# coding=utf-8
# Copyright 2020 The HuggingFace Inc. team.
#
# 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.
"""Convert Reformer checkpoint."""


import argparse
import pickle

import numpy as np
import torch
from torch import nn

from transformers import ReformerConfig, ReformerModelWithLMHead
from transformers.utils import logging


logging.set_verbosity_info()


def set_param(torch_layer, weight, bias=None):
    # set parameter of one layer
    assert torch_layer.weight.shape == weight.shape, f"{torch_layer} layer.weight does not match"
    torch_layer.weight = nn.Parameter(weight)
    if bias is not None:
        assert torch_layer.bias.shape == bias.shape, f"{torch_layer} layer.bias does not match"
        torch_layer.bias = nn.Parameter(bias)


def set_layer_weights_in_torch_lsh(weights, torch_layer, hidden_size):
    # set torch weights for 1-to-1 comparison
    np_query_key = np.asarray(weights[0])
    np_value = np.asarray(weights[1])
    np_dense = np.asarray(weights[2])

    set_param(
        torch_layer.self_attention.query_key,
        torch.tensor(np_query_key).transpose(1, 2).contiguous().view(-1, hidden_size),
    )
    set_param(
        torch_layer.self_attention.value,
        torch.tensor(np_value).transpose(1, 2).contiguous().view(-1, hidden_size),
    )
    set_param(
        torch_layer.output.dense,
        torch.tensor(np_dense).view(-1, hidden_size).contiguous().transpose(0, 1),
    )


def set_layer_weights_in_torch_local(weights, torch_layer, hidden_size):
    # set torch weights for 1-to-1 comparison
    np_query = np.asarray(weights[0])
    np_key = np.asarray(weights[1])
    np_value = np.asarray(weights[2])
    np_dense = np.asarray(weights[3])

    set_param(
        torch_layer.self_attention.query,
        torch.tensor(np_query).transpose(1, 2).contiguous().view(-1, hidden_size),
    )
    set_param(
        torch_layer.self_attention.key,
        torch.tensor(np_key).transpose(1, 2).contiguous().view(-1, hidden_size),
    )
    set_param(
        torch_layer.self_attention.value,
        torch.tensor(np_value).transpose(1, 2).contiguous().view(-1, hidden_size),
    )
    set_param(
        torch_layer.output.dense,
        torch.tensor(np_dense).view(-1, hidden_size).contiguous().transpose(0, 1),
    )


def set_block_weights_in_torch(weights, torch_block, hidden_size):
    # layernorm 1
    layer_norm_1 = weights[0][0][0]
    layer_norm_1_weight = np.asarray(layer_norm_1[0])
    layer_norm_1_bias = np.asarray(layer_norm_1[1])
    set_param(
        torch_block.attention.layer_norm,
        torch.tensor(layer_norm_1_weight),
        torch.tensor(layer_norm_1_bias),
    )

    # lsh weights + output
    attn_weights = weights[0][1]
    if len(attn_weights) < 4:
        set_layer_weights_in_torch_lsh(attn_weights, torch_block.attention, hidden_size)
    else:
        set_layer_weights_in_torch_local(attn_weights, torch_block.attention, hidden_size)

    # intermediate weighs
    intermediate_weights = weights[2][0][1][2]

    # Chunked Feed Forward
    if len(intermediate_weights) == 4:
        intermediate_weights = intermediate_weights[2]

    # layernorm 2
    layer_norm_2_weight = np.asarray(intermediate_weights[0][0])
    layer_norm_2_bias = np.asarray(intermediate_weights[0][1])
    set_param(
        torch_block.feed_forward.layer_norm,
        torch.tensor(layer_norm_2_weight),
        torch.tensor(layer_norm_2_bias),
    )

    # intermediate dense
    inter_dense_weight = np.asarray(intermediate_weights[1][0])
    inter_dense_bias = np.asarray(intermediate_weights[1][1])
    set_param(
        torch_block.feed_forward.dense.dense,
        torch.tensor(inter_dense_weight).transpose(0, 1).contiguous(),
        torch.tensor(inter_dense_bias),
    )

    # intermediate out
    out_dense_weight = np.asarray(intermediate_weights[4][0])
    out_dense_bias = np.asarray(intermediate_weights[4][1])
    set_param(
        torch_block.feed_forward.output.dense,
        torch.tensor(out_dense_weight).transpose(0, 1).contiguous(),
        torch.tensor(out_dense_bias),
    )


def set_model_weights_in_torch(weights, torch_model, hidden_size):
    # reformer model
    torch_model_reformer = torch_model.reformer

    # word embeds
    word_embeddings = np.asarray(weights[1])
    set_param(
        torch_model_reformer.embeddings.word_embeddings,
        torch.tensor(word_embeddings),
    )

    if isinstance(weights[3], tuple):
        position_embeddings = torch_model_reformer.embeddings.position_embeddings
        for emb_idx in range(len(position_embeddings.weights)):
            emb_weights = np.asarray(weights[3][emb_idx][0])
            assert (
                position_embeddings.weights[emb_idx].shape == emb_weights.shape
            ), f"{position_embeddings[emb_idx]} emb does not match"
            position_embeddings.weights[emb_idx] = nn.Parameter(torch.tensor(emb_weights))

    trax_layer_weights = weights[5]
    assert len(torch_model_reformer.encoder.layers) * 4 == len(
        trax_layer_weights
    ), "HF and trax model do not have the same number of layers"
    for layer_idx, layer in enumerate(torch_model_reformer.encoder.layers):
        block_weights = trax_layer_weights[4 * layer_idx : 4 * (layer_idx + 1)]
        set_block_weights_in_torch(block_weights, layer, hidden_size)

    # output layer norm
    layer_norm_out_weight = np.asarray(weights[7][0])
    layer_norm_out_bias = np.asarray(weights[7][1])
    set_param(
        torch_model_reformer.encoder.layer_norm,
        torch.tensor(layer_norm_out_weight),
        torch.tensor(layer_norm_out_bias),
    )

    # output embeddings
    output_embed_weights = np.asarray(weights[9][0])
    output_embed_bias = np.asarray(weights[9][1])
    set_param(
        torch_model.lm_head.decoder,
        torch.tensor(output_embed_weights).transpose(0, 1).contiguous(),
        torch.tensor(output_embed_bias),
    )


def convert_trax_checkpoint_to_pytorch(trax_model_pkl_path, config_file, pytorch_dump_path):
    # Initialise PyTorch model
    config = ReformerConfig.from_json_file(config_file)
    print(f"Building PyTorch model from configuration: {config}")
    model = ReformerModelWithLMHead(config)

    with open(trax_model_pkl_path, "rb") as f:
        model_weights = pickle.load(f)["weights"]

    set_model_weights_in_torch(model_weights, model, config.hidden_size)

    # Save pytorch-model
    print(f"Save PyTorch model to {pytorch_dump_path}")
    torch.save(model.state_dict(), pytorch_dump_path)


if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    # Required parameters
    parser.add_argument(
        "--trax_model_pkl_path", default=None, type=str, required=True, help="Path to the TensorFlow checkpoint path."
    )
    parser.add_argument(
        "--config_file",
        default=None,
        type=str,
        required=True,
        help=(
            "The config json file corresponding to the pre-trained Reformer model. \n"
            "This specifies the model architecture."
        ),
    )
    parser.add_argument(
        "--pytorch_dump_path", default=None, type=str, required=True, help="Path to the output PyTorch model."
    )
    args = parser.parse_args()
    convert_trax_checkpoint_to_pytorch(args.trax_model_pkl_path, args.config_file, args.pytorch_dump_path)
