"use client";

import { FormEvent, useEffect, useMemo, useRef, useState } from "react";
import { BookOpenCheck, Clock3, Home, MessageCircle, SendHorizonal, Settings, ShieldCheck, UserRound } from "lucide-react";
import { api } from "@/lib/api";
import type { CallableQAItem } from "@/lib/types";
import {
  findQaAnswer,
  initialMessages,
  mockCallableQa,
  suggestedQuestions,
  type ChatMessage
} from "@/lib/h5MockQa";
import ChatBubble from "./ChatBubble";
import MockAuthPanel, { type MockUser } from "./MockAuthPanel";

type MobileTab = "qa" | "history" | "me";

function nowText() {
  return new Intl.DateTimeFormat("zh-CN", {
    hour: "2-digit",
    minute: "2-digit",
    hour12: false
  }).format(new Date());
}

function buildAnswerMessage(question: string, qa: CallableQAItem): ChatMessage {
  return {
    id: `assistant-${Date.now()}`,
    role: "assistant",
    content: qa.standard_answer,
    source: `${qa.standard_code} / ${qa.primary_topic} / ${qa.course_stage}`,
    boundary: qa.answer_boundary ?? "答复仅基于已审核答疑资产生成，不能替代专业诊断、法律判断或医疗建议。",
    createdAt: nowText()
  };
}

function EmptyState({ tab }: { tab: MobileTab }) {
  const copy = {
    history: "登录后这里会展示你的历史提问记录。当前先用本机 mock 会话演示。",
    me: "账号、学习阶段、隐私设置后续会接真实接口；现在先预留微信授权入口。",
    qa: ""
  };

  if (tab === "qa") return null;

  return (
    <div className="flex flex-1 items-center justify-center px-6 text-center">
      <div>
        <div className="mx-auto mb-3 flex h-12 w-12 items-center justify-center rounded-md bg-teal-50 text-jade">
          {tab === "history" ? <Clock3 className="h-6 w-6" aria-hidden /> : <UserRound className="h-6 w-6" aria-hidden />}
        </div>
        <p className="text-sm leading-6 text-slate-500">{copy[tab]}</p>
      </div>
    </div>
  );
}

export default function H5QAExperience() {
  const [activeTab, setActiveTab] = useState<MobileTab>("qa");
  const [authOpen, setAuthOpen] = useState(false);
  const [input, setInput] = useState("");
  const [messages, setMessages] = useState<ChatMessage[]>(initialMessages);
  const [callableQa, setCallableQa] = useState<CallableQAItem[]>([]);
  const [loadingQa, setLoadingQa] = useState(true);
  const [user, setUser] = useState<MockUser | null>(null);
  const bottomRef = useRef<HTMLDivElement | null>(null);

  const qaSource = useMemo(() => (callableQa.length > 0 ? callableQa : mockCallableQa), [callableQa]);

  useEffect(() => {
    api
      .get<CallableQAItem[]>("/standard-qa/callable")
      .then(setCallableQa)
      .catch(() => setCallableQa([]))
      .finally(() => setLoadingQa(false));
  }, []);

  useEffect(() => {
    bottomRef.current?.scrollIntoView({ behavior: "smooth", block: "end" });
  }, [messages, activeTab]);

  function mockLogin(mode: MockUser["mode"]) {
    setUser({
      mode,
      name: mode === "login" ? "大本营学员" : "新学员",
      phone: "138****2026"
    });
    setAuthOpen(false);
  }

  function ask(question: string) {
    const trimmed = question.trim();
    if (!trimmed) return;

    const matchedQa = findQaAnswer(trimmed, qaSource);
    setMessages((current) => [
      ...current,
      {
        id: `user-${Date.now()}`,
        role: "user",
        content: trimmed,
        createdAt: nowText()
      },
      buildAnswerMessage(trimmed, matchedQa)
    ]);
    setInput("");
    setActiveTab("qa");
  }

  function submit(event: FormEvent<HTMLFormElement>) {
    event.preventDefault();
    ask(input);
  }

  return (
    <div className="min-h-screen bg-[#eef3f1] text-ink lg:grid lg:grid-cols-[minmax(0,1fr)_420px_minmax(0,1fr)]">
      <aside className="hidden px-8 py-10 lg:block">
        <div className="sticky top-10 ml-auto max-w-sm">
          <div className="mb-5 flex items-center gap-3">
            <BookOpenCheck className="h-7 w-7 text-jade" aria-hidden />
            <div>
              <div className="text-lg font-semibold">千问千答 H5</div>
              <div className="text-sm text-slate-500">手机优先的问答交互入口</div>
            </div>
          </div>
          <div className="space-y-3 text-sm leading-6 text-slate-600">
            <p>当前页面只做前端加法：登录注册为 mock 状态，问答优先读取已审核可调用库，没有数据时使用本地演示问答。</p>
            <p>后续封装微信小程序时，主交互可以保留：顶部身份区、聊天流、快捷问题、底部导航和账号面板。</p>
          </div>
        </div>
      </aside>

