import os
import os.notify
import net
import time

// This example demonstrates a single threaded TCP server using os.notify to be
// notified of events on file descriptors. You can connect to the server using
// netcat in separate shells, for example: `nc localhost 9001`

fn main() {
    $if !linux {
        eprintln('This example only works on Linux')
        exit(1)
    }

    // create TCP listener
    mut listener := net.listen_tcp(.ip, 'localhost:9001')!
    defer {
        listener.close() or {}
    }
    addr := listener.addr()!
    eprintln('Listening on ${addr}')
    eprintln('Type `stop` to stop the server')

    // create file descriptor notifier
    mut notifier := notify.new()!
    defer {
        notifier.close() or {}
    }
    notifier.add(os.stdin().fd, .read)!
    notifier.add(listener.sock.handle, .read)!

    for {
        for event in notifier.wait(time.infinite) {
            match event.fd {
                listener.sock.handle {
                    // someone is trying to connect
                    eprint('trying to connect.. ')
                    if conn := listener.accept() {
                        notifier.add(conn.sock.handle, .read | .peer_hangup) or {
                            eprintln('error adding to notifier: ${err}')
                            return
                        }
                        eprintln('connected')
                    } else {
                        eprintln('unable to accept: ${err}')
                    }
                }
                0 {
                    // stdin
                    s, _ := os.fd_read(event.fd, 10)
                    if s == 'stop\n' {
                        eprintln('stopping')
                        return
                    }
                }
                else {
                    // remote connection
                    if event.kind.has(.peer_hangup) {
                        notifier.remove(event.fd) or {
                            eprintln('error removing from notifier: ${err}')
                            return
                        }
                        eprintln('remote disconnected')
                    } else {
                        s, _ := os.fd_read(event.fd, 10)
                        os.fd_write(event.fd, s)
                    }
                }
            }
        }
    }
}