import { useEffect } from "react";
import { useSearchParams, Form } from "@remix-run/react";
import { type MetaFunction, type LoaderFunctionArgs, type ActionFunctionArgs, redirect } from "@remix-run/node";
import { OAuthClient } from "~/api/login/oauth-client";
import { OAUTH_CONFIG } from "~/config/api-config";
import { getUserSession, getSession, createUserSession } from "~/api/login/auth.server";
import styles from "~/styles/pages/login.css?url";

export const links = () => [
  { rel: "stylesheet", href: styles }
];

export const meta: MetaFunction = () => {
  return [
    { title: "中国烟草AI合同及卷宗审核系统 - 登录" },
    { name: "description", content: "中国烟草AI合同及卷宗审核系统登录页面" },
  ];
};

// 加载器，获取当前会话状态
export async function loader({ request }: LoaderFunctionArgs) {
  const { isAuthenticated } = await getUserSession(request);
  
  // 如果已登录，重定向到首页
  if (isAuthenticated) {
    return redirect("/");
  }

  // 获取重定向URL并保存到session
  const url = new URL(request.url);
  const redirectTo = url.searchParams.get("redirect") || "/";
  
  const session = await getSession(request);
  session.set("redirectTo", redirectTo);
  
  return Response.json({ 
    isAuthenticated: false,
    redirectTo 
  });
}

// 处理表单提交的action函数
export async function action({ request }: ActionFunctionArgs) {
  const formData = await request.formData();
  const intent = formData.get("intent");

  if (intent === "temp_admin_login") {
    // 获取重定向目标
    const session = await getSession(request);
    const redirectTo = session.get("redirectTo") || "/";
    
    // 创建管理员会话
    return createUserSession(true, 'developer', redirectTo);
  }

  return null;
}

export default function Login() {
  const [searchParams] = useSearchParams();
  const error = searchParams.get("error");
  
  // 获取错误消息的友好描述
  const getErrorMessage = (error: string | null) => {
    if (!error) return null;
    
    switch (error) {
      case "missing_code":
        return "登录过程中缺少授权码，请重新登录";
      case "invalid_state":
        return "登录状态验证失败，请重新登录";
      case "token_error":
        return "获取访问令牌失败，请重新登录";
      case "userinfo_error":
        return "获取用户信息失败，请重新登录";
      case "callback_error":
        return "登录回调处理失败，请重新登录";
      default:
        return decodeURIComponent(error);
    }
  };

  // 处理OAuth2.0登录
  const handleOAuthLogin = () => {
    try {
      // 创建OAuth客户端
      const oauthClient = new OAuthClient(OAUTH_CONFIG);
      
      // 生成状态值
      const state = oauthClient.generateState();
      
      // 将状态值保存到localStorage（用于后续验证）
      localStorage.setItem("oauth_state", state);
      
      // 获取授权URL
      const authorizeUrl = oauthClient.getAuthorizeUrl(state);
      
      // 重定向到IDaaS登录页面
      window.location.href = authorizeUrl;
    } catch (error) {
      console.error("启动OAuth2.0登录失败:", error);
      alert("登录系统初始化失败，请联系系统管理员");
    }
  };

  useEffect(() => {
    // 检查OAuth配置是否完整
    if (!OAUTH_CONFIG.serverUrl || !OAUTH_CONFIG.clientId || !OAUTH_CONFIG.clientSecret) {
      console.error("OAuth2.0配置不完整:", OAUTH_CONFIG);
    }
  }, []);
  
  return (
    <div className="login-page">
      <div className="login-container">
        <div className="login-header">
          <h1 className="login-title">中国烟草AI合同及卷宗审核系统</h1>
        </div>
        
        <div className="login-form-container">
          <h2 className="login-subtitle">统一身份认证登录</h2>
          
          {error && (
            <div className="error-message-container">
              <div className="error-icon"><i className="ri-error-warning-line"></i></div>
              <div className="error-text">{getErrorMessage(error)}</div>
            </div>
          )}
          
          <div className="oauth-login-section">
            <div className="login-description">
              <p>请点击下方按钮进行统一身份认证登录</p>
            </div>
            
            <button 
              onClick={handleOAuthLogin}
              className="oauth-login-button"
              type="button"
            >
              <i className="ri-shield-user-line"></i>
              统一身份认证登录
            </button>
            
            <div className="login-tips">
              <p>
                <i className="ri-information-line"></i>
                系统将跳转到统一身份认证平台进行登录
              </p>
            </div>
          </div>

          {/* 临时管理员登录区域 */}
          <div className="temp-login-section">
            <div className="section-divider">
              <span>或</span>
            </div>
            
            <Form method="post" className="temp-login-form">
              <input type="hidden" name="intent" value="temp_admin_login" />
              <button 
                type="submit"
                className="temp-admin-login-button"
              >
                <i className="ri-admin-line"></i>
                临时管理员登录
              </button>
              <div className="temp-login-tips">
                <p>
                  <i className="ri-alert-line"></i>
                  仅供开发测试使用，将以管理员身份登录
                </p>
              </div>
            </Form>
          </div>
        </div>
        
        <div className="login-footer">
          <p>© 2025 中国烟草 版权所有</p>
        </div>
      </div>
    </div>
  );
}