import numpy as np
import warnings
from shap.explainers.explainer import Explainer
from .misc import standard_combine_mult_and_diffref
from distutils.version import LooseVersion
import sys
keras = None
tf = None
tf_ops = None
tf_gradients_impl = None


class TFDeepExplainer(Explainer):
    """
    Using tf.gradients to implement the backgropagation was
    inspired by the gradient based implementation approach proposed by Ancona et al, ICLR 2018. Note
    that this package does not currently use the reveal-cancel rule for ReLu units proposed in DeepLIFT.
    """

    def __init__(self, model, data, session=None, learning_phase_flags=None,
                       combine_mult_and_diffref=
                        standard_combine_mult_and_diffref):
        """ An explainer object for a deep model using a given background dataset.

        Note that the complexity of the method scales linearly with the number of background data
        samples. Passing the entire training dataset as `data` will give very accurate expected
        values, but be unreasonably expensive. The variance of the expectation estimates scale by
        roughly 1/sqrt(N) for N background data samples. So 100 samples will give a good estimate,
        and 1000 samples a very good estimate of the expected values.

        Parameters
        ----------
        model : keras.Model or (input : [tf.Operation], output : tf.Operation)
            A keras model object or a pair of TensorFlow operations (or a list and an op) that
            specifies the input and output of the model to be explained. Note that SHAP values
            are specific to a single output value, so you get an explanation for each element of
            the output tensor (which must be a flat rank one vector).

        data : [numpy.array] or [pandas.DataFrame] or function
            The background dataset to use for integrating out features. DeepExplainer integrates
            over all these samples for each explanation. The data passed here must match the input
            operations given to the model. If a function is supplied, it must be a function that
            takes a particular input example and generates the background dataset for that example
        session : None or tensorflow.Session
            The TensorFlow session that has the model we are explaining. If None is passed then
            we do our best to find the right session, first looking for a keras session, then
            falling back to the default TensorFlow session.

        learning_phase_flags : None or list of tensors
            If you have your own custom learning phase flags pass them here. When explaining a prediction
            we need to ensure we are not in training mode, since this changes the behavior of ops like
            batch norm or dropout. If None is passed then we look for tensors in the graph that look like
            learning phase flags (this works for Keras models). Note that we assume all the flags should
            have a value of False during predictions (and hence explanations).

        combine_mult_and_diffref : function
            This function determines how to combine the multipliers,
             the original input and the reference input to get
             the final attributions. Defaults to
             standard_combine_mult_and_diffref, which just multiplies
             the multipliers with the difference-from-reference (in
             accordance with the standard DeepLIFT formulation) and then
             averages the importance scores across the different references.
             However, different approaches may be applied depending on
             the use case (e.g. for computing hypothetical contributions
             in genomic data)
        """

        self.combine_mult_and_diffref = combine_mult_and_diffref

        # warnings.warn(
        #     "Please keep in mind DeepExplainer is brand new, and we are still developing it and working on " +
        #     "characterizing/testing it on large networks. This means you should keep an eye out for odd " +
        #     "behavior. Post any issues you run into on github."
        # )

        # try and import keras and tensorflow
        global tf, tf_ops, tf_gradients_impl
        if tf is None:
            from tensorflow.python.framework import ops as tf_ops # pylint: disable=E0611
            from tensorflow.python.ops import gradients_impl as tf_gradients_impl # pylint: disable=E0611
            if not hasattr(tf_gradients_impl, "_IsBackpropagatable"):
                from tensorflow.python.ops import gradients_util as tf_gradients_impl
            import tensorflow as tf
            if LooseVersion(tf.__version__) < LooseVersion("1.4.0"):
                warnings.warn("Your TensorFlow version is older than 1.4.0 and not supported.")
        global keras
        if keras is None:
            try:
                import keras
                if LooseVersion(keras.__version__) < LooseVersion("2.1.0"):
                    warnings.warn("Your Keras version is older than 2.1.0 and not supported.")
            except:
                pass

