import {
  ApiOutlined,
  ClearOutlined,
  RobotOutlined,
  SendOutlined,
  SettingOutlined,
  StopOutlined,
  UserOutlined,
} from '@ant-design/icons';
import {
  Alert,
  Avatar,
  Button,
  Drawer,
  Empty,
  Form,
  Input,
  Space,
  Spin,
  Tag,
  Tooltip,
  message,
} from 'antd';
import { type FC, useEffect, useMemo, useRef, useState } from 'react';
import './index.less';

interface ChatMessage {
  id: string;
  role: 'system' | 'user' | 'assistant';
  content: string;
  createdAt: string;
}

interface AiSettings {
  baseUrl: string;
  apiKey: string;
  model: string;
}

// v2：服务商切换为 TokenFree，旧版本地缓存不再复用，避免过期默认值残留
const SETTINGS_KEY = 'parking-ai-settings-v2';
const LEGACY_SETTINGS_KEY = 'parking-ai-settings';
const MESSAGES_KEY = 'parking-ai-messages';

const PROVIDER_HOME = 'https://www.tokenfree.com/';

const DEFAULT_SETTINGS: AiSettings = {
  baseUrl: 'https://www.tokenfree.com/v1',
  apiKey: '',
  model: 'kimi-k2.6',
};

const loadSettings = (): AiSettings => {
  try {
    const raw = localStorage.getItem(SETTINGS_KEY);
    if (raw) return { ...DEFAULT_SETTINGS, ...JSON.parse(raw) };
    // 仅迁移用户在旧服务商下已填写的 API Key，地址/模型强制使用新默认值
    const legacyRaw = localStorage.getItem(LEGACY_SETTINGS_KEY);
    if (legacyRaw) {
      const legacy = JSON.parse(legacyRaw) as Partial<AiSettings>;
      const migrated = {
        ...DEFAULT_SETTINGS,
        apiKey: typeof legacy.apiKey === 'string' ? legacy.apiKey : '',
      };
      localStorage.setItem(SETTINGS_KEY, JSON.stringify(migrated));
      return migrated;
    }
    return DEFAULT_SETTINGS;
  } catch {
    return DEFAULT_SETTINGS;
  }
};

const createMessage = (
  role: ChatMessage['role'],
  content: string,
): ChatMessage => ({
  id: `${Date.now()}-${Math.random().toString(16).slice(2)}`,
  role,
  content,
  createdAt: new Date().toLocaleString(),
});

const AiChat: FC = () => {
  const [settings, setSettings] = useState<AiSettings>(loadSettings);
  const [messages, setMessages] = useState<ChatMessage[]>(() => {
    try {
      return JSON.parse(localStorage.getItem(MESSAGES_KEY) || '[]');
    } catch {
      return [];
    }
  });
  const [input, setInput] = useState('');
  const [loading, setLoading] = useState(false);
  const [settingsOpen, setSettingsOpen] = useState(false);
  const [settingsForm] = Form.useForm<AiSettings>();
  const abortRef = useRef<AbortController | null>(null);
  const listRef = useRef<HTMLDivElement | null>(null);

  const normalizedBaseUrl = useMemo(
    () => settings.baseUrl.replace(/\/+$/, ''),
    [settings.baseUrl],
  );

  useEffect(() => {
    document.title = 'AI对话 - 智慧停车管理平台';
  }, []);

  useEffect(() => {
    localStorage.setItem(MESSAGES_KEY, JSON.stringify(messages));
    listRef.current?.scrollTo({
      top: listRef.current.scrollHeight,
      behavior: 'smooth',
    });
  }, [messages]);

  const saveSettings = async () => {
    const values = await settingsForm.validateFields();
    const next = {
      ...values,
      baseUrl: values.baseUrl.replace(/\/+$/, ''),
    };
    setSettings(next);
    localStorage.setItem(SETTINGS_KEY, JSON.stringify(next));
    setSettingsOpen(false);
    message.success('AI 接口配置已保存');
  };

  const testConnection = async () => {
    const values = settingsForm.getFieldsValue();
    const baseUrl = values.baseUrl.replace(/\/+$/, '');
    if (!baseUrl) {
      message.warning('请先填写 API Base URL');
      return;
    }

    try {
      const res = await fetch(`${baseUrl}/models`, {
        headers: { Authorization: `Bearer ${values.apiKey}` },
      });
      if (!res.ok) throw new Error(res.statusText);
      message.success('连接测试成功');
    } catch (error) {
      message.error(`连接失败：${String(error)}`);
    }
  };

  const stopGenerating = () => {
    abortRef.current?.abort();
    setLoading(false);
  };

