import asyncio
from collections import defaultdict
import logging
from timeit import default_timer

from tlz import groupby, valmap

from dask.utils import stringify
from .plugin import SchedulerPlugin
from ..utils import key_split, key_split_group, log_errors


logger = logging.getLogger(__name__)


def dependent_keys(tasks, complete=False):
    """
    All keys that need to compute for these keys to finish.

    If *complete* is false, omit tasks that are busy processing or
    have finished executing.
    """
    out = set()
    errors = set()
    stack = list(tasks)
    while stack:
        ts = stack.pop()
        key = ts.key
        if key in out:
            continue
        if not complete and ts.who_has:
            continue
        if ts.exception is not None:
            errors.add(key)
            if not complete:
                continue

        out.add(key)
        stack.extend(ts.dependencies)
    return out, errors


class Progress(SchedulerPlugin):
    """Tracks progress of a set of keys or futures

    On creation we provide a set of keys or futures that interest us as well as
    a scheduler.  We traverse through the scheduler's dependencies to find all
    relevant keys on which our keys depend.  We then plug into the scheduler to
    learn when our keys become available in memory at which point we record
    their completion.

    State
    -----
    keys: set
        Set of keys that are not yet computed
    all_keys: set
        Set of all keys that we track

    This class performs no visualization.  However it is used by other classes,
    notably TextProgressBar and ProgressWidget, which do perform visualization.
    """

    def __init__(self, keys, scheduler, minimum=0, dt=0.1, complete=False):
        self.keys = {k.key if hasattr(k, "key") else k for k in keys}
        self.keys = {stringify(k) for k in self.keys}
        self.scheduler = scheduler
        self.complete = complete
        self._minimum = minimum
        self._dt = dt
        self.last_duration = 0
        self._start_time = default_timer()
        self._running = False
        self.status = None
        self.extra = {}

    async def setup(self):
        keys = self.keys

        while not keys.issubset(self.scheduler.tasks):
            await asyncio.sleep(0.05)

        tasks = [self.scheduler.tasks[k] for k in keys]

        self.keys = None

        self.scheduler.add_plugin(self)  # subtle race condition here
        self.all_keys, errors = dependent_keys(tasks, complete=self.complete)
        if not self.complete:
            self.keys = self.all_keys.copy()
        else:
            self.keys, _ = dependent_keys(tasks, complete=False)
        self.all_keys.update(keys)
        self.keys |= errors & self.all_keys

        if not self.keys:
            self.stop(exception=None, key=None)

        logger.debug("Set up Progress keys")

        for k in errors:
            self.transition(k, None, "erred", exception=True)

    def transition(self, key, start, finish, *args, **kwargs):
        if key in self.keys and start == "processing" and finish == "memory":
            logger.debug("Progress sees key %s", key)
            self.keys.remove(key)

            if not self.keys:
                self.stop()

        if key in self.all_keys and finish == "erred":
            logger.debug("Progress sees task erred")
            self.stop(exception=kwargs["exception"], key=key)

        if key in self.keys and finish == "forgotten":
            logger.debug("A task was cancelled (%s), stopping progress", key)
            self.stop(exception=True, key=key)

    def restart(self, scheduler):
        self.stop()

    def stop(self, exception=None, key=None):
        if self in self.scheduler.plugins:
            self.scheduler.plugins.remove(self)
        if exception:
            self.status = "error"
            self.extra.update({"exception": self.scheduler.exceptions[key], "key": key})
        else:
            self.status = "finished"
        logger.debug("Remove Progress plugin")


class MultiProgress(Progress):
    """Progress variant that keeps track of different groups of keys

    See Progress for most details.  This only adds a function ``func=``
    that splits keys.  This defaults to ``key_split`` which aligns with naming
    conventions chosen in the dask project (tuples, hyphens, etc..)

    State
    -----
    keys: dict
        Maps group name to set of not-yet-complete keys for that group
    all_keys: dict
        Maps group name to set of all keys for that group

    Examples
    --------
    >>> split = lambda s: s.split('-')[0]
    >>> p = MultiProgress(['y-2'], func=split)  # doctest: +SKIP
    >>> p.keys   # doctest: +SKIP
    {'x': {'x-1', 'x-2', 'x-3'},
     'y': {'y-1', 'y-2'}}
    """

    def __init__(
        self, keys, scheduler=None, func=key_split, minimum=0, dt=0.1, complete=False
    ):
        self.func = func
        Progress.__init__(
            self, keys, scheduler, minimum=minimum, dt=dt, complete=complete
        )

    async def setup(self):
        keys = self.keys

        while not keys.issubset(self.scheduler.tasks):
            await asyncio.sleep(0.05)

        tasks = [self.scheduler.tasks[k] for k in keys]

        self.keys = None

        self.scheduler.add_plugin(self)  # subtle race condition here
        self.all_keys, errors = dependent_keys(tasks, complete=self.complete)
        if not self.complete:
            self.keys = self.all_keys.copy()
        else:
            self.keys, _ = dependent_keys(tasks, complete=False)
        self.all_keys.update(keys)
        self.keys |= errors & self.all_keys

        if not self.keys:
            self.stop(exception=None, key=None)

