#   Copyright (c) 2019 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.
"""BERT pretraining."""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import six
import sys
if six.PY2:
    reload(sys)
    sys.setdefaultencoding('utf8')

import os
import time
import argparse
import numpy as np
import multiprocessing

import paddle
import paddle.fluid as fluid

from reader.pretraining import DataReader
from model.bert import BertModel, BertConfig
from optimization import optimization
from utils.args import ArgumentGroup, print_arguments, check_cuda
from utils.init import init_checkpoint, init_pretraining_params

# yapf: disable
parser = argparse.ArgumentParser(__doc__)
model_g = ArgumentGroup(parser, "model", "model configuration and paths.")
model_g.add_arg("bert_config_path",      str,  "./config/bert_config.json",  "Path to the json file for bert model config.")
model_g.add_arg("init_checkpoint",       str,  None,                         "Init checkpoint to resume training from.")
model_g.add_arg("checkpoints",           str,  "checkpoints",                "Path to save checkpoints.")
model_g.add_arg("weight_sharing",        bool, True,                         "If set, share weights between word embedding and masked lm.")
model_g.add_arg("generate_neg_sample",   bool, True,                         "If set, randomly generate negtive samples by positive samples.")

train_g = ArgumentGroup(parser, "training", "training options.")
train_g.add_arg("epoch",             int,    100,     "Number of epoches for training.")
train_g.add_arg("learning_rate",     float,  0.0001,  "Learning rate used to train with warmup.")
train_g.add_arg("lr_scheduler",      str,    "linear_warmup_decay",
                "scheduler of learning rate.", choices=['linear_warmup_decay', 'noam_decay'])
train_g.add_arg("weight_decay",      float,  0.01,    "Weight decay rate for L2 regularizer.")
train_g.add_arg("num_train_steps",   int,    1000000, "Total steps to perform pretraining.")
train_g.add_arg("warmup_steps",      int,    4000,    "Total steps to perform warmup when pretraining.")
train_g.add_arg("save_steps",        int,    10000,   "The steps interval to save checkpoints.")
train_g.add_arg("validation_steps",  int,    1000,    "The steps interval to evaluate model performance.")
train_g.add_arg("use_fp16",          bool,   False,   "Whether to use fp16 mixed precision training.")
train_g.add_arg("use_dynamic_loss_scaling",    bool,   True,   "Whether to use dynamic loss scaling in mixed precision training.")
train_g.add_arg("init_loss_scaling",           float,  2**32,
                "Loss scaling factor for mixed precision training, only valid when use_fp16 is enabled.")
train_g.add_arg("incr_every_n_steps",          int,    1000,   "Increases loss scaling every n consecutive.")
train_g.add_arg("decr_every_n_nan_or_inf",     int,    2,
                "Decreases loss scaling every n accumulated steps with nan or inf gradients.")
train_g.add_arg("incr_ratio",                  float,  2.0,
                "The multiplier to use when increasing the loss scaling.")
train_g.add_arg("decr_ratio",                  float,  0.8,
                "The less-than-one-multiplier to use when decreasing.")

log_g = ArgumentGroup(parser,     "logging", "logging related.")
log_g.add_arg("skip_steps",          int,    10,    "The steps interval to print loss.")
log_g.add_arg("verbose",             bool,   False, "Whether to output verbose log.")

data_g = ArgumentGroup(parser, "data", "Data paths, vocab paths and data processing options")
data_g.add_arg("data_dir",            str,  "./data/train/",       "Path to training data.")
data_g.add_arg("validation_set_dir",  str,  "./data/validation/",  "Path to validation data.")
data_g.add_arg("test_set_dir",        str,  None,                  "Path to test data.")
data_g.add_arg("vocab_path",          str,  "./config/vocab.txt",  "Vocabulary path.")
data_g.add_arg("max_seq_len",         int,  512,                   "Tokens' number of the longest seqence allowed.")
data_g.add_arg("batch_size",          int,  8192,
               "The total number of examples in one batch for training, see also --in_tokens.")
data_g.add_arg("in_tokens",           bool, True,
               "If set, the batch size will be the maximum number of tokens in one batch. "
               "Otherwise, it will be the maximum number of examples in one batch.")

