#
# Copyright CEA/DAM/DIF (2011, 2012)
#  Contributor: Stephane THIELL <stephane.thiell@cea.fr>
#
# This file is part of the ClusterShell library.
#
# This software is governed by the CeCILL-C license under French law and
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# modify and/ or redistribute the software under the terms of the CeCILL-C
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# "http://www.cecill.info".
#
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"""
ClusterShell v2 tree propagation worker
"""

import logging
import os

from ClusterShell.Event import EventHandler
from ClusterShell.NodeSet import NodeSet
from ClusterShell.Worker.Worker import DistantWorker

from ClusterShell.Propagation import PropagationTreeRouter


class MetaWorkerEventHandler(EventHandler):
    """
    """
    def __init__(self, metaworker):
        self.metaworker = metaworker

    def ev_start(self, worker):
        """
        Called to indicate that a worker has just started.
        """
        self.metaworker._start_count += 1
        self.metaworker._check_ini()

    def ev_read(self, worker):
        """
        Called to indicate that a worker has data to read.
        """
        self.metaworker._on_node_msgline(worker.current_node,
                                         worker.current_msg)

    def ev_error(self, worker):
        """
        Called to indicate that a worker has error to read (on stderr).
        """
        self.metaworker._on_node_errline(worker.current_node,
                                         worker.current_errmsg)

    def ev_written(self, worker):
        """
        Called to indicate that writing has been done.
        """
        metaworker = self.metaworker
        metaworker.current_node = worker.current_node
        metaworker.eh.ev_written(metaworker)

    def ev_hup(self, worker):
        """
        Called to indicate that a worker's connection has been closed.
        """
        #print >>sys.stderr, "ev_hup?"
        self.metaworker._on_node_rc(worker.current_node, worker.current_rc)

    def ev_timeout(self, worker):
        """
        Called to indicate that a worker has timed out (worker timeout only).
        """
        # WARNING!!! this is not possible as metaworking is changing task's
        # shared timeout set!
        #for node in worker.iter_keys_timeout():
        #    self.metaworker._on_node_timeout(node)
        # we use NodeSet to copy set
        for node in NodeSet._fromlist1(worker.iter_keys_timeout()):
            self.metaworker._on_node_timeout(node)

    def ev_close(self, worker):
        """
        Called to indicate that a worker has just finished (it may already
        have failed on timeout).
        """
        #self.metaworker._check_fini()
        pass
        ##print >>sys.stderr, "ev_close?"
        #self._completed += 1
        #if self._completed >= self.grpcount:
        #    #print >>sys.stderr, "ev_close!"
        #    metaworker = self.metaworker
        #    metaworker.eh.ev_close(metaworker)


class WorkerTree(DistantWorker):
    """
    ClusterShell tree worker Class.

    """

    def __init__(self, nodes, handler, timeout, **kwargs):
        """
        Initialize Tree worker instance.

        @param nodes: Targeted nodeset.
        @param handler: Worker EventHandler.
        @param timeout: Timeout value for worker.
        @param command: Command to execute.
        @param topology: Force specific TopologyTree.
        @param newroot: Root node of TopologyTree.
        """
        DistantWorker.__init__(self, handler)

        self.workers = []
        self.nodes = NodeSet(nodes)
        self.timeout = timeout
        self.command = kwargs.get('command')
        self.source = kwargs.get('source')
        self.dest = kwargs.get('dest')
        autoclose = kwargs.get('autoclose', False)
        self.stderr = kwargs.get('stderr', False)
        self._close_count = 0
        self._start_count = 0
        self._child_count = 0
        self._target_count = 0
        self._has_timeout = False
        self.logger = logging.getLogger(__name__)

        if self.command is not None:
            pass
        elif self.source:
            raise NotImplementedError
        else:
            raise ValueError("missing command or source parameter in " \
			     "WorkerTree constructor")

