# Copyright (c) 2016-present, Facebook, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
##############################################################################

## @package layers
# Module caffe2.python.layers.layers
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

import logging
from caffe2.python import core, schema, scope, workspace
from caffe2.python.layers.tags import TagContext
from caffe2.proto import caffe2_pb2

from collections import namedtuple
import numpy as np
logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)

# Some types to simplify descriptions of things traveling between ops
IdList = schema.List(np.int64)
IdScoreList = schema.Map(np.int64, np.float32)


def get_key(record):
    if schema.equal_schemas(record, IdList):
        key = 'values'
    elif schema.equal_schemas(record, IdScoreList, check_field_types=False):
        key = 'values:keys'
    else:
        raise NotImplementedError()
    assert record[key].metadata is not None, (
        "Blob {} doesn't have metadata".format(str(record[key]())))
    return record[key]


def get_categorical_limit(record):
    key = get_key(record)
    return key.metadata.categorical_limit


def get_avg_length(record):
    return record['lengths'].metadata.expected_value


def set_request_only(field):
    for f in field.all_scalars():
        categorical_limit, expected_value = None, None
        if not f.metadata:
            feature_specs = schema.FeatureSpec(
                feature_is_request_only=True,
            )
        elif not f.metadata.feature_specs:
            categorical_limit = f.metadata.categorical_limit
            expected_value = f.metadata.expected_value
            feature_specs = schema.FeatureSpec(
                feature_is_request_only=True,
            )
        else:
            categorical_limit = f.metadata.categorical_limit
            expected_value = f.metadata.expected_value
            feature_specs = schema.FeatureSpec(
                feature_type=f.metadata.feature_specs.feature_type,
                feature_names=f.metadata.feature_specs.feature_names,
                feature_ids=f.metadata.feature_specs.feature_ids,
                feature_is_request_only=True,
                desired_hash_size=f.metadata.feature_specs.desired_hash_size,
            )

        # make sure not to set categorical_limit for a non-integer field
        if not np.issubdtype(f.field_type(), np.integer):
            assert categorical_limit is None, \
                "categorical_limit shouldn't be set for no-integer field"

        f.set_metadata(
            schema.Metadata(
                categorical_limit=categorical_limit,
                expected_value=expected_value,
                feature_specs=feature_specs,
            )
        )


class InstantiationContext(object):
    """
    List of contexts where layer could be instantitated
    """
    # The layers support this context will accumulate predictions, labels,
    # weights. The accumulated data can later be used to compute
    # calibration or for other
    # purpose.
    ACCUMULATE_PRED = 'accumulate_pred'
    EVAL = 'eval'
    PREDICTION = 'prediction'
    TRAINING = 'training'


_LAYER_REGISTRY = {}


def register_layer(name, layer):
    assert name not in _LAYER_REGISTRY, "{0} already exists".format(name)
    _LAYER_REGISTRY[name] = layer


def layer_exists(name):
    return name in _LAYER_REGISTRY


def get_layer_class(name):
    return _LAYER_REGISTRY[name]


def create_layer(layer_name, *args, **kwargs):
    return _LAYER_REGISTRY[layer_name](*args, **kwargs)


LayerPsParam = namedtuple('LayerPsParam', ['sparse_key', 'average_length'])


class LayerParameter(object):

    def __init__(self, parameter=None, optimizer=None, initializer=None,
                 ps_param=None):
        assert isinstance(parameter, core.BlobReference), \
            "expect {0} to be a blob reference".format(str(parameter))
        # need to put the following line (shape) before initialier
        # shape will be updated once initializer is (re)set
        self._shape = None
        self.parameter = parameter
        self.optimizer = optimizer
        self.initializer = initializer
        self.ps_param = ps_param

    @property
    def initializer(self):
        return self._initializer

    @initializer.setter
    def initializer(self, op):
        assert op is None or core.IsOperator(getattr(op, 'type', None)), \
            "initializer expects an operator, got type: {}".format(type(op))
        self._initializer = op
        if op is not None:
            shape = self._infer_shape_from_initializer()
            assert self.shape is None or self.shape == shape, \
                "inconsistent shape for layer parameter:"\
                " {}, expect: {}, but got {}".format(self, self.shape, shape)
            self._shape = shape

    @property
    def shape(self):
        return self._shape

    def _infer_shape_from_initializer(self):
        for arg in self.initializer.arg:
            if arg.name == 'shape':
                return list(arg.ints)
        with workspace.WorkspaceGuard("model_init_by_loading_params"):
            try:
                net = core.Net("shape_checker")
                net._net.op.extend([self.initializer])
                shape_blob = net.NextScopedBlob(self.parameter + "_shape")
                net.Shape([self.parameter], shape_blob)
                workspace.RunNetOnce(net)
                return workspace.FetchBlob(shape_blob).tolist()
            except RuntimeError:
                logger.warning(
                    "Cannot infer the shape of blob {} from operator {}".format(
                        self.parameter, self.initializer.type)
                )
                workspace.ResetWorkspace()
                return None

    def __str__(self):
        return str(self.parameter)


def is_request_only_scalar(scalar):
    if len(scalar.field_metadata()) == 0:
        return False
    for metadata in scalar.field_metadata():
        if not (metadata and metadata.feature_specs and getattr(
                metadata.feature_specs, 'feature_is_request_only', False)):
            return False
    return True


class ModelLayer(object):

    def __init__(self, model, prefix, input_record,
                 predict_input_record_fields=None, tags=None, **kwargs):
        """
        Base class for model layers. Layer is an abstraction that allows to
        provide model description in terms of meta-operators, where each of the
        meta-operators can have different implementations for training,
        evaluation and prediction, that are instantiated later. As an example
        SampledSoftmax can do something related to sampling depending on
        supervision during the training and just apply softmax if it's used for
        prediction/evaluation.