        # Group keys by func name
        self.keys = valmap(set, groupby(self.func, self.keys))
        self.all_keys = valmap(set, groupby(self.func, self.all_keys))
        for k in self.all_keys:
            if k not in self.keys:
                self.keys[k] = set()

        for k in errors:
            self.transition(k, None, "erred", exception=True)
        logger.debug("Set up Progress keys")

    def transition(self, key, start, finish, *args, **kwargs):
        if start == "processing" and finish == "memory":
            s = self.keys.get(self.func(key), None)
            if s and key in s:
                s.remove(key)

            if not self.keys or not any(self.keys.values()):
                self.stop()

        if finish == "erred":
            logger.debug("Progress sees task erred")
            k = self.func(key)
            if k in self.all_keys and key in self.all_keys[k]:
                self.stop(exception=kwargs.get("exception"), key=key)

        if finish == "forgotten":
            k = self.func(key)
            if k in self.all_keys and key in self.all_keys[k]:
                logger.debug("A task was cancelled (%s), stopping progress", key)
                self.stop(exception=True)


def format_time(t):
    """Format seconds into a human readable form.

    >>> format_time(10.4)
    '10.4s'
    >>> format_time(1000.4)
    '16min 40.4s'
    >>> format_time(100000.4)
    '27hr 46min 40.4s'
    """
    m, s = divmod(t, 60)
    h, m = divmod(m, 60)
    if h:
        return "{0:2.0f}hr {1:2.0f}min {2:4.1f}s".format(h, m, s)
    elif m:
        return "{0:2.0f}min {1:4.1f}s".format(m, s)
    else:
        return "{0:4.1f}s".format(s)


class AllProgress(SchedulerPlugin):
    """ Keep track of all keys, grouped by key_split """

    def __init__(self, scheduler):
        self.all = defaultdict(set)
        self.nbytes = defaultdict(lambda: 0)
        self.state = defaultdict(lambda: defaultdict(set))
        self.scheduler = scheduler

        for ts in self.scheduler.tasks.values():
            key = ts.key
            prefix = ts.prefix.name
            self.all[prefix].add(key)
            self.state[ts.state][prefix].add(key)
            if ts.nbytes >= 0:
                self.nbytes[prefix] += ts.nbytes

        scheduler.add_plugin(self)

    def transition(self, key, start, finish, *args, **kwargs):
        ts = self.scheduler.tasks[key]
        prefix = ts.prefix.name
        self.all[prefix].add(key)
        try:
            self.state[start][prefix].remove(key)
        except KeyError:  # TODO: remove me once we have a new or clean state
            pass

        if start == "memory" and ts.nbytes >= 0:
            # XXX why not respect DEFAULT_DATA_SIZE?
            self.nbytes[prefix] -= ts.nbytes
        if finish == "memory" and ts.nbytes >= 0:
            self.nbytes[prefix] += ts.nbytes

        if finish != "forgotten":
            self.state[finish][prefix].add(key)
        else:
            s = self.all[prefix]
            s.remove(key)
            if not s:
                del self.all[prefix]
                self.nbytes.pop(prefix, None)
                for v in self.state.values():
                    v.pop(prefix, None)

    def restart(self, scheduler):
        self.all.clear()
        self.state.clear()


class GroupProgress(SchedulerPlugin):
    """ Keep track of all keys, grouped by key_split """

    def __init__(self, scheduler):
        self.scheduler = scheduler
        self.keys = dict()
        self.groups = dict()
        self.nbytes = dict()
        self.durations = dict()
        self.dependencies = defaultdict(set)
        self.dependents = defaultdict(set)

        for key, ts in self.scheduler.tasks.items():
            k = key_split_group(key)
            if k not in self.groups:
                self.create(key, k)
            self.keys[k].add(key)
            self.groups[k][ts.state] += 1
            if ts.state == "memory" and ts.nbytes >= 0:
                self.nbytes[k] += ts.nbytes

        scheduler.add_plugin(self)

    def create(self, key, k):
        with log_errors():
            ts = self.scheduler.tasks[key]
            g = {"memory": 0, "erred": 0, "waiting": 0, "released": 0, "processing": 0}
            self.keys[k] = set()
            self.groups[k] = g
            self.nbytes[k] = 0
            self.durations[k] = 0
            self.dependents[k] = {key_split_group(dts.key) for dts in ts.dependents}
            for dts in ts.dependencies:
                d = key_split_group(dts.key)
                self.dependents[d].add(k)
                self.dependencies[k].add(d)

    def transition(self, key, start, finish, *args, **kwargs):
        with log_errors():
            ts = self.scheduler.tasks[key]
            k = key_split_group(key)
            if k not in self.groups:
                self.create(key, k)

            g = self.groups[k]

            if key not in self.keys[k]:
                self.keys[k].add(key)
            else:
                g[start] -= 1

            if finish != "forgotten":
                g[finish] += 1
            else:
                self.keys[k].remove(key)
                if not self.keys[k]:
                    del self.groups[k]
                    del self.nbytes[k]
                    for dep in self.dependencies.pop(k):
                        self.dependents[key_split_group(dep)].remove(k)

            if start == "memory" and ts.nbytes >= 0:
                self.nbytes[k] -= ts.nbytes
            if finish == "memory" and ts.nbytes >= 0:
                self.nbytes[k] += ts.nbytes

    def restart(self, scheduler):
        self.keys.clear()
        self.groups.clear()
        self.nbytes.clear()
        self.durations.clear()
        self.dependencies.clear()
        self.dependents.clear()