        # determine the model inputs and outputs
        if str(type(model)).endswith("keras.engine.sequential.Sequential'>"):
            self.model_inputs = model.inputs
            self.model_output = model.layers[-1].output
        elif str(type(model)).endswith("keras.models.Sequential'>"):
            self.model_inputs = model.inputs
            self.model_output = model.layers[-1].output
        elif str(type(model)).endswith("keras.engine.training.Model'>"):
            self.model_inputs = model.inputs
            self.model_output = model.layers[-1].output
        elif str(type(model)).endswith("tuple'>"):
            self.model_inputs = model[0]
            self.model_output = model[1]
        else:
            assert False, str(type(model)) + " is not currently a supported model type!"
        assert type(self.model_output) != list, "The model output to be explained must be a single tensor!"
        assert len(self.model_output.shape) < 3, "The model output must be a vector or a single value!"
        self.multi_output = True
        if len(self.model_output.shape) == 1:
            self.multi_output = False

        # check if we have multiple inputs
        self.multi_input = True
        if type(self.model_inputs) != list or len(self.model_inputs) == 1:
            self.multi_input = False
            if type(self.model_inputs) != list:
                self.model_inputs = [self.model_inputs]
        if type(data) != list and (hasattr(data, '__call__')==False):
            data = [data]
        self.data = data
        
        self._vinputs = {} # used to track what op inputs depends on the model inputs
        self.orig_grads = {}
        
        # if we are not given a session find a default session
        if session is None:
            try:
                if keras is not None and hasattr(keras.backend.tensorflow_backend, "_SESSION") and keras.backend.tensorflow_backend._SESSION is not None:
                    self.session = keras.backend.get_session()
                else:
                    #tf1
                    self.session=tf.keras.backend.get_session()
            except:
                #tf2
                self.session = tf.compat.v1.keras.backend.get_session()
        else:
            self.session= session
        # if no learning phase flags were given we go looking for them
        # ...this will catch the one that keras uses
        # we need to find them since we want to make sure learning phase flags are set to False
        if learning_phase_flags is None:
            self.learning_phase_ops = []
            for op in self.session.graph.get_operations():
                if 'learning_phase' in op.name and op.type == "Const" and len(op.outputs[0].shape) == 0:
                    if op.outputs[0].dtype == tf.bool:
                        self.learning_phase_ops.append(op)
            self.learning_phase_flags = [op.outputs[0] for op in self.learning_phase_ops]
        else:
            self.learning_phase_ops = [t.op for t in learning_phase_flags]

        # save the expected output of the model
        # if self.data is a function, set self.expected_value to None
        if (hasattr(self.data, '__call__')):
            self.expected_value = None
        else:
            if self.data[0].shape[0] > 5000:
                warnings.warn("You have provided over 5k background samples! For better performance consider using smaller random sample.")
            self.expected_value = self.run(self.model_output, self.model_inputs, self.data).mean(0)

        # find all the operations in the graph between our inputs and outputs
        tensor_blacklist = tensors_blocked_by_false(self.learning_phase_ops) # don't follow learning phase branches
        dependence_breakers = [k for k in op_handlers if op_handlers[k] == break_dependence]
        back_ops = backward_walk_ops(
            [self.model_output.op], tensor_blacklist,
            dependence_breakers
        )
        self.between_ops = forward_walk_ops(
            [op for input in self.model_inputs for op in input.consumers()],
            tensor_blacklist, dependence_breakers,
            within_ops=back_ops
        )

        # save what types are being used
        self.used_types = {}
        for op in self.between_ops:
            self.used_types[op.type] = True
            if (op.type not in op_handlers):
                print("Warning: ",op.type,"used in model but handling of op"
                      +" is not specified by shap; will use original "
                      +" gradients")

        # make a blank array that will get lazily filled in with the SHAP value computation
        # graphs for each output. Lazy is important since if there are 1000 outputs and we
        # only explain the top 5 it would be a waste to build graphs for the other 995
        if not self.multi_output:
            self.phi_symbolics = [None]
        else:
            noutputs = self.model_output.shape.as_list()[1]
            if noutputs is not None:
                self.phi_symbolics = [None for i in range(noutputs)]
            else:
                raise Exception("The model output tensor to be explained cannot have a static shape in dim 1 of None!")
    def _variable_inputs(self, op):
        """ Return which inputs of this operation are variable (i.e. depend on the model inputs).
        """
        if op.name not in self._vinputs:
            self._vinputs[op.name] = np.array([t.op in self.between_ops or t.name in [x.name for x in self.model_inputs] for t in op.inputs])
        return self._vinputs[op.name]

    def phi_symbolic(self, i):
        """ Get the SHAP value computation graph for a given model output.
        """
        if self.phi_symbolics[i] is None:

