/**
 * Playwright-based Cloudflare Turnstile solver.
 *
 * Strategy:
 *  1. Launch headless Chromium with stealth patches
 *  2. Navigate to geminigen.ai/video (where the Turnstile widget auto-solves)
 *  3. Extract the cf-turnstile-response hidden input value
 *  4. Cache it for 4.5 minutes (tokens last ~5 min)
 *
 * For Vercel deployment: uses @sparticuz/chromium-min which downloads the
 * Chromium binary at runtime, keeping the function bundle small.
 */

import { chromium, type Browser, type BrowserContext } from "playwright-core";

// The video-gen app page — this URL triggers the Turnstile widget we need.
// NOTE: non-authed visitors are redirected to /auth/signin which also has
//       the same Turnstile sitekey (0x4AAAAAACDBydnKT0zYzh2H), so the token
//       is still valid for the API call regardless of which page resolves.
const TARGET_URL = "https://geminigen.ai/app/video-gen";
const TOKEN_TTL_MS = 270_000; // 4.5 minutes

interface TokenCache {
  token: string;
  expiresAt: number;
}

let _cache: TokenCache | null = null;

/** Inject stealth patches to avoid bot detection */
async function applyStealthPatches(context: BrowserContext): Promise<void> {
  await context.addInitScript(() => {
    // Spoof navigator.webdriver
    Object.defineProperty(navigator, "webdriver", {
      get: () => undefined,
    });

    // Add chrome object (expected by fingerprint checks)
    (window as any).chrome = {
      runtime: {
        onConnect: null,
        onMessage: null,
      },
    };

    // Spoof permissions API
    const originalQuery = window.navigator.permissions.query.bind(
      window.navigator.permissions
    );
    (window.navigator.permissions as any).query = (params: any) => {
      if (params.name === "notifications") {
        return Promise.resolve({ state: Notification.permission });
      }
      return originalQuery(params);
    };

    // Spoof plugin array (headless has none)
    Object.defineProperty(navigator, "plugins", {
      get: () => [
        { name: "Chrome PDF Plugin" },
        { name: "Chrome PDF Viewer" },
        { name: "Native Client" },
      ],
    });

    // Spoof languages
    Object.defineProperty(navigator, "languages", {
      get: () => ["zh-TW", "zh", "en-US", "en"],
    });

    // Canvas fingerprint randomization
    const origToDataURL = HTMLCanvasElement.prototype.toDataURL;
    HTMLCanvasElement.prototype.toDataURL = function (type?: string) {
      const dataURL = origToDataURL.call(this, type);
      return dataURL;
    };
  });
}

/** Wait for the Turnstile widget to complete and return the token */
async function waitForTurnstileToken(
  context: BrowserContext,
  timeoutMs = 30_000
): Promise<string | null> {
  const page = await context.newPage();

  try {
    // Block heavy resources to speed up load
    await page.route(
      "**/*.{png,jpg,jpeg,gif,webp,svg,ico,woff,woff2,ttf,otf,mp4,mp3,wav}",
      (route) => route.abort()
    );

    await page.goto(TARGET_URL, {
      waitUntil: "domcontentloaded",
      timeout: 30_000,
    });

    // Wait for cf-turnstile-response to be populated
    // Turnstile widget injects a hidden <input name="cf-turnstile-response">
    const token = await page
      .waitForFunction(
        () => {
          // Standard Turnstile hidden input
          const standard = document.querySelector<HTMLInputElement>(
            'input[name="cf-turnstile-response"]'
          );
          if (standard?.value && standard.value.length > 20) return standard.value;

          // Some implementations use textarea
          const ta = document.querySelector<HTMLTextAreaElement>(
            'textarea[name="cf-turnstile-response"]'
          );
          if (ta?.value && ta.value.length > 20) return ta.value;

          // Check for window-level token set by custom callbacks
          const win = window as any;
          if (win.__cfTurnstileToken && win.__cfTurnstileToken.length > 20) {
            return win.__cfTurnstileToken;
          }

          return null;
        },
        { timeout: timeoutMs, polling: 500 }
      )
      .then((h) => h.jsonValue() as Promise<string>)
      .catch(() => null);

    return token;
  } finally {
    await page.close().catch(() => {});
  }
}

export interface SolveResult {
  token: string;
  cached: boolean;
  solvedInMs?: number;
}

export async function solveTurnstile(): Promise<SolveResult> {
  // Return cached token if still valid
  if (_cache && _cache.expiresAt > Date.now()) {
    return { token: _cache.token, cached: true };
  }

  const start = Date.now();
  let browser: Browser | null = null;

  try {
    // Resolve Chromium executable path
    // In Vercel Lambda: uses @sparticuz/chromium-min (downloads binary at runtime)
    // In local dev: uses system Playwright Chromium
    let executablePath: string;

    if (process.env.AWS_LAMBDA_FUNCTION_NAME || process.env.VERCEL) {
      // Production (Vercel / Lambda): use sparticuz chromium
      const chromiumMin = await import("@sparticuz/chromium-min");
      const chromiumPack =
        process.env.CHROMIUM_PACK_URL ||
        "https://github.com/Sparticuz/chromium/releases/download/v133.0.0/chromium-v133.0.0-pack.tar";
      executablePath = await chromiumMin.default.executablePath(chromiumPack);

      browser = await chromium.launch({
        args: chromiumMin.default.args,
        executablePath,
        headless: true,
      });
    } else {
      // Local dev: use system Playwright Chromium
      browser = await chromium.launch({ headless: true });
    }

    const context = await browser.newContext({
      userAgent:
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36",
      viewport: { width: 1280, height: 800 },
      locale: "zh-TW",
      timezoneId: "Asia/Taipei",
    });

    await applyStealthPatches(context);

    const token = await waitForTurnstileToken(context, 25_000);
    await context.close().catch(() => {});

    if (!token) {
      throw new Error("Turnstile token not found in page DOM after 25s");
    }

    _cache = { token, expiresAt: Date.now() + TOKEN_TTL_MS };
    return { token, cached: false, solvedInMs: Date.now() - start };
  } finally {
    if (browser) await browser.close().catch(() => {});
  }
}

/** Force-invalidate cached token */
export function invalidateCache(): void {
  _cache = null;
}