# Copyright (C) 2018-2022 Intel Corporation
# SPDX-License-Identifier: Apache-2.0

import numpy as np

from openvino.tools.mo.ops.split import VariadicSplit
from openvino.tools.mo.front.common.partial_infer.utils import int64_array, dynamic_dimension, dynamic_dimension_value, \
    is_dynamic_slice
from openvino.tools.mo.front.common.partial_infer.utils import mo_array
from openvino.tools.mo.front.tf.graph_utils import create_op_with_const_inputs
from openvino.tools.mo.graph.graph import Graph, Node
from openvino.tools.mo.graph.perm_inputs import PermuteInputs
from openvino.tools.mo.middle.replacement import MiddleReplacementPattern
from openvino.tools.mo.ops.concat import Concat
from openvino.tools.mo.ops.const import Const
from openvino.tools.mo.ops.op import PermuteAttrs
from openvino.tools.mo.ops.strided_slice import StridedSlice
from openvino.tools.mo.utils.error import Error


class StridedSliceNormalizer(MiddleReplacementPattern):
    r"""
    StridedSlice is not normal if it cannot be permuted by ApplyPermutations. This normalizer
    inserts blank colons ':' in slice expression so that it can be correctly permuted
    from NHWC to NCHW layout. It changes masks and inserts blank begin, end and strides values.
    In order to successfully handle StridedSlice in ShapeOf subgraphs
    changes must be done by inserting nodes not just by overwriting constants.

    StridedSlice is not normal in 2 cases:
        1. rank of a slice expression is less than rank of input tensor
        2. there is an ellipsis

    1st case example
    BEFORE:
                  |
                begin
           value=[0, 0]
                  |

    AFTER:
                  |
                begin          Const
           value=[0, 0]     value=[0, 0]
                  \             /
                   \           /
                      Concat
                 value=[0, 0, 0, 0]
                        |

    Input of a shape [16, 100, 100, 3] in NHWC layout, output = input[:, 0:50].
    StridedSlice will be extended to input[:, 0:50, :, :].
    After permutation to NCHW output = input[:, :, 0:50, :].
    Example for 'begin' input transformation is shown above on the picture.
    'end' and 'strides' inputs will be transformed the same way.

    2nd case example
    BEFORE:
                  |
                begin
           value=[1, 50]
                  |

    AFTER:
                  |
                begin
           value=[1, 1, 1]
                  |
             VariadicSplit
           /              \
          /                \
         /       Const      \
         \     val=[0, 0]   /
          \       |        /
           \      |       /
               Concat
           value=[1, 0, 0, 1, 1]
                  |

    Input of a shape [16, 10, 100, 100, 3] in NDHWC layout, output = input[1:4, ..., 1:51, 1:3],
    output_shape = [3, 10, 100, 50, 2]. In order to perform correct layout permutation
    ellipsis must be replaced with colons: input[1:4, ..., 1:51, 1:3] => input[1:4, :, :, 1:51, 1:3].
    After layour permutation input[1:4, 1:3, :, : 1:5].

    In the places of colons blank begin, end and strides values should be inserted.
    In order to do that we split input and insert blank zeros to the middle.
    Example for 'begin' input transformation is shown above on the picture.
    'end' and 'strides' inputs will be transformed the same way.
    """
    enabled = True

    def run_before(self):
        from openvino.tools.mo.middle.LayoutChangeForConstantShapePaths import LayoutChangeForConstantShapePaths
        return [LayoutChangeForConstantShapePaths]

    def run_after(self):
        from openvino.tools.mo.middle.SliceConverter import ConvertSlice
        return [ConvertSlice]

    def find_and_replace_pattern(self, graph: Graph):
        for node in graph.get_op_nodes(type='StridedSlice'):
            StridedSliceNormalizer.normalize_strided_slice(graph, node)
            PermuteAttrs.create_permute_attrs(node,
                                              attrs=[('begin_mask', 'input:0'),  # but indeed depends from slice_rank
                                                     ('end_mask', 'input:0'),
                                                     ('new_axis_mask', 'input:0'),
                                                     ('shrink_axis_mask', 'input:0'),
                                                     ('ellipsis_mask', 'input:0')])

