import { BrowserWindow, nativeTheme } from "electron/main";
import type { BrowserWindow as ElectronBrowserWindow, Session } from "electron/main";
import type { Browser as PlaywrightBrowser, Page as PlaywrightPage } from "playwright-core";

import {
  isReclaimableHiddenPlaywrightTarget,
  type CDPTargetDescriptor,
} from "./playwright-cdp-targets";
import { STANDARD_USER_AGENT } from "./user-agent";

const hiddenPlaywrightIdleTTLms = 5 * 60_000;
const hiddenPlaywrightReaperIntervalMs = 60_000;
const defaultConnectTimeoutMs = 10_000;
const defaultPageTimeoutMs = 45_000;
const hiddenBootstrapMetaName = "geo-hidden-playwright-token";
const cdpPort = Number.parseInt(process.env.GEO_ELECTRON_CDP_PORT ?? "9339", 10);
const cdpEndpointURL = `http://127.0.0.1:${cdpPort}`;
const cdpTargetsListURL = `${cdpEndpointURL}/json/list`;

interface HiddenPlaywrightRecord {
  key: string;
  accountId: string;
  title: string;
  targetURL: string;
  window: ElectronBrowserWindow;
  browser: PlaywrightBrowser;
  page: PlaywrightPage;
  retainCount: number;
  activatedAt: number;
  lastReleasedAt: number | null;
}

export interface HiddenPlaywrightLease {
  accountId: string;
  browser: PlaywrightBrowser;
  page: PlaywrightPage;
  release(): Promise<void>;
}

const records = new Map<string, HiddenPlaywrightRecord>();
let reaperHandle: ReturnType<typeof setInterval> | null = null;
let connectPromise: Promise<PlaywrightBrowser> | null = null;
let connectedBrowser: PlaywrightBrowser | null = null;

export function getPlaywrightCDPPort(): number {
  return cdpPort;
}

export function startHiddenPlaywrightReaper(): void {
  if (reaperHandle) {
    return;
  }

  reaperHandle = setInterval(() => {
    reapIdleHiddenPlaywrightPages();
  }, hiddenPlaywrightReaperIntervalMs);
  reaperHandle.unref?.();
}

export async function retainHiddenPlaywrightPage(options: {
  accountId: string;
  session: Session;
  targetURL: string;
  title: string;
}): Promise<HiddenPlaywrightLease> {
  startHiddenPlaywrightReaper();

  const key = hiddenPlaywrightKey(options.accountId, options.targetURL);
  const existing = records.get(key);
  if (existing && !existing.window.isDestroyed() && !existing.page.isClosed()) {
    await ensureRecordTarget(existing, options.targetURL);
    existing.retainCount += 1;
    existing.activatedAt = Date.now();
    existing.lastReleasedAt = null;
    return createLease(existing);
  }

  const browser = await connectBrowserOverCDP();
  const knownPages = new Set(defaultContext(browser).pages());
  const bootstrapToken = createHiddenBootstrapToken();
  const bootstrapURL = buildHiddenWindowBootstrapURL(options.title, bootstrapToken);
  const window = createHiddenWindow(options.title, options.session, bootstrapURL);
  const page = await waitForNewPage(browser, knownPages, bootstrapToken);

  page.setDefaultTimeout(defaultPageTimeoutMs);
  page.setDefaultNavigationTimeout(defaultPageTimeoutMs);
  await page.goto(options.targetURL, {
    timeout: defaultPageTimeoutMs,
    waitUntil: "domcontentloaded",
  });

  const record: HiddenPlaywrightRecord = {
    key,
    accountId: options.accountId,
    title: options.title,
    targetURL: options.targetURL,
    window,
    browser,
    page,
    retainCount: 1,
    activatedAt: Date.now(),
    lastReleasedAt: null,
  };

  window.once("closed", () => {
    records.delete(key);
  });
  page.once("close", () => {
    records.delete(key);
  });

  records.set(key, record);
  return createLease(record);
}

export async function releaseHiddenPlaywrightPage(accountId: string, targetURL: string): Promise<void> {
  const key = hiddenPlaywrightKey(accountId, targetURL);
  const record = records.get(key);
  if (!record) {
    return;
  }

  if (record.retainCount > 0) {
    record.retainCount -= 1;
  }
  if (record.retainCount === 0) {
    record.lastReleasedAt = Date.now();
  }
}

export function reapIdleHiddenPlaywrightPages(
  now = Date.now(),
  idleTTLms = hiddenPlaywrightIdleTTLms,
): string[] {
  const reclaimed: string[] = [];