        All inputs/outputs from layers are represented as a record (instance of
        schema bounded to blobs) and are accessible through input_record and
        output_schema. If Layer needs to have only a subset of inputs/provides
        subset of outputs during the inference - it should provide
        predict_input_record and predict_output_schema correspondingly (those
        records are expected to be a subset of input_record/output_schema).

        Each layer has a list of Tags associated with it, that depends on
        current context and arguments. It's possible to use those tags during
        the instantiation time.

        """
        self.name = model.next_layer_name(prefix)
        self.model = model
        self.kwargs = kwargs
        self._input_record = input_record
        if predict_input_record_fields:
            if not isinstance(predict_input_record_fields, list):
                predict_input_record_fields = [predict_input_record_fields]
            self._predict_input_record = self._input_record[
                predict_input_record_fields]
        else:
            self._predict_input_record = None

        self.request_only = True
        if len(input_record.all_scalars()) == 0:
            self.request_only = False
        for scalar in input_record.all_scalars():
            if not is_request_only_scalar(scalar):
                self.request_only = False
                break

        self._output_schema = None
        self._predict_output_schema = None
        self.eval_output_schema = None
        self.tags = set(tags or [])
        self.tags.update(TagContext.current().tags)
        self.params = []

    def get_type(self):
        return self.__class__.__name__

    def _check_output_schema(self):
        assert self._output_schema is not None, "Schema is not initialized"
        assert (self._predict_output_schema is None or
                schema.is_schema_subset(self._predict_output_schema,
                                        self._output_schema)), (
            "predict_output_schema is not a subset of the output_schema")

    @property
    def predict_input_record(self):
        return self._predict_input_record or self._input_record

    @property
    def input_record(self):
        return self._input_record

    @property
    def predict_output_schema(self):
        self._check_output_schema()
        return self._predict_output_schema or self._output_schema

    @predict_output_schema.setter
    def predict_output_schema(self, output_schema):
        assert self._predict_output_schema is None
        self._predict_output_schema = output_schema

    @property
    def output_schema(self):
        if self.request_only:
            set_request_only(self._output_schema)
        self._check_output_schema()
        return self._output_schema

    @output_schema.setter
    def output_schema(self, output_schema):
        assert self._output_schema is None
        self._output_schema = output_schema

    def get_parameters(self):
        return self.params

    def get_fp16_compatible_parameters(self):
        """Return a subset of parameters which can be converted to fp16"""
        return []

    def get_memory_usage(self):
        return 0

    def add_init_params(self, init_net):
        '''
        Adds layer initialization operators to passed net.
        '''
        for param in self.params:
            # TODO(amalevich): Either return back to lambdas, that add
            # all params (looks a bit safer and breaking less
            # abstractions) or extend Net interface to this type of
            # operations better
            # TODO(xlwang) init_net._net.op has type google.protobuf.\
            # internal.containers.RepeatedCompositeFieldContainer, but
            # the version of protobuf in fbcode does not support append
            # so extend is used
            init_op = param.initializer
            current_device_scope = scope.CurrentDeviceScope()
            if init_op:
                if not init_op.HasField('device_option') and\
                        current_device_scope:
                    init_op = caffe2_pb2.OperatorDef()
                    init_op.CopyFrom(param.initializer)
                    init_op.device_option.CopyFrom(current_device_scope)
                init_net._net.op.extend([init_op])

    def create_param(self, param_name, shape, initializer, optimizer,
                     ps_param=None):
        with scope.NameScope(self.name, reset=True):
            param = self.model.create_param(param_name=param_name,
                                            shape=shape,
                                            initializer=initializer,
                                            optimizer=optimizer,
                                            ps_param=ps_param)

            # make sure we don't share parameters in the same layer
            assert all(param.parameter != p.parameter for p in self.params)

            self.params.append(param)
            return param.parameter

    def get_next_blob_reference(self, name):
        with scope.NameScope(self.name, reset=True):
            return self.model.net.NextScopedBlob(name)

    def add_operators(self, net, init_net=None,
                      context=InstantiationContext.TRAINING):
        '''
        Adds layer trainig or initialization operators to the passed in net.
        init_net can be None and can be called independently from add_init_params
        '''
        # Namescope below should warranty that all intermediate blobs will be
        # assiciated with the layer that produces them
        with scope.NameScope(self.name):
            if context not in {InstantiationContext.PREDICTION,
                               InstantiationContext.EVAL,
                               InstantiationContext.ACCUMULATE_PRED}:
                assert init_net, (
                    "Only prediction and eval context don't need init_net")
            if init_net:
                self.add_init_params(init_net)
            if context == InstantiationContext.TRAINING:
                self.add_train_ops(net)
            elif context == InstantiationContext.EVAL:
                self.add_eval_ops(net)
            elif context == InstantiationContext.ACCUMULATE_PRED:
                self.add_ops_to_accumulate_pred(net)
            else:
                self.add_ops(net)

    def add_ops(self, net):
        # Predict layer implementation.
        raise NotImplementedError

    def add_eval_ops(self, net):
        # Default eval layer implementation is completely matching
        # predict layer implementation.
        self.add_ops(net)

    def add_train_ops(self, net):
        # Default train layer implementation is completely matching
        # eval layer implementation.
        self.add_eval_ops(net)

    def add_ops_to_accumulate_pred(self, net):
        # This adds operators to accumulate predictions/labels/weights. The
        # accumulated data can later be used to compute calibration or for other
        # purpose. Default layer implementation is completely matching eval
        # layer implementation.
        self.add_eval_ops(net)