            # StridedSliceNormalizer inserted nodes that changed original begin, end, and strides data nodes
            # Until now it was not possible to set correct permutations
            PermuteInputs().set_input_permutation(node.in_node(1), node, 'input:1', 'slice', 'dim_size')
            PermuteInputs().set_input_permutation(node.in_node(2), node, 'input:2', 'slice', 'dim_size')
            if node.is_in_port_connected(3):
                PermuteInputs().set_input_permutation(node.in_node(3), node, 'input:3', 'slice', 'dim_size')

            # If there are new_axis_mask or shrink_axis_mask then StridedSlice should be performed in the
            # original layout, same as for Squeeze, Unsqueeze, Reshape, Gather
            if np.count_nonzero(node['new_axis_mask']) > 0 or np.count_nonzero(node['shrink_axis_mask']) > 0:
                node['reinterp_shape'] = True
                node['nchw_layout'] = True

    @staticmethod
    def normalize_strided_slice(graph: Graph, node: Node):
        input_shape = node.in_port(0).data.get_shape()
        input_rank = len(input_shape)
        begin = node.in_port(1).data.get_value()
        if begin is not None:
            slice_rank = len(begin)
        else:
            slice_rank = input_rank + np.count_nonzero(node.new_axis_mask) - np.count_nonzero(node.shrink_axis_mask)

        StridedSlice.align_mask_with_slice_rank(node, slice_rank)  # if StridedSlice is created after partial_infer
        StridedSliceNormalizer.normalize_slices_attr(node)

        num_insertions = input_rank - slice_rank + np.count_nonzero(node.new_axis_mask)
        assert num_insertions >= 0, 'slice_rank - num_new_axis must <= input rank. Got instead: ' \
                                    'input_rank = {}, slice_rank = {}, num_new_axis = {}'. \
            format(input_rank, slice_rank, np.count_nonzero(node.new_axis_mask))

        if np.any(node.ellipsis_mask):
            assert np.count_nonzero(node.ellipsis_mask) == 1, 'only one ellipsis_mask nonzero value is allowed'
            ellipsis_start = np.nonzero(node.ellipsis_mask)[0][0]
            # since we don't expect values in begin and end: take the whole range along ellipsis_start
            node.begin_mask[ellipsis_start] = 0
            node.end_mask[ellipsis_start] = 0
            node.ellipsis_mask[ellipsis_start] = 0
            insertion_start_idx = ellipsis_start + 1

            StridedSliceNormalizer.unroll_ellipsis_for_inputs(graph, node, ellipsis_start, num_insertions)
        elif num_insertions > 0:
            insertion_start_idx = slice_rank  # insert blank values to mask ends
            StridedSliceNormalizer.extend_inputs(node, num_insertions)

        if num_insertions > 0:
            # insert blank values for ellipsis unrolling and extending
            for mask_name in StridedSlice.get_mask_names():
                node[mask_name] = np.insert(node[mask_name], insertion_start_idx, [0] * num_insertions).astype(int)

    @staticmethod
    def unroll_ellipsis_for_inputs(graph: Graph, node: Node, ellipsis_start: int, num_insertions: int):
        node_name = node.soft_get('name', node.id)

        for i, input_name in [(1, 'begin'), (2, 'end'), (3, 'strides')]:
            if i == 3 and not node.is_in_port_connected(3):
                continue  # no need to extend strides if they are not connected

            blank_values_arr = np.zeros(num_insertions) if input_name != 'strides' else np.ones(num_insertions)
            blank_values_node = Const(graph, {'name': node_name + '/const_to_unroll_{}_ellipsis'.format(input_name),
                                              'value': int64_array(blank_values_arr)}).create_node()

            concat_in_ports_count = 3 if ellipsis_start != 0 else 2
            concat = Concat(graph, {'axis': 0, 'name': node_name + '/concat_{}'.format(input_name),
                                    'in_ports_count': concat_in_ports_count}).create_node()

