import { useState, useRef, useEffect } from 'react';
import { motion } from 'framer-motion';
import { Input } from '@/components/ui/input';
import { Button } from '@/components/ui/button';
import { ScrollArea } from '@/components/ui/scroll-area';
import { Badge } from '@/components/ui/badge';
import {
  Send,
  Sparkles,
  Plus,
  Search,
  Settings,
  MessageSquare,
  Copy,
  ThumbsUp,
  ThumbsDown,
  RotateCcw,
  Trash2,
  Loader2,
} from 'lucide-react';
import {
  useConversations,
  useMessages,
  useCreateConversation,
  useSendMessage,
  useDeleteConversation,
} from '@/hooks/useApi';
import type { Conversation, ChatMessage } from '@/api/client';

export function ChatPage() {
  const [selectedConv, setSelectedConv] = useState<string | null>(null);
  const [input, setInput] = useState('');
  const messagesEndRef = useRef<HTMLDivElement>(null);
  const [streamingContent, setStreamingContent] = useState('');

  // API hooks
  const { data: conversations = [], isLoading: convsLoading } = useConversations();
  const { data: messages = [], isLoading: msgsLoading } = useMessages(selectedConv);
  const createConv = useCreateConversation();
  const sendMessage = useSendMessage(selectedConv || '');
  const deleteConv = useDeleteConversation();

  const scrollToBottom = () => {
    messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' });
  };

  useEffect(() => {
    scrollToBottom();
  }, [messages, streamingContent]);

  const handleNewChat = async () => {
    try {
      const conv = await createConv.mutateAsync({ title: '新对话' });
      setSelectedConv(conv.id);
    } catch {}
  };

  const handleSend = async () => {
    if (!input.trim() || !selectedConv) return;
    const content = input;
    setInput('');
    setStreamingContent('');

    try {
      // Try streaming first
      const stream = chatApi.streamMessage(selectedConv, { content });
      let accumulated = '';
      for await (const chunk of stream) {
        accumulated += chunk;
        setStreamingContent(accumulated);
      }
      setStreamingContent('');
      // Refresh messages
    } catch {
      // Fallback to regular send
      await sendMessage.mutateAsync({ content });
    }
  };

  const handleDelete = async (id: string) => {
    try {
      await deleteConv.mutateAsync(id);
      if (selectedConv === id) setSelectedConv(null);
    } catch {}
  };

  return (
    <div className="flex h-[calc(100vh-4rem)] gap-4">
      {/* Conversation List */}
      <div className="w-72 flex-shrink-0 flex flex-col border border-border rounded-xl bg-white dark:bg-gray-950 overflow-hidden">
        <div className="p-3 border-b border-border">
          <div className="relative">
            <Search className="absolute left-3 top-1/2 -translate-y-1/2 h-4 w-4 text-muted-foreground" />
            <input
              type="text"
              placeholder="搜索对话..."
              className="h-9 w-full rounded-lg bg-muted pl-9 pr-3 text-sm focus:outline-none focus:ring-2 focus:ring-ring"
            />
          </div>
        </div>

        <Button
          className="mx-3 mt-3 gap-2"
          variant="outline"
          onClick={handleNewChat}
          disabled={createConv.isPending}
        >
          <Plus size={16} /> 新建对话
        </Button>

        <ScrollArea className="flex-1 px-2 py-2">
          <div className="space-y-1">
            {convsLoading ? (
              <div className="flex items-center justify-center py-8">
                <Loader2 size={20} className="animate-spin text-muted-foreground" />
              </div>
            ) : (
              conversations.map((conv: Conversation) => (
                <div key={conv.id} className="group relative">
                  <button
                    onClick={() => setSelectedConv(conv.id)}
                    className={`w-full text-left px-3 py-2.5 rounded-lg transition-colors ${
                      selectedConv === conv.id
                        ? 'bg-primary/10 text-primary'
                        : 'hover:bg-muted text-muted-foreground'
                    }`}
                  >
                    <div className="flex items-center gap-2">
                      <MessageSquare size={14} className="shrink-0" />
                      <span className="text-sm truncate flex-1">{conv.title}</span>
                    </div>
                    <div className="flex items-center gap-2 mt-1 ml-5">
                      <Badge variant="secondary" className="text-[10px] px-1.5 py-0">
                        {conv.model || 'Auto'}
                      </Badge>
                      <span className="text-[10px] text-muted-foreground">
                        {new Date(conv.updated_at).toLocaleDateString('zh-CN')}
                      </span>
                    </div>
                  </button>
                  <button
                    onClick={(e) => { e.stopPropagation(); handleDelete(conv.id); }}
                    className="absolute right-2 top-2 p-1 rounded opacity-0 group-hover:opacity-100 hover:bg-destructive/10 transition-opacity"
                  >
                    <Trash2 size={12} className="text-destructive" />
                  </button>
                </div>
              ))
            )}
          </div>
        </ScrollArea>
      </div>

