use crate::ipc::{self, ClientMessage, ClientRole, ServerMessage};
use interprocess::local_socket::traits::{ListenerExt as _, Stream as _};
use interprocess::local_socket::{ListenerOptions, Stream};
use std::io::{BufReader, BufWriter};
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::mpsc;
use std::thread;

static NEXT_CLIENT_ID: AtomicUsize = AtomicUsize::new(1);

pub enum IpcEvent {
    ClientConnected {
        client_id: usize,
        role: ClientRole,
        width: u16,
        height: u16,
        tx: mpsc::SyncSender<ServerMessage>,
    },
    ClientDisconnected {
        client_id: usize,
    },
    Message {
        client_id: usize,
        msg: ClientMessage,
    },
}

pub fn start(socket_path: &str, event_tx: mpsc::Sender<IpcEvent>) {
    // På unix: städa bort en ev. kvarlämnad socket-fil från en tidigare körning.
    #[cfg(unix)]
    let _ = std::fs::remove_file(socket_path);

    let name = match ipc::socket_name(socket_path) {
        Ok(n) => n,
        Err(e) => {
            eprintln!("Ogiltigt socket-namn {}: {}", socket_path, e);
            return;
        }
    };
    let listener = match ListenerOptions::new().name(name).create_sync() {
        Ok(l) => l,
        Err(e) => {
            eprintln!("Kunde inte binda lokal socket {}: {}", socket_path, e);
            return;
        }
    };
    let socket_path = socket_path.to_string();
    thread::spawn(move || {
        for stream in listener.incoming() {
            match stream {
                Ok(stream) => {
                    let client_id = NEXT_CLIENT_ID.fetch_add(1, Ordering::SeqCst);
                    let event_tx = event_tx.clone();
                    let sp = socket_path.clone();
                    thread::spawn(move || {
                        handle_client(client_id, stream, event_tx, sp);
                    });
                }
                // Transienta accept-fel (kan hända för named pipes) — fortsätt lyssna.
                Err(_) => continue,
            }
        }
    });
}

fn handle_client(
    client_id: usize,
    stream: Stream,
    event_tx: mpsc::Sender<IpcEvent>,
    socket_path: String,
) {
    let (recv_half, send_half) = stream.split();
    let mut reader = BufReader::new(recv_half);
    let (tx, rx) = mpsc::sync_channel::<ServerMessage>(64);

    // Writer thread
    thread::spawn(move || {
        let mut writer = BufWriter::new(send_half);
        for msg in rx {
            if ipc::write_message(&mut writer, &msg).is_err() {
                break;
            }
        }
    });

    // Read Hello
    let hello: ClientMessage = match ipc::read_message(&mut reader) {
        Ok(m) => m,
        Err(_) => return,
    };
    let (role, width, height) = match &hello {
        ClientMessage::Hello { role, width, height, .. } => (role.clone(), *width, *height),
        _ => return,
    };

    let _ = tx.send(ServerMessage::HelloOk {
        version: ipc::VERSION.to_string(),
        socket_path: socket_path.clone(),
    });

    let _ = event_tx.send(IpcEvent::ClientConnected {
        client_id,
        role,
        width,
        height,
        tx: tx.clone(),
    });

    loop {
        match ipc::read_message::<_, ClientMessage>(&mut reader) {
            Ok(msg) => {
                if event_tx.send(IpcEvent::Message { client_id, msg }).is_err() {
                    break;
                }
            }
            Err(_) => break,
        }
    }

    let _ = event_tx.send(IpcEvent::ClientDisconnected { client_id });
}