#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserve.
#
# 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.

import unittest
import numpy as np
import random
import itertools
import paddle.v2.fluid.core as core
import collections
from paddle.v2.fluid.backward import append_backward
from paddle.v2.fluid.op import Operator
from paddle.v2.fluid.executor import Executor
from paddle.v2.fluid.framework import Program, OpProtoHolder


def randomize_probability(batch_size, class_num, dtype='float32'):
    prob = np.random.uniform(
        0.1, 1.0, size=(batch_size, class_num)).astype(dtype)
    prob_sum = prob.sum(axis=1)
    for i in xrange(len(prob)):
        prob[i] /= prob_sum[i]
    return prob


def create_op(scope, op_type, inputs, outputs, attrs):
    kwargs = dict()

    def __create_var__(name, var_name):
        scope.var(var_name).get_tensor()
        kwargs[name].append(var_name)

    for in_name, in_dup in Operator.get_op_inputs(op_type):
        if in_name in inputs:
            kwargs[in_name] = []
            if in_dup:
                sub_in = inputs[in_name]
                for item in sub_in:
                    sub_in_name, _ = item[0], item[1]
                    __create_var__(in_name, sub_in_name)
            else:
                __create_var__(in_name, in_name)

    for out_name, out_dup in Operator.get_op_outputs(op_type):
        if out_name in outputs:
            kwargs[out_name] = []
            if out_dup:
                sub_out = outputs[out_name]
                for item in sub_out:
                    sub_out_name, _ = item[0], item[1]
                    __create_var__(out_name, sub_out_name)
            else:
                __create_var__(out_name, out_name)

    for attr_name in Operator.get_op_attr_names(op_type):
        if attr_name in attrs:
            kwargs[attr_name] = attrs[attr_name]

    return Operator(op_type, **kwargs)


def set_input(scope, op, inputs, place):
    def __set_input__(var_name, var):
        if isinstance(var, tuple) or isinstance(var, np.ndarray):
            tensor = scope.find_var(var_name).get_tensor()
            if isinstance(var, tuple):
                tensor.set_lod(var[1])
                var = var[0]
            tensor.set_dims(var.shape)
            tensor.set(var, place)
        elif isinstance(var, float):
            scope.find_var(var_name).set_float(var)
        elif isinstance(var, int):
            scope.find_var(var_name).set_int(var)

    for in_name, in_dup in Operator.get_op_inputs(op.type()):
        if in_name in inputs:
            if in_dup:
                sub_in = inputs[in_name]
                for item in sub_in:
                    sub_in_name, sub_in_val = item[0], item[1]
                    __set_input__(sub_in_name, sub_in_val)
            else:
                __set_input__(in_name, inputs[in_name])


def get_numeric_gradient(place,
                         scope,
                         op,
                         inputs,
                         input_to_check,
                         output_names,
                         delta=0.005,
                         in_place=False):
    # FIXME: change this method by compile time concepts
    set_input(scope, op, inputs, place)

    def product(dim):
        return reduce(lambda a, b: a * b, dim, 1)

    def get_output():
        sum = []
        for output_name in output_names:
            op.run(scope, place)
            sum.append(
                np.array(scope.find_var(output_name).get_tensor()).mean())
        return np.array(sum).mean()

    tensor_to_check = scope.find_var(input_to_check).get_tensor()
    tensor_size = product(tensor_to_check.get_dims())
    tensor_to_check_dtype = tensor_to_check.dtype()
    if tensor_to_check_dtype == core.DataType.FP32:
        tensor_to_check_dtype = np.float32
    elif tensor_to_check_dtype == core.DataType.FP64:
        tensor_to_check_dtype = np.float64
    else:
        raise ValueError("Not supported data type " + str(
            tensor_to_check_dtype))

    gradient_flat = np.zeros(shape=(tensor_size, ), dtype=tensor_to_check_dtype)

    def __get_elem__(tensor, i):
        if tensor_to_check_dtype == np.float32:
            return tensor.get_float_element(i)
        else:
            return tensor.get_double_element(i)

    def __set_elem__(tensor, i, e):
        if tensor_to_check_dtype == np.float32:
            tensor.set_float_element(i, e)
        else:
            tensor.set_double_element(i, e)

    # we only compute gradient of one element each time.
    # we use a for loop to compute the gradient of every element.
    for i in xrange(tensor_size):
        if in_place:
            set_input(scope, op, inputs, place)

