#!/usr/bin/python3
import os
import readline
import shlex
import sys
import subprocess
import socket
import pwd
import grp
import traceback
from collections import namedtuple

tuerSock = "/run/tuer.sock"

# use a histfile
histfile = os.path.join(os.path.expanduser("~"), ".tyshellhist")
try:
    readline.read_history_file(histfile)
except IOError:
    pass
import atexit
atexit.register(readline.write_history_file, histfile)

# available commands
def helpcmd(c):
	if (len(c) > 1):
		print(commands.get(c[1],(None,'Can\'t find help for command %s'%(c[1]))).helpstring)
	else:
		print("Available commands: %s" % ", ".join(sorted(commands.keys())))
		print("Use 'help command' to get more information on the command 'command'")

def extcmd(cmd):
	def run(c):
		ret = subprocess.call(cmd)
		if ret != 0:
			print("Command returned non-zero exit statis %d" % ret)
	return run

def sendcmd(addr, cmd):
	def run(c):
		print("206 Sending command %s..." % (cmd))
		s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
		s.connect(addr)
		s.settimeout(60.0)
		s.send(cmd.encode())
		while True:
			data = s.recv(256)
			if not len(data): break
			print(data.decode('utf-8'))
		s.close()
	return run

def exitcmd(c):
	print("Bye")
	return True

def whocmd(c):
	for n in grp.getgrnam("tuer").gr_mem:
		p = pwd.getpwnam(n)
		print (p.pw_name, " - ", p.pw_gecos)

def alias (cmds, aliases):
	for newname, oldname in aliases.items():
		cmds[newname] = cmds[oldname]
	return cmds

def prompt_sure(f,msg):
	def run(c):
		try:
			command = input("%s Are you sure? (yes/no) > " % msg)
		except EOFError:
			print()
			return
		if command[0] == 'y':
			return f(c)
	return run

CmdEntry = namedtuple('CmdEntry','function helpstring')

commands = alias({
	'exit': CmdEntry(exitcmd, 'Quits this shell'),
	'help': CmdEntry(helpcmd, 'Helps you getting to know the available commands'),
	'unlock': CmdEntry(sendcmd(tuerSock, 'unlock'), 'Will try to unlock the apartment door'),
	'lock': CmdEntry(sendcmd(tuerSock, 'lock'), 'If in fallback mode, try to lock the apartment door. If not in fallback mode, you must use the switch near the door.'),
	'buzz': CmdEntry(sendcmd(tuerSock, 'buzz'), 'Will buzz the buzzer for the street door'),
	'who': CmdEntry(whocmd, 'Shows the list of people, who are allowed to control this system'),
	'fallback_mode_on': CmdEntry(prompt_sure(sendcmd(tuerSock, 'fallback_mode_on'),'WARNING: This action will be reported to the admins. Use this only in case of Sphinx hardware failure when you need to ignore erroneous sensor input!'), 'Sets the system in a state where it is less dependent on sensoric input. Use it only when sensors are broken.'),
	'fallback_mode_off': CmdEntry(prompt_sure(sendcmd(tuerSock, 'fallback_mode_off'),'WARNING: This action will be reported to the admins. Use this only if you have fixed the sensors of the Sphinx or activated fallback mode by accident!'), 'Resets the system to the default state. Use this when you have just repaired the sensors of the Sphinx.'),
	'status': CmdEntry(sendcmd(tuerSock, 'status'), 'Shows internal state and sensor information.'),
},{
	# aliases
	'open': 'unlock',
})

def complete_command(cmd):
	'''returns a list of commands (as strings) starting with cmd'''
	return list(filter(lambda x: x.startswith(cmd), commands.keys()))
readline.set_completer(lambda cmd, num: (complete_command(cmd)+[None])[num]) # wrap complete_command for readline's weird completer API
readline.parse_and_bind("tab: complete") # run completion on tab

# input loop
print("Welcome to tyshell. Use help to see what you can do.")
while True:
	try:
		command = input("$ ")
	except EOFError:
		print()
		break
	command = shlex.split(command)
	if not len(command): continue
	# find suiting commands
	if command[0] in commands: # needed in case a complete command is a prefix of another one
		cmdoptions = [command[0]]
	else:
		cmdoptions = complete_command(command[0])
	# check how many we found
	if len(cmdoptions) == 0: # no commands fit prefix
		print("Command %s not found. Use help." % command[0])
	elif len(cmdoptions) == 1: # exactly one command fits (prefix)
		try:
			res = commands[cmdoptions[0]].function(command)
			if res: break
		except Exception as e:
			print("Error while executing %s: %s" % (command[0], str(e)))
			#print(traceback.format_exc())
	else: # multiple commands fit the prefix
		print("Ambiguous command prefix, please choose one of the following:")
		print("\t", " ".join(cmdoptions))
		# TODO: put current "command[0]" into the shell for the next command, but such that it is deletable with backspace