"use client";

import { useSearchParams } from "next/navigation";
import { useCallback, useEffect, useRef, useState } from "react";
import { useParams } from "react-router-dom";

import { loginByUsername } from "@/core/auth/api";
import { setStoredAuth } from "@/core/auth";
import { resolveEmbedChatParams } from "@/core/embed/params";
import { registerEmbedSession } from "@/core/embed/status-api";
import { useThreadSettings } from "@/core/settings";
import { useThreadStream } from "@/core/threads/hooks";
import { uuid } from "@/core/utils/uuid";
import { ChatBox } from "@/components/workspace/chats";
import {
  MessageList,
  MESSAGE_LIST_DEFAULT_PADDING_BOTTOM,
} from "@/components/workspace/messages";
import { ThreadContext } from "@/components/workspace/messages/context";
import { useModels } from "@/core/models/hooks";
import { cn } from "@/lib/utils";

const EMBED_ROUTE_BASE = "/embed/chats";

export default function EmbedChatPage() {
  const { thread_id: threadIdFromPath } = useParams<{ thread_id: string }>();
  const searchParams = useSearchParams();
  // 主题不在这里处理 —— ?theme= 由 AppProviders 通过 forcedTheme 强制
  // （不落 localStorage），避免污染主站用户自己选的主题。
  const embedParams = resolveEmbedChatParams(searchParams.toString());
  const [authReady, setAuthReady] = useState(false);
  const [authError, setAuthError] = useState<string | null>(null);
  const [threadId, setThreadId] = useState(() =>
    threadIdFromPath === "new" ? uuid() : (threadIdFromPath ?? uuid()),
  );
  const [isNewThread, setIsNewThread] = useState(threadIdFromPath === "new");
  const hasAutoSentRef = useRef(false);
  const lastRegisteredThreadRef = useRef<string | null>(null);

  useEffect(() => {
    if (threadIdFromPath === "new" || !threadIdFromPath) {
      return;
    }
    setIsNewThread(false);
    setThreadId(threadIdFromPath);
  }, [threadIdFromPath]);

  const [settings] = useThreadSettings(threadId);
  const { tokenUsageEnabled } = useModels();

  useEffect(() => {
    let cancelled = false;
    async function runLogin() {
      setAuthError(null);
      try {
        const auth = await loginByUsername(embedParams.username);
        if (cancelled) return;
        setStoredAuth(auth);
        setAuthReady(true);
      } catch (error) {
        if (cancelled) return;
        setAuthError(
          error instanceof Error ? error.message : "Login request failed.",
        );
      }
    }
    void runLogin();
    return () => {
      cancelled = true;
    };
  }, [embedParams.username]);

  const registerSessionForThread = useCallback(
    (resolvedThreadId: string) => {
      if (!embedParams.sessionId || lastRegisteredThreadRef.current === resolvedThreadId) {
        return;
      }
      lastRegisteredThreadRef.current = resolvedThreadId;
      void registerEmbedSession(embedParams.sessionId, resolvedThreadId).catch(
        (error) => {
          console.error("[embed] failed to register session mapping", error);
          lastRegisteredThreadRef.current = null;
        },
      );
    },
    [embedParams.sessionId],
  );

  const [thread, sendMessage] = useThreadStream({
    threadId: authReady && !isNewThread ? threadId : undefined,
    context: settings.context,
    isMock: false,
    onStart: (createdThreadId) => {
      setThreadId(createdThreadId);
      setIsNewThread(false);
      registerSessionForThread(createdThreadId);
      history.replaceState(
        null,
        "",
        `${window.location.pathname}${window.location.search}#${EMBED_ROUTE_BASE}/${createdThreadId}`,
      );
    },
  });

  useEffect(() => {
    if (!authReady || !threadId) {
      return;
    }
    registerSessionForThread(threadId);
  }, [authReady, threadId, registerSessionForThread]);

  const handleClarificationSubmit = useCallback(
    (answer: string) => {
      void sendMessage(threadId, { text: answer, files: [] });
    },
    [sendMessage, threadId],
  );

  useEffect(() => {
    if (!authReady || !embedParams.message || hasAutoSentRef.current) {
      return;
    }
    hasAutoSentRef.current = true;
    void sendMessage(threadId, { text: embedParams.message, files: [] });
  }, [authReady, embedParams.message, sendMessage, threadId]);

  if (!embedParams.sessionId) {
    return (
      <div className="flex size-full items-center justify-center bg-background p-6 text-center text-sm text-red-600">
        缺少参数 sessionId：父页面需在 iframe URL 中传入由己方生成的会话 id，用于查询问答是否结束。
      </div>
    );
  }

  if (authError) {
    return (
      <div className="flex size-full items-center justify-center bg-background p-6 text-sm text-red-600">
        登录失败：{authError}
      </div>
    );
  }

  if (!authReady) {
    return (
      <div className="flex size-full items-center justify-center bg-background p-6 text-sm text-muted-foreground">
        正在进入问答…
      </div>
    );
  }

  return (
    <ThreadContext.Provider value={{ thread, isMock: false }}>
      <ChatBox threadId={threadId}>
        <div className="relative flex size-full min-h-0">
          <main className="flex min-h-0 max-w-full grow flex-col">
            <div className="flex size-full justify-center">
              <MessageList
                className={cn("size-full")}
                threadId={threadId}
                thread={thread}
                paddingBottom={MESSAGE_LIST_DEFAULT_PADDING_BOTTOM}
                tokenUsageEnabled={tokenUsageEnabled}
                onClarificationSubmit={handleClarificationSubmit}
              />
            </div>
          </main>
        </div>
      </ChatBox>
    </ThreadContext.Provider>
  );
}