import { useEffect, useState } 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, simpleRootLogin } from "~/api/login/auth.server";
import styles from "~/styles/pages/login.css?url";
import { toastService } from "~/components/ui";

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");
  const username = formData.get("username")?.toString().trim();
  const password = formData.get("password")?.toString().trim();

  if (intent === "password_login") {
    // 获取重定向目标
    const session = await getSession(request);
    const redirectTo = session.get("redirectTo") || "/";
    
    // 调用 simpleRootLogin 方法进行登录
    const response = await simpleRootLogin(username || "", password || "", redirectTo);
    
    // 检查响应状态
    if (response.status === 302) {
      // 登录成功，直接返回重定向响应
      return response;
    } else {
      // 登录失败，解析错误信息并重定向到登录页面
      const errorData = await response.json();
      const errorMsg = errorData.error || "登录失败";
      return redirect(`/login?error=${encodeURIComponent(errorMsg)}`);
    }
  }

  return null;
}

export default function Login() {
  const [searchParams] = useSearchParams();
  const error = searchParams.get("error");
  const [isFlipped, setIsFlipped] = useState(false);
  const [username, setUsername] = useState("");
  const [password, setPassword] = useState("");
  
  // 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";
      case "用户名和密码不能为空":
      case "用户名和密码不能为空，请重新输入":
        return "用户名和密码不能为空，请重新输入";
      case "登录失败，请检查用户名和密码":
      case "用户名或密码错误，请重新输入":
        return "用户名或密码错误，请重新输入";
      case "登录请求失败，请稍后重试":
      case "网络连接失败，请稍后重试":
        return "网络连接失败，请稍后重试";
      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);
      console.log("授权URL:", authorizeUrl);
      // 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");
    }
  };

  // 处理管理员登录
  const handleAdminLogin = () => {
    setIsFlipped(true);
  };

  // 处理返回OAuth登录
  const handleBackToOAuth = () => {
    setIsFlipped(false);
    setUsername("");
    setPassword("");
  };

  // 处理账号密码登录表单提交
  const handlePasswordLoginSubmit = (e: React.FormEvent) => {
    // 客户端验证
    if (!username.trim()) {
      e.preventDefault();
      toastService.error("请输入用户名");
      return;
    }
    
    if (!password.trim()) {
      e.preventDefault();
      toastService.error("请输入密码");
      return;
    }
    
    // 验证通过，让表单正常提交
  };

  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 ${isFlipped ? 'flipped' : ''}`}>
        <div className="login-card">
          {/* 正面 - OAuth登录 */}
          <div className="login-card-front">
            <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>

              {/* 管理员登录链接 */}
              <div className="admin-login-link">
                <button 
                  onClick={handleAdminLogin}
                  className="admin-login-text"
                  type="button"
                >
                  管理员登录
                </button>
              </div>
            </div>
            
            <div className="login-footer">
              <p>© 2025 中国烟草 版权所有</p>
            </div>
          </div>

          {/* 背面 - 管理员登录 */}
          <div className="login-card-back">
            <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">管理员登录</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>
              )}
              
              <Form method="post" className="admin-login-form" onSubmit={handlePasswordLoginSubmit}>
                <input type="hidden" name="intent" value="password_login" />
                
                <div className="form-group">
                  <label htmlFor="username" className="form-label">用户名</label>
                  <input
                    type="text"
                    id="username"
                    name="username"
                    value={username}
                    onChange={(e) => setUsername(e.target.value)}
                    className="form-input"
                    placeholder="请输入用户名"
                    required
                  />
                </div>
                
                <div className="form-group">
                  <label htmlFor="password" className="form-label">密码</label>
                  <input
                    type="password"
                    id="password"
                    name="password"
                    value={password}
                    onChange={(e) => setPassword(e.target.value)}
                    className="form-input"
                    placeholder="请输入密码"
                    required
                  />
                </div>
                
                <button 
                  type="submit"
                  className="admin-login-button"
                >
                  <i className="ri-login-box-line"></i>
                  登录
                </button>
              </Form>
              
              <div className="back-to-oauth">
                <button 
                  onClick={handleBackToOAuth}
                  className="back-button"
                  type="button"
                >
                  <i className="ri-arrow-left-line"></i>
                  返回统一身份认证登录
                </button>
              </div>
            </div>
            
            <div className="login-footer">
              <p>© 2025 中国烟草 版权所有</p>
            </div>
          </div>
        </div>
      </div>
    </div>
  );
}