            # replace the gradients for all the non-linear activations
            # we do this by hacking our way into the registry (TODO: find a public API for this if it exists)
            reg = tf_ops._gradient_registry._registry
            for n in op_handlers:
                if n in reg:
                    self.orig_grads[n] = reg[n]["type"]
                    if op_handlers[n] is not passthrough:
                        reg[n]["type"] = self.custom_grad
                elif n in self.used_types:
                    raise Exception(n + " was used in the model but is not in the gradient registry!")
            # In TensorFlow 1.10 they started pruning out nodes that they think can't be backpropped
            # unfortunately that includes the index of embedding layers so we disable that check here
            if hasattr(tf_gradients_impl, "_IsBackpropagatable"):
                orig_IsBackpropagatable = tf_gradients_impl._IsBackpropagatable
                tf_gradients_impl._IsBackpropagatable = lambda tensor: True
            
            # define the computation graph for the attribution values using custom a gradient-like computation
            try:
                out = self.model_output[:,i] if self.multi_output else self.model_output
                self.phi_symbolics[i] = tf.gradients(out, self.model_inputs)

            finally:

                # reinstate the backpropagatable check
                if hasattr(tf_gradients_impl, "_IsBackpropagatable"):
                    tf_gradients_impl._IsBackpropagatable = orig_IsBackpropagatable

                # restore the original gradient definitions
                for n in op_handlers:
                    if n in reg:
                        reg[n]["type"] = self.orig_grads[n]
        return self.phi_symbolics[i]

    def shap_values(self, X, ranked_outputs=None, output_rank_order="max",
                             progress_message=None):

        # check if we have multiple inputs
        if not self.multi_input:
            if type(X) == list and len(X) != 1:
                assert False, "Expected a single tensor as model input!"
            elif type(X) != list:
                X = [X]
        else:
            assert type(X) == list, "Expected a list of model inputs!"
        assert len(self.model_inputs) == len(X), "Number of model inputs (%d) does not match the number given (%d)!" % (len(self.model_inputs), len(X))

        # rank and determine the model outputs that we will explain
        if ranked_outputs is not None and self.multi_output:
            model_output_values = self.run(self.model_output, self.model_inputs, X)
            if output_rank_order == "max":
                model_output_ranks = np.argsort(-model_output_values)
            elif output_rank_order == "min":
                model_output_ranks = np.argsort(model_output_values)
            elif output_rank_order == "max_abs":
                model_output_ranks = np.argsort(np.abs(model_output_values))
            else:
                assert False, "output_rank_order must be max, min, or max_abs!"
            model_output_ranks = model_output_ranks[:,:ranked_outputs]
        else:
            model_output_ranks = np.tile(np.arange(len(self.phi_symbolics)), (X[0].shape[0], 1))

        # compute the attributions
        output_phis = []
        for i in range(model_output_ranks.shape[1]):
            phis = []
            for k in range(len(X)):
                phis.append(np.zeros(X[k].shape))
            for j in range(X[0].shape[0]):
                if (progress_message is not None):
                    if ((j%progress_message)==0):
                        print("Done",j,"examples of",
                              X[0].shape[0])
                        sys.stdout.flush()
                if (hasattr(self.data, '__call__')):
                    bg_data = self.data([X[l][j] for l in range(len(X))])
                    if type(bg_data) != list:
                        bg_data = [bg_data]
                else:
                    bg_data = self.data
                # tile the inputs to line up with the reference data samples
                tiled_X = [np.tile(X[l][j:j+1], (bg_data[l].shape[0],) + tuple([1 for k in range(len(X[l].shape)-1)])) for l in range(len(X))]
                joint_input = [np.concatenate([tiled_X[l], bg_data[l]], 0) for l in range(len(X))]
                # run attribution computation graph
                feature_ind = model_output_ranks[j,i]
                sample_phis = self.run(self.phi_symbolic(feature_ind), self.model_inputs, joint_input)

