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use alloc::vec;
use lose_net_stack::packets::tcp::TCPPacket;
use lose_net_stack::IPv4;
use lose_net_stack::MacAddress;
use lose_net_stack::TcpFlags;

use crate::{drivers::NET_DEVICE, fs::File};

use super::socket::get_s_a_by_index;
use super::{
    net_interrupt_handler,
    socket::{add_socket, pop_data, remove_socket},
    LOSE_NET_STACK,
};

// add tcp packet info to this structure
pub struct TCP {
    pub target: IPv4,
    pub sport: u16,
    pub dport: u16,
    pub seq: u32,
    pub ack: u32,
    pub socket_index: usize,
}

impl TCP {
    pub fn new(target: IPv4, sport: u16, dport: u16, seq: u32, ack: u32) -> Self {
        let index = add_socket(target, sport, dport).expect("can't add socket");

        Self {
            target,
            sport,
            dport,
            seq,
            ack,
            socket_index: index,
        }
    }
}

impl File for TCP {
    fn readable(&self) -> bool {
        true
    }

    fn writable(&self) -> bool {
        true
    }

    fn read(&self, mut buf: crate::mm::UserBuffer) -> usize {
        loop {
            if let Some(data) = pop_data(self.socket_index) {
                let data_len = data.len();
                let mut left = 0;
                for i in 0..buf.buffers.len() {
                    let buffer_i_len = buf.buffers[i].len().min(data_len - left);

                    buf.buffers[i][..buffer_i_len]
                        .copy_from_slice(&data[left..(left + buffer_i_len)]);

                    left += buffer_i_len;
                    if left == data_len {
                        break;
                    }
                }
                return left;
            } else {
                net_interrupt_handler();
            }
        }
    }

    fn write(&self, buf: crate::mm::UserBuffer) -> usize {
        let lose_net_stack = LOSE_NET_STACK.0.exclusive_access();

        let mut data = vec![0u8; buf.len()];

        let mut left = 0;
        for i in 0..buf.buffers.len() {
            data[left..(left + buf.buffers[i].len())].copy_from_slice(buf.buffers[i]);
            left += buf.buffers[i].len();
        }

        let len = data.len();

        // get sock and sequence
        let (ack, seq) = get_s_a_by_index(self.socket_index).map_or((0, 0), |x| x);

        let tcp_packet = TCPPacket {
            source_ip: lose_net_stack.ip,
            source_mac: lose_net_stack.mac,
            source_port: self.sport,
            dest_ip: self.target,
            dest_mac: MacAddress::new([0xff, 0xff, 0xff, 0xff, 0xff, 0xff]),
            dest_port: self.dport,
            data_len: len,
            seq,
            ack,
            flags: TcpFlags::A,
            win: 65535,
            urg: 0,
            data: data.as_ref(),
        };
        NET_DEVICE.transmit(&tcp_packet.build_data());
        len
    }
}

impl Drop for TCP {
    fn drop(&mut self) {
        remove_socket(self.socket_index)
    }
}