run_type_g = ArgumentGroup(parser, "run_type", "running type options.")
run_type_g.add_arg("is_distributed",               bool,   False,  "If set, then start distributed training.")
run_type_g.add_arg("use_cuda",                     bool,   True,   "If set, use GPU for training.")
run_type_g.add_arg("use_fast_executor",            bool,   False,  "If set, use fast parallel executor (in experiment).")
run_type_g.add_arg("num_iteration_per_drop_scope", int,    1,      "Ihe iteration intervals to clean up temporary variables.")
run_type_g.add_arg("do_test",                      bool,   False,  "Whether to perform evaluation on test data set.")

args = parser.parse_args()
# yapf: enable.


def create_model(bert_config):
    input_fields = {
        'names': ['src_ids', 'pos_ids', 'sent_ids', 'input_mask', 'mask_label', 'mask_pos', 'labels'],
        'shapes': [[None, None], [None, None], [None, None],
                [None, None, 1], [None, 1], [None, 1], [None, 1]],
        'dtypes': ['int64', 'int64', 'int64', 'float32', 'int64', 'int64', 'int64'],
        'lod_levels': [0, 0, 0, 0, 0, 0, 0],
    }

    inputs = [fluid.data(name=input_fields['names'][i],
                      shape=input_fields['shapes'][i],
                      dtype=input_fields['dtypes'][i],
                      lod_level=input_fields['lod_levels'][i]) for i in range(len(input_fields['names']))]

    (src_ids, pos_ids, sent_ids, input_mask, mask_label, mask_pos, labels) = inputs

    data_loader = fluid.io.DataLoader.from_generator(feed_list=inputs, capacity=50, iterable=False)

    bert = BertModel(
        src_ids=src_ids,
        position_ids=pos_ids,
        sentence_ids=sent_ids,
        input_mask=input_mask,
        config=bert_config,
        weight_sharing=args.weight_sharing,
        use_fp16=args.use_fp16)

    next_sent_acc, mask_lm_loss, total_loss = bert.get_pretraining_output(
        mask_label, mask_pos, labels)

    return data_loader, next_sent_acc, mask_lm_loss, total_loss


def predict_wrapper(args,
                    exe,
                    bert_config,
                    test_prog=None,
                    data_loader=None,
                    fetch_list=None):
    # Context to do validation.
    data_path = args.test_set_dir if args.do_test else args.validation_set_dir
    data_reader = DataReader(
        data_path,
        vocab_path=args.vocab_path,
        batch_size=args.batch_size,
        in_tokens=args.in_tokens,
        voc_size=bert_config['vocab_size'],
        shuffle_files=False,
        epoch=1,
        max_seq_len=args.max_seq_len,
        is_test=True)

    data_loader.set_batch_generator(data_reader.data_generator())

    if args.do_test:
        assert args.init_checkpoint is not None, "[FATAL] Please use --init_checkpoint '/path/to/checkpoints' \
                                                  to specify you pretrained model checkpoints"

        init_pretraining_params(exe, args.init_checkpoint, test_prog)

    def predict(exe=exe, data_loader=data_loader):
        data_loader.start()

        cost = 0
        lm_cost = 0
        acc = 0
        steps = 0
        time_begin = time.time()
        while True:
            try:
                each_next_acc, each_mask_lm_cost, each_total_cost = exe.run(
                    fetch_list=fetch_list, program=test_prog)
                acc += each_next_acc
                lm_cost += each_mask_lm_cost
                cost += each_total_cost
                steps += 1
                if args.do_test and steps % args.skip_steps == 0:
                    print("[test_set] steps: %d" % steps)

            except fluid.core.EOFException:
                data_loader.reset()
                break

        used_time = time.time() - time_begin
        return cost, lm_cost, acc, steps, (args.skip_steps / used_time)

    return predict


def test(args):
    bert_config = BertConfig(args.bert_config_path)
    bert_config.print_config()

    test_prog = fluid.Program()
    test_startup = fluid.Program()
    with fluid.program_guard(test_prog, test_startup):
        with fluid.unique_name.guard():
            test_data_loader, next_sent_acc, mask_lm_loss, total_loss = create_model(
                bert_config=bert_config)

    test_prog = test_prog.clone(for_test=True)

    place = fluid.CUDAPlace(0) if args.use_cuda == True else fluid.CPUPlace()
    exe = fluid.Executor(place)
    exe.run(test_startup)

    predict = predict_wrapper(
        args,
        exe,
        bert_config,
        test_prog=test_prog,
        data_loader=test_data_loader,
        fetch_list=[next_sent_acc.name, mask_lm_loss.name, total_loss.name])