      <main className="mx-auto flex min-h-screen w-full max-w-[430px] flex-col bg-[#f7faf8] shadow-2xl shadow-slate-900/10 lg:my-6 lg:min-h-[860px] lg:overflow-hidden lg:rounded-[22px]">
        <header className="shrink-0 border-b border-line bg-white px-4 pb-3 pt-4">
          <div className="flex items-center justify-between gap-3">
            <div className="flex items-center gap-3">
              <div className="flex h-10 w-10 items-center justify-center rounded-md bg-jade text-white">
                <MessageCircle className="h-5 w-5" aria-hidden />
              </div>
              <div>
                <h1 className="text-lg font-semibold leading-6">千问千答助手</h1>
                <div className="mt-0.5 flex items-center gap-1 text-xs text-slate-500">
                  <ShieldCheck className="h-3.5 w-3.5 text-jade" aria-hidden />
                  {loadingQa ? "正在检查可调用库" : callableQa.length > 0 ? "已连接可调用库" : "演示模式"}
                </div>
              </div>
            </div>
            <button
              onClick={() => setAuthOpen(true)}
              className="flex h-10 min-w-10 items-center justify-center rounded-md border border-line bg-white px-3 text-sm font-medium hover:bg-slate-50"
            >
              {user ? user.name.slice(0, 2) : <UserRound className="h-5 w-5" aria-hidden />}
            </button>
          </div>
        </header>

        <section className="relative flex min-h-0 flex-1 flex-col">
          {activeTab === "qa" ? (
            <>
              <div className="flex-1 overflow-y-auto px-4 py-4">
                <div className="mb-4 rounded-md border border-teal-100 bg-teal-50 px-3 py-2 text-xs leading-5 text-teal-800">
                  回答会优先遵守审核边界；涉及医疗、法律、极端风险或个人隐私时，请以人工复核为准。
                </div>
                <div className="space-y-4">
                  {messages.map((message) => (
                    <ChatBubble key={message.id} message={message} />
                  ))}
                </div>
                <div ref={bottomRef} />
              </div>

              <div className="shrink-0 border-t border-line bg-white px-4 py-3">
                <div className="mb-3 flex gap-2 overflow-x-auto pb-1">
                  {suggestedQuestions.map((item) => (
                    <button
                      key={item.id}
                      onClick={() => ask(item.text)}
                      className="shrink-0 rounded-md border border-line bg-panel px-3 py-2 text-left text-xs leading-5 text-slate-700 hover:bg-teal-50 hover:text-jade"
                    >
                      {item.text}
                    </button>
                  ))}
                </div>
                <form onSubmit={submit} className="flex items-end gap-2">
                  <textarea
                    value={input}
                    onChange={(event) => setInput(event.target.value)}
                    rows={1}
                    placeholder="输入你的问题..."
                    className="max-h-28 min-h-11 flex-1 resize-none rounded-md border border-line bg-panel px-3 py-3 text-[15px] leading-5 outline-none focus:border-jade focus:bg-white"
                  />
                  <button
                    type="submit"
                    disabled={!input.trim()}
                    className="flex h-11 w-11 shrink-0 items-center justify-center rounded-md bg-jade text-white hover:bg-teal-800 disabled:bg-slate-300"
                    aria-label="发送"
                  >
                    <SendHorizonal className="h-5 w-5" aria-hidden />
                  </button>
                </form>
              </div>
            </>
          ) : (
            <EmptyState tab={activeTab} />
          )}

          <MockAuthPanel
            open={authOpen}
            user={user}
            onClose={() => setAuthOpen(false)}
            onMockLogin={mockLogin}
            onLogout={() => {
              setUser(null);
              setAuthOpen(false);
            }}
          />
        </section>

        <nav className="grid h-[62px] shrink-0 grid-cols-3 border-t border-line bg-white text-xs">
          {[
            { key: "qa" as const, label: "问答", icon: Home },
            { key: "history" as const, label: "记录", icon: Clock3 },
            { key: "me" as const, label: "我的", icon: Settings }
          ].map((item) => {
            const Icon = item.icon;
            const active = activeTab === item.key;
            return (
              <button
                key={item.key}
                onClick={() => setActiveTab(item.key)}
                className={`flex flex-col items-center justify-center gap-1 ${active ? "text-jade" : "text-slate-400"}`}
              >
                <Icon className="h-5 w-5" aria-hidden />
                <span>{item.label}</span>
              </button>
            );
          })}
        </nav>
      </main>

      <aside className="hidden px-8 py-10 lg:block">
        <div className="sticky top-10 max-w-sm rounded-md border border-line bg-white p-5 shadow-sm">
          <h2 className="text-base font-semibold">后续接真实能力时的接口边界</h2>
          <ul className="mt-4 space-y-3 text-sm leading-6 text-slate-600">
            <li>登录注册：替换 mock 面板，接微信授权或手机号验证码。</li>
            <li>问答检索：从当前可调用库接口升级为语义检索或智能体接口。</li>
            <li>历史记录：按用户维度保存问题、答案、反馈和风险提示。</li>
            <li>安全策略：继续只允许调用已审核、可调用、低/中风险内容。</li>
          </ul>
        </div>
      </aside>
    </div>
  );
}