                #combine the multipliers with the difference from reference
                # to get the final attributions
                phis_j = self.combine_mult_and_diffref(
                    mult=[sample_phis[l][:-bg_data[l].shape[0]]
                          for l in range(len(X))],
                    orig_inp=[X[l][j] for l in range(len(X))],
                    bg_data=bg_data)

                # assign the attributions to the right part of the output arrays
                for l in range(len(X)):
                    phis[l][j] = phis_j[l] 

            output_phis.append(phis[0] if not self.multi_input else phis)
        if not self.multi_output:
            return output_phis[0]
        elif ranked_outputs is not None:
            return output_phis, model_output_ranks
        else:
            return output_phis

    def run(self, out, model_inputs, X):
        """ Runs the model while also setting the learning phase flags to False.
        """
        feed_dict = dict(zip(model_inputs, X))
        for t in self.learning_phase_flags:
            feed_dict[t] = False
        return self.session.run(out, feed_dict)

    def custom_grad(self, op, *grads):
        """ Passes a gradient op creation request to the correct handler.
        """
        return op_handlers[op.type](self, op, *grads)


def tensors_blocked_by_false(ops):
    """ Follows a set of ops assuming their value is False and find blocked Switch paths.

    This is used to prune away parts of the model graph that are only used during the training
    phase (like dropout, batch norm, etc.).
    """
    blocked = []
    def recurse(op):
        if op.type == "Switch":
            blocked.append(op.outputs[1]) # the true path is blocked since we assume the ops we trace are False
        else:
            for out in op.outputs:
                for c in out.consumers():
                    recurse(c)
    for op in ops:
        recurse(op)

    return blocked

def backward_walk_ops(start_ops, tensor_blacklist, op_type_blacklist):
    found_ops = []
    op_stack = [op for op in start_ops]
    while len(op_stack) > 0:
        op = op_stack.pop()
        if op.type not in op_type_blacklist and op not in found_ops:
            found_ops.append(op)
            for input in op.inputs:
                if input not in tensor_blacklist:
                    op_stack.append(input.op)
    return found_ops

def forward_walk_ops(start_ops, tensor_blacklist, op_type_blacklist, within_ops):
    found_ops = []
    op_stack = [op for op in start_ops]
    while len(op_stack) > 0:
        op = op_stack.pop()
        if op.type not in op_type_blacklist and op in within_ops and op not in found_ops:
            found_ops.append(op)
            for out in op.outputs:
                if out not in tensor_blacklist:
                    for c in out.consumers():
                        op_stack.append(c)
    return found_ops


def softmax(explainer, op, *grads):
    """ Just decompose softmax into its components and recurse, we can handle all of them :)

    We assume the 'axis' is the last dimension because the TF codebase swaps the 'axis' to
    the last dimension before the softmax op if 'axis' is not already the last dimension.
    We also don't subtract the max before tf.exp for numerical stability since that might
    mess up the attributions and it seems like TensorFlow doesn't define softmax that way
    (according to the docs)
    """
    in0 = op.inputs[0]
    in0_max = tf.reduce_max(in0, axis=-1, keepdims=True, name="in0_max")
    in0_centered = in0 - in0_max
    evals = tf.exp(in0_centered, name="custom_exp")
    rsum = tf.reduce_sum(evals, axis=-1, keepdims=True)
    div = evals / rsum
    explainer.between_ops.extend([evals.op, rsum.op, div.op, in0_centered.op]) # mark these as in-between the inputs and outputs
    out = tf.gradients(div, in0_centered, grad_ys=grads[0])[0]
    del explainer.between_ops[-4:]

