#!/usr/bin/env python
# -*- coding: utf-8 -*-
# File: concurrency.py
# Author: Yuxin Wu <ppwwyyxxc@gmail.com>

import multiprocessing
import six
from six.moves import queue, range
import tensorflow as tf

from ..utils import logger
from ..utils.concurrency import DIE, StoppableThread, ShareSessionThread
from ..tfutils.model_utils import describe_trainable_vars
from .base import OnlinePredictor, OfflinePredictor, AsyncPredictorBase

__all__ = ['MultiProcessPredictWorker', 'MultiProcessQueuePredictWorker',
           'MultiThreadAsyncPredictor']


class MultiProcessPredictWorker(multiprocessing.Process):
    """ Base class for predict worker that runs offline in multiprocess"""

    def __init__(self, idx, config):
        """
        Args:
            idx (int): index of the worker. the 0th worker will print log.
            config (PredictConfig): the config to use.
        """
        super(MultiProcessPredictWorker, self).__init__()
        self.name = "MultiProcessPredictWorker-{}".format(idx)
        self.idx = idx
        self.config = config

    def _init_runtime(self):
        """ Call _init_runtime under different CUDA_VISIBLE_DEVICES, you'll
            have workers that run on multiGPUs
        """
        if self.idx != 0:
            from tensorpack.models.common import disable_layer_logging
            disable_layer_logging()
        self.predictor = OfflinePredictor(self.config)
        if self.idx == 0:
            with self.predictor.graph.as_default():
                describe_trainable_vars()


class MultiProcessQueuePredictWorker(MultiProcessPredictWorker):
    """
    An offline predictor worker that takes input and produces output by queue.
    Each process will exit when they see :class:`DIE`.
    """

    def __init__(self, idx, inqueue, outqueue, config):
        """
        Args:
            idx, config: same as in :class:`MultiProcessPredictWorker`.
            inqueue (multiprocessing.Queue): input queue to get data point. elements are (task_id, dp)
            outqueue (multiprocessing.Queue): output queue to put result. elements are (task_id, output)
        """
        super(MultiProcessQueuePredictWorker, self).__init__(idx, config)
        self.inqueue = inqueue
        self.outqueue = outqueue
        assert isinstance(self.inqueue, multiprocessing.queues.Queue)
        assert isinstance(self.outqueue, multiprocessing.queues.Queue)

    def run(self):
        self._init_runtime()
        while True:
            tid, dp = self.inqueue.get()
            if tid == DIE:
                self.outqueue.put((DIE, None))
                return
            else:
                self.outqueue.put((tid, self.predictor(dp)))


class PredictorWorkerThread(StoppableThread, ShareSessionThread):
    def __init__(self, queue, pred_func, id, batch_size=5):
        super(PredictorWorkerThread, self).__init__()
        self.name = "PredictorWorkerThread-{}".format(id)
        self.queue = queue
        self.func = pred_func
        self.daemon = True
        self.batch_size = batch_size
        self.id = id

    def run(self):
        with self.default_sess():
            while not self.stopped():
                batched, futures = self.fetch_batch()
                try:
                    outputs = self.func(batched)
                except tf.errors.CancelledError:
                    for f in futures:
                        f.cancel()
                    logger.warn("In PredictorWorkerThread id={}, call was cancelled.".format(self.id))
                    return
                # print "Worker {} batched {} Queue {}".format(
                #         self.id, len(futures), self.queue.qsize())
                #  debug, for speed testing
                # if not hasattr(self, 'xxx'):
                    # self.xxx = outputs = self.func(batched)
                # else:
                    # outputs = [[self.xxx[0][0]] * len(batched[0]), [self.xxx[1][0]] * len(batched[0])]

                for idx, f in enumerate(futures):
                    f.set_result([k[idx] for k in outputs])

    def fetch_batch(self):
        """ Fetch a batch of data without waiting"""
        inp, f = self.queue.get()
        nr_input_var = len(inp)
        batched, futures = [[] for _ in range(nr_input_var)], []
        for k in range(nr_input_var):
            batched[k].append(inp[k])
        futures.append(f)
        while len(futures) < self.batch_size:
            try:
                inp, f = self.queue.get_nowait()
                for k in range(nr_input_var):
                    batched[k].append(inp[k])
                futures.append(f)
            except queue.Empty:
                break   # do not wait
        return batched, futures


class MultiThreadAsyncPredictor(AsyncPredictorBase):
    """
    An multithread online async predictor which runs a list of OnlinePredictor.
    It would do an extra batching internally.
    """

    def __init__(self, predictors, batch_size=5):
        """
        Args:
            predictors (list): a list of OnlinePredictor avaiable to use.
            batch_size (int): the maximum of an internal batch.
        """
        assert len(predictors)
        self._need_default_sess = False
        for k in predictors:
            assert isinstance(k, OnlinePredictor), type(k)
            if k.sess is None:
                self._need_default_sess = True
            # TODO support predictors.return_input here
            assert not k.return_input
        self.input_queue = queue.Queue(maxsize=len(predictors) * 100)
        self.threads = [
            PredictorWorkerThread(
                self.input_queue, f, id, batch_size=batch_size)
            for id, f in enumerate(predictors)]

        if six.PY2:
            # TODO XXX set logging here to avoid affecting TF logging
            import tornado.options as options
            options.parse_command_line(['--logging=debug'])
            logger.warn("MultiThreadAsyncPredictor is inefficient in Python 2! Switch to Python 3 instead.")

    def start(self):
        if self._need_default_sess:
            assert tf.get_default_session() is not None, \
                "Not session is bind to predictors, " \
                "MultiThreadAsyncPredictor.start() has to be called under a default session!"
        for t in self.threads:
            t.start()

    def put_task(self, dp, callback=None):
        """
        Same as in :meth:`AsyncPredictorBase.put_task`.
        """
        f = Future()
        if callback is not None:
            f.add_done_callback(callback)
        self.input_queue.put((dp, f))
        return f


try:
    if six.PY2:
        from tornado.concurrent import Future
    else:
        from concurrent.futures import Future
except ImportError:
    from ..utils.develop import create_dummy_class
    MultiThreadAsyncPredictor = create_dummy_class('MultiThreadAsyncPredictor', 'tornado.concurrent')  # noqa