  for (const [key, record] of records.entries()) {
    if (record.retainCount > 0) {
      continue;
    }

    const idleSince = record.lastReleasedAt ?? record.activatedAt;
    if (now - idleSince < idleTTLms) {
      continue;
    }

    closeRecord(record);
    records.delete(key);
    reclaimed.push(key);
  }

  return reclaimed;
}

export function getHiddenPlaywrightSnapshot() {
  return {
    cdpPort,
    cdpEndpointURL,
    connected: Boolean(connectedBrowser?.isConnected()),
    pageCount: records.size,
    idleTTLms: hiddenPlaywrightIdleTTLms,
    records: [...records.values()].map((record) => ({
      accountId: record.accountId,
      title: record.title,
      targetURL: record.targetURL,
      retainCount: record.retainCount,
      activatedAt: record.activatedAt,
      lastReleasedAt: record.lastReleasedAt,
      windowDestroyed: record.window.isDestroyed(),
      pageClosed: record.page.isClosed(),
    })),
  };
}

function createLease(record: HiddenPlaywrightRecord): HiddenPlaywrightLease {
  return {
    accountId: record.accountId,
    browser: record.browser,
    page: record.page,
    release: () => releaseHiddenPlaywrightPage(record.accountId, record.targetURL),
  };
}

function createHiddenWindow(
  title: string,
  session: Session,
  bootstrapURL: string,
): ElectronBrowserWindow {
  const window = new BrowserWindow({
    show: false,
    width: 1320,
    height: 900,
    skipTaskbar: true,
    focusable: false,
    hiddenInMissionControl: true,
    autoHideMenuBar: true,
    backgroundColor: nativeTheme.shouldUseDarkColors ? "#15191a" : "#f4f1ea",
    title,
    webPreferences: {
      session,
      sandbox: true,
      contextIsolation: true,
      nodeIntegration: false,
      backgroundThrottling: false,
    },
  });

  window.webContents.setUserAgent(STANDARD_USER_AGENT);
  void window.loadURL(bootstrapURL);
  return window;
}

function createHiddenBootstrapToken(): string {
  if (typeof globalThis.crypto?.randomUUID === "function") {
    return globalThis.crypto.randomUUID();
  }
  return `${Date.now()}-${Math.random().toString(16).slice(2)}`;
}

function escapeHtml(value: string): string {
  return value
    .replaceAll("&", "&amp;")
    .replaceAll("<", "&lt;")
    .replaceAll(">", "&gt;")
    .replaceAll("\"", "&quot;")
    .replaceAll("'", "&#39;");
}

function buildHiddenWindowBootstrapURL(title: string, token: string): string {
  const html = [
    "<!doctype html>",
    "<html lang=\"en\">",
    "<head>",
    "  <meta charset=\"utf-8\">",
    `  <meta name=\"${hiddenBootstrapMetaName}\" content=\"${escapeHtml(token)}\">`,
    `  <title>${escapeHtml(title)} · hidden-playwright</title>`,
    "</head>",
    `  <body data-${hiddenBootstrapMetaName}=\"${escapeHtml(token)}\"></body>`,
    "</html>",
  ].join("");
  return `data:text/html;charset=utf-8,${encodeURIComponent(html)}`;
}

async function ensureRecordTarget(record: HiddenPlaywrightRecord, targetURL: string): Promise<void> {
  record.targetURL = targetURL;

  const currentURL = safePageURL(record.page);
  if (currentURL === targetURL) {
    return;
  }

  await record.page.goto(targetURL, {
    timeout: defaultPageTimeoutMs,
    waitUntil: "domcontentloaded",
  });
}

async function connectBrowserOverCDP(): Promise<PlaywrightBrowser> {
  if (connectedBrowser?.isConnected()) {
    return connectedBrowser;
  }
  if (connectPromise) {
    return connectPromise;
  }

  connectPromise = (async () => {
    await waitForCDPEndpoint();
    const { chromium } = await import("playwright-core");
    await pruneStaleCDPTargets();

    try {
      return await openBrowserOverCDP(chromium);
    } catch (error) {
      if (!isConnectOverCDPTimeout(error)) {
        throw error;
      }

      const prunedTargetCount = await pruneStaleCDPTargets();
      if (prunedTargetCount <= 0) {
        throw error;
      }

      return openBrowserOverCDP(chromium);
    }
  })();