    print("test begin")
    loss, lm_loss, acc, steps, speed = predict()
    print(
        "[test_set] loss: %f, global ppl: %f, next_sent_acc: %f, speed: %f steps/s"
        % (np.mean(np.array(loss) / steps),
           np.exp(np.mean(np.array(lm_loss) / steps)),
           np.mean(np.array(acc) / steps), speed))


def train(args):
    print("pretraining start")
    bert_config = BertConfig(args.bert_config_path)
    bert_config.print_config()

    train_program = fluid.Program()
    startup_prog = fluid.Program()
    with fluid.program_guard(train_program, startup_prog):
        with fluid.unique_name.guard():
            train_data_loader, next_sent_acc, mask_lm_loss, total_loss = create_model(
                bert_config=bert_config)
            scheduled_lr, loss_scaling = optimization(
                loss=total_loss,
                warmup_steps=args.warmup_steps,
                num_train_steps=args.num_train_steps,
                learning_rate=args.learning_rate,
                train_program=train_program,
                startup_prog=startup_prog,
                weight_decay=args.weight_decay,
                scheduler=args.lr_scheduler,
                use_fp16=args.use_fp16,
                use_dynamic_loss_scaling=args.use_dynamic_loss_scaling,
                init_loss_scaling=args.init_loss_scaling,
                incr_every_n_steps=args.incr_every_n_steps,
                decr_every_n_nan_or_inf=args.decr_every_n_nan_or_inf,
                incr_ratio=args.incr_ratio,
                decr_ratio=args.decr_ratio)

    test_prog = fluid.Program()
    with fluid.program_guard(test_prog, startup_prog):
        with fluid.unique_name.guard():
            test_data_loader, next_sent_acc, mask_lm_loss, total_loss = create_model(
                bert_config=bert_config)

    test_prog = test_prog.clone(for_test=True)

    if args.use_cuda:
        place = fluid.CUDAPlace(0)
        dev_count = fluid.core.get_cuda_device_count()
    else:
        place = fluid.CPUPlace()
        dev_count = int(os.environ.get('CPU_NUM', multiprocessing.cpu_count()))

    print("Device count %d" % dev_count)

    nccl2_num_trainers = 1
    nccl2_trainer_id = 0
    print("args.is_distributed:", args.is_distributed)
    if args.is_distributed:
        worker_endpoints_env = os.getenv("worker_endpoints")
        worker_endpoints = worker_endpoints_env.split(",")
        trainers_num = len(worker_endpoints)
        current_endpoint = os.getenv("current_endpoint")
        trainer_id = worker_endpoints.index(current_endpoint)
        if trainer_id == 0:
            print("train_id == 0, sleep 60s")
            time.sleep(60)
        print("worker_endpoints:{} trainers_num:{} current_endpoint:{} \
              trainer_id:{}"
                            .format(worker_endpoints, trainers_num,
                                    current_endpoint, trainer_id))

        # prepare nccl2 env.
        config = fluid.DistributeTranspilerConfig()
        config.mode = "nccl2"
        t = fluid.DistributeTranspiler(config=config)
        t.transpile(
            trainer_id,
            trainers=worker_endpoints_env,
            current_endpoint=current_endpoint,
            program=train_program,
            startup_program=startup_prog)
        nccl2_num_trainers = trainers_num
        nccl2_trainer_id = trainer_id

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

    if args.init_checkpoint and args.init_checkpoint != "":
        init_checkpoint(exe, args.init_checkpoint, train_program, args.use_fp16)

    data_reader = DataReader(
        data_dir=args.data_dir,
        batch_size=args.batch_size,
        in_tokens=args.in_tokens,
        vocab_path=args.vocab_path,
        voc_size=bert_config['vocab_size'],
        epoch=args.epoch,
        max_seq_len=args.max_seq_len,
        generate_neg_sample=args.generate_neg_sample)

    exec_strategy = fluid.ExecutionStrategy()
    exec_strategy.use_experimental_executor = args.use_fast_executor
    exec_strategy.num_threads = dev_count
    exec_strategy.num_iteration_per_drop_scope = args.num_iteration_per_drop_scope