      {/* Chat Area */}
      <div className="flex-1 flex flex-col border border-border rounded-xl bg-white dark:bg-gray-950 overflow-hidden">
        {/* Messages */}
        <ScrollArea className="flex-1 p-6">
          {!selectedConv ? (
            <div className="h-full flex flex-col items-center justify-center text-center">
              <div className="w-16 h-16 rounded-2xl bg-primary/10 flex items-center justify-center mb-4">
                <Sparkles className="h-8 w-8 text-primary" />
              </div>
              <h3 className="text-lg font-semibold text-foreground mb-2">开始与 AI 对话吧</h3>
              <p className="text-sm text-muted-foreground max-w-md">
                支持 Markdown 渲染和代码高亮，选择合适的模型开始聊天
              </p>
              <Button className="mt-4 gap-2" onClick={handleNewChat}>
                <Plus size={16} /> 新建对话
              </Button>
            </div>
          ) : msgsLoading ? (
            <div className="h-full flex items-center justify-center">
              <Loader2 size={24} className="animate-spin text-primary" />
            </div>
          ) : (
            <div className="space-y-6">
              {messages.map((msg: ChatMessage) => (
                <motion.div
                  key={msg.id}
                  initial={{ opacity: 0, y: 10 }}
                  animate={{ opacity: 1, y: 0 }}
                  className={`flex ${msg.role === 'user' ? 'justify-end' : 'justify-start'}`}
                >
                  <div className={`max-w-[80%] rounded-xl px-4 py-3 ${
                    msg.role === 'user'
                      ? 'bg-primary text-primary-foreground'
                      : 'bg-muted text-foreground'
                  }`}>
                    <div className="text-sm whitespace-pre-wrap">{msg.content}</div>
                    {msg.role === 'assistant' && (
                      <div className="flex items-center gap-2 mt-2 pt-2 border-t border-border/50">
                        <button className="p-1 hover:bg-background/50 rounded transition-colors">
                          <Copy size={14} className="text-muted-foreground" />
                        </button>
                        <button className="p-1 hover:bg-background/50 rounded transition-colors">
                          <ThumbsUp size={14} className="text-muted-foreground" />
                        </button>
                        <button className="p-1 hover:bg-background/50 rounded transition-colors">
                          <ThumbsDown size={14} className="text-muted-foreground" />
                        </button>
                        <button className="p-1 hover:bg-background/50 rounded transition-colors">
                          <RotateCcw size={14} className="text-muted-foreground" />
                        </button>
                      </div>
                    )}
                  </div>
                </motion.div>
              ))}

              {/* Streaming indicator */}
              {streamingContent && (
                <motion.div
                  initial={{ opacity: 0, y: 10 }}
                  animate={{ opacity: 1, y: 0 }}
                  className="flex justify-start"
                >
                  <div className="max-w-[80%] rounded-xl px-4 py-3 bg-muted text-foreground">
                    <div className="text-sm whitespace-pre-wrap">{streamingContent}</div>
                    <div className="flex items-center gap-1 mt-2">
                      <div className="w-1.5 h-1.5 rounded-full bg-primary animate-pulse" />
                      <div className="w-1.5 h-1.5 rounded-full bg-primary animate-pulse [animation-delay:0.2s]" />
                      <div className="w-1.5 h-1.5 rounded-full bg-primary animate-pulse [animation-delay:0.4s]" />
                    </div>
                  </div>
                </motion.div>
              )}
              <div ref={messagesEndRef} />
            </div>
          )}
        </ScrollArea>

        {/* Input Area */}
        <div className="p-4 border-t border-border">
          <div className="flex gap-2">
            <Input
              value={input}
              onChange={(e) => setInput(e.target.value)}
              onKeyDown={(e) => e.key === 'Enter' && !e.shiftKey && handleSend()}
              placeholder={selectedConv ? '输入消息... (Shift+Enter 换行)' : '请先选择或创建对话'}
              className="flex-1"
              disabled={!selectedConv || sendMessage.isPending}
            />
            <Button
              onClick={handleSend}
              disabled={!input.trim() || !selectedConv || sendMessage.isPending}
              className="gap-2"
            >
              {sendMessage.isPending ? (
                <Loader2 size={16} className="animate-spin" />
              ) : (
                <Send size={16} />
              )}
            </Button>
          </div>
          <div className="flex items-center justify-between mt-2">
            <div className="flex items-center gap-2 text-xs text-muted-foreground">
              <Sparkles size={12} /> Auto（自动匹配）
            </div>
            <button className="p-1 hover:bg-muted rounded transition-colors">
              <Settings size={16} className="text-muted-foreground" />
            </button>
          </div>
        </div>
      </div>
    </div>
  );
}

// Import for streaming
import { chatApi } from '@/api/client';