// 版权所有 (c) ling 保留所有权利。
// 除非另行说明，否则仅允许在LingTransmit中使用此文件中的代码。
//
// 由 ling 创建于 2025/1/19.
#![allow(non_snake_case)]

use crate::packet::code::*;
use crate::stream::{OwnedReadHalfAbstraction, OwnedWriteHalfAbstraction};
use log::trace;
use openssl::x509::{X509NameEntryRef, X509};
use std::io;
use std::sync::Arc;
use tokio::io::{AsyncReadExt, AsyncWriteExt};
use tokio::net::{TcpStream, ToSocketAddrs};
use tokio::sync::Mutex;

/// 客户端
pub struct Client {
    read: Arc<Mutex<dyn OwnedReadHalfAbstraction>>,
    write: Arc<Mutex<dyn OwnedWriteHalfAbstraction>>,
}

impl Client {
    fn init(
        read: Arc<Mutex<dyn OwnedReadHalfAbstraction>>,
        write: Arc<Mutex<dyn OwnedWriteHalfAbstraction>>,
    ) -> Self {
        Client { read, write }
    }

    pub async fn tcp_connect<A: ToSocketAddrs>(addr: A, ca: X509) -> io::Result<Self> {
        let stream = TcpStream::connect(addr).await?;
        let (read, write) = stream.into_split();

        let read: Arc<Mutex<dyn OwnedReadHalfAbstraction>> = Arc::new(Mutex::new(read));
        let write: Arc<Mutex<dyn OwnedWriteHalfAbstraction>> = Arc::new(Mutex::new(write));

        let buffer = Self::protocol_connection(read.clone(), write.clone()).await?;
        let cert = X509::from_pem(&*buffer)?;
        //先验证证书签名
        let ca_public = ca
            .public_key()
            .map_err(|_| io::Error::new(io::ErrorKind::NotFound, "无法提取CA公钥"))?;

        if !cert.verify(&ca_public).map_err(|e| {
            io::Error::new(
                io::ErrorKind::NotFound,
                format!("无法验证服务器证书签名：{}", e.to_string()),
            )
        })? {
            return Err(io::Error::new(
                io::ErrorKind::NotFound,
                "服务器证书缺少信任的CA签名",
            ));
        }
        //在此实现中阻止私域证书
        let subject_name = cert.subject_name();
        let cn = match subject_name
            .entries_by_nid(openssl::nid::Nid::COMMONNAME)
            .next()
        {
            None => {
                return Err(io::Error::new(
                    io::ErrorKind::NotFound,
                    "无法获得签发对象信息",
                ));
            }
            Some(cn) => cn,
        };

        todo!()
    }

    /// 执行协议握手，
    async fn protocol_connection(
        read: Arc<Mutex<dyn OwnedReadHalfAbstraction>>,
        write: Arc<Mutex<dyn OwnedWriteHalfAbstraction>>,
    ) -> io::Result<Vec<u8>> {
        let mut write = write.lock().await;
        let mut read = read.lock().await;
        //请求执行 Ling Transmit V1.1 握手
        write.write_i32_le(LING_SYN_V1).await?;
        //读取证书大小
        let ca_size = read.read_i64_le().await?;
        if ca_size <= 0 {
            return Err(io::Error::new(
                io::ErrorKind::NetworkDown,
                format!("读取到异常数据包大小：{}", ca_size),
            ));
        }
        trace!("证书大小：{:X}", ca_size);
        //读取服务器证书
        let mut buffer = Vec::new();
        buffer.resize(ca_size as usize, 0u8);
        read.read_exact(&mut buffer).await?;

        Ok(buffer)
    }
}