    build_strategy = fluid.BuildStrategy()
    if not sys.platform == "win32":
        build_strategy.num_trainers = nccl2_num_trainers
    elif  nccl2_num_trainers > 1:
        raise ValueError("Windows platform doesn't support distributed training!")
    build_strategy.trainer_id = nccl2_trainer_id
    # use_ngraph is for CPU only, please refer to README_ngraph.md for details
    use_ngraph = os.getenv('FLAGS_use_ngraph')
    if not use_ngraph:
        train_compiled_program = fluid.CompiledProgram(train_program).with_data_parallel(
                 loss_name=total_loss.name,
                 exec_strategy=exec_strategy,
                 build_strategy=build_strategy)

    if args.validation_set_dir and args.validation_set_dir != "":
        predict = predict_wrapper(
            args,
            exe,
            bert_config,
            test_prog=test_prog,
            data_loader=test_data_loader,
            fetch_list=[
                next_sent_acc.name, mask_lm_loss.name, total_loss.name
            ])

    train_data_loader.set_batch_generator(data_reader.data_generator())
    train_data_loader.start()
    steps = 0
    cost = []
    lm_cost = []
    acc = []
    time_begin = time.time()
    while steps < args.num_train_steps:
        try:
            steps += 1
            skip_steps = args.skip_steps * nccl2_num_trainers

            if nccl2_trainer_id != 0:
                if use_ngraph:
                    exe.run(fetch_list=[], program=train_program)
                else:
                    exe.run(fetch_list=[], program=train_compiled_program)
                continue

            if steps % args.skip_steps != 0:
                if use_ngraph:
                    exe.run(fetch_list=[], program=train_program)
                else:
                    exe.run(fetch_list=[], program=train_compiled_program)

            else:
                fetch_list=[next_sent_acc.name, mask_lm_loss.name, total_loss.name,
                        scheduled_lr.name]
                if args.use_fp16:
                    fetch_list.append(loss_scaling.name)

                if use_ngraph:
                    outputs = exe.run(
                        fetch_list=fetch_list, program=train_program)
                else:
                    outputs = exe.run(
                        fetch_list=fetch_list, program=train_compiled_program)

                if args.use_fp16:
                    each_next_acc, each_mask_lm_cost, each_total_cost, np_lr, np_scaling = outputs
                else:
                    each_next_acc, each_mask_lm_cost, each_total_cost, np_lr = outputs

                acc.extend(each_next_acc)
                lm_cost.extend(each_mask_lm_cost)
                cost.extend(each_total_cost)

                time_end = time.time()
                used_time = time_end - time_begin
                epoch, current_file_index, total_file, current_file = data_reader.get_progress(
                )
                if args.verbose:
                    verbose = "feed_queue size: %d, " %train_data_loader.queue.size()
                    verbose += "current learning_rate: %f, " % np_lr[0]
                    if args.use_fp16:
                        verbose += "loss scaling: %f" % np_scaling[0]
                    print(verbose)

                print("epoch: %d, progress: %d/%d, step: %d, loss: %f, "
                      "ppl: %f, next_sent_acc: %f, speed: %f steps/s, file: %s"
                      % (epoch, current_file_index, total_file, steps,
                         np.mean(np.array(cost)),
                         np.mean(np.exp(np.array(lm_cost))),
                         np.mean(np.array(acc)), skip_steps / used_time,
                         current_file))
                cost = []
                lm_cost = []
                acc = []
                time_begin = time.time()

            if steps % args.save_steps == 0:
                save_path = os.path.join(args.checkpoints, "step_" + str(steps))
                fluid.io.save_persistables(exe, save_path, train_program)

            if args.validation_set_dir and steps % args.validation_steps == 0:
                vali_cost, vali_lm_cost, vali_acc, vali_steps, vali_speed = predict(
                )
                print("[validation_set] epoch: %d, step: %d, "
                      "loss: %f, global ppl: %f, batch-averged ppl: %f, "
                      "next_sent_acc: %f, speed: %f steps/s" %
                      (epoch, steps,
                       np.mean(np.array(vali_cost) / vali_steps),
                       np.exp(np.mean(np.array(vali_lm_cost) / vali_steps)),
                       np.mean(np.exp(np.array(vali_lm_cost) / vali_steps)),
                       np.mean(np.array(vali_acc) / vali_steps), vali_speed))

        except fluid.core.EOFException:
            train_data_loader.reset()
            break

if __name__ == '__main__':
    print_arguments(args)
    check_cuda(args.use_cuda)
    if args.do_test:
        test(args)
    else:
        train(args)
