"use client";

import { useEffect, useRef, useState } from "react";
import Image from "next/image";
import { useRouter } from "next/navigation";

import { useAuthState } from "@/stores/auth/auth-context";
import type { LoginStatus } from "@/data/dto/auth";
import { AppStorage } from "@/data/storage/app/app_storage";
import { AuthStorage } from "@/data/storage/auth/auth_storage";
import { UserStorage } from "@/data/storage/user/user_storage";
import { useChatDispatch, useChatState } from "@/stores/chat/chat-context";
import { AppEnvUtil, BrowserDetector, todayString, UrlLauncherUtil } from "@/utils";
import { ROUTE_BUILDERS, ROUTES } from "@/router/routes";

import { MobileShell } from "@/app/_components/core";

import {
  BrowserHintOverlay,
  ChatArea,
  ChatHeader,
  ChatInputBar,
  ChatQuotaExhaustedBanner,
  ExternalBrowserDialog,
  PwaInstallOverlay,
} from "./components";
import styles from "./components/chat-screen.module.css";


/**
 * 派生 isGuest —— 单一来源：`auth.loginStatus`
 */
function deriveIsGuest(loginStatus: LoginStatus): boolean {
  return loginStatus === "guest";
}

export function ChatScreen() {
  const state = useChatState();
  const chatDispatch = useChatDispatch();
  const authState = useAuthState();
  const router = useRouter();
  const [showExternalBrowserDialog, setShowExternalBrowserDialog] =
    useState(false);

  // isGuest 派生（chat-screen 是唯一知道这个值的地方 —— chat 机器无 isGuest 字段）
  const isGuest = deriveIsGuest(authState.loginStatus);

  // 消息数量限制由后端统一返回 blocked，前端不再处理本地额度。
  const showMessageLimitBanner =
    state.paywallTriggered &&
    (state.paywallReason === "daily_limit" ||
      state.paywallReason === "total_limit");
  const messageLimitTitle =
    state.paywallReason === "total_limit"
      ? "The limit for free chat times\nhas been reached"
      : undefined;
  const messageLimitCta = isGuest ? "Log in to continue chatting" : undefined;
  const showPhotoPaywallBanner =
    state.paywallTriggered && state.paywallReason === "photo_paywall";
  const showPrivatePaywallBanner =
    state.paywallTriggered && state.paywallReason === "private_paywall";
  const showInlineUpgradeBanner =
    showPhotoPaywallBanner || showPrivatePaywallBanner;
  const inlineUpgradeTitle = showPrivatePaywallBanner
    ? "Unlock VIP to view private messages"
    : "Unlock VIP to view Elio's photos";
  const inlineUpgradeCta = showPrivatePaywallBanner
    ? "Activate VIP to view private messages"
    : "Activate VIP to view photos";

  const externalBrowserPromptShownRef = useRef(false);

  useEffect(() => {
    if (!authState.hasInitialized || authState.isLoading) return;
    const isDev = AppEnvUtil.isDevelopment();
    const canTriggerPrompt =
      isDev ||
      (authState.loginStatus === "facebook" && BrowserDetector.isInAppBrowser());
    if (!canTriggerPrompt) return;

    let mounted = true;
    let timer: number | undefined;

    const init = async () => {
      if (externalBrowserPromptShownRef.current) return;

      const today = todayString();
      const canShowResult = await AppStorage.canShowExternalBrowserDialog(today);
      if (!mounted || !canShowResult.success || !canShowResult.data) return;

      externalBrowserPromptShownRef.current = true;
      timer = window.setTimeout(() => {
        if (!mounted) return;
        setShowExternalBrowserDialog(true);
        void AppStorage.recordExternalBrowserDialogShown(today);
      }, 3000);
    };

    void init();

    return () => {
      mounted = false;
      if (timer !== undefined) window.clearTimeout(timer);
    };
  }, [
    authState.hasInitialized,
    authState.isLoading,
    authState.loginStatus,
  ]);

  async function handleOpenExternalBrowser(): Promise<void> {
    setShowExternalBrowserDialog(false);

    const authStorage = AuthStorage.getInstance();
    const userStorage = UserStorage.getInstance();
    const [deviceIdR, facebookIdR, avatarUrlR] = await Promise.all([
      authStorage.getDeviceId(),
      authStorage.getFacebookId(),
      userStorage.getAvatarUrl(),
    ]);

    const deviceId = deviceIdR.success ? deviceIdR.data : null;
    const facebookId = facebookIdR.success ? facebookIdR.data : null;
    const avatarUrl = avatarUrlR.success ? avatarUrlR.data : null;

    if (deviceId && facebookId) {
      UrlLauncherUtil.openUrlWithExternalBrowser(
        ROUTE_BUILDERS.chatDeviceId(deviceId),
        {
          queryParams: {
            fbid: facebookId,
            ...(avatarUrl ? { avatarUrl } : {}),
          },
        },
      );
      return;
    }

    UrlLauncherUtil.openUrlWithExternalBrowser(ROUTES.splash);
  }

  function handleUnlockPrivateMessage(messageId: string): void {
    chatDispatch({ type: "ChatUnlockPrivateMessage", messageId });
  }

  function handleMessageLimitUnlock(): void {
    if (isGuest) {
      router.push(ROUTES.auth);
      return;
    }
    router.push(`${ROUTES.subscription}?type=vip`);
  }

  return (
    <MobileShell>
      <div className={styles.shell}>
        {/* 背景图（与原 Dart MobileLayout 一致） */}
        <div className={styles.background}>
          <Image
            src="/images/chat/bg-chatpage.png"
            alt=""
            fill
            priority
            sizes="(max-width: 500px) 100vw, 500px"
          />
        </div>

        <div className={styles.layout}>
          {/* isGuest 派生自 auth.loginStatus */}
          <ChatHeader isGuest={isGuest} />

          <ChatArea
            messages={state.messages}
            isReplyingAI={state.isReplyingAI}
            isGuest={isGuest}
            unlockingPrivateMessageId={state.unlockingPrivateMessageId}
            onUnlockPrivateMessage={handleUnlockPrivateMessage}
          />

          {showInlineUpgradeBanner ? (
            <ChatQuotaExhaustedBanner
              title={inlineUpgradeTitle}
              ctaLabel={inlineUpgradeCta}
            />
          ) : null}

          {showMessageLimitBanner ? (
            <ChatQuotaExhaustedBanner
              title={messageLimitTitle}
              ctaLabel={messageLimitCta}
              onUnlock={handleMessageLimitUnlock}
            />
          ) : (
            <ChatInputBar disabled={state.isReplyingAI} />
          )}

        </div>

        {/* 浏览器提示（应用内浏览器检测） */}
        <BrowserHintOverlay forceShow={AppEnvUtil.isDevelopment()} />

        {/* PWA 安装提示触发器（无可见 UI，3.5s 后弹 dialog） */}
        <PwaInstallOverlay />

        <ExternalBrowserDialog
          open={showExternalBrowserDialog}
          onClose={() => setShowExternalBrowserDialog(false)}
          onConfirm={() => void handleOpenExternalBrowser()}
        />
      </div>
    </MobileShell>
  );
}