from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

from caffe2.python import core, dataio
from caffe2.python.task import TaskGroup


class _QueueReader(dataio.Reader):
    def __init__(self, wrapper):
        assert wrapper.schema is not None, (
            'Queue needs a schema in order to be read from.')
        dataio.Reader.__init__(self, wrapper.schema())
        self._wrapper = wrapper

    def setup_ex(self, init_net, exit_net):
        exit_net.CloseBlobsQueue([self._wrapper.queue()], 0)

    def read_ex(self, local_init_net, local_finish_net):
        self._wrapper._new_reader(local_init_net)
        dequeue_net = core.Net('dequeue_net')
        fields, status_blob = dequeue(
            dequeue_net,
            self._wrapper.queue(),
            len(self.schema().field_names()))
        return [dequeue_net], status_blob, fields


class _QueueWriter(dataio.Writer):
    def __init__(self, wrapper):
        self._wrapper = wrapper

    def setup_ex(self, init_net, exit_net):
        exit_net.CloseBlobsQueue([self._wrapper.queue()], 0)

    def write_ex(self, fields, local_init_net, local_finish_net, status):
        self._wrapper._new_writer(self.schema(), local_init_net)
        enqueue_net = core.Net('enqueue_net')
        enqueue(enqueue_net, self._wrapper.queue(), fields, status)
        return [enqueue_net]


class QueueWrapper(dataio.Pipe):
    def __init__(self, handler, schema=None):
        dataio.Pipe.__init__(self, schema, TaskGroup.LOCAL_SETUP)
        self._queue = handler

    def reader(self):
        return _QueueReader(self)

    def writer(self):
        return _QueueWriter(self)

    def queue(self):
        return self._queue


class Queue(QueueWrapper):
    def __init__(self, capacity, schema=None, name='queue'):
        # find a unique blob name for the queue
        net = core.Net(name)
        queue_blob = net.AddExternalInput(net.NextName('handler'))
        QueueWrapper.__init__(self, queue_blob, schema)
        self.capacity = capacity
        self._setup_done = False

    def setup(self, global_init_net):
        assert self._schema, 'This queue does not have a schema.'
        self._setup_done = True
        global_init_net.CreateBlobsQueue(
            [],
            [self._queue],
            capacity=self.capacity,
            num_blobs=len(self._schema.field_names()))


def enqueue(net, queue, data_blobs, status=None):
    if status is None:
        status = net.NextName("%s_enqueue_status" % str(queue))
    results = net.SafeEnqueueBlobs([queue] + data_blobs, data_blobs + [status])
    return results[-1]


def dequeue(net, queue, num_blobs, status=None):
    data_names = [net.NextName("%s_dequeue_data", i) for i in range(num_blobs)]
    if status is None:
        status = net.NextName("%s_dequeue_status")
    results = net.SafeDequeueBlobs(queue, data_names + [status])
    results = list(results)
    status_blob = results.pop(-1)
    return results, status_blob


def close_queue(step, *queues):
    close_net = core.Net("close_queue_net")
    for queue in queues:
        close_net.CloseBlobsQueue([queue], 0)
    close_step = core.execution_step("%s_step" % str(close_net), close_net)
    return core.execution_step(
        "%s_wraper_step" % str(close_net),
        [step, close_step])