            if ellipsis_start != 0:
                split = create_op_with_const_inputs(graph, VariadicSplit, {1: int64_array(0),
                                                                           2: int64_array([ellipsis_start, -1])},
                                                    {'name': node_name + '/split_for_{}_ellipsis'.format(input_name),
                                                     'out_ports_count': 2})
                node.in_port(i).get_connection().set_destination(split.in_port(0))

                concat.in_port(0).connect(split.out_port(0))
                concat.in_port(1).connect(blank_values_node.out_port(0))
                concat.in_port(2).connect(split.out_port(1))
            else:
                concat.in_port(0).connect(blank_values_node.out_port(0))
                node.in_port(i).get_connection().set_destination(concat.in_port(1))

            concat.out_port(0).get_connection().set_destination(node.in_port(i))

    @staticmethod
    def extend_inputs(node: Node, num_insertions: int):
        graph = node.graph
        node_name = node.soft_get('name', node.id)

        for i, input_name in [(1, 'begin'), (2, 'end'), (3, 'strides')]:
            if i == 3 and not node.is_in_port_connected(3):
                continue  # no need to extend strides if they are not connected

            blank_values_arr = np.zeros(num_insertions) if input_name != 'strides' else np.ones(num_insertions)
            blank_values_node = Const(graph, {'name': node_name + '/extend_{}_const'.format(input_name),
                                              'value': int64_array(blank_values_arr)}).create_node()

            if node.in_port(i).get_source().node.soft_get('type') == 'Concat':
                # concat already exists
                concat = node.in_port(i).get_source().node
                last_in_port = max(concat.in_ports().keys())
                assert not concat.in_port(last_in_port).disconnected(), 'The last in_port of Concat node {} ' \
                                                                        'should be connected'. \
                    format(concat.soft_get('name', node.id))

                concat.add_input_port(last_in_port + 1)
                concat.in_port(last_in_port + 1).connect(blank_values_node.out_port(0))
            else:
                # have to create concat
                concat = Concat(graph, {'axis': 0, 'name': node_name + '/concat_{}'.format(input_name),
                                        'in_ports_count': 2}).create_node()
                node.in_port(i).get_connection().set_destination(concat.in_port(0))
                concat.in_port(1).connect(blank_values_node.out_port(0))
                concat.out_port(0).get_connection().set_destination(node.in_port(i))

    @staticmethod
    def normalize_slices_attr(node: Node):
        # removes negative starts, ends and magic numbers from 'slice' attr which is used by ConvertGroupedStridedSlice
        slice_rank = len(node['slices'])
        data_shape = node.in_port(0).data.get_shape()

        node_name = node.soft_get('name', node.id)
        if node.is_in_port_connected(3):
            strides = node.in_port(3).data.get_value()
            if strides is None:
                raise Error('StridedSlice operation for node {} supports only constant strides input'.format(node_name))
        else:
            strides = np.ones(len(node['slices']), dtype=np.int32)

        num_ellipsis_inserts = len(data_shape) - slice_rank + np.count_nonzero(node.new_axis_mask) + 1
        res_slices = []

        in_idx = 0
        for i, s in enumerate(node['slices']):
            if node.new_axis_mask[i]:
                res_slices.append(slice(0, 1, 1))
            elif node.shrink_axis_mask[i]:
                res_slices.append(slice(s, s + 1, strides[i]))  # need strides if shrink index is negative
            elif node.ellipsis_mask[i]:
                for idx in range(num_ellipsis_inserts):
                    res_slices.append(slice(0, data_shape[in_idx], 1))
                    in_idx += 1
            else:
                res_slices.append(s)

            if not (node.new_axis_mask[i] or node.ellipsis_mask[i]):
                if res_slices[-1] != dynamic_dimension_value and data_shape[in_idx] is not dynamic_dimension and \
                        res_slices[-1] is not None and not is_dynamic_slice(res_slices[-1]):
                    res_slices[-1] = slice(*res_slices[-1].indices(data_shape[in_idx]))  # convert negative begins/ends
                in_idx += 1
        node.slices = mo_array(res_slices)