        # build gateway invocation command
        invoke_gw_args = []
        for envname in ('PYTHONPATH', \
                        'CLUSTERSHELL_GW_LOG_DIR', \
                        'CLUSTERSHELL_GW_LOG_LEVEL'):
            envval = os.getenv(envname)
            if envval:
                invoke_gw_args.append("%s=%s" % (envname, envval))
        invoke_gw_args.append("python -m ClusterShell/Gateway -Bu")
        self.invoke_gateway = ' '.join(invoke_gw_args)

        self.topology = kwargs.get('topology')
        if self.topology is not None:
            self.newroot = kwargs.get('newroot') or str(self.topology.root.nodeset)
            self.router = PropagationTreeRouter(self.newroot, self.topology)
        else:
            self.router = None

        self.upchannel = None
        self.metahandler = MetaWorkerEventHandler(self)

    def _set_task(self, task):
        """
        Bind worker to task. Called by task.schedule().
        WorkerTree metaworker: override to schedule sub-workers.
        """
        ##if fanout is None:
        ##    fanout = self.router.fanout
        ##self.task.set_info('fanout', fanout)

        DistantWorker._set_task(self, task)
        # Now bound to task - initalize router
        self.topology = self.topology or task.topology
        self.router = self.router or task._default_router()
        # And launch stuffs
        next_hops = self._distribute(self.task.info("fanout"), self.nodes)
        for gw, targets in next_hops.iteritems():
            if gw == targets:
                self.logger.debug('task.shell cmd=%s nodes=%s timeout=%d' % \
                    (self.command, self.nodes, self.timeout))
                self._child_count += 1
                self._target_count += len(targets)
                self.workers.append(self.task.shell(self.command,
                    nodes=targets, timeout=self.timeout,
                    handler=self.metahandler, stderr=self.stderr, tree=False))
            else:
                self._execute_remote(self.command, targets, gw, self.timeout)

    def _distribute(self, fanout, dst_nodeset):
        """distribute target nodes between next hop gateways"""
        distribution = {}
        self.router.fanout = fanout

        for gw, dstset in self.router.dispatch(dst_nodeset):
            if gw in distribution:
                distribution[gw].add(dstset)
            else:
                distribution[gw] = dstset
        return distribution

    def _execute_remote(self, cmd, targets, gateway, timeout):
        """run command against a remote node via a gateway"""
        self.logger.debug("_execute_remote gateway=%s cmd=%s targets=%s" % \
            (gateway, cmd, targets))
        #self._start_count += 1
        #self._child_count += 1
        self._target_count += len(targets)
        self.task.pchannel(gateway, self).shell(nodes=targets,
            command=cmd, worker=self, timeout=timeout, stderr=self.stderr,
            gw_invoke_cmd=self.invoke_gateway)

    def _engine_clients(self):
        """
        Access underlying engine clients.
        """
        return []

    def _on_node_rc(self, node, rc):
        DistantWorker._on_node_rc(self, node, rc)
        self._close_count += 1
        self._check_fini()

    def _on_node_timeout(self, node):
        DistantWorker._on_node_timeout(self, node)
        self._close_count += 1
        self._has_timeout = True
        self._check_fini()

    def _check_ini(self):
        self.logger.debug("WorkerTree: _check_ini (%d, %d)" % \
            (self._start_count,self._child_count))
        if self._start_count >= self._child_count:
            self.eh.ev_start(self)

    def _check_fini(self):
        if self._close_count >= self._target_count:
            handler = self.eh
            if handler:
                if self._has_timeout:
                    handler.ev_timeout(self)
                handler.ev_close(self)
            self.task._pchannel_release(self)

    def write(self, buf):
        """
        Write to worker clients.
        """
        for c in self._engine_clients():
            c._write(buf)

    def set_write_eof(self):
        """
        Tell worker to close its writer file descriptor once flushed. Do not
        perform writes after this call.
        """
        for c in self._engine_clients():
            c._set_write_eof()

    def abort(self):
        """
        Abort processing any action by this worker.
        """
        for c in self._engine_clients():
            c.abort()