#!/usr/bin/env python3
import os
import sys
import re
import subprocess
import signal
import time
import datetime
import traceback
from threading import Thread
import importlib.machinery as imp
#################################################################################
# Load configuration

__all_config_files__ = (
        'mcwrapper.conf',
        '~/.mcwrapper.conf',
        '~/.config/mcwrapper.conf',
        '/etc/mcwrapper.conf',
        )

def __set_empty_config__():
    global conf
    global conf_source
    print('Warning: User configuration not loaded. Using default.', file=sys.stderr)
    conf = type('default config', (object,), {})

__config_file__ = None
try:
    __config_file__ = os.environ['CONFIG'] # get config file from environment
except KeyError:
        # Find configuration in predefined paths
    for cf in __all_config_files__:
        if os.path.isfile(cf):
            __config_file__ = cf
            break
if __config_file__ == None: # If no configuration find. Set empty config
    __set_empty_config__()
else: # else load configuration
    try:
        conf = imp.SourceFileLoader("conf", __config_file__).load_module()
    except Exception:
        traceback.print_exc()
        __set_empty_config__()

# Set additional runtime configuration variables
try:
    conf.verbose_level
except AttributeError:
    conf.verbose_level = 0
try:
    conf.command
except AttributeError:
    conf.command = []
try:
    conf.server
except AttributeError:
    conf.server = dict()

#################################################################################

__STATUSSTRINGS__ = {
    0: "Not running",
    1: "Starting",
    2: "Running",
    3: "Stopping",
    }

def __server_start__():
    if conf.verbose_level >= 0:
        print("Wrapper initializing with identifier: " + conf.identifier)
    try:
        os.mkdir(conf.status)
    except FileExistsError:
        pass
    if os.path.isfile(inputPipe):
        if conf.verbose_level >= -1:
            print("Error: Server input pipe already exists. Is another wrapper running?")
        sys.exit(4)
    os.mkfifo(inputPipe, 0o640)
    global statusFile
    statusFile = conf.status + '/status'
    with open(statusFile, 'w') as f:
        f.write(__STATUSSTRINGS__[1])

def __server_clean__():
    if conf.verbose_level >= 0:
        print("Wrapper clean.")
    try:
        os.remove(inputPipe)
    except FileNotFoundError:
        pass
    try:
        os.remove(statusFile)
    except FileNotFoundError:
        pass

def __parse_line__(line):
    if ': Done' in line:
        print("Server start.")
        with open(statusFile, 'w') as f:
            f.write(__STATUSSTRINGS__[2] + '\n')
    elif ': Stopping the server' in line:
        print("Server stop.")
        with open(statusFile, 'w') as f:
            f.write(__STATUSSTRINGS__[3] + '\n')

#################################################################################

class __InputThread__(Thread):
    def __init__(self, pipeprocess):
        Thread.__init__(self, name='InputThread')
        self.pipeprocess = pipeprocess
        self.stopread = False
    def stopexec(self):
        self.stopread = True
    def wake(self):
        with open(inputPipe, 'w') as f:
            f.write("\n")
            f.flush()
    def run(self):
        with open(inputPipe, 'r') as p:
            while not self.stopread:
                ln = p.readline()
                if ln.rstrip():
                    if conf.verbose_level >= 1:
                        print("Input: " + ln, end="")
                    self.pipeprocess.write(bytes(ln, sys.getdefaultencoding()))
                    self.pipeprocess.flush()
                else:
                    time.sleep(1)

def __server_send_stop__():
    global prc
    prc.stdin.write(bytes("/stop\n", sys.getdefaultencoding()))
    prc.stdin.flush()

def mcexec():
    """Executes cmd and parses output for server status changes.
    """
    global prc
    __server_start__()
    if type(conf.command) != str:
        conf.command = ' '.join(conf.command)
    if conf.verbose_level >= 1:
        print("Folder: " + conf.folder)
        print("Start command: " + conf.command)
    os.chdir(conf.folder)
    prc = subprocess.Popen(conf.command, stdin=subprocess.PIPE,
            stdout=subprocess.PIPE, stderr=subprocess.STDOUT, shell=True)
    inputThread = __InputThread__(prc.stdin)
    inputThread.start()
    inputThread.wake() # Input thread is stuck in waiting for first line
    for linen in prc.stdout:
        line = linen.decode(sys.getdefaultencoding())
        if conf.verbose_level >= 2:
            print(line.rstrip())
        __parse_line__(line.rstrip())
    inputThread.stopexec()
    __server_clean__()

