import random
from itertools import izip_longest, groupby, chain

from wa.framework.configuration.core import (MetaConfiguration, RunConfiguration,
                                             JobGenerator, Status, settings)
from wa.framework.configuration.parsers import ConfigParser
from wa.framework.configuration.plugin_cache import PluginCache
from wa.framework.exception import NotFoundError
from wa.framework.job import Job
from wa.utils import log


class CombinedConfig(object):

    @staticmethod
    def from_pod(pod):
        instance = CombinedConfig()
        instance.settings = MetaConfiguration.from_pod(pod.get('settings', {}))
        instance.run_config = RunConfiguration.from_pod(pod.get('run_config', {}))
        return instance

    def __init__(self, settings=None, run_config=None):
        self.settings = settings
        self.run_config = run_config

    def to_pod(self):
        return {'settings': self.settings.to_pod(),
                'run_config': self.run_config.to_pod()}


class ConfigManager(object):
    """
    Represents run-time state of WA. Mostly used as a container for loaded
    configuration and discovered plugins.

    This exists outside of any command or run and is associated with the running
    instance of wA itself.
    """

    @property
    def enabled_instruments(self):
        return self.jobs_config.enabled_instruments

    @property
    def enabled_processors(self):
        return self.jobs_config.enabled_processors

    @property
    def job_specs(self):
        if not self._jobs_generated:
            msg = 'Attempting to access job specs before '\
                  'jobs have been generated'
            raise RuntimeError(msg)
        return [j.spec for j in self._jobs]

    @property
    def jobs(self):
        if not self._jobs_generated:
            msg = 'Attempting to access jobs before '\
                  'they have been generated'
            raise RuntimeError(msg)
        return self._jobs

    def __init__(self, settings=settings):
        self.settings = settings
        self.run_config = RunConfiguration()
        self.plugin_cache = PluginCache()
        self.jobs_config = JobGenerator(self.plugin_cache)
        self.loaded_config_sources = []
        self._config_parser = ConfigParser()
        self._jobs = []
        self._jobs_generated = False
        self.agenda = None

    def load_config_file(self, filepath):
        self._config_parser.load_from_path(self, filepath)
        self.loaded_config_sources.append(filepath)

    def load_config(self, values, source, wrap_exceptions=True):
        self._config_parser.load(self, values, source)
        self.loaded_config_sources.append(source)

    def get_plugin(self, name=None, kind=None, *args, **kwargs):
        return self.plugin_cache.get_plugin(name, kind, *args, **kwargs)

    def get_instruments(self, target):
        instruments = []
        for name in self.enabled_instruments:
            try:
                instruments.append(self.get_plugin(name, kind='instrument',
                                                   target=target))
            except NotFoundError:
                msg = 'Instrument "{}" not found'
                raise NotFoundError(msg.format(name))
        return instruments

    def get_processors(self):
        processors = []
        for name in self.enabled_processors:
            try:
                proc = self.plugin_cache.get_plugin(name, kind='output_processor')
            except NotFoundError:
                msg = 'Output Processor "{}" not found'
                raise NotFoundError(msg.format(name))
            processors.append(proc)
        return processors

    def finalize(self):
        if not self.agenda:
            msg = 'Attempting to finalize config before agenda has been set'
            raise RuntimeError(msg)
        self.run_config.merge_device_config(self.plugin_cache)
        return CombinedConfig(self.settings, self.run_config)

    def generate_jobs(self, context):
        job_specs = self.jobs_config.generate_job_specs(context.tm)
        exec_order = self.run_config.execution_order
        log.indent()
        for spec, i in permute_iterations(job_specs, exec_order):
            job = Job(spec, i, context)
            job.load(context.tm.target)
            self._jobs.append(job)
            context.run_state.add_job(job)
        log.dedent()
        self._jobs_generated = True


def permute_by_job(specs):
    """
    This is that "classic" implementation that executes all iterations of a
    workload spec before proceeding onto the next spec.

    """
    for spec in specs:
        for i in range(1, spec.iterations + 1):
            yield (spec, i)


def permute_by_iteration(specs):
    """
    Runs the first iteration for all benchmarks first, before proceeding to the
    next iteration, i.e. A1, B1, C1, A2, B2, C2...  instead of  A1, A1, B1, B2,
    C1, C2...

    If multiple sections where specified in the agenda, this will run all
    sections for the first global spec first, followed by all sections for the
    second spec, etc.

    e.g. given sections X and Y, and global specs A and B, with 2 iterations,
    this will run

    X.A1, Y.A1, X.B1, Y.B1, X.A2, Y.A2, X.B2, Y.B2

    """
    groups = [list(g) for k, g in groupby(specs, lambda s: s.workload_id)]

    all_tuples = []
    for spec in chain(*groups):
        all_tuples.append([(spec, i + 1)
                           for i in xrange(spec.iterations)])
    for t in chain(*map(list, izip_longest(*all_tuples))):
        if t is not None:
            yield t


def permute_by_section(specs):
    """
    Runs the first iteration for all benchmarks first, before proceeding to the
    next iteration, i.e. A1, B1, C1, A2, B2, C2...  instead of  A1, A1, B1, B2,
    C1, C2...

    If multiple sections where specified in the agenda, this will run all specs
    for the first section followed by all specs for the seciod section, etc.

    e.g. given sections X and Y, and global specs A and B, with 2 iterations,
    this will run

    X.A1, X.B1, Y.A1, Y.B1, X.A2, X.B2, Y.A2, Y.B2

    """
    groups = [list(g) for k, g in groupby(specs, lambda s: s.section_id)]

    all_tuples = []
    for spec in chain(*groups):
        all_tuples.append([(spec, i + 1)
                           for i in xrange(spec.iterations)])
    for t in chain(*map(list, izip_longest(*all_tuples))):
        if t is not None:
            yield t


def permute_randomly(specs):
    """
    This will generate a random permutation of specs/iteration tuples.

    """
    result = []
    for spec in specs:
        for i in xrange(1, spec.iterations + 1):
            result.append((spec, i))
    random.shuffle(result)
    for t in result:
        yield t


permute_map = {
    'by_iteration': permute_by_iteration,
    'by_job': permute_by_job,
    'by_section': permute_by_section,
    'random': permute_randomly,
}


def permute_iterations(specs, exec_order):
    if exec_order not in permute_map:
        msg = 'Unknown execution order "{}"; must be in: {}'
        raise ValueError(msg.format(exec_order, permute_map.keys()))
    return permute_map[exec_order](specs)