import socket
import selectors
from threading import Thread
from queue import Queue

from msg.container import MsgContainer
from transceiver import Transceiver, ATransceiver

from backend.a_backend import ABackend


class NetworkBackend(ABackend):
	def __init__(self, servers: list[dict], on_disconnect=None):
		self.sel = None
		self.sock_list = [{'name': s['name'], 'addr': (socket.gethostbyname(s['host']), s['port']), 'xcvr': None, 'queue': Queue(), 'display_name': s['name']} for s in servers]
		self.thread = Thread(target=self.event_loop)
		self.loop_enable = True
		self.on_disconnect = on_disconnect

	def set_display_name(self, name: str, display_name: str):
		sock = self.find_by_name(name)
		if sock is not None:
			sock['display_name'] = display_name

	def send(self, xcvr: ATransceiver, data: bytes):
		sock = self.find_by_name(xcvr.name)
		sock['queue'].put(data)
		if sock is not None:
			self.sel.modify(sock['sock'], selectors.EVENT_READ + selectors.EVENT_WRITE, sock)

	def start(self):
		self.thread.start()

	def stop(self):
		if self.loop_enable:
			self.loop_enable = False
			self.thread.join()

	def register_xcvr(self, xcvr: Transceiver):
		found = False
		for sock in self.sock_list:
			if xcvr.name in sock['name']:
				found = True
				sock['xcvr'] = xcvr
				xcvr.on_register(self)
				break

		if not found:
			raise Exception(f"No socket found for \"{xcvr.name}\"")

	def find_by_name(self, name: str):
		for sock in self.sock_list:
			if sock['name'] == name:
				return sock
		return None

	def _prepare(self):
		for server in self.sock_list:
			sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
			sock.setblocking(False)
			server['sock'] = sock

	def connect(self):
		self._prepare()
		self.sel = selectors.DefaultSelector()
		events = selectors.EVENT_READ
		for sock in self.sock_list:
			print(f"Starting connection {sock['display_name']} to {sock['addr']}")
			self.sel.register(sock['sock'], events, data=sock)
			sock['sock'].connect_ex(sock['addr'])

	def disconnect(self):
		for sock in self.sock_list:
			sock['sock'].close()

	def event_loop(self):
		try:
			while self.loop_enable:
				events = self.sel.select(timeout=0.1)
				for key, mask in events:
					sock = key.data
					try:
						if mask & selectors.EVENT_READ:
							data = key.fileobj.recv(64)
							if not data:
								raise OSError("connection closed by peer")
							sock['xcvr'].on_recv(MsgContainer(data, sock['xcvr']))
						if mask & selectors.EVENT_WRITE:
							data = sock['queue'].get()
							key.fileobj.send(data)
							print(f"Send: {sock['display_name']}: {data}")
							if sock['queue'].empty():
								self.sel.modify(sock['sock'], selectors.EVENT_READ, sock)
					except OSError as exc:
						print(f"Connection {sock['display_name']} to {sock['addr']} lost: {exc}")
						self.sel.unregister(key.fileobj)
						key.fileobj.close()
						if self.on_disconnect:
							self.on_disconnect(sock['name'])
					except Exception as exc:
						print(f"Connection {sock['display_name']}: error processing data, ignoring: {exc}")

		except KeyboardInterrupt:
			print("Caught keyboard interrupt, exiting")
		finally:
			self.sel.close()