import React, { useEffect, useState, useCallback, useRef } from 'react';
import {
  App,
  Card,
  Form,
  Input,
  Button,
  Select,
  Switch,
  InputNumber,
  Tag,
  Descriptions,
  Spin,
  Alert,
  Typography,
  Space,
} from 'antd';
import {
  SaveOutlined,
  ApiOutlined,
  CheckCircleOutlined,
  CloseCircleOutlined,
  KeyOutlined,
  WarningOutlined,
} from '@ant-design/icons';
import api from '../../api';
import { message } from '../../ui/app-message';
import { usePermission } from '../../hooks/usePermission';
import type { AiProvider } from './helpers';
import {
  PROVIDER_OPTIONS,
  PROVIDER_DEFAULTS,
  FIXED_PROVIDERS,
  formatDateTime,
  sourceLabel,
  sourceColor,
  shouldAutoSwapBaseUrl,
  extractErrorMessage,
} from './helpers';
import styles from './index.module.css';

// ---------------------------------------------------------------------------
// Types
// ---------------------------------------------------------------------------

interface AiConfigData {
  id: number;
  provider: AiProvider;
  baseUrl: string;
  hasApiKey: boolean;
  hasDatabaseKey: boolean;
  maskedApiKey: string | null;
  keySource: 'database' | 'environment' | 'none';
  defaultModel: string | null;
  enabled: boolean;
  timeoutMs: number;
  verified: boolean;
  lastTestedAt: string | null;
  lastTestLatencyMs: number | null;
  createdAt: string;
  updatedAt: string;
}

interface TestResult {
  success: boolean;
  latencyMs: number | null;
  modelCount: number | null;
  modelAvailable: boolean;
  testedAt: string;
  message: string;
}

interface ApiResponse<T> {
  success: boolean;
  data: T;
  message?: string;
}

// ---------------------------------------------------------------------------
// Page Component
// ---------------------------------------------------------------------------

const AiConfigPage: React.FC = () => {
  const { hasPermission } = usePermission();
  const { modal } = App.useApp();
  const [form] = Form.useForm();

  const [loading, setLoading] = useState(true);
  const [saving, setSaving] = useState(false);
  const [testing, setTesting] = useState(false);
  const [config, setConfig] = useState<AiConfigData | null>(null);
  const [testResult, setTestResult] = useState<TestResult | null>(null);
  const [error, setError] = useState<string | null>(null);

  const lastProviderRef = useRef<AiProvider | null>(null);

  const canWrite = hasPermission('ai:config:write');
  const canTest = hasPermission('ai:config:test');
  const canRead = hasPermission('ai:config:read');

  // ── Load config ──

  const loadConfig = useCallback(async () => {
    setLoading(true);
    setError(null);
    try {
      const res = await api.get<ApiResponse<AiConfigData>>('/ai/config');
      setConfig(res.data);
      form.setFieldsValue({
        provider: res.data.provider,
        baseUrl: res.data.baseUrl,
        defaultModel: res.data.defaultModel ?? undefined,
        enabled: res.data.enabled,
        timeoutMs: res.data.timeoutMs,
      });
      lastProviderRef.current = res.data.provider;
    } catch (err: unknown) {
      setError(extractErrorMessage(err, '加载配置失败'));
    } finally {
      setLoading(false);
    }
  }, [form]);

  useEffect(() => {
    loadConfig();
  }, [loadConfig]);

  // ── Provider change → swap baseUrl ──

  const handleProviderChange = useCallback(
    (provider: AiProvider) => {
      const currentBaseUrl = form.getFieldValue('baseUrl') || '';
      const result = shouldAutoSwapBaseUrl(provider, currentBaseUrl, lastProviderRef.current);
      if (result.shouldSwap) {
        form.setFieldValue('baseUrl', result.baseUrl);
      }
      lastProviderRef.current = provider;
    },
    [form],
  );

  const currentProvider = Form.useWatch('provider', form) as AiProvider | undefined;
  const isFixedProvider = currentProvider ? FIXED_PROVIDERS.includes(currentProvider) : false;

  // ── Save ──

  const handleSave = useCallback(async () => {
    try {
      const values = await form.validateFields();
      setSaving(true);

      // Validate baseUrl for OPENAI_COMPATIBLE
      if (values.provider === 'OPENAI_COMPATIBLE' && !values.baseUrl) {
        message.error('OPENAI_COMPATIBLE 模式必须填写 Base URL');
        setSaving(false);
        return;
      }

      const body: Record<string, unknown> = {
        provider: values.provider,
        baseUrl: values.baseUrl,
        defaultModel: values.defaultModel || undefined,
        enabled: values.enabled,
        timeoutMs: values.timeoutMs,
      };

      if (values.apiKey && values.apiKey !== '••••') {
        body.apiKey = values.apiKey;
      }

      await api.put('/ai/config', body);
      message.success('配置已保存');
      form.setFieldValue('apiKey', '');
    } catch (err: unknown) {
      message.error(extractErrorMessage(err, '保存失败'));
      setSaving(false);
      return;
    }

