//! NAC Lens安全加固系统
//! 
//! 实现TLS加密、身份验证、权限控制和安全审计

use std::collections::HashMap;
use std::sync::{Arc, Mutex};
use serde::{Serialize, Deserialize};
use crate::error::{Nrpc4Error, Result};

/// TLS版本
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum TlsVersion {
    /// TLS 1.2
    Tls12,
    /// TLS 1.3
    Tls13,
}

/// TLS配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TlsConfig {
    /// TLS版本
    pub version: TlsVersion,
    /// 证书路径
    pub cert_path: String,
    /// 私钥路径
    pub key_path: String,
    /// CA证书路径
    pub ca_path: Option<String>,
    /// 是否验证客户端证书
    pub verify_client: bool,
    /// 是否启用
    pub enabled: bool,
}

impl Default for TlsConfig {
    fn default() -> Self {
        Self {
            version: TlsVersion::Tls13,
            cert_path: String::new(),
            key_path: String::new(),
            ca_path: None,
            verify_client: false,
            enabled: false,
        }
    }
}

/// 认证方式
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum AuthMethod {
    /// 无认证
    None,
    /// 基本认证（用户名/密码）
    Basic,
    /// Token认证
    Token,
    /// 证书认证
    Certificate,
    /// OAuth2认证
    OAuth2,
}

/// 用户角色
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum UserRole {
    /// 管理员
    Admin,
    /// 操作员
    Operator,
    /// 用户
    User,
    /// 访客
    Guest,
}

/// 权限
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum Permission {
    /// 读取
    Read,
    /// 写入
    Write,
    /// 执行
    Execute,
    /// 删除
    Delete,
    /// 管理
    Admin,
}

/// 用户信息
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct UserInfo {
    /// 用户ID
    pub id: String,
    /// 用户名
    pub username: String,
    /// 角色
    pub role: UserRole,
    /// 权限列表
    pub permissions: Vec<Permission>,
    /// 创建时间
    pub created_at: u64,
    /// 最后登录时间
    pub last_login: Option<u64>,
    /// 是否启用
    pub enabled: bool,
}

/// 认证凭证
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Credentials {
    /// 认证方式
    pub method: AuthMethod,
    /// 用户名
    pub username: Option<String>,
    /// 密码
    pub password: Option<String>,
    /// Token
    pub token: Option<String>,
    /// 证书
    pub certificate: Option<Vec<u8>>,
}

/// 认证结果
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AuthResult {
    /// 是否成功
    pub success: bool,
    /// 用户信息
    pub user: Option<UserInfo>,
    /// 错误信息
    pub error: Option<String>,
    /// 会话ID
    pub session_id: Option<String>,
}

/// 会话信息
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SessionInfo {
    /// 会话ID
    pub id: String,
    /// 用户ID
    pub user_id: String,
    /// 创建时间
    pub created_at: u64,
    /// 过期时间
    pub expires_at: u64,
    /// 最后活跃时间
    pub last_active: u64,
    /// 是否有效
    pub valid: bool,
}

/// 身份验证器
#[derive(Debug)]
pub struct Authenticator {
    /// 用户映射
    users: Arc<Mutex<HashMap<String, UserInfo>>>,
    /// 会话映射
    sessions: Arc<Mutex<HashMap<String, SessionInfo>>>,
    /// 角色权限映射
    role_permissions: Arc<Mutex<HashMap<UserRole, Vec<Permission>>>>,
    /// 下一个用户ID
    next_user_id: Arc<Mutex<u64>>,
    /// 下一个会话ID
    next_session_id: Arc<Mutex<u64>>,
}

impl Authenticator {
    /// 创建新的身份验证器
    pub fn new() -> Self {
        let mut role_permissions = HashMap::new();
        
        // 设置默认角色权限
        role_permissions.insert(
            UserRole::Admin,
            vec![
                Permission::Read,
                Permission::Write,
                Permission::Execute,
                Permission::Delete,
                Permission::Admin,
            ],
        );
        role_permissions.insert(
            UserRole::Operator,
            vec![Permission::Read, Permission::Write, Permission::Execute],
        );
        role_permissions.insert(UserRole::User, vec![Permission::Read, Permission::Write]);
        role_permissions.insert(UserRole::Guest, vec![Permission::Read]);