    # rescale to account for our shift by in0_max (which we did for numerical stability)
    xin0,rin0 = tf.split(in0, 2)
    xin0_centered,rin0_centered = tf.split(in0_centered, 2)
    delta_in0 = xin0 - rin0
    dup0 = [2] + [1 for i in delta_in0.shape[1:]]
    return tf.where(
        tf.tile(tf.abs(delta_in0), dup0) < 1e-6,
        out,
        out * tf.tile((xin0_centered - rin0_centered) / delta_in0, dup0)
    )

def maxpool(explainer, op, *grads):
    xin0,rin0 = tf.split(op.inputs[0], 2)
    xout,rout = tf.split(op.outputs[0], 2)
    delta_in0 = xin0 - rin0
    dup0 = [2] + [1 for i in delta_in0.shape[1:]]
    cross_max = tf.maximum(xout, rout)
    diffs = tf.concat([cross_max - rout, xout - cross_max], 0)
    xmax_pos,rmax_pos = tf.split(explainer.orig_grads[op.type](op, grads[0] * diffs), 2)
    return tf.tile(tf.where(
        tf.abs(delta_in0) < 1e-7,
        tf.zeros_like(delta_in0),
        (xmax_pos + rmax_pos) / delta_in0
    ), dup0)

def gather(explainer, op, *grads):
    #params = op.inputs[0]
    indices = op.inputs[1]
    #axis = op.inputs[2]
    var = explainer._variable_inputs(op)
    if var[1] and not var[0]:
        assert len(indices.shape) == 2, "Only scalar indices supported right now in GatherV2!"

        xin1,rin1 = tf.split(tf.to_float(op.inputs[1]), 2)
        xout,rout = tf.split(op.outputs[0], 2)
        dup_in1 = [2] + [1 for i in xin1.shape[1:]]
        dup_out = [2] + [1 for i in xout.shape[1:]]
        delta_in1_t = tf.tile(xin1 - rin1, dup_in1)
        out_sum = tf.reduce_sum(grads[0] * tf.tile(xout - rout, dup_out), list(range(len(indices.shape), len(grads[0].shape))))
        if op.type == "ResourceGather":
            return [None, tf.where(
                tf.abs(delta_in1_t) < 1e-6,
                tf.zeros_like(delta_in1_t),
                out_sum / delta_in1_t
            )]
        return [None, tf.where(
            tf.abs(delta_in1_t) < 1e-6,
            tf.zeros_like(delta_in1_t),
            out_sum / delta_in1_t
        ), None]
    elif var[0] and not var[1]:
        return [explainer.orig_grads[op.type](op, grads[0]), None] # linear in this case
    else:
        assert False, "Axis not yet supported to be varying for gather op!"

def linearity_1d_nonlinearity_2d(input_ind0, input_ind1, op_func):
    def handler(explainer, op, *grads):
        var = explainer._variable_inputs(op)
        if var[input_ind0] and not var[input_ind1]:
            return linearity_1d_handler(input_ind0, explainer, op, *grads)
        elif var[input_ind1] and not var[input_ind0]:
            return linearity_1d_handler(input_ind1, explainer, op, *grads)
        elif var[input_ind0] and var[input_ind1]:
            return nonlinearity_2d_handler(input_ind0, input_ind1, op_func, explainer, op, *grads)
        else:
            return [None for _ in op.inputs] # no inputs vary, we must be hidden by a switch function
    return handler

def nonlinearity_1d_nonlinearity_2d(input_ind0, input_ind1, op_func):
    def handler(explainer, op, *grads):
        var = explainer._variable_inputs(op)
        if var[input_ind0] and not var[input_ind1]:
            return nonlinearity_1d_handler(input_ind0, explainer, op, *grads)
        elif var[input_ind1] and not var[input_ind0]:
            return nonlinearity_1d_handler(input_ind1, explainer, op, *grads)
        elif var[input_ind0] and var[input_ind1]:
            return nonlinearity_2d_handler(input_ind0, input_ind1, op_func, explainer, op, *grads)
        else: 
            return [None for _ in op.inputs] # no inputs vary, we must be hidden by a switch function
    return handler

def nonlinearity_1d(input_ind):
    def handler(explainer, op, *grads):
        return nonlinearity_1d_handler(input_ind, explainer, op, *grads)
    return handler

def nonlinearity_1d_handler(input_ind, explainer, op, *grads):

