#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
#
# 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 numpy as np
import argparse
import time
import math

import paddle
import paddle.fluid as fluid
from paddle.fluid import core
import os
import sys
import six
import transformer_model
import paddle.dataset.wmt16 as wmt16

# Fix seed for test
fluid.default_startup_program().random_seed = 1
fluid.default_main_program().random_seed = 1

WMT16_RECORDIO_FILE = "/tmp/wmt16.recordio"


class ModelHyperParams(object):
    # Dictionary size for source and target language. This model directly uses
    # paddle.dataset.wmt16 in which <bos>, <eos> and <unk> token has
    # alreay been added, but the <pad> token is not added. Transformer requires
    # sequences in a mini-batch are padded to have the same length. A <pad> token is
    # added into the original dictionary in paddle.dateset.wmt16.

    # size of source word dictionary.
    src_vocab_size = 10000
    # index for <pad> token in source language.
    src_pad_idx = src_vocab_size

    # size of target word dictionay
    trg_vocab_size = 10000
    # index for <pad> token in target language.
    trg_pad_idx = trg_vocab_size

    # position value corresponding to the <pad> token.
    pos_pad_idx = 0

    # max length of sequences. It should plus 1 to include position
    # padding token for position encoding.
    max_length = 50

    # the dimension for word embeddings, which is also the last dimension of
    # the input and output of multi-head attention, position-wise feed-forward
    # networks, encoder and decoder.

    d_model = 512
    # size of the hidden layer in position-wise feed-forward networks.
    d_inner_hid = 1024
    # the dimension that keys are projected to for dot-product attention.
    d_key = 64
    # the dimension that values are projected to for dot-product attention.
    d_value = 64
    # number of head used in multi-head attention.
    n_head = 8
    # number of sub-layers to be stacked in the encoder and decoder.
    n_layer = 6
    # dropout rate used by all dropout layers.
    dropout = 0.1


def prepare_batch_input(insts, src_pad_idx, trg_pad_idx, n_head):
    """
    Pad the instances to the max sequence length in batch, and generate the
    corresponding position data and attention bias. Then, convert the numpy
    data to tensors and return a dict mapping names to tensors.
    """

    def __pad_batch_data(insts,
                         pad_idx,
                         is_target=False,
                         return_pos=True,
                         return_attn_bias=True,
                         return_max_len=True):
        """
        Pad the instances to the max sequence length in batch, and generate the
        corresponding position data and attention bias.
        """
        return_list = []
        max_len = max(len(inst) for inst in insts)
        inst_data = np.array(
            [inst + [pad_idx] * (max_len - len(inst)) for inst in insts])
        return_list += [inst_data.astype("int64").reshape([-1, 1])]
        if return_pos:
            inst_pos = np.array([[
                pos_i + 1 if w_i != pad_idx else 0
                for pos_i, w_i in enumerate(inst)
            ] for inst in inst_data])

            return_list += [inst_pos.astype("int64").reshape([-1, 1])]
        if return_attn_bias:
            if is_target:
                # This is used to avoid attention on paddings and subsequent
                # words.
                slf_attn_bias_data = np.ones((inst_data.shape[0], max_len,
                                              max_len))
                slf_attn_bias_data = np.triu(slf_attn_bias_data, 1).reshape(
                    [-1, 1, max_len, max_len])
                slf_attn_bias_data = np.tile(slf_attn_bias_data,
                                             [1, n_head, 1, 1]) * [-1e9]
            else:
                # This is used to avoid attention on paddings.
                slf_attn_bias_data = np.array([[0] * len(inst) + [-1e9] *
                                               (max_len - len(inst))
                                               for inst in insts])
                slf_attn_bias_data = np.tile(
                    slf_attn_bias_data.reshape([-1, 1, 1, max_len]),
                    [1, n_head, max_len, 1])
            return_list += [slf_attn_bias_data.astype("float32")]
        if return_max_len:
            return_list += [max_len]
        return return_list if len(return_list) > 1 else return_list[0]

    src_word, src_pos, src_slf_attn_bias, src_max_len = __pad_batch_data(
        [inst[0] for inst in insts], src_pad_idx, is_target=False)
    trg_word, trg_pos, trg_slf_attn_bias, trg_max_len = __pad_batch_data(
        [inst[1] for inst in insts], trg_pad_idx, is_target=True)
    trg_src_attn_bias = np.tile(src_slf_attn_bias[:, :, ::src_max_len, :],
                                [1, 1, trg_max_len, 1]).astype("float32")
    lbl_word = __pad_batch_data([inst[2] for inst in insts], trg_pad_idx, False,
                                False, False, False)
    lbl_weight = (lbl_word != trg_pad_idx).astype("float32").reshape([-1, 1])

    return [
        src_word, src_pos, trg_word, trg_pos, src_slf_attn_bias,
        trg_slf_attn_bias, trg_src_attn_bias, lbl_word, lbl_weight
    ]