    // Reload config from server (non-fatal if it fails)
    try {
      await loadConfig();
    } catch (err: unknown) {
      message.warning(extractErrorMessage(err, '配置已保存，但刷新失败'));
    } finally {
      setSaving(false);
    }
  }, [form, loadConfig]);

  // ── Test connection ──

  const handleTest = useCallback(async () => {
    try {
      // Validated fields: compatible requires baseUrl
      const fieldsToValidate = ['provider', 'timeoutMs'] as string[];
      if (currentProvider === 'OPENAI_COMPATIBLE') {
        fieldsToValidate.push('baseUrl');
      }
      const values = await form.validateFields(fieldsToValidate);

      setTesting(true);
      setTestResult(null);

      const body: Record<string, unknown> = {
        timeoutMs: values.timeoutMs,
      };

      // Always send provider if form has it
      if (currentProvider) body.provider = currentProvider;
      if (values.baseUrl) body.baseUrl = values.baseUrl;

      // Include defaultModel so backend checks target model
      const defaultModel = form.getFieldValue('defaultModel');
      if (defaultModel) body.defaultModel = defaultModel;

      const typedKey = form.getFieldValue('apiKey');
      if (typedKey && typedKey !== '••••') {
        body.apiKey = typedKey;
      }

      const res = await api.post<TestResult>('/ai/config/test', body);
      setTestResult(res);
      await loadConfig();
    } catch (err: unknown) {
      setTestResult({
        success: false,
        latencyMs: null,
        modelCount: null,
        modelAvailable: false,
        testedAt: new Date().toISOString(),
        message: extractErrorMessage(err, '测试请求失败'),
      });
    } finally {
      setTesting(false);
    }
  }, [form, loadConfig, currentProvider]);

  // ── Clear key ──

  const handleClearKey = useCallback(() => {
    const isEnv = config?.keySource === 'environment';
    modal.confirm({
      title: '确认清除密钥',
      content: isEnv
        ? '数据库中的密钥将被清除，但环境变量 AI_API_KEY 仍可使用。确定继续？'
        : '密钥将被永久清除，之后将无法使用 AI 功能。确定继续？',
      okText: '确认清除',
      okType: 'danger',
      cancelText: '取消',
      onOk: async () => {
        try {
          await api.post('/ai/config/clear-key');
          message.success('密钥已清除');
          await loadConfig();
        } catch (err: unknown) {
          message.error(extractErrorMessage(err, '清除失败'));
        }
      },
    });
  }, [config, loadConfig, modal]);

  // ── No read permission ──

  if (!canRead) {
    return (
      <div className={styles.container}>
        <Alert type="error" title="您没有查看 AI 配置的权限" showIcon />
      </div>
    );
  }

  if (loading) {
    return (
      <div className={styles.container} style={{ textAlign: 'center', paddingTop: 80 }}>
        <Spin size="large" />
      </div>
    );
  }

  if (error && !config) {
    return (
      <div className={styles.container}>
        <Alert type="error" title={error} showIcon />
      </div>
    );
  }

  // ── Render ──

  return (
    <div className={styles.container}>
      <div className={styles.header}>
        <h2>AI 模型配置</h2>
        <p className={styles.headerDesc}>密钥仅保存在服务器端，浏览器无法读取明文</p>
        <div className={styles.statusRow}>
          <Space size="small">
            <Tag color={config?.enabled ? 'green' : 'default'}>
              {config?.enabled ? '已启用' : '未启用'}
            </Tag>
            {config?.verified && <Tag color="blue">已验证</Tag>}
            {config?.hasApiKey && (
              <Tag color={sourceColor(config?.keySource || 'none')}>
                密钥: {sourceLabel(config?.keySource || 'none')}
              </Tag>
            )}
          </Space>
        </div>
      </div>

      <Form form={form} layout="vertical" initialValues={{ timeoutMs: 30000, enabled: false }}>
        <div className={styles.grid}>
          {/* Left: 模型路由 */}
          <Card title={<span className={styles.cardTitle}>模型路由</span>} extra={<ApiOutlined />}>
            <Form.Item
              name="provider"
              label="Provider"
              rules={[{ required: true, message: '请选择 Provider' }]}
            >
              <Select
                options={PROVIDER_OPTIONS}
                onChange={handleProviderChange}
                disabled={!canWrite}
              />
            </Form.Item>

            <Form.Item
              name="baseUrl"
              label="Base URL"
              rules={[
                { required: true, message: '请输入 Base URL' },
                { type: 'url', message: '请输入合法的 URL' },
              ]}
            >
              <Input
                placeholder={
                  config?.provider
                    ? PROVIDER_DEFAULTS[config.provider]
                    : 'https://api.openai.com/v1'
                }
                disabled={!canWrite || (isFixedProvider && canWrite)}
              />
            </Form.Item>

