srcset|poster|data)\s*=\s*(["'])([\s\S]*?)\1/gi;
  for (const match of html.matchAll(attrPattern)) {
    if (isSelfContainedAssetRef(match[2])) {
      continue;
    }
    for (const part of match[2].split(",")) {
      const candidate = part.trim().split(/\s+/)[0];
      if (candidate && !isSelfContainedAssetRef(candidate)) {
        refs.add(candidate);
      }
    }
  }
  const linkPattern = /<link\b[^>]*>/gi;
  for (const match of html.matchAll(linkPattern)) {
    const tag = match[0];
    const rel = readAttribute(tag, "rel") || "";
    if (!/\b(?:stylesheet|icon|apple-touch-icon|image_src|preload)\b/i.test(rel)) {
      continue;
    }
    const href = readAttribute(tag, "href");
    if (href && !isSelfContainedAssetRef(href)) {
      refs.add(href);
    }
  }
  const cssUrlPattern = /url\(\s*(["']?)([^"')]+)\1\s*\)/gi;
  for (const match of html.matchAll(cssUrlPattern)) {
    const candidate = match[2].trim();
    if (candidate && !isSelfContainedAssetRef(candidate)) {
      refs.add(candidate);
    }
  }
  return Array.from(refs).sort();
}

function isSelfContainedAssetRef(value) {
  const trimmed = value.trim();
  return (
    !trimmed ||
    trimmed.startsWith("#") ||
    /^(?:data|about|javascript|mailto|tel):/i.test(trimmed)
  );
}

function readAttribute(tag, attr) {
  const match = tag.match(new RegExp(`\\b${attr}\\s*=\\s*("([^"]*)"|'([^']*)'|([^\\s>]+))`, "i"));
  return match ? match[2] ?? match[3] ?? match[4] ?? "" : "";
}