def transformer(use_feed):
    assert not use_feed, "transfomer doesn't support feed yet"
    return transformer_model.transformer(
        ModelHyperParams.src_vocab_size + 1,
        ModelHyperParams.trg_vocab_size + 1, ModelHyperParams.max_length + 1,
        ModelHyperParams.n_layer, ModelHyperParams.n_head,
        ModelHyperParams.d_key, ModelHyperParams.d_value,
        ModelHyperParams.d_model, ModelHyperParams.d_inner_hid,
        ModelHyperParams.dropout, ModelHyperParams.src_pad_idx,
        ModelHyperParams.trg_pad_idx, ModelHyperParams.pos_pad_idx)


def get_model():
    avg_cost = transformer(use_feed=False)
    optimizer = fluid.optimizer.Adam()
    optimizer.minimize(avg_cost)
    return avg_cost


def get_transpiler(trainer_id, main_program, pserver_endpoints, trainers):
    t = fluid.DistributeTranspiler()
    t.transpile(
        trainer_id=trainer_id,
        program=main_program,
        pservers=pserver_endpoints,
        trainers=trainers)
    return t


class DistTransformer2x2(object):
    def run_pserver(self, pserver_endpoints, trainers, current_endpoint,
                    trainer_id):
        get_model()
        t = get_transpiler(trainer_id,
                           fluid.default_main_program(), pserver_endpoints,
                           trainers)
        pserver_prog = t.get_pserver_program(current_endpoint)
        startup_prog = t.get_startup_program(current_endpoint, pserver_prog)

        place = fluid.CPUPlace()
        exe = fluid.Executor(place)
        exe.run(startup_prog)
        exe.run(pserver_prog)

    def _wait_ps_ready(self, pid):
        retry_times = 20
        while True:
            assert retry_times >= 0, "wait ps ready failed"
            time.sleep(3)
            print("waiting ps ready: ", pid)
            try:
                # the listen_and_serv_op would touch a file which contains the listen port
                # on the /tmp directory until it was ready to process all the RPC call.
                os.stat("/tmp/paddle.%d.port" % pid)
                return
            except os.error:
                retry_times -= 1

    def run_trainer(self, place, endpoints, trainer_id, trainers, is_dist=True):
        avg_cost = get_model()
        if is_dist:
            t = get_transpiler(trainer_id,
                               fluid.default_main_program(), endpoints,
                               trainers)
            trainer_prog = t.get_trainer_program()
        else:
            trainer_prog = fluid.default_main_program()

        startup_exe = fluid.Executor(place)
        startup_exe.run(fluid.default_startup_program())

        strategy = fluid.ExecutionStrategy()
        strategy.num_threads = 1
        strategy.allow_op_delay = False
        exe = fluid.ParallelExecutor(
            True, loss_name=avg_cost.name, exec_strategy=strategy)

        first_loss, = exe.run(fetch_list=[avg_cost.name])
        print(first_loss)
        for i in six.moves.xrange(5):
            _ = exe.run(fetch_list=[avg_cost.name])
        last_loss, = exe.run(fetch_list=[avg_cost.name])
        print(last_loss)


def main(role="pserver",
         endpoints="127.0.0.1:9123",
         trainer_id=0,
         current_endpoint="127.0.0.1:9123",
         trainers=1,
         is_dist=True):

    reader = paddle.batch(
        wmt16.train(ModelHyperParams.src_vocab_size,
                    ModelHyperParams.trg_vocab_size),
        batch_size=transformer_model.batch_size)

    with fluid.recordio_writer.create_recordio_writer(
            WMT16_RECORDIO_FILE) as writer:
        for batch in reader():
            for tensor in prepare_batch_input(
                    batch, ModelHyperParams.src_pad_idx,
                    ModelHyperParams.trg_pad_idx, ModelHyperParams.n_head):
                t = fluid.LoDTensor()
                t.set(tensor, fluid.CPUPlace())
                writer.append_tensor(t)
            writer.complete_append_tensor()

    model = DistTransformer2x2()
    if role == "pserver":
        model.run_pserver(endpoints, trainers, current_endpoint, trainer_id)
    else:
        p = fluid.CUDAPlace(0) if core.is_compiled_with_cuda(
        ) else fluid.CPUPlace()
        model.run_trainer(p, endpoints, trainer_id, trainers, is_dist)


if __name__ == "__main__":
    if len(sys.argv) != 7:
        print(
            "Usage: python dist_transformer.py [pserver/trainer] [endpoints] [trainer_id] [current_endpoint] [trainers] [is_dist]"
        )
    role = sys.argv[1]
    endpoints = sys.argv[2]
    trainer_id = int(sys.argv[3])
    current_endpoint = sys.argv[4]
    trainers = int(sys.argv[5])
    is_dist = True if sys.argv[6] == "TRUE" else False
    main(
        role=role,
        endpoints=endpoints,
        trainer_id=trainer_id,
        current_endpoint=current_endpoint,
        trainers=trainers,
        is_dist=is_dist)