#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import sys
import os
import subprocess
import time
import platform
from threading import Thread

CONF = "conf"
IS_WINDOWS = platform.system() == "Windows"
LIB = "lib"

ENV_KEYS = ["JAVA_HOME", "HADOOP_CONF_DIR", "SLIDER_CONF_DIR", "SLIDER_JVM_OPTS", "SLIDER_CLASSPATH_EXTRA"]
SLIDER_CONF_DIR = "SLIDER_CONF_DIR"
SLIDER_JVM_OPTS = "SLIDER_JVM_OPTS"
SLIDER_CLASSPATH_EXTRA = "SLIDER_CLASSPATH_EXTRA"
HADOOP_CONF_DIR = "HADOOP_CONF_DIR"

SLIDER_CLASSNAME = "org.apache.slider.Slider"
SLIDER_CONFDIR_OPTS ="-Dslider.confdir=%s"
SLIDER_LIBDIR_OPTS ="-Dslider.libdir=%s"
DEFAULT_JVM_OPTS = "-Djava.net.preferIPv4Stack=true -Djava.awt.headless=true -Xmx256m"

ON_POSIX = 'posix' in sys.builtin_module_names

finished = False
DEBUG = False

"""
Launches slider

Nonblocking IO on windows is "tricky" ... see
http://stackoverflow.com/questions/375427/non-blocking-read-on-a-subprocess-pipe-in-python
to explain the code here


"""

def executeEnvSh(confDir):
  envscript = '%s/slider-env.sh' % confDir
  if not IS_WINDOWS and os.path.exists(envscript):
    envCmd = 'source %s && env' % envscript
    command = ['bash', '-c', envCmd]

    proc = subprocess.Popen(command, stdout = subprocess.PIPE)

    for line in proc.stdout:
      (key, _, value) = line.strip().partition("=")
      if key in ENV_KEYS:
        os.environ[key] = value

    proc.communicate()


def scriptDir():
  """ 
  get the script path
  """
  return os.path.dirname(os.path.realpath(__file__))

def sliderDir():
  return os.path.dirname(scriptDir())

def libDir(sliderdir) :
  return os.path.join(sliderdir, LIB)

def confDir(sliderdir):
  """
  determine the active configuration directory 
  :param sliderdir: slider directory 
  :return: the configuration directory -any env var will
  override the relative path
  """
  localconf = os.path.join(sliderdir, CONF)
  return os.environ.get(SLIDER_CONF_DIR, localconf)

def dirMustExist(dirname):
  if not os.path.exists(dirname):
    raise Exception("Directory does not exist: %s " % dirname)
  return dirname


def debug(text):
  if DEBUG: print '[DEBUG] ' + text


def error(text):
  print '[ERROR] ' + text
  sys.stdout.flush()

def info(text):
  print text
  sys.stdout.flush()


def out(toStdErr, text) :
  """
  Write to one of the system output channels.
  This action does not add newlines. If you want that: write them yourself
  :param toStdErr: flag set if stderr is to be the dest
  :param text: text to write.
  :return:
  """
  if toStdErr:
    sys.stderr.write(text)
  else:
    sys.stdout.write(text)

def flush(toStdErr) :
  """
  Flush the output stream
  :param toStdErr: flag set if stderr is to be the dest
  :return:
  """
  if toStdErr:
    sys.stderr.flush()
  else:
    sys.stdout.flush()

def read(pipe, line):
  """
  read a char, append to the listing if there is a char that is not \n
  :param pipe: pipe to read from 
  :param line: line being built up
  :return: (the potentially updated line, flag indicating newline reached)
  """

  c = pipe.read(1)
  if c != "":
    o = c.decode('utf-8')
    if o != '\n':
      line += o
      return line, False
    else:
      return line, True
  else:
    return line, False


def print_output(name, src, toStdErr):
  """
  Relay the output stream to stdout line by line 
  :param name: 
  :param src: source stream
  :param toStdErr: flag set if stderr is to be the dest
  :return:
  """