  const sendMessage = async () => {
    const content = input.trim();
    if (!content) return;
    if (!settings.apiKey) {
      setSettingsOpen(true);
      message.warning('请先配置 API Key');
      return;
    }

    const userMessage = createMessage('user', content);
    const assistantMessage = createMessage('assistant', '');
    const nextMessages = [...messages, userMessage, assistantMessage];
    setMessages(nextMessages);
    setInput('');
    setLoading(true);

    const controller = new AbortController();
    abortRef.current = controller;

    const payload = {
      model: settings.model,
      stream: true,
      messages: [
        {
          role: 'system',
          content:
            '你是智慧停车管理平台AI助手，可解答停车运营、设备状态、异常报警、园区监控和数据分析相关问题。',
        },
        ...messages
          .filter((item) => item.role !== 'system')
          .map((item) => ({ role: item.role, content: item.content })),
        { role: 'user', content },
      ],
    };

    try {
      const response = await fetch(`${normalizedBaseUrl}/chat/completions`, {
        method: 'POST',
        signal: controller.signal,
        headers: {
          Authorization: `Bearer ${settings.apiKey}`,
          'Content-Type': 'application/json',
        },
        body: JSON.stringify(payload),
      });

      if (!response.ok || !response.body) {
        throw new Error(response.statusText || 'AI 服务响应异常');
      }

      const reader = response.body.getReader();
      const decoder = new TextDecoder('utf-8');
      let buffer = '';
      let answer = '';

      const patchLastMessage = (text: string) => {
        setMessages((current) =>
          current.map((item, index) =>
            index === current.length - 1 ? { ...item, content: text } : item,
          ),
        );
      };

      while (true) {
        const { value, done } = await reader.read();
        if (done) break;
        buffer += decoder.decode(value, { stream: true });
        const chunks = buffer.split('\n\n');
        buffer = chunks.pop() || '';

        chunks.forEach((chunk) => {
          chunk
            .split('\n')
            .filter((line) => line.startsWith('data:'))
            .forEach((line) => {
              const data = line.replace(/^data:\s*/, '').trim();
              if (!data || data === '[DONE]') return;
              try {
                const json = JSON.parse(data);
                const delta = json.choices?.[0]?.delta?.content || '';
                answer += delta;
                patchLastMessage(answer);
              } catch {
                // 忽略心跳或非标准分片
              }
            });
        });
      }

      if (!answer) patchLastMessage('暂未收到有效回复，请稍后重试。');
    } catch (error) {
      const text =
        error instanceof DOMException && error.name === 'AbortError'
          ? answerOrStopped()
          : `AI 服务连接失败：${String(error)}`;
      setMessages((current) =>
        current.map((item, index) =>
          index === current.length - 1 ? { ...item, content: text } : item,
        ),
      );
    } finally {
      setLoading(false);
      abortRef.current = null;
    }
  };

  const answerOrStopped = () => '已停止生成。';

  const clearHistory = () => {
    setMessages([]);
    localStorage.removeItem(MESSAGES_KEY);
    message.success('对话记录已清空');
  };

  const openSettings = () => {
    settingsForm.setFieldsValue(settings);
    setSettingsOpen(true);
  };

  return (
    <div className="ai-chat-page">
      <div className="ai-chat-shell panel-card">
        <div className="ai-chat-header">
          <div>
            <Space>
              <Avatar
                className="ai-robot-avatar"
                icon={<RobotOutlined />}
                size="large"
              />
              <div>
                <h2>智慧停车 AI 助手</h2>
                <p>
                  <Tag color="cyan">{settings.model}</Tag>
                  <span className="ai-status-dot" />
                  流式对话已就绪
                </p>
              </div>
            </Space>
          </div>
          <Space>
            <Tooltip title="接口配置">
              <Button
                icon={<SettingOutlined />}
                onClick={openSettings}
                shape="circle"
              />
            </Tooltip>
            <Tooltip title="清空对话">
              <Button
                danger
                icon={<ClearOutlined />}
                onClick={clearHistory}
                shape="circle"
              />
            </Tooltip>
          </Space>
        </div>

        {!settings.apiKey && (
          <Alert
            className="ai-config-alert"
            message="尚未配置 API Key"
            description="默认已接入 TokenFree（标准 Chat Completions 接口），请点击右上角设置按钮填写您的 API Key 后即可开始对话。"
            type="warning"
            showIcon
            action={
              <Button size="small" type="primary" onClick={openSettings}>
                立即配置
              </Button>
            }
          />
        )}

