import { isWechatMiniProgramRuntime } from './payment/paymentPlatform';

const WECHAT_JS_SDK_URL = 'https://res.wx.qq.com/open/js/jweixin-1.6.0.js';
const SUBSCRIBE_RESULT_HASH_KEY = 'wx_subscribe_result';
const SUBSCRIBE_RESULT_TIMEOUT_MS = 30_000;
const SUBSCRIBE_RESULT_RETURN_FALLBACK_MS = 800;

function clearSubscribeResultHash() {
  const rawHash = window.location.hash.replace(/^#/, '');
  if (!rawHash.includes(`${SUBSCRIBE_RESULT_HASH_KEY}=`)) {
    return;
  }

  const params = new URLSearchParams(rawHash);
  params.delete(SUBSCRIBE_RESULT_HASH_KEY);
  const nextHash = params.toString();
  window.history.replaceState(
    null,
    '',
    `${window.location.pathname}${window.location.search}${nextHash ? `#${nextHash}` : ''}`,
  );
}

function readSubscribeResultFromHash() {
  const value = new URLSearchParams(window.location.hash.replace(/^#/, '')).get(
    SUBSCRIBE_RESULT_HASH_KEY,
  );
  if (!value) {
    return null;
  }
  clearSubscribeResultHash();
  return value;
}

function waitSubscribeResultFromHash(timeoutMs = SUBSCRIBE_RESULT_TIMEOUT_MS) {
  const immediateResult = readSubscribeResultFromHash();
  if (immediateResult) {
    return Promise.resolve(immediateResult);
  }

  return new Promise<string | null>((resolve) => {
    let timer: number | null = null;
    let resumeFallbackTimer: number | null = null;
    const cleanup = () => {
      window.removeEventListener('hashchange', handleHashChange);
      window.removeEventListener('focus', handleResume);
      window.removeEventListener('pageshow', handleResume);
      document.removeEventListener('visibilitychange', handleResume);
      if (timer !== null) {
        window.clearTimeout(timer);
      }
      if (resumeFallbackTimer !== null) {
        window.clearTimeout(resumeFallbackTimer);
      }
    };
    const finish = (result: string | null) => {
      cleanup();
      resolve(result);
    };
    const consume = () => {
      const result = readSubscribeResultFromHash();
      if (result) {
        finish(result);
        return true;
      }
      return false;
    };
    const handleHashChange = () => {
      consume();
    };
    const handleResume = () => {
      if (
        typeof document !== 'undefined' &&
        document.visibilityState === 'hidden'
      ) {
        return;
      }
      if (consume()) {
        return;
      }
      // 中文注释：订阅授权只影响后续通知，不应阻断生成；原生页返回但没有 hash
      // 回灌时，按已返回处理，让原本的生成提交流程继续执行。
      if (resumeFallbackTimer === null) {
        resumeFallbackTimer = window.setTimeout(
          () => finish('returned'),
          SUBSCRIBE_RESULT_RETURN_FALLBACK_MS,
        );
      }
    };

    window.addEventListener('hashchange', handleHashChange);
    window.addEventListener('focus', handleResume);
    window.addEventListener('pageshow', handleResume);
    document.addEventListener('visibilitychange', handleResume);
    timer = window.setTimeout(() => finish(null), timeoutMs);
  });
}

function loadWechatJsSdk() {
  if (
    !isWechatMiniProgramRuntime() ||
    typeof window === 'undefined'
  ) {
    return Promise.reject(new Error('not_mini_program'));
  }
  if (window.wx?.miniProgram?.navigateTo) {
    return Promise.resolve(window.wx);
  }

  return new Promise<NonNullable<Window['wx']>>((resolve, reject) => {
    const existingScript = document.querySelector<HTMLScriptElement>(
      `script[src="${WECHAT_JS_SDK_URL}"]`,
    );
    const complete = () => {
      if (window.wx?.miniProgram?.navigateTo) {
        resolve(window.wx);
      } else {
        reject(new Error('wechat_js_sdk_unavailable'));
      }
    };

    if (existingScript) {
      existingScript.addEventListener('load', complete, { once: true });
      existingScript.addEventListener('error', () => reject(new Error('wechat_js_sdk_load_failed')), {
        once: true,
      });
      complete();
      return;
    }

    const script = document.createElement('script');
    script.src = WECHAT_JS_SDK_URL;
    script.async = true;
    script.onload = complete;
    script.onerror = () => reject(new Error('wechat_js_sdk_load_failed'));
    document.head.appendChild(script);
  });
}

export async function requestGenerationResultSubscribePermission() {
  if (!isWechatMiniProgramRuntime() || typeof window === 'undefined') {
    return false;
  }

  let wxBridge: NonNullable<Window['wx']>;
  try {
    wxBridge = await loadWechatJsSdk();
  } catch {
    return false;
  }

  const miniProgram = wxBridge.miniProgram;
  if (!miniProgram || typeof miniProgram.navigateTo !== 'function') {
    return false;
  }

  const requestId = `subscribe_generation_result_${Date.now()}`;
  const navigated = await new Promise<boolean>((resolve) => {
    miniProgram.navigateTo?.({
      url: `/pages/subscribe-message/index?requestId=${encodeURIComponent(requestId)}&scene=generation-result&autoRequest=1`,
      success() {
        resolve(true);
      },
      fail() {
        resolve(false);
      },
    });
  });
  if (!navigated) {
    return false;
  }
  const resultPromise = waitSubscribeResultFromHash();
  const result = await resultPromise;
  return Boolean(result);
}