//! 日志中间件模块

use axum::{
    extract::{Request, ConnectInfo},
    middleware::Next,
    response::Response,
    http::{Method, Uri, HeaderMap},
};
use std::{
    net::SocketAddr,
    time::{Duration, Instant},
};
use tracing::{info, warn, error, Span};
use uuid::Uuid;

/// 请求日志中间件
pub async fn request_logging_middleware(
    ConnectInfo(addr): ConnectInfo<SocketAddr>,
    request: Request,
    next: Next,
) -> Response {
    let start_time = Instant::now();
    let method = request.method().clone();
    let uri = request.uri().clone();
    let version = request.version();
    let headers = request.headers().clone();
    
    // 生成请求ID
    let request_id = Uuid::new_v4();
    
    // 提取用户代理和其他有用的头信息
    let user_agent = headers
        .get("user-agent")
        .and_then(|v| v.to_str().ok())
        .unwrap_or("unknown");
    
    let content_length = headers
        .get("content-length")
        .and_then(|v| v.to_str().ok())
        .and_then(|v| v.parse::<u64>().ok())
        .unwrap_or(0);

    // 创建 span 用于结构化日志
    let span = tracing::info_span!(
        "http_request",
        request_id = %request_id,
        method = %method,
        uri = %uri,
        version = ?version,
        remote_addr = %addr,
        user_agent = user_agent,
        content_length = content_length,
    );

    let _enter = span.enter();

    info!(
        "开始处理请求: {} {} from {}",
        method, uri, addr
    );

    // 处理请求
    let response = next.run(request).await;
    
    let duration = start_time.elapsed();
    let status = response.status();
    let response_size = response
        .headers()
        .get("content-length")
        .and_then(|v| v.to_str().ok())
        .and_then(|v| v.parse::<u64>().ok())
        .unwrap_or(0);

    // 根据状态码选择日志级别
    match status.as_u16() {
        200..=299 => {
            info!(
                status = status.as_u16(),
                duration_ms = duration.as_millis(),
                response_size = response_size,
                "请求处理完成"
            );
        }
        300..=399 => {
            info!(
                status = status.as_u16(),
                duration_ms = duration.as_millis(),
                response_size = response_size,
                "请求重定向"
            );
        }
        400..=499 => {
            warn!(
                status = status.as_u16(),
                duration_ms = duration.as_millis(),
                response_size = response_size,
                "客户端错误"
            );
        }
        500..=599 => {
            error!(
                status = status.as_u16(),
                duration_ms = duration.as_millis(),
                response_size = response_size,
                "服务器错误"
            );
        }
        _ => {
            info!(
                status = status.as_u16(),
                duration_ms = duration.as_millis(),
                response_size = response_size,
                "请求处理完成"
            );
        }
    }

    response
}

/// 性能监控中间件
pub async fn performance_middleware(
    request: Request,
    next: Next,
) -> Response {
    let start_time = Instant::now();
    let method = request.method().clone();
    let uri = request.uri().clone();
    
    let response = next.run(request).await;
    let duration = start_time.elapsed();
    
    // 记录慢请求
    if duration > Duration::from_millis(1000) {
        warn!(
            method = %method,
            uri = %uri,
            duration_ms = duration.as_millis(),
            "慢请求检测"
        );
    }
    
    // 记录性能指标
    tracing::debug!(
        method = %method,
        uri = %uri,
        duration_ms = duration.as_millis(),
        status = response.status().as_u16(),
        "请求性能指标"
    );
    
    response
}

/// 错误日志中间件
pub async fn error_logging_middleware(
    request: Request,
    next: Next,
) -> Response {
    let method = request.method().clone();
    let uri = request.uri().clone();
    
    let response = next.run(request).await;
    
    // 记录错误响应的详细信息
    if response.status().is_server_error() {
        error!(
            method = %method,
            uri = %uri,
            status = response.status().as_u16(),
            "服务器内部错误"
        );
    } else if response.status().is_client_error() {
        warn!(
            method = %method,
            uri = %uri,
            status = response.status().as_u16(),
            "客户端请求错误"
        );
    }
    
    response
}

/// 安全日志中间件
pub async fn security_logging_middleware(
    ConnectInfo(addr): ConnectInfo<SocketAddr>,
    request: Request,
    next: Next,
) -> Response {
    let method = request.method().clone();
    let uri = request.uri().clone();
    let headers = request.headers().clone();
    
    // 检测可疑的请求模式
    let suspicious_patterns = [
        "admin", "login", "auth", "password", "token",
        "sql", "script", "exec", "cmd", "shell",
        "..", "etc/passwd", "proc/", "sys/",
    ];
    
    let uri_str = uri.to_string().to_lowercase();
    let is_suspicious = suspicious_patterns.iter().any(|&pattern| uri_str.contains(pattern));
    
    if is_suspicious {
        warn!(
            remote_addr = %addr,
            method = %method,
            uri = %uri,
            user_agent = headers.get("user-agent")
                .and_then(|v| v.to_str().ok())
                .unwrap_or("unknown"),
            "检测到可疑请求"
        );
    }
    
    // 检测暴力破解尝试
    if uri.path().contains("login") || uri.path().contains("auth") {
        info!(
            remote_addr = %addr,
            method = %method,
            uri = %uri,
            "认证尝试"
        );
    }
    
    let response = next.run(request).await;
    
    // 记录认证失败
    if response.status() == 401 || response.status() == 403 {
        warn!(
            remote_addr = %addr,
            method = %method,
            uri = %uri,
            status = response.status().as_u16(),
            "认证或授权失败"
        );
    }
    
    response
}

#[cfg(test)]
mod tests {
    use super::*;
    use axum::{
        body::Body,
        http::{Request, StatusCode},
        response::Response,
        middleware::Next,
    };
    use std::convert::Infallible;

    async fn dummy_handler(_req: Request<Body>) -> Result<Response<Body>, Infallible> {
        Ok(Response::builder()
            .status(StatusCode::OK)
            .body(Body::empty())
            .unwrap())
    }

    #[tokio::test]
    async fn test_request_logging_middleware() {
        let request = Request::builder()
            .method("GET")
            .uri("/test")
            .body(Body::empty())
            .unwrap();

        let addr = "127.0.0.1:8080".parse().unwrap();
        let next = Next::new(dummy_handler);

        let response = request_logging_middleware(
            ConnectInfo(addr),
            request,
            next,
        ).await;

        assert_eq!(response.status(), StatusCode::OK);
    }

    #[tokio::test]
    async fn test_performance_middleware() {
        let request = Request::builder()
            .method("GET")
            .uri("/test")
            .body(Body::empty())
            .unwrap();

        let next = Next::new(dummy_handler);
        let response = performance_middleware(request, next).await;

        assert_eq!(response.status(), StatusCode::OK);
    }
}