#################################################################################

def __signal_term__(_signo, _stack_frame):
    __server_send_stop__()

def print_help():
    print('mcwrapper [arguments...] ACTION ...')
    print('  This script is executing Minecraft server and reads its output.')
    print('')
    print(' arguments')
    print('   -h, --help')
    print('       Prints this help text.')
    print('   -v, --verbose')
    print('       Increase verbose level of output.')
    print('   -q, --quiet')
    print('       Decrease verbose level of output.')
    print('')
    print(' Common action arguments')
    print('   IDENTIFIER')
    print('     Identifier for new server instance. This allows multiple server')
    print('     instances running with this wrapper.')
    print('     Identifier is word without spaces and preferably without special')
    print('     characters.')
    print('')
    print(' ACTION and it\'s arguments')
    print('   start INDETIFIER')
    print('     Start server under "IDENTIFIER"')
    print('   stop IDENTIFIER')
    print('       Sends stop command to server under "IDENTIFIER"')
    sys.exit()

if __name__ == '__main__':
    action = None
    identifier = None
    for arg in sys.argv[1:]:
        if (action == 'start' or action == 'stop') \
          and identifier == None:
            identifier = arg
            continue
        if arg[0] == '-':
            if len(arg) > 2 and arg[1] == '-':
                if arg == '--help':
                    print_help()
                if arg == '--verbose':
                    conf.verbose_level += 1
                if arg == '--quiet':
                    conf.verbose_level += 1
                    continue
            else:
                for l in arg[1:]:
                    if l == 'h':
                        print_help()
                    elif l == 'v':
                        conf.verbose_level += 1
                    elif l == 'q':
                        conf.verbose_level -= 1
                    else:
                        sys.exit("Unknown short argument " + l)
                continue
        if action == None:
            if arg.lower() == 'start':
                action = 'start'
                continue
            if arg.lower() == 'stop':
                action = 'stop'
                continue
        sys.exit("Unknown argument: " + arg)
    # Parsing args ends

    # Replace identifier if provided
    if identifier:
        conf.identifier = identifier
    # Expand configuration for specified identifier
    if action == 'start' or action == 'stop':
        if not conf.identifier:
            print('Missing server identifier argument!')
            print('')
            print_help()
        try:
            conf.server[conf.identifier]
            vars(conf).update(conf.server[conf.identifier])
        except KeyError:
            if conf.verbose_level >= -1:
                sys.exit('Error: No configuration associated with identifier: ' + conf.identifier)
        # Set configurations for server
        try:
            conf.folder
        except AttributeError:
            sys.exit('Missing "folder" config')
        try:
            conf.command
        except AttributeError:
            sys.exit('Missing server start command!')
        try:
            conf.status
        except AttributeError:
            conf.status = '/dev/shm/mcwrapper-' + conf.identifier
        # Set inputPipe
        global inputPipe
        inputPipe = conf.status + '/input_pipe'

    if action == 'start':
        signal.signal(signal.SIGTERM, __signal_term__)
        signal.signal(signal.SIGINT, __signal_term__)
        mcexec()
    elif action == 'stop':
        if not os.path.exists(inputPipe):
            sys.exit("Such server is not running")
        with open(inputPipe, 'w') as f:
            f.write("/stop\n")
            f.flush()
        while os.path.exists(inputPipe): # Block until server stops
            pass
    else:
        print_help()