# Copyright (c) 2020 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.
"""
Training use fluid with one node only.
"""

from __future__ import print_function

import time
import logging

import paddle.fluid as fluid

from paddlerec.core.trainers.transpiler_trainer import TranspileTrainer
from paddlerec.core.utils import envs

logging.basicConfig(format="%(asctime)s - %(levelname)s - %(message)s")
logger = logging.getLogger("fluid")
logger.setLevel(logging.INFO)


class SingleTrainer(TranspileTrainer):
    def processor_register(self):
        self.regist_context_processor('uninit', self.instance)
        self.regist_context_processor('init_pass', self.init)
        self.regist_context_processor('startup_pass', self.startup)

        if envs.get_platform() == "LINUX" and envs.get_global_env(
                "dataset_class", None, "train.reader") != "DataLoader":
            self.regist_context_processor('train_pass', self.dataset_train)
        else:
            self.regist_context_processor('train_pass', self.dataloader_train)

        self.regist_context_processor('infer_pass', self.infer)
        self.regist_context_processor('terminal_pass', self.terminal)

    def init(self, context):
        self.model.train_net()
        optimizer = self.model.optimizer()
        optimizer.minimize((self.model.get_avg_cost()))

        self.fetch_vars = []
        self.fetch_alias = []
        self.fetch_period = self.model.get_fetch_period()

        metrics = self.model.get_metrics()
        if metrics:
            self.fetch_vars = metrics.values()
            self.fetch_alias = metrics.keys()
        evaluate_only = envs.get_global_env(
            'evaluate_only', False, namespace='evaluate')
        if evaluate_only:
            context['status'] = 'infer_pass'
        else:
            context['status'] = 'startup_pass'

    def startup(self, context):
        self._exe.run(fluid.default_startup_program())
        context['status'] = 'train_pass'

    def dataloader_train(self, context):
        reader = self._get_dataloader("TRAIN")
        epochs = envs.get_global_env("train.epochs")

        program = fluid.compiler.CompiledProgram(fluid.default_main_program(
        )).with_data_parallel(loss_name=self.model.get_avg_cost().name)

        metrics_varnames = []
        metrics_format = []

        metrics_format.append("{}: {{}}".format("epoch"))
        metrics_format.append("{}: {{}}".format("batch"))

        for name, var in self.model.get_metrics().items():
            metrics_varnames.append(var.name)
            metrics_format.append("{}: {{}}".format(name))

        metrics_format = ", ".join(metrics_format)

        for epoch in range(epochs):
            reader.start()
            batch_id = 0
            try:
                while True:
                    metrics_rets = self._exe.run(program=program,
                                                 fetch_list=metrics_varnames)

                    metrics = [epoch, batch_id]
                    metrics.extend(metrics_rets)

                    if batch_id % self.fetch_period == 0 and batch_id != 0:
                        print(metrics_format.format(*metrics))
                    batch_id += 1
            except fluid.core.EOFException:
                reader.reset()
            self.save(epoch, "train", is_fleet=False)

        context['status'] = 'infer_pass'

    def dataset_train(self, context):
        dataset = self._get_dataset("TRAIN")
        ins = self._get_dataset_ins()

        epochs = envs.get_global_env("train.epochs")
        for i in range(epochs):
            begin_time = time.time()
            self._exe.train_from_dataset(
                program=fluid.default_main_program(),
                dataset=dataset,
                fetch_list=self.fetch_vars,
                fetch_info=self.fetch_alias,
                print_period=self.fetch_period)
            end_time = time.time()
            times = end_time - begin_time
            print("epoch {} using time {}, speed {:.2f} lines/s".format(
                i, times, ins / times))

            self.save(i, "train", is_fleet=False)
        context['status'] = 'infer_pass'

    def terminal(self, context):
        for model in self.increment_models:
            print("epoch :{}, dir: {}".format(model[0], model[1]))
        context['is_exit'] = True