    # make sure only the given input varies
    for i in range(len(op.inputs)):
        if i != input_ind:
            assert not explainer._variable_inputs(op)[i], str(i) + "th input to " + op.name + " cannot vary!"
    
    xin0,rin0 = tf.split(op.inputs[input_ind], 2)
    xout,rout = tf.split(op.outputs[input_ind], 2)
    delta_in0 = xin0 - rin0
    dup0 = [2] + [1 for i in delta_in0.shape[1:]]
    out = [None for _ in op.inputs]
    orig_grads = explainer.orig_grads[op.type](op, grads[0])
    out[input_ind] = tf.where(
        tf.tile(tf.abs(delta_in0), dup0) < 1e-6,
        orig_grads[input_ind] if len(op.inputs) > 1 else orig_grads,
        grads[0] * tf.tile((xout - rout) / delta_in0, dup0)
    )
    return out

def nonlinearity_2d_handler(input_ind0, input_ind1, op_func, explainer, op, *grads):
    assert input_ind0 == 0 and input_ind1 == 1, "TODO: Can't yet handle double inputs that are not first!"
    xout,rout = tf.split(op.outputs[0], 2)
    xin0,rin0 = tf.split(op.inputs[input_ind0], 2)
    xin1,rin1 = tf.split(op.inputs[input_ind1], 2)
    delta_in0 = xin0 - rin0
    delta_in1 = xin1 - rin1
    dup0 = [2] + [1 for i in delta_in0.shape[1:]]
    out10 = op_func(xin0, rin1)
    out01 = op_func(rin0, xin1)
    out11,out00 = xout,rout
    out0 = 0.5 * (out11 - out01 + out10 - out00)
    out0 = grads[0] * tf.tile(out0 / delta_in0, dup0)
    out1 = 0.5 * (out11 - out10 + out01 - out00)
    out1 = grads[0] * tf.tile(out1 / delta_in1, dup0)

    # see if due to broadcasting our gradient shapes don't match our input shapes
    if (np.any(np.array(out1.shape) != np.array(delta_in1.shape))):
        broadcast_index = np.where(np.array(out1.shape) != np.array(delta_in1.shape))[0][0]
        out1 = tf.reduce_sum(out1, axis=broadcast_index, keepdims=True)
    elif (np.any(np.array(out0.shape) != np.array(delta_in0.shape))):
        broadcast_index = np.where(np.array(out0.shape) != np.array(delta_in0.shape))[0][0]
        out0 = tf.reduce_sum(out0, axis=broadcast_index, keepdims=True)

    # Avoid divide by zero nans
    out0 = tf.where(tf.abs(tf.tile(delta_in0, dup0)) < 1e-7, tf.zeros_like(out0), out0)
    out1 = tf.where(tf.abs(tf.tile(delta_in1, dup0)) < 1e-7, tf.zeros_like(out1), out1)

    return [out0, out1]

def linearity_1d(input_ind):
    def handler(explainer, op, *grads):
        return linearity_1d_handler(input_ind, explainer, op, *grads)
    return handler

def linearity_1d_handler(input_ind, explainer, op, *grads):
    # make sure only the given input varies (negative means only that input cannot vary, and is measured from the end of the list)
    for i in range(len(op.inputs)):
        if i != input_ind:
            assert not explainer._variable_inputs(op)[i], str(i) + "th input to " + op.name + " cannot vary!"
    return explainer.orig_grads[op.type](op, *grads)

def linearity_with_excluded(input_inds):
    def handler(explainer, op, *grads):
        return linearity_with_excluded_handler(input_inds, explainer, op, *grads)
    return handler

def linearity_with_excluded_handler(input_inds, explainer, op, *grads):
    # make sure the given inputs don't vary (negative is measured from the end of the list)
    for i in range(len(op.inputs)):
        if i in input_inds or i - len(op.inputs) in input_inds:
            assert not explainer._variable_inputs(op)[i], str(i) + "th input to " + op.name + " cannot vary!"
    return explainer.orig_grads[op.type](op, *grads)

def passthrough(explainer, op, *grads):
    return explainer.orig_grads[op.type](op, *grads)

def break_dependence(explainer, op, *grads):
    """ This function name is used to break attribution dependence in the graph traversal.
     