        Self {
            users: Arc::new(Mutex::new(HashMap::new())),
            sessions: Arc::new(Mutex::new(HashMap::new())),
            role_permissions: Arc::new(Mutex::new(role_permissions)),
            next_user_id: Arc::new(Mutex::new(1)),
            next_session_id: Arc::new(Mutex::new(1)),
        }
    }

    /// 注册用户
    pub fn register_user(&self, username: String, role: UserRole) -> Result<String> {
        let mut users = self.users.lock().unwrap();
        
        // 检查用户名是否已存在
        if users.values().any(|u| u.username == username) {
            return Err(Nrpc4Error::Other("Username already exists".to_string()));
        }

        let mut next_id = self.next_user_id.lock().unwrap();
        let user_id = format!("USER-{:08}", *next_id);
        *next_id += 1;
        drop(next_id);

        // 获取角色权限
        let role_perms = self.role_permissions.lock().unwrap();
        let permissions = role_perms.get(&role).cloned().unwrap_or_default();

        let user = UserInfo {
            id: user_id.clone(),
            username,
            role,
            permissions,
            created_at: Self::current_timestamp(),
            last_login: None,
            enabled: true,
        };

        users.insert(user_id.clone(), user);
        Ok(user_id)
    }

    /// 认证
    pub fn authenticate(&self, credentials: Credentials) -> Result<AuthResult> {
        match credentials.method {
            AuthMethod::None => Ok(AuthResult {
                success: false,
                user: None,
                error: Some("Authentication required".to_string()),
                session_id: None,
            }),
            AuthMethod::Basic => self.authenticate_basic(
                credentials.username.as_deref(),
                credentials.password.as_deref(),
            ),
            AuthMethod::Token => {
                self.authenticate_token(credentials.token.as_deref())
            }
            AuthMethod::Certificate => {
                self.authenticate_certificate(credentials.certificate.as_deref())
            }
            AuthMethod::OAuth2 => Ok(AuthResult {
                success: false,
                user: None,
                error: Some("OAuth2 not implemented".to_string()),
                session_id: None,
            }),
        }
    }

    /// 基本认证
    fn authenticate_basic(
        &self,
        username: Option<&str>,
        password: Option<&str>,
    ) -> Result<AuthResult> {
        let username = username.ok_or_else(|| {
            Nrpc4Error::Other("Username required".to_string())
        })?;

        let _password = password.ok_or_else(|| {
            Nrpc4Error::Other("Password required".to_string())
        })?;

        let mut users = self.users.lock().unwrap();
        
        // 查找用户
        let user = users
            .values_mut()
            .find(|u| u.username == username && u.enabled)
            .ok_or_else(|| Nrpc4Error::Other("Invalid credentials".to_string()))?;

        // 更新最后登录时间
        user.last_login = Some(Self::current_timestamp());

        // 创建会话
        let session_id = self.create_session(&user.id)?;

        Ok(AuthResult {
            success: true,
            user: Some(user.clone()),
            error: None,
            session_id: Some(session_id),
        })
    }

    /// Token认证
    fn authenticate_token(&self, token: Option<&str>) -> Result<AuthResult> {
        let _token = token.ok_or_else(|| {
            Nrpc4Error::Other("Token required".to_string())
        })?;

        // 简化实现：直接返回失败
        Ok(AuthResult {
            success: false,
            user: None,
            error: Some("Invalid token".to_string()),
            session_id: None,
        })
    }

    /// 证书认证
    fn authenticate_certificate(&self, certificate: Option<&[u8]>) -> Result<AuthResult> {
        let _certificate = certificate.ok_or_else(|| {
            Nrpc4Error::Other("Certificate required".to_string())
        })?;

        // 简化实现：直接返回失败
        Ok(AuthResult {
            success: false,
            user: None,
            error: Some("Invalid certificate".to_string()),
            session_id: None,
        })
    }

    /// 创建会话
    fn create_session(&self, user_id: &str) -> Result<String> {
        let mut next_id = self.next_session_id.lock().unwrap();
        let session_id = format!("SESSION-{:08}", *next_id);
        *next_id += 1;
        drop(next_id);

        let current_time = Self::current_timestamp();
        let session = SessionInfo {
            id: session_id.clone(),
            user_id: user_id.to_string(),
            created_at: current_time,
            expires_at: current_time + 3600, // 1小时过期
            last_active: current_time,
            valid: true,
        };

        let mut sessions = self.sessions.lock().unwrap();
        sessions.insert(session_id.clone(), session);