            <Form.Item noStyle shouldUpdate={(prev, curr) => prev.enabled !== curr.enabled}>
              {({ getFieldValue }) => {
                const enabled = getFieldValue('enabled');
                return (
                  <Form.Item
                    name="defaultModel"
                    label="默认模型"
                    rules={enabled ? [{ required: true, message: '启用时默认模型为必填项' }] : []}
                  >
                    <Input placeholder="例如: gpt-4, deepseek-chat" disabled={!canWrite} />
                  </Form.Item>
                );
              }}
            </Form.Item>

            <Form.Item name="enabled" label="启用" valuePropName="checked">
              <Switch disabled={!canWrite} />
            </Form.Item>

            <Form.Item
              name="timeoutMs"
              label="请求超时 (毫秒)"
              rules={[
                { required: true, message: '请输入超时时间' },
                { type: 'number', min: 1000, max: 120000, message: '范围: 1000-120000' },
              ]}
            >
              <InputNumber
                min={1000}
                max={120000}
                step={1000}
                style={{ width: '100%' }}
                disabled={!canWrite}
              />
            </Form.Item>
          </Card>

          {/* Right: 密钥保险库 */}
          <Card
            title={<span className={styles.cardTitle}>密钥保险库</span>}
            extra={<KeyOutlined />}
          >
            <Form.Item name="apiKey" label="API Key">
              <Input.Password
                placeholder={config?.hasApiKey ? '已安全保存，留空则保持不变' : '请输入 API Key'}
                disabled={!canWrite}
                autoComplete="new-password"
              />
            </Form.Item>

            {config && (
              <Descriptions column={1} size="small" style={{ marginBottom: 12 }}>
                <Descriptions.Item label="状态">
                  {config.hasApiKey ? (
                    <Tag color="green">{config.maskedApiKey || '••••'}</Tag>
                  ) : (
                    <Tag color="default">未配置</Tag>
                  )}
                </Descriptions.Item>
                <Descriptions.Item label="来源">
                  <Tag color={sourceColor(config.keySource)}>{sourceLabel(config.keySource)}</Tag>
                  {config.keySource === 'environment' && (
                    <span style={{ marginLeft: 8, fontSize: 12, color: '#999' }}>
                      由环境变量托管，需在服务器修改
                    </span>
                  )}
                </Descriptions.Item>
                <Descriptions.Item label="最后更新">
                  {formatDateTime(config.updatedAt)}
                </Descriptions.Item>
              </Descriptions>
            )}

            {config?.hasDatabaseKey && canWrite && (
              <div style={{ marginBottom: 8 }}>
                <Button danger size="small" onClick={handleClearKey}>
                  清除服务器保存密钥
                </Button>
              </div>
            )}

            {config?.keySource === 'environment' && !config.hasDatabaseKey && (
              <div style={{ marginBottom: 8, fontSize: 12, color: '#999' }}>
                密钥由环境变量提供，无法通过页面清除
              </div>
            )}

            <div className={styles.safetyNote}>
              API Key 使用 AES-256-GCM 加密存储，每次保存使用随机 IV。 传输层通过 HTTPS
              保护，服务端日志不记录密钥。
            </div>
            <div className={styles.safetyNoteKey}>
              也可通过环境变量 <Typography.Text code>AI_API_KEY</Typography.Text> 注入密钥，
              环境变量优先级高于数据库存储。
            </div>
          </Card>
        </div>

        {/* Actions */}
        <div className={styles.actions}>
          {canWrite ? (
            <Button type="primary" icon={<SaveOutlined />} onClick={handleSave} loading={saving}>
              保存配置
            </Button>
          ) : null}
          {canTest ? (
            <Button icon={<ApiOutlined />} onClick={handleTest} loading={testing}>
              测试连接
            </Button>
          ) : null}
        </div>
      </Form>

      {/* Test result */}
      {testResult && (
        <Card size="small" className={styles.testResult}>
          <Descriptions column={{ xs: 1, sm: 2 }} size="small">
            <Descriptions.Item label="结果">
              {testResult.success ? (
                testResult.modelAvailable ? (
                  <Tag icon={<CheckCircleOutlined />} color="success">
                    成功
                  </Tag>
                ) : (
                  <Tag icon={<WarningOutlined />} color="warning">
                    模型未找到
                  </Tag>
                )
              ) : (
                <Tag icon={<CloseCircleOutlined />} color="error">
                  失败
                </Tag>
              )}
            </Descriptions.Item>
            <Descriptions.Item label="延迟">
              {testResult.latencyMs != null ? `${testResult.latencyMs} ms` : '-'}
            </Descriptions.Item>
            <Descriptions.Item label="模型数量">
              {testResult.modelCount != null ? testResult.modelCount : '-'}
            </Descriptions.Item>
            <Descriptions.Item label="测试时间">
              {formatDateTime(testResult.testedAt)}
            </Descriptions.Item>
          </Descriptions>
          <Alert
            type={
              testResult.success ? (testResult.modelAvailable ? 'success' : 'warning') : 'error'
            }
            title={testResult.message}
            style={{ marginTop: 8 }}
          />
        </Card>
      )}
    </div>
  );
};

export default AiConfigPage;
