import json
import logging
import socket
import threading

log = logging.getLogger(__name__)


def _accept_loop(
    server_sock: socket.socket,
    clients: list,
    lock: threading.Lock,
) -> None:
    while True:
        try:
            conn, addr = server_sock.accept()
            log.info("Push client connected from %s", addr)
            with lock:
                clients.append(conn)
        except OSError:
            break


def broadcast(snapshot: dict, clients: list, lock: threading.Lock) -> None:
    line = (json.dumps(snapshot, default=str) + "\n").encode()
    with lock:
        dead = []
        for conn in clients:
            try:
                conn.sendall(line)
            except OSError:
                dead.append(conn)
        for conn in dead:
            clients.remove(conn)
            conn.close()
            log.info("Push client disconnected")


def start_push_server(host: str, port: int) -> tuple:
    server_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server_sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server_sock.bind((host, port))
    server_sock.listen()
    clients: list = []
    lock = threading.Lock()
    t = threading.Thread(target=_accept_loop, args=(server_sock, clients, lock), daemon=True)
    t.start()
    log.info("Push server listening on %s:%d", host, port)
    return clients, lock