import { useEffect, useMemo, useRef, useState } from 'react';
import { useChat } from '../context/ChatProvider';
import { buildSelectedAssetGreeting } from '../utils/mindspaceChatContext';
import { shouldShowChatMessage } from '../utils/message';
import type { Message, MindSpaceChatContext, MindSpaceSaveCategory, PortalUser } from '../types';
import { SpaceChatFab } from './SpaceChatFab';
import { SpaceChatPanel } from './SpaceChatPanel';

const SELECTED_ASSET_GREETING_ID = 'mindspace-selected-asset-greeting';

function buildSelectedAssetGreetingMessage(
  asset: NonNullable<MindSpaceChatContext['selectedAssets']>[number],
): Message {
  const text = buildSelectedAssetGreeting(asset);
  return {
    id: SELECTED_ASSET_GREETING_ID,
    role: 'assistant',
    created: Math.floor(Date.now() / 1000),
    content: [{ type: 'text', text }],
    metadata: {
      userVisible: true,
      agentVisible: false,
      displayText: text,
    },
  };
}

export function MindSpaceSpaceChat({
  context,
  user,
  onOpenFullChat,
  onPageSaved,
  open: controlledOpen,
  onOpenChange,
  variant = 'default',
  chatBridge,
  hideOpenFullChat = false,
  title,
}: {
  context: MindSpaceChatContext;
  user: PortalUser;
  onOpenFullChat: () => void;
  onPageSaved?: (result: {
    kind: 'page' | 'category';
    pageId?: string;
    categoryCode?: MindSpaceSaveCategory;
  }) => void;
  open?: boolean;
  onOpenChange?: (open: boolean) => void;
  variant?: 'default' | 'overlay';
  chatBridge?: import('../hooks/usePageEditSubChat').PageEditSubChatBridge;
  hideOpenFullChat?: boolean;
  title?: string;
}) {
  const { chatState, pendingTool, newSession, switchSession, session, messages } = useChat();
  const [internalOpen, setInternalOpen] = useState(false);
  const open = controlledOpen ?? internalOpen;
  const setOpen = onOpenChange ?? setInternalOpen;
  const wasOpenRef = useRef(false);
  const restoreSessionIdRef = useRef<string | null>(null);
  const messagesRef = useRef(messages);
  messagesRef.current = messages;

  useEffect(() => {
    if (chatBridge) {
      wasOpenRef.current = open;
      return;
    }

    const wasOpen = wasOpenRef.current;
    if (open && !wasOpen) {
      restoreSessionIdRef.current = session?.id ?? null;
      newSession();
    } else if (!open && wasOpen) {
      if (messagesRef.current.length === 0 && restoreSessionIdRef.current) {
        switchSession(restoreSessionIdRef.current);
      }
      restoreSessionIdRef.current = null;
    }
    wasOpenRef.current = open;
  }, [chatBridge, newSession, open, session?.id, switchSession]);

  useEffect(() => {
    if (chatBridge) return;
    return () => {
      if (messagesRef.current.length === 0 && restoreSessionIdRef.current) {
        switchSession(restoreSessionIdRef.current);
      }
    };
  }, [chatBridge, switchSession]);

  const prefillMessages = useMemo(() => {
    if (chatBridge || !open) return [];
    if (messages.some((message) => message.role === 'user' && shouldShowChatMessage(message))) return [];
    const selected = context.selectedAssets ?? [];
    if (selected.length !== 1) return [];
    return [buildSelectedAssetGreetingMessage(selected[0])];
  }, [chatBridge, context.selectedAssets, messages, open]);

  const wrapperClass =
    variant === 'overlay' ? 'space-chat-stack space-chat-stack-overlay' : 'space-chat-stack';

  return (
    <div className={wrapperClass}>
      {open ? (
        <button
          type="button"
          className="space-chat-backdrop"
          aria-label="收起对话"
          onClick={() => setOpen(false)}
        />
      ) : null}
      <SpaceChatFab
        open={open}
        streaming={chatState === 'waiting' || chatState === 'streaming'}
        pendingTool={Boolean(pendingTool)}
        onClick={() => setOpen(!open)}
      />
      <SpaceChatPanel
        open={open}
        context={context}
        user={user}
        onClose={() => setOpen(false)}
        onOpenFullChat={onOpenFullChat}
        onPageSaved={onPageSaved}
        chatBridge={chatBridge}
        hideOpenFullChat={hideOpenFullChat}
        title={title}
        prefillMessages={prefillMessages}
      />
    </div>
  );
}