use std::{
    fmt::Display,
    net::{Ipv4Addr, SocketAddr, SocketAddrV4, UdpSocket},
    str::{from_utf8, FromStr},
    time::{Duration, Instant},
};

use crate::NetworkLogFile;

use anyhow::Result;

const READ_BUFFER_SIZE: usize = 1024;
const RETRIES: usize = 3;

#[derive(Debug, Clone)]
pub enum SocketContent {
    Message(SocketAddr, String),
    NewConnection(SocketAddr),
    TimeOut(SocketAddr),
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum LogLevel {
    None,
    Debug,
    Verbose,
}

impl Default for LogLevel {
    fn default() -> Self {
        Self::None
    }
}

impl FromStr for LogLevel {
    type Err = anyhow::Error;

    fn from_str(s: &str) -> Result<Self> {
        match s {
            "None" => Ok(Self::None),
            "Debug" => Ok(Self::Debug),
            "Verbose" => Ok(Self::Verbose),

            _ => Err(anyhow::Error::msg(format!(
                "Failed parsing LogLevel from {}",
                s
            ))),
        }
    }
}

impl Display for LogLevel {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::None => write!(f, "None"),
            Self::Debug => write!(f, "Debug"),
            Self::Verbose => write!(f, "Verbose"),
        }
    }
}

#[derive(Debug, Clone)]
pub struct SocketCreateInfo {
    pub port: u16,
    pub connection_time_out: Duration,
    pub heartbeat_interval: Duration,
    pub log_level: LogLevel,
}

pub struct Socket {
    udp_socket: UdpSocket,
    connection_time_out: Duration,

    log_level: LogLevel,
    pub(crate) heartbeat_interval: Duration,
    pub(crate) start: Instant,
}

impl Socket {
    pub fn new(info: SocketCreateInfo) -> Result<Self> {
        let socket = UdpSocket::bind(SocketAddr::from(SocketAddrV4::new(
            Ipv4Addr::new(0, 0, 0, 0),
            info.port,
        )))?;

        socket.set_nonblocking(true)?;

        Ok(Self {
            udp_socket: socket,
            connection_time_out: info.connection_time_out,

            log_level: info.log_level,
            heartbeat_interval: info.heartbeat_interval,
            start: Instant::now(),
        })
    }

    pub fn set_nonblocking(&self, nonblocking: bool) -> Result<()> {
        self.udp_socket.set_nonblocking(nonblocking)?;

        Ok(())
    }

    pub fn set_broadcast(&self, broadcast: bool) -> Result<()> {
        self.udp_socket.set_broadcast(broadcast)?;

        Ok(())
    }

    pub fn connection_time_out(&self) -> Duration {
        self.connection_time_out
    }

    pub fn send(&self, addr: SocketAddr, mut msg: &str) -> Result<()> {
        let total_length = msg.len();

        match self.log_level {
            LogLevel::None => (),
            LogLevel::Debug => {
                if total_length > 0 {
                    NetworkLogFile::log(format!("SOCKET SEND [{}]: {}", addr, msg))?;
                }
            }
            LogLevel::Verbose => {
                NetworkLogFile::log(format!("SOCKET SEND [{}]: {}", addr, msg))?;
            }
        }

        let mut tries = 0;

        loop {
            let mut total_bytes_send = 0;

            if msg.len() >= READ_BUFFER_SIZE {
                let fragments = msg.len() / READ_BUFFER_SIZE;

                for _ in 0..fragments {
                    let (first, second) = msg.split_at(READ_BUFFER_SIZE);
                    msg = second;

                    total_bytes_send += self.send_bytes(addr, first.as_bytes())?.unwrap_or(0);
                }

                total_bytes_send += self.send_bytes(addr, msg.as_bytes())?.unwrap_or(0);
            } else {
                total_bytes_send = self.send_bytes(addr, msg.as_bytes())?.unwrap_or(0);
            }

            if total_bytes_send != total_length {
                println!(
                    "Error when send message did not match the expected length ({} vs {})",
                    total_length, total_bytes_send,
                );

                if tries < RETRIES {
                    break;
                }

                tries += 1;
            } else {
                break;
            }
        }

        Ok(())
    }

    #[inline]
    fn send_bytes(&self, addr: SocketAddr, bytes: &[u8]) -> Result<Option<usize>> {
        Self::filter_would_block(self.udp_socket.send_to(bytes, addr))
            .map_err(|err| anyhow::Error::msg(format!("Failed to send message {:?}", err.kind())))
    }

    pub fn receive(&self) -> Result<Option<(SocketAddr, String)>> {
        let mut address = None;
        let mut msg = String::new();
        let mut buffer = [0; READ_BUFFER_SIZE];

        while let Some((bytes_read, addr)) = Self::filter_connection_reset(
            Self::filter_would_block(self.udp_socket.recv_from(&mut buffer)),
        )
        .map_err(|err| anyhow::Error::msg(format!("Failed to receive message {:?}", err.kind())))?
        .flatten()
        {
            let bytes = &buffer[0..bytes_read];

            match address {
                Some(address) => {
                    if address != addr {
                        return Err(anyhow::Error::msg(format!(
                            "Error when messages are from different sources ({} vs {})",
                            address, addr
                        )));
                    }
                }
                None => {
                    address = Some(addr);
                }
            }

            msg += from_utf8(bytes)?;

            if bytes_read < READ_BUFFER_SIZE {
                match self.log_level {
                    LogLevel::None => (),
                    LogLevel::Debug => {
                        if !msg.is_empty() {
                            NetworkLogFile::log(format!("SOCKET RECEIVE [{}]: {}", addr, msg))?;
                        }
                    }
                    LogLevel::Verbose => {
                        NetworkLogFile::log(format!("SOCKET RECEIVE [{}]: {}", addr, msg))?;
                    }
                }

                return Ok(Some((addr, msg)));
            }
        }

        return Ok(None);
    }

    /// Filters std::io::ErrorKind::WouldBlock and creates Option<T>
    fn filter_would_block<T: std::fmt::Debug>(
        result: std::result::Result<T, std::io::Error>,
    ) -> std::result::Result<Option<T>, std::io::Error> {
        match result {
            Ok(t) => Ok(Some(t)),
            Err(err) => match err.kind() {
                std::io::ErrorKind::WouldBlock => Ok(None),
                _ => Err(err),
            },
        }
    }

    fn filter_connection_reset<T: std::fmt::Debug>(
        result: std::result::Result<T, std::io::Error>,
    ) -> std::result::Result<Option<T>, std::io::Error> {
        match result {
            Ok(t) => Ok(Some(t)),
            Err(err) => match err.kind() {
                std::io::ErrorKind::ConnectionReset => Ok(None),
                _ => Err(err),
            },
        }
    }
}