use std::{collections::HashMap, net::SocketAddr, time::Instant};

use super::socket::{Socket, SocketContent, SocketCreateInfo};
use crate::Sender;

use anyhow::Result;

struct ClientInfo {
    last_send: Instant,
    last_received: Instant,
}

pub struct Server {
    socket: Socket,

    clients: HashMap<SocketAddr, ClientInfo>,
}

impl Server {
    pub fn new(create_info: SocketCreateInfo) -> Result<Self> {
        Ok(Self {
            socket: Socket::new(create_info)?,

            clients: HashMap::new(),
        })
    }

    pub fn check_heartbeat(&mut self) -> Result<()> {
        let now = Instant::now();

        for (addr, client_info) in self.clients.iter_mut() {
            if (now - client_info.last_send) > self.socket.heartbeat_interval {
                client_info.last_send += self.socket.heartbeat_interval;

                self.socket.send(*addr, "")?;
            }
        }

        Ok(())
    }

    pub fn remove_client(&mut self, addr: impl Into<SocketAddr>) {
        let addr = addr.into();

        debug_assert!(self.clients.get(&addr).is_some(), "client not found!");

        self.clients.remove(&addr);
    }

    pub fn send(&self, addr: impl Into<SocketAddr>, msg: &str) -> Result<()> {
        let address = addr.into();

        #[cfg(debug_assertions)]
        if self.clients.get(&address).is_none() {
            println!(
                "sending message to a not connected client ({}, available {:?})",
                address,
                self.clients.keys()
            );
        }

        self.socket.send(address, msg)
    }

    pub fn receive(&mut self) -> Result<Vec<SocketContent>> {
        let now = Instant::now();
        let mut content = Vec::new();

        while let Some((addr, msg)) = match self.socket.receive() {
            Ok(r) => r,
            Err(err) => {
                // if content is empty return the error
                // if not, ignore the error and break the loop
                if content.is_empty() {
                    return Err(err);
                } else {
                    None
                }
            }
        } {
            match self.clients.get_mut(&addr) {
                Some(info) => {
                    info.last_received = now;
                }
                None => {
                    self.clients.insert(
                        addr,
                        ClientInfo {
                            last_send: now,
                            last_received: now,
                        },
                    );
                    content.push(SocketContent::NewConnection(addr));
                }
            }

            if !msg.is_empty() {
                content.push(SocketContent::Message(addr, msg));
            }
        }

        let mut to_remove = Vec::new();

        for (addr, info) in self.clients.iter() {
            if (now - info.last_received) > self.socket.connection_time_out() {
                content.push(SocketContent::TimeOut(*addr));
                to_remove.push(*addr);
            }
        }

        for addr in to_remove.into_iter() {
            self.remove_client(addr);
        }

        Ok(content)
    }
}

impl Sender for Server {
    fn send(&mut self, addr: SocketAddr, msg: &str) -> Result<()> {
        Server::send(self, addr, msg)
    }

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