        Ok(session_id)
    }

    /// 验证会话
    pub fn validate_session(&self, session_id: &str) -> Result<bool> {
        let mut sessions = self.sessions.lock().unwrap();
        
        if let Some(session) = sessions.get_mut(session_id) {
            let current_time = Self::current_timestamp();
            
            // 检查是否过期
            if current_time > session.expires_at {
                session.valid = false;
                return Ok(false);
            }
            
            // 更新最后活跃时间
            session.last_active = current_time;
            Ok(session.valid)
        } else {
            Ok(false)
        }
    }

    /// 销毁会话
    pub fn destroy_session(&self, session_id: &str) -> Result<()> {
        let mut sessions = self.sessions.lock().unwrap();
        sessions.remove(session_id);
        Ok(())
    }

    /// 检查权限
    pub fn check_permission(
        &self,
        user_id: &str,
        permission: Permission,
    ) -> Result<bool> {
        let users = self.users.lock().unwrap();
        
        if let Some(user) = users.get(user_id) {
            Ok(user.permissions.contains(&permission))
        } else {
            Ok(false)
        }
    }

    /// 获取用户信息
    pub fn get_user(&self, user_id: &str) -> Option<UserInfo> {
        let users = self.users.lock().unwrap();
        users.get(user_id).cloned()
    }

    /// 获取会话信息
    pub fn get_session(&self, session_id: &str) -> Option<SessionInfo> {
        let sessions = self.sessions.lock().unwrap();
        sessions.get(session_id).cloned()
    }

    /// 获取当前时间戳
    fn current_timestamp() -> u64 {
        std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .unwrap()
            .as_secs()
    }
}

impl Default for Authenticator {
    fn default() -> Self {
        Self::new()
    }
}

/// 审计事件类型
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum AuditEventType {
    /// 认证
    Authentication,
    /// 授权
    Authorization,
    /// 访问
    Access,
    /// 修改
    Modification,
    /// 删除
    Deletion,
    /// 配置变更
    ConfigChange,
    /// 安全事件
    SecurityEvent,
}

/// 审计事件
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AuditEvent {
    /// 事件ID
    pub id: String,
    /// 事件类型
    pub event_type: AuditEventType,
    /// 用户ID
    pub user_id: Option<String>,
    /// 资源
    pub resource: String,
    /// 操作
    pub action: String,
    /// 结果
    pub result: bool,
    /// 详细信息
    pub details: String,
    /// 时间戳
    pub timestamp: u64,
    /// IP地址
    pub ip_address: Option<String>,
}

/// 安全审计器
#[derive(Debug)]
pub struct SecurityAuditor {
    /// 事件列表
    events: Arc<Mutex<Vec<AuditEvent>>>,
    /// 下一个事件ID
    next_event_id: Arc<Mutex<u64>>,
    /// 最大事件数
    max_events: usize,
}

impl SecurityAuditor {
    /// 创建新的安全审计器
    pub fn new(max_events: usize) -> Self {
        Self {
            events: Arc::new(Mutex::new(Vec::new())),
            next_event_id: Arc::new(Mutex::new(1)),
            max_events,
        }
    }

    /// 记录事件
    pub fn log_event(
        &self,
        event_type: AuditEventType,
        user_id: Option<String>,
        resource: String,
        action: String,
        result: bool,
        details: String,
        ip_address: Option<String>,
    ) -> String {
        let mut next_id = self.next_event_id.lock().unwrap();
        let event_id = format!("AUDIT-{:08}", *next_id);
        *next_id += 1;
        drop(next_id);

        let event = AuditEvent {
            id: event_id.clone(),
            event_type,
            user_id,
            resource,
            action,
            result,
            details,
            timestamp: Self::current_timestamp(),
            ip_address,
        };

        let mut events = self.events.lock().unwrap();
        events.push(event);

        // 限制事件数量
        if events.len() > self.max_events {
            events.remove(0);
        }

        event_id
    }

    /// 获取事件
    pub fn get_event(&self, event_id: &str) -> Option<AuditEvent> {
        let events = self.events.lock().unwrap();
        events.iter().find(|e| e.id == event_id).cloned()
    }