  debug ("starting printer for %s" % name )
  line = ""
  while not finished:
    (line, done) = read(src, line)
    if done:
      out(toStdErr, line + "\n")
      flush(toStdErr)
      line = ""
  out(toStdErr, line)
  # closedown: read remainder of stream
  c = src.read(1)
  while c!="" :
    c = c.decode('utf-8')
    out(toStdErr, c)
    if c == "\n":
      flush(toStdErr)
    c = src.read(1)
  flush(toStdErr)
  src.close()


def runProcess(commandline):
  """
  Run a process
  :param commandline: command line 
  :return:the return code
  """
  global finished
  debug ("Executing : %s" % commandline)
  exe = subprocess.Popen(commandline,
                         stdin=None,
                         stdout=subprocess.PIPE,
                         stderr=subprocess.PIPE,
                         shell=False,
                         bufsize=1, 
                         close_fds=ON_POSIX)

  t = Thread(target=print_output, args=("stdout", exe.stdout, False))
  t.daemon = True 
  t.start()
  t2 = Thread(target=print_output, args=("stderr", exe.stderr, True))
  t2.daemon = True 
  t2.start()

  debug("Waiting for completion")
  while exe.poll() is None:
    # process is running; grab output and echo every line
    time.sleep(1)
  debug("completed with exit code : %d" % exe.returncode)
  finished = True
  t.join()
  t2.join()
  return exe.returncode


def is_exe(fpath):
  return os.path.isfile(fpath) and os.access(fpath, os.X_OK)

def which(program):
  
  fpath, fname = os.path.split(program)
  if fpath:
    if is_exe(program):
      return program
  else:
    for path in os.environ["PATH"].split(os.pathsep):
      path = path.strip('"')
      exe_file = os.path.join(path, program)
      if is_exe(exe_file):
        return exe_file

  return None

def java(classname, args, classpath, jvm_opts_list):
  """
  Execute a java process, hooking up stdout and stderr
  and printing them a line at a time as they come in
  :param classname: classname
  :param args:  arguments to the java program
  :param classpath: classpath
  :param jvm_opts_list: list of JVM options
  :return: the exit code.
  """
  # split the JVM opts by space
  # java = "/usr/bin/java"
  if os.environ["JAVA_HOME"] is not None and os.environ["JAVA_HOME"]:
    prg = os.path.join(os.environ["JAVA_HOME"], "bin", "java")
  else:
    prg = which("java")
  
  commandline = [prg]
  commandline.extend(jvm_opts_list)
  commandline.append("-classpath")
  commandline.append(classpath)
  commandline.append(classname)
  commandline.extend(args)
  return runProcess(commandline)


def main():
  """
  Slider main method
  :return: exit code of the process
  """
  args = sys.argv[1:]
  slider_home = sliderDir()
  libdir = dirMustExist(libDir(slider_home))
  confdir = dirMustExist(confDir(slider_home))
  executeEnvSh(confdir)

  #create sys property for conf dirs
  jvm_opts_list = (SLIDER_CONFDIR_OPTS % confdir).split()

  #extend with libdir
  libdir_jvm_opts = (SLIDER_LIBDIR_OPTS % libdir)
  jvm_opts_list.extend(libdir_jvm_opts.split())

  #append user specified additional properties
  default_jvm_opts = DEFAULT_JVM_OPTS
  slider_jvm_opts = os.environ.get(SLIDER_JVM_OPTS, default_jvm_opts)
  jvm_opts_list.extend(slider_jvm_opts.split())

  slider_classpath_extra = os.environ.get(SLIDER_CLASSPATH_EXTRA, "")
  hadoop_conf_dir = os.environ.get(HADOOP_CONF_DIR, "")
  p = os.pathsep    # path separator
  d = os.sep        # dir separator
  slider_classpath = libdir + d + "*" + p \
                     + confdir + p \
                     + slider_classpath_extra  + p \
                     + hadoop_conf_dir


  debug("slider_home = \"%s\"" % slider_home)
  debug("slider_jvm_opts = \"%s\"" % slider_jvm_opts)
  debug("slider_classpath = \"%s\"" % slider_classpath)

  return java(SLIDER_CLASSNAME,
              args,
              slider_classpath,
              jvm_opts_list)

if __name__ == '__main__':
  """
  Entry point
  """
  try:
    returncode = main()
  except Exception as e:
    print "Exception: %s " % str(e)
    returncode = -1
  
  sys.exit(returncode)