##############################################################################
# Copyright 2018 EuropeanSoftwareMarketingLtd.
# ===================================================================
#  Licensed under the ApacheLicense, Version2.0 (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
#
# 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
##############################################################################
# vnftest comment: this is a modified copy of
# rally/rally/benchmark/runners/base.py

from __future__ import absolute_import

import importlib
import logging
import multiprocessing
import subprocess
import time
import traceback
from Queue import Empty

import vnftest.common.utils as utils
from vnftest.steps import base as base_step

log = logging.getLogger(__name__)


def _execute_shell_command(command):
    """execute shell script with error handling"""
    exitcode = 0
    try:
        output = subprocess.check_output(command, shell=True)
    except Exception:
        exitcode = -1
        output = traceback.format_exc()
        log.error("exec command '%s' error:\n ", command)
        log.error(traceback.format_exc())

    return exitcode, output


def _single_action(seconds, command, queue):
    """entrypoint for the single action process"""
    log.debug("single action, fires after %d seconds (from now)", seconds)
    time.sleep(seconds)
    log.debug("single action: executing command: '%s'", command)
    ret_code, data = _execute_shell_command(command)
    if ret_code < 0:
        log.error("single action error! command:%s", command)
        queue.put({'single-action-data': data})
        return
    log.debug("single action data: \n%s", data)
    queue.put({'single-action-data': data})


def _periodic_action(interval, command, queue):
    """entrypoint for the periodic action process"""
    log.debug("periodic action, fires every: %d seconds", interval)
    time_spent = 0
    while True:
        time.sleep(interval)
        time_spent += interval
        log.debug("periodic action, executing command: '%s'", command)
        ret_code, data = _execute_shell_command(command)
        if ret_code < 0:
            log.error("periodic action error! command:%s", command)
            queue.put({'periodic-action-data': data})
            break
        log.debug("periodic action data: \n%s", data)
        queue.put({'periodic-action-data': data})


class Runner(object):
    runners = []

    @staticmethod
    def get_cls(runner_type):
        """return class of specified type"""
        for runner in utils.findsubclasses(Runner):
            if runner_type == runner.__execution_type__:
                return runner
        raise RuntimeError("No such runner_type %s" % runner_type)

    @staticmethod
    def get_types():
        """return a list of known runner type (class) names"""
        types = []
        for runner in utils.findsubclasses(Runner):
            types.append(runner)
        return types

    @staticmethod
    def get(runner_cfg):
        """Returns instance of a step runner for execution type.
        """
        return Runner.get_cls(runner_cfg["type"])(runner_cfg)

    @staticmethod
    def release(runner):
        """Release the runner"""
        if runner in Runner.runners:
            Runner.runners.remove(runner)

    @staticmethod
    def terminate(runner):
        """Terminate the runner"""
        if runner.process and runner.process.is_alive():
            runner.process.terminate()

    @staticmethod
    def terminate_all():
        """Terminate all runners (subprocesses)"""
        log.debug("Terminating all runners", exc_info=True)

        # release dumper process as some errors before any runner is created
        if not Runner.runners:
            return

        for runner in Runner.runners:
            log.debug("Terminating runner: %s", runner)
            if runner.process:
                runner.process.terminate()
                runner.process.join()
            if runner.periodic_action_process:
                log.debug("Terminating periodic action process")
                runner.periodic_action_process.terminate()
                runner.periodic_action_process = None
            Runner.release(runner)

    def __init__(self, config):
        self.config = config
        self.periodic_action_process = None
        self.output_queue = multiprocessing.Queue()
        self.result_queue = multiprocessing.Queue()
        self.process = None
        self.aborted = multiprocessing.Event()
        Runner.runners.append(self)

    def run_post_stop_action(self):
        """run a potentially configured post-stop action"""
        if "post-stop-action" in self.config:
            command = self.config["post-stop-action"]["command"]
            log.debug("post stop action: command: '%s'", command)
            ret_code, data = _execute_shell_command(command)
            if ret_code < 0:
                log.error("post action error! command:%s", command)
                self.result_queue.put({'post-stop-action-data': data})
                return
            log.debug("post-stop data: \n%s", data)
            self.result_queue.put({'post-stop-action-data': data})

    def _run_step(self, cls, method_name, step_cfg, context_cfg, input_params):
        raise NotImplementedError

    def run(self, step_cfg, context_cfg, input_params):
        step_type = step_cfg["type"]
        class_name = base_step.Step.get(step_type)
        path_split = class_name.split(".")
        module_path = ".".join(path_split[:-1])
        module = importlib.import_module(module_path)
        cls = getattr(module, path_split[-1])

        self.config['object'] = class_name
        self.aborted.clear()

        # run a potentially configured pre-start action
        if "pre-start-action" in self.config:
            command = self.config["pre-start-action"]["command"]
            log.debug("pre start action: command: '%s'", command)
            ret_code, data = _execute_shell_command(command)
            if ret_code < 0:
                log.error("pre-start action error! command:%s", command)
                self.result_queue.put({'pre-start-action-data': data})
                return
            log.debug("pre-start data: \n%s", data)
            self.result_queue.put({'pre-start-action-data': data})

        if "single-shot-action" in self.config:
            single_action_process = multiprocessing.Process(
                target=_single_action,
                name="single-shot-action",
                args=(self.config["single-shot-action"]["after"],
                      self.config["single-shot-action"]["command"],
                      self.result_queue))
            single_action_process.start()

        if "periodic-action" in self.config:
            self.periodic_action_process = multiprocessing.Process(
                target=_periodic_action,
                name="periodic-action",
                args=(self.config["periodic-action"]["interval"],
                      self.config["periodic-action"]["command"],
                      self.result_queue))
            self.periodic_action_process.start()

        self._run_step(cls, "run", step_cfg, context_cfg, input_params)

    def abort(self):
        """Abort the execution of a step"""
        self.aborted.set()

    QUEUE_JOIN_INTERVAL = 5

    def poll(self, timeout=QUEUE_JOIN_INTERVAL):
        self.process.join(timeout)
        return self.process.exitcode

    def join(self, outputs, result, interval=QUEUE_JOIN_INTERVAL):
        while self.process.exitcode is None:
            # drain the queue while we are running otherwise we won't terminate
            outputs.update(self.get_output())
            result.extend(self.get_result())
            self.process.join(interval)
        # drain after the process has exited
        outputs.update(self.get_output())
        result.extend(self.get_result())

        self.process.terminate()
        if self.periodic_action_process:
            self.periodic_action_process.join(1)
            self.periodic_action_process.terminate()
            self.periodic_action_process = None

        self.run_post_stop_action()
        return self.process.exitcode

    def get_output(self):
        result = {}
        while not self.output_queue.empty():
            log.debug("output_queue size %s", self.output_queue.qsize())
            try:
                result.update(self.output_queue.get(True, 1))
            except Empty:
                pass
        return result

    def get_result(self):
        result = []
        while not self.result_queue.empty():
            log.debug("result_queue size %s", self.result_queue.qsize())
            try:
                result.append(self.result_queue.get(True, 1))
            except Empty:
                pass
        return result