#! /usr/bin/python

# Eric LaForest, November 2008
# laforest AT eecg.utoronto.ca

# Python Remote Objects
import Pyro.core
import Pyro.naming
import Pyro.util
import Pyro.errors
import sys
import os
import pwd

# FIXME
# See server code for possible future improvements/fixes

class batch_client:

    process_parameters = {
        'cwd':None,
        'uid':None,
        'gid':None,
        'logname':None,
        # FIXME add password request code
        'passwd':None,
        'env':None,
        }

    def __init__(self):
        self.get_process_parameters()
    
    def get_logname(self):
        """Gets username matching uid in /etc/passwd
           instead of the forgeable LOGNAME variable"""
        return pwd.getpwuid(os.getuid())[0]
    
    def get_process_parameters(self):
        self.process_parameters['cwd'] = os.getcwd()
        self.process_parameters['gid'] = os.getgid()
        self.process_parameters['uid'] = os.getuid()
        self.process_parameters['logname'] = self.get_logname()
        self.process_parameters['env'] = os.environ
        
def usage():
    instructions = """
Please supply your command as one quoted string,
as if you were writing it by itself.
e.g.: %s "my_command"

The standard input, output, and error of your command are not
accessible (meaning, you won't see anything, or read anything piped in)
But you can redirect them to/from files, *inside the quotes*.
e.g.: "my_command < infile > outfile"

The return value is True (1) if your task was queued, False (0) otherwise.
You can use this in a slow loop (use 'sleep'!) to automatically
queue all your jobs in sequence.

Give the command "show_queue" to see where everyone's job is sitting.
The topmost entry is the currently running one.
This command always returns True (1).
""" % sys.argv[0]
    print instructions

def print_exception_message():
        message = """
***************************************************************
Congratulations! You've just raised an exception.
Something is wrong with the batch client or server.
Please immediately email the following text to the TA.
***************************************************************
"""
        print message

def print_exception_backtrace(exception):
        """Includes local and remote exception backtrace"""
        print ''.join(Pyro.util.getPyroTraceback(exception))

def batch_server(server_address, server_name):
    """See http://pyro.sourceforge.net/manual/4-usage.html"""
    try:
        Pyro.core.initClient(banner=0)
        locator = Pyro.naming.NameServerLocator()
        ns = locator.getNS(host = server_address)
        uri = ns.resolve(server_name)
        server = Pyro.core.getProxyForURI(uri)
        return server
    except Exception,x:
        print_exception_message()
        print "Summary: Likely either the Pyro Name Server or the batch server is not running.\n"
        print_exception_backtrace(x)
        sys.exit(False)

def print_queue(queue):
    if len(queue) == 0:
        print "Queue Empty\n"
        return
    for (name, command) in queue:
        print "%s:\t%s" % (name, command)
    print

def run_on_server(server, process_parameters, command):
    try:
        if command == "show_queue":
            print_queue(server.get_queue())
            return True
        else:
            return server.queue_client_job(process_parameters, command)
    except Exception,x:
        print_exception_message()
        print "Summary: The server was unable to run your command. Badly so. It's dead, Jim.\n"
        print "process_parameters:%s\n" % process_parameters
        print "command:%s\n" % command
        print_exception_backtrace(x)
        sys.exit(False)


def main():
    if len(sys.argv) != 2:
        usage()
        return
    server = batch_server("localhost", "batch_server")
    client = batch_client()
    # only the first argument matters, other are discarded
    command = sys.argv[1]
    run_on_server(server, client.process_parameters, command)
    return True

if __name__ == "__main__":
    # carry the return value to the shell
    sys.exit(main())