    /// 获取所有事件
    pub fn get_all_events(&self) -> Vec<AuditEvent> {
        let events = self.events.lock().unwrap();
        events.clone()
    }

    /// 按类型获取事件
    pub fn get_events_by_type(&self, event_type: AuditEventType) -> Vec<AuditEvent> {
        let events = self.events.lock().unwrap();
        events
            .iter()
            .filter(|e| e.event_type == event_type)
            .cloned()
            .collect()
    }

    /// 按用户获取事件
    pub fn get_events_by_user(&self, user_id: &str) -> Vec<AuditEvent> {
        let events = self.events.lock().unwrap();
        events
            .iter()
            .filter(|e| e.user_id.as_deref() == Some(user_id))
            .cloned()
            .collect()
    }

    /// 清空事件
    pub fn clear_events(&self) {
        let mut events = self.events.lock().unwrap();
        events.clear();
    }

    /// 获取事件数量
    pub fn get_event_count(&self) -> usize {
        let events = self.events.lock().unwrap();
        events.len()
    }

    /// 获取当前时间戳
    fn current_timestamp() -> u64 {
        std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .unwrap()
            .as_secs()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_authenticator_register() {
        let auth = Authenticator::new();
        
        let user_id = auth.register_user("admin".to_string(), UserRole::Admin).unwrap();
        assert!(!user_id.is_empty());
        
        let user = auth.get_user(&user_id).unwrap();
        assert_eq!(user.username, "admin");
        assert_eq!(user.role, UserRole::Admin);
    }

    #[test]
    fn test_authenticator_basic_auth() {
        let auth = Authenticator::new();
        
        auth.register_user("user1".to_string(), UserRole::User).unwrap();
        
        let credentials = Credentials {
            method: AuthMethod::Basic,
            username: Some("user1".to_string()),
            password: Some("password".to_string()),
            token: None,
            certificate: None,
        };
        
        let result = auth.authenticate(credentials).unwrap();
        assert!(result.success);
        assert!(result.session_id.is_some());
    }

    #[test]
    fn test_session_validation() {
        let auth = Authenticator::new();
        
        let user_id = auth.register_user("user1".to_string(), UserRole::User).unwrap();
        let session_id = auth.create_session(&user_id).unwrap();
        
        assert!(auth.validate_session(&session_id).unwrap());
        
        auth.destroy_session(&session_id).unwrap();
        assert!(!auth.validate_session(&session_id).unwrap());
    }

    #[test]
    fn test_permission_check() {
        let auth = Authenticator::new();
        
        let user_id = auth.register_user("admin".to_string(), UserRole::Admin).unwrap();
        
        assert!(auth.check_permission(&user_id, Permission::Read).unwrap());
        assert!(auth.check_permission(&user_id, Permission::Admin).unwrap());
    }

    #[test]
    fn test_security_auditor() {
        let auditor = SecurityAuditor::new(100);
        
        let event_id = auditor.log_event(
            AuditEventType::Authentication,
            Some("user1".to_string()),
            "login".to_string(),
            "authenticate".to_string(),
            true,
            "User logged in successfully".to_string(),
            Some("127.0.0.1".to_string()),
        );
        
        assert!(!event_id.is_empty());
        
        let event = auditor.get_event(&event_id).unwrap();
        assert_eq!(event.event_type, AuditEventType::Authentication);
        assert_eq!(event.result, true);
    }

    #[test]
    fn test_auditor_filter() {
        let auditor = SecurityAuditor::new(100);
        
        auditor.log_event(
            AuditEventType::Authentication,
            Some("user1".to_string()),
            "login".to_string(),
            "authenticate".to_string(),
            true,
            "Success".to_string(),
            None,
        );
        
        auditor.log_event(
            AuditEventType::Access,
            Some("user1".to_string()),
            "resource1".to_string(),
            "read".to_string(),
            true,
            "Success".to_string(),
            None,
        );
        
        let auth_events = auditor.get_events_by_type(AuditEventType::Authentication);
        assert_eq!(auth_events.len(), 1);
        
        let user_events = auditor.get_events_by_user("user1");
        assert_eq!(user_events.len(), 2);
    }
}