import json
import logging
import socket
import threading
from typing import Callable

log = logging.getLogger(__name__)


def _accept_loop(
    server_sock: socket.socket,
    clients: list,
    lock: threading.Lock,
    store_ref: dict,
    load_today: Callable | None,
) -> None:
    while True:
        try:
            conn, addr = server_sock.accept()
            log.info("Push client connected from %s", addr)
            with lock:
                store = store_ref["current"]
                records = store["records"] if store else []
                if not records and load_today is not None:
                    log.info("In-memory store empty — loading today's records from disk")
                    records = load_today()
                try:
                    for record in records:
                        conn.sendall((json.dumps(record, default=str) + "\n").encode())
                    if records:
                        log.info("Sent %d record(s) to %s", len(records), addr)
                except OSError:
                    log.debug("Failed to send history to %s", addr)
                    conn.close()
                    continue
                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,
    load_today: Callable | None = None,
) -> 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()
    store_ref: dict = {"current": None}
    t = threading.Thread(
        target=_accept_loop,
        args=(server_sock, clients, lock, store_ref, load_today),
        daemon=True,
    )
    t.start()
    log.info("Push server listening on %s:%d", host, port)
    return clients, lock, store_ref