        <div className="ai-message-list" ref={listRef}>
          {messages.length === 0 ? (
            <Empty
              description="开始询问停车运营、设备状态或异常报警问题"
              image={Empty.PRESENTED_IMAGE_SIMPLE}
            />
          ) : (
            messages.map((item) => (
              <div
                key={item.id}
                className={`ai-message-row ${
                  item.role === 'user' ? 'is-user' : 'is-assistant'
                }`}
              >
                <Avatar
                  className="ai-message-avatar"
                  icon={
                    item.role === 'user' ? <UserOutlined /> : <RobotOutlined />
                  }
                />
                <div className="ai-bubble">
                  <div className="ai-bubble-content">
                    {item.content || (loading ? <Spin size="small" /> : '')}
                  </div>
                  <div className="ai-bubble-time">{item.createdAt}</div>
                </div>
              </div>
            ))
          )}
        </div>

        <div className="ai-input-bar">
          <Input.TextArea
            autoSize={{ minRows: 1, maxRows: 4 }}
            className="ai-textarea"
            placeholder="输入你的问题，Enter 发送，Shift + Enter 换行"
            value={input}
            onChange={(event) => setInput(event.target.value)}
            onPressEnter={(event) => {
              if (!event.shiftKey) {
                event.preventDefault();
                void sendMessage();
              }
            }}
          />
          {loading ? (
            <Button
              danger
              icon={<StopOutlined />}
              onClick={stopGenerating}
              size="large"
            >
              停止
            </Button>
          ) : (
            <Button
              icon={<SendOutlined />}
              onClick={() => void sendMessage()}
              size="large"
              type="primary"
            >
              发送
            </Button>
          )}
        </div>
      </div>

      <Drawer
        className="ai-settings-drawer"
        title={
          <Space>
            <ApiOutlined />
            AI 接口配置
          </Space>
        }
        open={settingsOpen}
        onClose={() => setSettingsOpen(false)}
        width={380}
        extra={
          <Space>
            <Button onClick={testConnection}>测试连接</Button>
            <Button type="primary" onClick={() => void saveSettings()}>
              保存
            </Button>
          </Space>
        }
      >
        <div className="api-key-tip">
          <p className="api-key-tip-title">
            <strong>TokenFree 使用教程</strong>
          </p>
          <p className="api-key-tip-sub">
            TokenFree 是统一 AI API 网关，支持标准 Chat Completions 接口协议
            （流式输出 / Models 列表），注册后即可调用
            Kimi、Qwen、Claude 等多家模型。
          </p>
          <ol className="api-key-steps">
            <li>
              打开{' '}
              <a href={PROVIDER_HOME} target="_blank" rel="noreferrer">
                <strong>https://www.tokenfree.com/</strong>
              </a>
              ，点击注册并完成邮箱验证后登录。
            </li>
            <li>
              登录后进入控制台「令牌 / API Keys」页面，点击「添加令牌」，
              复制生成的 Key（以 <code>sk-</code> 开头）。
            </li>
            <li>
              将 API Key 粘贴到下方表单；接口地址与默认模型已预填，
              一般无需修改。
            </li>
            <li>
              点击「测试连接」验证 Key 是否有效，通过后点击「保存」，
              返回页面即可开始对话。
            </li>
          </ol>
          <p className="api-key-tip-meta">
            <span>接口地址：<code>https://www.tokenfree.com/v1</code></span>
            <span>默认模型：<code>kimi-k2.6</code></span>
          </p>
          <p className="api-key-tip-note">
            提示：也可在「模型 / Model」处填写 TokenFree 支持的其他模型名称；
            Key 仅保存在本地浏览器，不会上传到本系统服务器。
          </p>
        </div>

        <Form layout="vertical" form={settingsForm}>
          <Form.Item
            label="API Base URL"
            name="baseUrl"
            rules={[{ required: true, message: '请输入 API Base URL' }]}
            extra="默认：https://www.tokenfree.com/v1（标准 Chat Completions 接口，一般无需修改）"
          >
            <Input placeholder="https://www.tokenfree.com/v1" />
          </Form.Item>
          <Form.Item
            label="API Key"
            name="apiKey"
            rules={[{ required: true, message: '请输入 API Key' }]}
            extra="在 TokenFree 控制台「令牌」页面创建并复制"
          >
            <Input.Password placeholder="sk-..." />
          </Form.Item>
          <Form.Item
            label="Model"
            name="model"
            rules={[{ required: true, message: '请输入模型名称' }]}
            extra="默认 kimi-k2.6，也可填写 TokenFree 支持的其他模型"
          >
            <Input placeholder="kimi-k2.6" />
          </Form.Item>
        </Form>
      </Drawer>
    </div>
  );
};

export default AiChat;