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#       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
#
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#       KIND, either express or implied.  See the License for the
#       specific language governing permissions and limitations
#       under the License.

import logging
import os
import time
import Queue
from contextlib import contextmanager
from datetime import datetime, timedelta
import signal
import sys

import faulthandler
import pylons
from setproctitle import setproctitle, getproctitle
import tg
from paste.deploy import loadapp
from paste.deploy.converters import asint
from webob import Request

import base

faulthandler.enable()

status_log = logging.getLogger('taskdstatus')

log = logging.getLogger(__name__)

@contextmanager
def proctitle(title):
    """Temporarily change the process title, then restore it."""
    orig_title = getproctitle()
    try:
        setproctitle(title)
        yield
        setproctitle(orig_title)
    except:
        setproctitle(orig_title)
        raise


class TaskdCommand(base.Command):
    summary = 'Task server'
    parser = base.Command.standard_parser(verbose=True)
    parser.add_option('--only', dest='only', type='string', default=None,
                      help='only handle tasks of the given name(s) (can be comma-separated list)')

    def command(self):
        setproctitle('taskd')
        self.basic_setup()
        self.keep_running = True
        self.restart_when_done = False
        base.log.info('Starting taskd, pid %s' % os.getpid())
        signal.signal(signal.SIGHUP, self.graceful_restart)
        signal.signal(signal.SIGTERM, self.graceful_stop)
        signal.signal(signal.SIGUSR1, self.log_current_task)
        # restore default behavior of not interrupting system calls
        # see http://docs.python.org/library/signal.html#signal.siginterrupt
        # and http://linux.die.net/man/3/siginterrupt
        signal.siginterrupt(signal.SIGHUP, False)
        signal.siginterrupt(signal.SIGTERM, False)
        signal.siginterrupt(signal.SIGUSR1, False)
        self.worker()

    def graceful_restart(self, signum, frame):
        base.log.info('taskd pid %s recieved signal %s preparing to do a graceful restart' % (os.getpid(), signum))
        self.keep_running = False
        self.restart_when_done = True

    def graceful_stop(self, signum, frame):
        base.log.info('taskd pid %s recieved signal %s preparing to do a graceful stop' % (os.getpid(), signum))
        self.keep_running = False

    def log_current_task(self, signum, frame):
        entry = 'taskd pid %s is currently handling task %s' % (os.getpid(), getattr(self, 'task', None))
        status_log.info(entry)
        base.log.info(entry)

    def worker(self):
        from allura import model as M
        name = '%s pid %s' % (os.uname()[1], os.getpid())
        wsgi_app = loadapp('config:%s#task' % self.args[0],relative_to=os.getcwd())
        poll_interval = asint(pylons.config.get('monq.poll_interval', 10))
        only = self.options.only
        if only:
            only = only.split(',')

        def start_response(status, headers, exc_info=None):
            if status != '200 OK':
                log.warn('Unexpected http response from taskd request: %s.  Headers: %s',
                             status, headers)

        def waitfunc_amqp():
            try:
                return pylons.app_globals.amq_conn.queue.get(timeout=poll_interval)
            except Queue.Empty:
                return None

        def waitfunc_noq():
            time.sleep(poll_interval)

        def check_running(func):
            def waitfunc_checks_running():
                if self.keep_running:
                    return func()
                else:
                    raise StopIteration
            return waitfunc_checks_running

        if pylons.app_globals.amq_conn:
            waitfunc = waitfunc_amqp
        else:
            waitfunc = waitfunc_noq
        waitfunc = check_running(waitfunc)
        while self.keep_running:
            if pylons.app_globals.amq_conn:
                pylons.app_globals.amq_conn.reset()
            try:
                while self.keep_running:
                    self.task = M.MonQTask.get(
                            process=name,
                            waitfunc=waitfunc,
                            only=only)
                    if self.task:
                        with(proctitle("taskd:{0}:{1}".format(
                                self.task.task_name, self.task._id))):
                            # Build the (fake) request
                            request_path = '/--%s--/%s/' % (self.task.task_name, self.task._id)
                            r = Request.blank(request_path,
                                              base_url=tg.config['base_url'].rstrip('/') + request_path,
                                              environ={'task': self.task,
                                               })
                            list(wsgi_app(r.environ, start_response))
                            self.task = None
            except Exception as e:
                if self.keep_running:
                    base.log.exception('taskd error %s; pausing for 10s before taking more tasks' % e)
                    time.sleep(10)
                else:
                    base.log.exception('taskd error %s' % e)
        base.log.info('taskd pid %s stopping gracefully.' % os.getpid())

        if self.restart_when_done:
            base.log.info('taskd pid %s restarting itself' % os.getpid())
            os.execv(sys.argv[0], sys.argv)


class TaskCommand(base.Command):
    summary = 'Task command'
    parser = base.Command.standard_parser(verbose=True)
    parser.add_option('-s', '--state', dest='state', default='ready',
                      help='state of processes to examine')
    parser.add_option('-t', '--timeout', dest='timeout', type=int, default=60,
                      help='timeout (in seconds) for busy tasks')
    min_args = 2
    max_args = None
    usage = '<ini file> [list|retry|purge|timeout|commit]'

    def command(self):
        self.basic_setup()
        cmd = self.args[1]
        tab = dict(
            list=self._list,
            retry=self._retry,
            purge=self._purge,
            timeout=self._timeout,
            commit=self._commit)
        tab[cmd]()

    def _list(self):
        '''List tasks'''
        from allura import model as M
        base.log.info('Listing tasks of state %s', self.options.state)
        if self.options.state == '*':
            q = dict()
        else:
            q = dict(state=self.options.state)
        for t in M.MonQTask.query.find(q):
            print t

    def _retry(self):
        '''Retry tasks in an error state'''
        from allura import model as M
        base.log.info('Retry tasks in error state')
        M.MonQTask.query.update(
            dict(state='error'),
            {'$set': dict(state='ready')},
            multi=True)

    def _purge(self):
        '''Purge completed tasks'''
        from allura import model as M
        base.log.info('Purge complete/forget tasks')
        M.MonQTask.query.remove(
            dict(state='complete', result_type='forget'))

    def _timeout(self):
        '''Reset tasks that have been busy too long to 'ready' state'''
        from allura import model as M
        base.log.info('Reset tasks stuck for %ss or more', self.options.timeout)
        cutoff = datetime.utcnow() - timedelta(seconds=self.options.timeout)
        M.MonQTask.timeout_tasks(cutoff)

    def _commit(self):
        '''Schedule a SOLR commit'''
        from allura.tasks import index_tasks
        base.log.info('Commit to solr')
        index_tasks.commit.post()