        # get one input element throw it's index i.
        origin = __get_elem__(tensor_to_check, i)
        # add delta to it, run op and then get the sum of the result tensor.
        x_pos = origin + delta
        __set_elem__(tensor_to_check, i, x_pos)
        y_pos = get_output()

        if in_place:
            set_input(scope, op, inputs, place)

        x_neg = origin - delta
        __set_elem__(tensor_to_check, i, x_neg)
        y_neg = get_output()

        __set_elem__(tensor_to_check, i, origin)
        gradient_flat[i] = (y_pos - y_neg) / delta / 2

    return gradient_flat.reshape(tensor_to_check.get_dims())


def append_input_output(block, op_proto, np_list, is_input):
    '''Insert VarDesc and generate Python variable instance'''
    proto_list = op_proto.inputs if is_input else op_proto.outputs

    def create_var(block, name, np_list, var_proto):
        if name not in np_list:
            assert var_proto.intermediate, "{} not found".format(name)
            shape = None
            lod_level = None
        else:
            np_value = np_list[name]
            if isinstance(np_value, tuple):
                shape = list(np_value[0].shape)
                lod_level = len(np_value[1])
            else:
                shape = list(np_value.shape)
                lod_level = 0
        return block.create_var(
            dtype="float32", shape=shape, lod_level=lod_level, name=name)

    var_dict = {}
    for var_proto in proto_list:
        var_name = str(var_proto.name)
        if is_input:
            if (var_name not in np_list) and var_proto.dispensable:
                continue
            assert (var_name in np_list) or (var_proto.dispensable), \
                "Missing {} as input".format(var_name)
        if var_proto.duplicable:
            assert isinstance(np_list[var_name], list), \
                "Duplicable {} should be set as list".format(var_name)
            var_list = []
            for (name, np_value) in np_list[var_name]:
                var_list.append(
                    create_var(block, name, {name: np_value}, var_proto))
            var_dict[var_name] = var_list
        else:
            var_dict[var_name] = create_var(block, var_name, np_list, var_proto)

    return var_dict


class OpTest(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        '''Fix random seeds to remove randomness from tests'''
        cls._np_rand_state = np.random.get_state()
        cls._py_rand_state = random.getstate()

        np.random.seed(123)
        random.seed(124)

    @classmethod
    def tearDownClass(cls):
        '''Restore random seeds'''
        np.random.set_state(cls._np_rand_state)
        random.setstate(cls._py_rand_state)

    def feed_var(self, input_vars, place):
        feed_map = {}
        for var_name in input_vars:
            if isinstance(input_vars[var_name], list):
                for name, np_value in self.inputs[var_name]:
                    tensor = core.LoDTensor()
                    if isinstance(np_value, tuple):
                        tensor.set(np_value[0], place)
                        tensor.set_lod(np_value[1])
                    else:
                        tensor.set(np_value, place)
                    feed_map[name] = tensor
            else:
                tensor = core.LoDTensor()
                if isinstance(self.inputs[var_name], tuple):
                    tensor.set(self.inputs[var_name][0], place)
                    tensor.set_lod(self.inputs[var_name][1])
                else:
                    tensor.set(self.inputs[var_name], place)
                feed_map[var_name] = tensor

        return feed_map

    def check_output_with_place(self, place, atol):
        op_proto = OpProtoHolder.instance().get_op_proto(self.op_type)

        program = Program()
        block = program.global_block()

        inputs = append_input_output(block, op_proto, self.inputs, True)
        outputs = append_input_output(block, op_proto, self.outputs, False)
        op = block.append_op(
            type=self.op_type,
            inputs=inputs,
            outputs=outputs,
            attrs=self.attrs if hasattr(self, "attrs") else dict())
        # infer variable type and infer shape in compile-time
        op.desc.infer_var_type(block.desc)
        op.desc.infer_shape(block.desc)

        fetch_list = []
        for var_name, var in outputs.iteritems():
            if var_name in self.outputs:
                if isinstance(var, list):
                    for v in var:
                        fetch_list.append(v)
                else:
                    fetch_list.append(var)

        feed_map = self.feed_var(inputs, place)

        exe = Executor(place)
        outs = exe.run(program,
                       feed=feed_map,
                       fetch_list=fetch_list,
                       return_numpy=False)

        for out_name, out_dup in Operator.get_op_outputs(self.op_type):
            if out_name not in self.outputs:
                continue

