"""
Celery tasks for djeuscan
"""

from celery.task import task, group

from django.conf import settings

import portage

from djeuscan.models import Package, RefreshPackageQuery
from djeuscan.processing import scan, misc


class TaskFailedException(Exception):
    """
    Exception for failed tasks
    """
    pass


def group_one(task, seq, *args, **kwargs):
    """
    Create a group of tasks, each task handle one element of seq
    """
    tasks = []

    for elem in seq:
        if "attr_name" in kwargs:
            kwargs[kwargs["attr_name"]] = elem
            del kwargs["attr_name"]
            tasks.append(task.subtask(args=args, kwargs=kwargs))
        else:
            tasks.append(task.subtask(args=[elem] + list(args), kwargs=kwargs))
    return group(tasks)


def group_chunks(task, seq, n, *args, **kwargs):
    """
    Creates a group of tasks, each subtask has <n> elements to handle
    """
    tasks = []
    for i in xrange(0, len(seq), n):
        tasks.append(
            task.subtask(args=[seq[i:i + n]] + list(args), kwargs=kwargs)
        )
    return group(tasks)


@task
def regen_rrds():
    """
    Regenerate RRDs
    """
    misc.regen_rrds()
    return True


@task
def update_counters(fast=False):
    """
    Updates counters
    """
    logger = update_counters.get_logger()
    logger.info("Updating counters (fast=%s)...", fast)
    misc.update_counters(fast=fast)
    logger.info("Done")
    return True


@task
def scan_metadata(packages=[], category=None, populate=False):
    """
    Scans metadata for the given set of packages
    """
    logger = scan_metadata.get_logger()

    if packages:
        logger.info("Starting metadata scan for %d packages...",
                    len(packages))
    elif category:
        logger.info("Starting metadata scan for %s...",
                    category)
    else:
        logger.info("Starting metadata scan...")

    scan.scan_metadata(
        packages=packages,
        category=category,
        logger=logger,
        populate=populate,
    )
    return True


@task
def scan_portage(packages=[], category=None,
                 no_log=False, purge_packages=False,
                 purge_versions=False, prefetch=False):
    """
    Scans portage for the given set of packages
    """
    logger = scan_portage.get_logger()

    if packages:
        logger.info("Starting portage scan for %d packages...",
                    len(packages))
    elif category:
        logger.info("Starting portage scan for %s...",
                    category)
    else:
        logger.info("Starting portage scan...")

    scan.scan_portage(
        packages=packages,
        category=category,
        no_log=no_log,
        purge_packages=purge_packages,
        purge_versions=purge_versions,
        prefetch=prefetch,
        logger=logger,
    )
    return True


@task
def scan_upstream(packages=[], purge_versions=False):
    """
    Scans upstream for the given set of packages
    """
    logger = scan_upstream.get_logger()

    if len(packages):
        logger.info("Starting upstream scan subtask for %d packages...",
                    len(packages))
    else:
        logger.info("Starting upstream scan...",
                    len(packages))

    scan.scan_upstream(
        packages=packages,
        purge_versions=purge_versions,
        logger=logger,
    )
    return True


@task
def update_portage_trees():
    """
    Update portage tree
    """
    logger = update_portage_trees.get_logger()
    misc.update_portage_trees(logger=logger)
    return True


@task
def update_portage(packages=None):
    update_portage_trees()
    scan_metadata(packages=None, populate=True)
    (
        group_one(scan_portage, portage.settings.categories,
                  attr_name="category", purge_packages=True,
                  purge_versions=True, prefetch=True) |
        group_one(scan_metadata, portage.settings.categories,
                  attr_name="category") |
        update_counters.si(fast=False)
    )()
    return True


@task
def update_upstream():
    if settings.TASKS_UPSTREAM_GROUPS >= 1:
        packages = Package.objects.all().order_by('pk') # .order_by('?') ?

        scan_upstream_sub = group_chunks(scan_upstream, packages,
                                         settings.TASKS_UPSTREAM_GROUPS,
                                         purge_versions=True)
    else:
        scan_upstream_sub = scan_upstream.si(purge_versions=True)

    (
        scan_upstream_sub |
        update_counters.si(fast=False)
    )()
    return True


@task
def scan_package(package):
    scan_portage([package], purge_packages=True, purge_versions=True)
    scan_metadata([package])
    scan_upstream([package])
    return True


@task(rate_limit="1/m")
def scan_package_user(package):
    scan_package(package)
    return True


@task
def consume_refresh_package_request():
    """
    Satisfies user requests for package refreshing, runs every minute
    """
    try:
        query = RefreshPackageQuery.objects.all().order_by('-priority')[0]
    except IndexError:
        return

    pkg = query.package
    query.delete()
    scan_package_user.delay(pkg)


admin_tasks = [
    regen_rrds,
    update_counters,
    scan_metadata,
    scan_portage,
    scan_upstream,
    update_portage_trees,
    update_portage,
    update_upstream,
    scan_package,
]


# Chunk helpers (chunks can't use keyword arguments)
@task
def scan_metadata_category(category):
    """
    Helper for calling scan_metadata with a category
    """
    scan_metadata(category=category)
    return True


@task
def scan_upstream_purge(*packages):
    """
    Helper for calling scan_upstream with purge_versions=True
    """
    scan_upstream(packages, purge_versions=True)
    return True