    These operation types may be connected above input data values in the graph but their outputs
    don't depend on the input values (for example they just depend on the shape).
    """
    return [None for _ in op.inputs]


op_handlers = {}

# ops that are always linear
op_handlers["Identity"] = passthrough
op_handlers["StridedSlice"] = passthrough
op_handlers["Squeeze"] = passthrough
op_handlers["ExpandDims"] = passthrough
op_handlers["Pack"] = passthrough
op_handlers["BiasAdd"] = passthrough
op_handlers["Unpack"] = passthrough
op_handlers["Add"] = passthrough
op_handlers["Sub"] = passthrough
op_handlers["Merge"] = passthrough
op_handlers["Sum"] = passthrough
op_handlers["Mean"] = passthrough
op_handlers["Cast"] = passthrough
op_handlers["Transpose"] = passthrough
op_handlers["Enter"] = passthrough
op_handlers["Exit"] = passthrough
op_handlers["NextIteration"] = passthrough
op_handlers["Tile"] = passthrough
op_handlers["TensorArrayScatterV3"] = passthrough
op_handlers["TensorArrayReadV3"] = passthrough
op_handlers["TensorArrayWriteV3"] = passthrough

# ops that don't pass any attributions to their inputs
op_handlers["Shape"] = break_dependence
op_handlers["RandomUniform"] = break_dependence
op_handlers["ZerosLike"] = break_dependence
#op_handlers["StopGradient"] = break_dependence # this allows us to stop attributions when we want to (like softmax re-centering)

# ops that are linear and only allow a single input to vary
op_handlers["Reshape"] = linearity_1d(0)
op_handlers["Pad"] = linearity_1d(0)
op_handlers["ReverseV2"] = linearity_1d(0)
op_handlers["ConcatV2"] = linearity_with_excluded([-1])
op_handlers["Conv2D"] = linearity_1d(0)
op_handlers["Switch"] = linearity_1d(0)
op_handlers["AvgPool"] = linearity_1d(0)
op_handlers["FusedBatchNorm"] = linearity_1d(0)

# ops that are nonlinear and only allow a single input to vary
op_handlers["Relu"] = nonlinearity_1d(0)
op_handlers["Elu"] = nonlinearity_1d(0)
op_handlers["Sigmoid"] = nonlinearity_1d(0)
op_handlers["Tanh"] = nonlinearity_1d(0)
op_handlers["Softplus"] = nonlinearity_1d(0)
op_handlers["Exp"] = nonlinearity_1d(0)
op_handlers["Log"] = nonlinearity_1d(0)
op_handlers["ClipByValue"] = nonlinearity_1d(0)
op_handlers["Rsqrt"] = nonlinearity_1d(0)
op_handlers["Square"] = nonlinearity_1d(0)
op_handlers["Max"] = nonlinearity_1d(0)

# ops that are nonlinear and allow two inputs to vary
op_handlers["SquaredDifference"] = nonlinearity_1d_nonlinearity_2d(0, 1, lambda x, y: (x - y) * (x - y))
op_handlers["Minimum"] = nonlinearity_1d_nonlinearity_2d(0, 1, lambda x, y: tf.minimum(x, y))
op_handlers["Maximum"] = nonlinearity_1d_nonlinearity_2d(0, 1, lambda x, y: tf.maximum(x, y))

# ops that allow up to two inputs to vary are are linear when only one input varies
op_handlers["Mul"] = linearity_1d_nonlinearity_2d(0, 1, lambda x, y: x * y)
op_handlers["RealDiv"] = linearity_1d_nonlinearity_2d(0, 1, lambda x, y: x / y)
op_handlers["MatMul"] = linearity_1d_nonlinearity_2d(0, 1, lambda x, y: tf.matmul(x, y))

# ops that need their own custom attribution functions
op_handlers["GatherV2"] = gather
op_handlers["ResourceGather"] = gather
op_handlers["MaxPool"] = maxpool
op_handlers["Softmax"] = softmax


# TODO items
# TensorArrayGatherV3
# Max
# TensorArraySizeV3
# Range