  try {
    return await connectPromise;
  } finally {
    if (!connectedBrowser?.isConnected()) {
      connectPromise = null;
    }
  }
}

async function waitForCDPEndpoint(timeoutMs = defaultConnectTimeoutMs): Promise<void> {
  const startedAt = Date.now();
  while (Date.now() - startedAt < timeoutMs) {
    try {
      const response = await fetch(`${cdpEndpointURL}/json/version`);
      if (response.ok) {
        return;
      }
    } catch {
      // Ignore and continue polling.
    }

    await wait(200);
  }

  throw new Error("playwright_cdp_endpoint_unavailable");
}

async function openBrowserOverCDP(
  chromium: typeof import("playwright-core").chromium,
): Promise<PlaywrightBrowser> {
  const browser = await chromium.connectOverCDP(cdpEndpointURL, {
    timeout: defaultConnectTimeoutMs,
  });

  browser.on("disconnected", () => {
    connectedBrowser = null;
    connectPromise = null;
  });

  connectedBrowser = browser;
  return browser;
}

async function pruneStaleCDPTargets(): Promise<number> {
  let targets: CDPTargetDescriptor[] = [];
  try {
    const response = await fetch(cdpTargetsListURL);
    if (!response.ok) {
      return 0;
    }
    const payload = await response.json();
    if (Array.isArray(payload)) {
      targets = payload as CDPTargetDescriptor[];
    }
  } catch {
    return 0;
  }

  let closedCount = 0;
  for (const target of targets) {
    if (!isReclaimableHiddenPlaywrightTarget(target)) {
      continue;
    }

    try {
      const closeURL = `${cdpEndpointURL}/json/close/${encodeURIComponent(target.id ?? "")}`;
      const response = await fetch(closeURL);
      if (response.ok) {
        closedCount += 1;
      }
    } catch {
      // Ignore best-effort stale target cleanup failures.
    }
  }

  if (closedCount > 0) {
    await wait(150);
  }
  return closedCount;
}

function isConnectOverCDPTimeout(error: unknown): boolean {
  return error instanceof Error
    && error.name === "TimeoutError"
    && error.message.includes("connectOverCDP");
}

async function waitForNewPage(
  browser: PlaywrightBrowser,
  knownPages: Set<PlaywrightPage>,
  bootstrapToken: string,
): Promise<PlaywrightPage> {
  const context = defaultContext(browser);
  const startedAt = Date.now();

  while (Date.now() - startedAt < defaultPageTimeoutMs) {
    const nextPages = context.pages().filter((page) => !knownPages.has(page));
    for (const nextPage of nextPages) {
      if (isDevtoolsPage(nextPage)) {
        knownPages.add(nextPage);
        continue;
      }
      if (await matchesHiddenBootstrapPage(nextPage, bootstrapToken)) {
        return nextPage;
      }
    }
    await wait(100);
  }

  throw new Error("playwright_hidden_page_unavailable");
}

async function matchesHiddenBootstrapPage(
  page: PlaywrightPage,
  bootstrapToken: string,
): Promise<boolean> {
  const url = safePageURL(page);
  if (url.includes(bootstrapToken) || url.includes(encodeURIComponent(bootstrapToken))) {
    return true;
  }

  try {
    return await page.evaluate(
      ({ token, metaName }) => {
        const metaToken =
          document.querySelector(`meta[name="${metaName}"]`)?.getAttribute("content")
          ?? document.body?.getAttribute(`data-${metaName}`)
          ?? null;
        return metaToken === token;
      },
      {
        token: bootstrapToken,
        metaName: hiddenBootstrapMetaName,
      },
    );
  } catch {
    return false;
  }
}

function defaultContext(browser: PlaywrightBrowser) {
  const context = browser.contexts()[0];
  if (!context) {
    throw new Error("playwright_default_context_unavailable");
  }
  return context;
}

function hiddenPlaywrightKey(accountId: string, targetURL: string): string {
  return `${accountId}::${targetURL}`;
}

function safePageURL(page: PlaywrightPage): string {
  try {
    return page.url();
  } catch {
    return "";
  }
}

function isDevtoolsPage(page: PlaywrightPage): boolean {
  const url = safePageURL(page);
  return url.startsWith("devtools://");
}

function closeRecord(record: HiddenPlaywrightRecord): void {
  if (!record.window.isDestroyed()) {
    record.window.close();
  }
}

function wait(timeMs: number): Promise<void> {
  return new Promise((resolve) => {
    setTimeout(resolve, timeMs);
  });
}