import logging
import os

from wa.framework import signal
from wa.framework.plugin import Parameter
from wa.framework.target.descriptor import (get_target_descriptions,
                                            instantiate_target,
                                            instantiate_assistant)
from wa.framework.target.info import TargetInfo
from wa.framework.target.runtime_parameter_manager import RuntimeParameterManager

from devlib import Gem5SimulationPlatform
from devlib.utils.misc import memoized
from devlib.exception import TargetError


class TargetManager(object):
    """
    Instantiate the required target and perform configuration and validation of the device.
    """

    parameters = [
        Parameter('disconnect', kind=bool, default=False,
                  description="""
                  Specifies whether the target should be disconnected from
                  at the end of the run.
                  """),
    ]

    def __init__(self, name, parameters, outdir):
        self.outdir = outdir
        self.logger = logging.getLogger('tm')
        self.target_name = name
        self.target = None
        self.assistant = None
        self.platform_name = None
        self.parameters = parameters
        self.disconnect = parameters.get('disconnect')

        self._init_target()

        # If target supports hotplugging, online all cpus before perform discovery
        # and restore original configuration after completed.
        if self.target.has('hotplug'):
            online_cpus = self.target.list_online_cpus()
            try:
                self.target.hotplug.online_all()
            except TargetError:
                msg = 'Failed to online all CPUS - some information may not be '\
                      'able to be retrieved.'
                self.logger.debug(msg)
            self.rpm = RuntimeParameterManager(self.target)
            all_cpus = set(range(self.target.number_of_cpus))
            self.target.hotplug.offline(*all_cpus.difference(online_cpus))
        else:
            self.rpm = RuntimeParameterManager(self.target)

    def finalize(self):
        if self.disconnect or isinstance(self.target.platform, Gem5SimulationPlatform):
            self.logger.info('Disconnecting from the device')
            with signal.wrap('TARGET_DISCONNECT'):
                self.target.disconnect()

    def start(self):
        self.assistant.start()

    def stop(self):
        self.assistant.stop()

    def extract_results(self, context):
        self.assistant.extract_results(context)

    @memoized
    def get_target_info(self):
        return TargetInfo(self.target)

    def merge_runtime_parameters(self, parameters):
        return self.rpm.merge_runtime_parameters(parameters)

    def validate_runtime_parameters(self, parameters):
        self.rpm.validate_runtime_parameters(parameters)

    def commit_runtime_parameters(self, parameters):
        self.rpm.commit_runtime_parameters(parameters)

    def _init_target(self):
        target_map = {td.name: td for td in get_target_descriptions()}
        if self.target_name not in target_map:
            raise ValueError('Unknown Target: {}'.format(self.target_name))
        tdesc = target_map[self.target_name]

        extra_plat_params={}
        if tdesc.platform is Gem5SimulationPlatform:
            extra_plat_params['host_output_dir'] = self.outdir

        self.logger.debug('Creating {} target'.format(self.target_name))
        self.target = instantiate_target(tdesc, self.parameters, connect=False,
                                         extra_platform_params=extra_plat_params)

        with signal.wrap('TARGET_CONNECT'):
            self.target.connect()
        self.logger.info('Setting up target')
        self.target.setup()

        self.assistant = instantiate_assistant(tdesc, self.parameters, self.target)