#!/usr/bin/env python3
#netinterface.py

import os, time

class network_interface:
	timeout = 0.800 # 800 millisec
	addr_space = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
	own_addr = ''
	net_path = ''
	last_read = -1
	
	def __init__(self, path, addr):
		self.net_path = path
		self.own_addr = addr
        
		addr_dir = self.net_path + self.own_addr
		if not os.path.exists(addr_dir):
			os.mkdir(addr_dir)
			os.mkdir(addr_dir + '/IN')
			os.mkdir(addr_dir + '/OUT')
            
		in_dir = addr_dir + '/IN'
		msgs = sorted(os.listdir(in_dir))
		self.last_read = len(msgs) - 1

	
	def send_msg(self, dst, msg):

		out_dir = self.net_path + self.own_addr + '/OUT'
		msgs = sorted(os.listdir(out_dir))

		if len(msgs) > 0:
			last_msg = msgs[-1].split('--')[0]
			next_msg = (int.from_bytes(bytes.fromhex(last_msg), byteorder='big') + 1).to_bytes(2, byteorder='big').hex()
		else:
			next_msg = '0000'
		
		next_msg += '--' + dst
		with open(out_dir + '/' + next_msg, 'wb') as f: f.write(msg)

		return True

	def receive_msg(self, blocking=False):

		in_dir = self.net_path + self.own_addr + '/IN'

		status = False
		msg = b''

		while True:
			msgs = sorted(os.listdir(in_dir))
			if len(msgs) - 1 > self.last_read: 
				with open(in_dir + '/' + msgs[self.last_read + 1], 'rb') as f: msg = f.read()
				status = True
				self.last_read += 1

			if not blocking or status: return status, msg
			else: time.sleep(self.timeout)