            def find_actual(target_name, fetch_list):
                found = [
                    i for i, var in enumerate(fetch_list)
                    if var.name == target_name
                ]
                self.assertTrue(
                    len(found) == 1, "Found {} {}".format(
                        len(found), target_name))
                return found[0]

            if out_dup:
                sub_out = self.outputs[out_name]
                if not isinstance(sub_out, list):
                    raise AssertionError("sub_out type %s is not list",
                                         type(sub_out))
                for item in sub_out:
                    sub_out_name, expect = item[0], item[1]
                    idx = find_actual(sub_out_name, fetch_list)
                    actual = outs[idx]
                    actual_t = np.array(actual)
                    expect_t = expect[0] \
                        if isinstance(expect, tuple) else expect
                    self.assertTrue(
                        np.allclose(
                            actual_t, expect_t, atol=atol),
                        "Output (" + sub_out_name + ") has diff at " +
                        str(place))
                    if isinstance(expect, tuple):
                        self.assertListEqual(
                            actual.lod(), expect[1], "Output (" + sub_out_name +
                            ") has different lod at " + str(place))
            else:
                idx = find_actual(out_name, fetch_list)
                actual = outs[idx]
                actual_t = np.array(actual)
                expect = self.outputs[out_name]
                expect_t = expect[0] if isinstance(expect, tuple) else expect
                self.assertTrue(
                    np.allclose(
                        actual_t, expect_t, atol=atol),
                    "Output (" + out_name + ") has diff at " + str(place))
                if isinstance(expect, tuple):
                    self.assertListEqual(actual.lod(), expect[1],
                                         "Output (" + out_name +
                                         ") has different lod at " + str(place))

    def check_output(self, atol=1e-5):
        places = [core.CPUPlace()]
        if core.is_compiled_with_cuda() and core.op_support_gpu(self.op_type):
            places.append(core.CUDAPlace(0))
        for place in places:
            self.check_output_with_place(place, atol)

    def __assert_is_close(self, numeric_grads, analytic_grads, names,
                          max_relative_error, msg_prefix):

        for a, b, name in itertools.izip(numeric_grads, analytic_grads, names):
            abs_a = np.abs(a)
            abs_a[abs_a < 1e-3] = 1

            diff_mat = np.abs(a - b) / abs_a
            max_diff = np.max(diff_mat)

            def err_msg():
                offset = np.argmax(diff_mat > max_relative_error)
                return ("%s Variable %s max gradient diff %f over limit %f, "
                        "the first error element is %d, %f, %f") % (
                            msg_prefix, name, max_diff, max_relative_error,
                            offset, a.flatten()[offset], b.flatten()[offset])

            self.assertLessEqual(max_diff, max_relative_error, err_msg())

    def check_grad(self,
                   inputs_to_check,
                   output_names,
                   no_grad_set=None,
                   numeric_grad_delta=0.005,
                   in_place=False,
                   max_relative_error=0.005,
                   user_defined_grads=None):
        places = [core.CPUPlace()]
        if core.is_compiled_with_cuda() and core.op_support_gpu(self.op_type):
            places.append(core.CUDAPlace(0))
        for place in places:
            self.check_grad_with_place(place, inputs_to_check, output_names,
                                       no_grad_set, numeric_grad_delta,
                                       in_place, max_relative_error,
                                       user_defined_grads)

    def check_grad_with_place(self,
                              place,
                              inputs_to_check,
                              output_names,
                              no_grad_set=None,
                              numeric_grad_delta=0.005,
                              in_place=False,
                              max_relative_error=0.005,
                              user_defined_grads=None):
        self.scope = core.Scope()
        op_inputs = self.inputs if hasattr(self, "inputs") else dict()
        op_outputs = self.outputs if hasattr(self, "outputs") else dict()
        op_attrs = self.attrs if hasattr(self, "attrs") else dict()
        self.op = create_op(self.scope, self.op_type, op_inputs, op_outputs,
                            op_attrs)

        if no_grad_set is None:
            no_grad_set = set()

        if not type(output_names) is list:
            output_names = [output_names]

        numeric_grads = user_defined_grads or [
            get_numeric_gradient(
                place,
                self.scope,
                self.op,
                self.inputs,
                input_to_check,
                output_names,
                delta=numeric_grad_delta,
                in_place=in_place) for input_to_check in inputs_to_check
        ]
        analytic_grads = self._get_gradient(inputs_to_check, place,
                                            output_names, no_grad_set)

        self.__assert_is_close(numeric_grads, analytic_grads, inputs_to_check,
                               max_relative_error,
                               "Gradient Check On %s" % str(place))

    @staticmethod
    def _create_var_descs_(block, var_dict):
        # FIXME: Try unify with `append_input_output`
        for param_name in var_dict:
            var = var_dict[param_name]
            if not isinstance(var, list) and not isinstance(var, tuple):
                var = [(param_name, var, None)]
            if not isinstance(var[0], list) and not isinstance(var[0], tuple):
                var = [(param_name, var[0], var[1])]

            for i, item in enumerate(var):
                if not isinstance(item[0], basestring):
                    item = [[param_name] + list(item)]
                if len(item) == 2:
                    if isinstance(item[1], tuple):
                        var[i] = [item[0], item[1][0], item[1][1]]
                    else:
                        # only set var name and value, set lod to None
                        var[i] = list(item) + [None]
            var_descs = [(block.create_var(
                name=name, shape=each.shape, dtype=each.dtype), each, lod)
                         for name, each, lod in var]

            yield param_name, var_descs

    @staticmethod
    def _merge_list(iterable):
        return reduce(lambda a, b: list(a) + list(b), iterable, [])

    @staticmethod
    def _numpy_to_lod_tensor(np_value, lod, place):
        tensor = core.LoDTensor()
        tensor.set(np_value, place)
        if lod is not None:
            tensor.set_lod(lod)
        return tensor

    def _get_gradient(self, input_to_check, place, output_names, no_grad_set):
        prog = Program()
        block = prog.global_block()
        inputs_with_np = {
            key: value
            for (key, value) in OpTest._create_var_descs_(
                block, getattr(self, 'inputs', {}))
        }
        outputs_with_np = {
            key: val
            for (key, val) in OpTest._create_var_descs_(
                block, getattr(self, 'outputs', {}))
        }
        inputs = {
            k: [item[0] for item in inputs_with_np[k]]
            for k in inputs_with_np
        }
        outputs = {
            k: [item[0] for item in outputs_with_np[k]]
            for k in outputs_with_np
        }

        op = block.append_op(
            type=self.op_type,
            inputs=inputs,
            outputs=outputs,
            attrs=getattr(self, 'attrs', {}))

        # infer variable type and infer shape in compile-time
        op.desc.infer_var_type(block.desc)
        op.desc.infer_shape(block.desc)

        mean_inputs = map(block.var, output_names)

        if len(mean_inputs) == 1:
            loss = block.create_var(dtype=mean_inputs[0].dtype, shape=[1])
            op = block.append_op(
                inputs={"X": mean_inputs}, outputs={"Out": loss}, type='mean')
            op.desc.infer_var_type(block.desc)
            op.desc.infer_shape(block.desc)
        else:
            avg_sum = []
            for cur_loss in mean_inputs:
                cur_avg_loss = block.create_var(dtype=cur_loss.dtype, shape=[1])
                op = block.append_op(
                    inputs={"X": [cur_loss]},
                    outputs={"Out": [cur_avg_loss]},
                    type="mean")
                op.desc.infer_var_type(block.desc)
                op.desc.infer_shape(block.desc)
                avg_sum.append(cur_avg_loss)

            loss_sum = block.create_var(dtype=avg_sum[0].dtype, shape=[1])
            op_sum = block.append_op(
                inputs={"X": avg_sum}, outputs={"Out": loss_sum}, type='sum')
            op_sum.desc.infer_var_type(block.desc)
            op_sum.desc.infer_shape(block.desc)

            loss = block.create_var(dtype=loss_sum.dtype, shape=[1])
            op_loss = block.append_op(
                inputs={"X": loss_sum},
                outputs={"Out": loss},
                type='scale',
                attrs={'scale': 1.0 / float(len(avg_sum))})
            op_loss.desc.infer_var_type(block.desc)
            op_loss.desc.infer_shape(block.desc)

        param_grad_list = append_backward(
            loss=loss, parameter_list=input_to_check, no_grad_set=no_grad_set)

        feed_dict = {
            item[0].name: OpTest._numpy_to_lod_tensor(item[1], item[2], place)
            for p_name in inputs_with_np for item in inputs_with_np[p_name]
        }

        fetch_list = [g for p, g in param_grad_list]
        executor = Executor(place)
        return map(
            np.array,
            executor.run(prog, feed_dict, fetch_list, return_numpy=False))
