# Copyright (c) 2021 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 logging
from pathlib import Path
from typing import Dict

import paddle
from paddle import distributed as dist
from paddle.io import DataLoader
from paddle.nn import Layer
from paddle.optimizer import Optimizer
from paddle.optimizer.lr import LRScheduler

from paddlespeech.t2s.training.extensions.evaluator import StandardEvaluator
from paddlespeech.t2s.training.reporter import report
from paddlespeech.t2s.training.updaters.standard_updater import StandardUpdater
from paddlespeech.t2s.training.updaters.standard_updater import UpdaterState

logging.basicConfig(
    format='%(asctime)s [%(levelname)s] [%(filename)s:%(lineno)d] %(message)s',
    datefmt='[%Y-%m-%d %H:%M:%S]')
logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)


class PWGUpdater(StandardUpdater):
    def __init__(self,
                 models: Dict[str, Layer],
                 optimizers: Dict[str, Optimizer],
                 criterions: Dict[str, Layer],
                 schedulers: Dict[str, LRScheduler],
                 dataloader: DataLoader,
                 generator_train_start_steps: int=0,
                 discriminator_train_start_steps: int=100000,
                 lambda_adv: float=1.0,
                 lambda_aux: float=1.0,
                 output_dir: Path=None):
        self.models = models
        self.generator: Layer = models['generator']
        self.discriminator: Layer = models['discriminator']

        self.optimizers = optimizers
        self.optimizer_g: Optimizer = optimizers['generator']
        self.optimizer_d: Optimizer = optimizers['discriminator']

        self.criterions = criterions
        self.criterion_stft = criterions['stft']
        self.criterion_mse = criterions['mse']

        self.schedulers = schedulers
        self.scheduler_g = schedulers['generator']
        self.scheduler_d = schedulers['discriminator']

        self.dataloader = dataloader

        self.generator_train_start_steps = generator_train_start_steps
        self.discriminator_train_start_steps = discriminator_train_start_steps
        self.lambda_adv = lambda_adv
        self.lambda_aux = lambda_aux

        self.state = UpdaterState(iteration=0, epoch=0)
        self.train_iterator = iter(self.dataloader)

        log_file = output_dir / 'worker_{}.log'.format(dist.get_rank())
        self.filehandler = logging.FileHandler(str(log_file))
        logger.addHandler(self.filehandler)
        self.logger = logger
        self.msg = ""

    def update_core(self, batch):
        self.msg = "Rank: {}, ".format(dist.get_rank())
        losses_dict = {}
        # parse batch
        wav, mel = batch

        # Generator
        if self.state.iteration > self.generator_train_start_steps:
            noise = paddle.randn(wav.shape)
            wav_ = self.generator(noise, mel)

            # initialize
            gen_loss = 0.0
            aux_loss = 0.0

            # multi-resolution stft loss
            sc_loss, mag_loss = self.criterion_stft(wav_, wav)
            aux_loss += sc_loss + mag_loss
            report("train/spectral_convergence_loss", float(sc_loss))
            report("train/log_stft_magnitude_loss", float(mag_loss))

            gen_loss += aux_loss * self.lambda_aux

            losses_dict["spectral_convergence_loss"] = float(sc_loss)
            losses_dict["log_stft_magnitude_loss"] = float(mag_loss)

            # adversarial loss
            if self.state.iteration > self.discriminator_train_start_steps:
                p_ = self.discriminator(wav_)
                adv_loss = self.criterion_mse(p_, paddle.ones_like(p_))
                report("train/adversarial_loss", float(adv_loss))
                losses_dict["adversarial_loss"] = float(adv_loss)

                gen_loss += self.lambda_adv * adv_loss

            report("train/generator_loss", float(gen_loss))
            losses_dict["generator_loss"] = float(gen_loss)

            self.optimizer_g.clear_grad()
            gen_loss.backward()

            self.optimizer_g.step()
            self.scheduler_g.step()

        # Disctiminator
        if self.state.iteration > self.discriminator_train_start_steps:
            with paddle.no_grad():
                wav_ = self.generator(noise, mel)
            p = self.discriminator(wav)
            p_ = self.discriminator(wav_.detach())
            real_loss = self.criterion_mse(p, paddle.ones_like(p))
            fake_loss = self.criterion_mse(p_, paddle.zeros_like(p_))
            dis_loss = real_loss + fake_loss
            report("train/real_loss", float(real_loss))
            report("train/fake_loss", float(fake_loss))
            report("train/discriminator_loss", float(dis_loss))
            losses_dict["real_loss"] = float(real_loss)
            losses_dict["fake_loss"] = float(fake_loss)
            losses_dict["discriminator_loss"] = float(dis_loss)

            self.optimizer_d.clear_grad()
            dis_loss.backward()

            self.optimizer_d.step()
            self.scheduler_d.step()

        self.msg += ', '.join('{}: {:>.6f}'.format(k, v)
                              for k, v in losses_dict.items())


class PWGEvaluator(StandardEvaluator):
    def __init__(self,
                 models: Dict[str, Layer],
                 criterions: Dict[str, Layer],
                 dataloader: DataLoader,
                 lambda_adv: float=1.0,
                 lambda_aux: float=1.0,
                 output_dir: Path=None):
        self.models = models
        self.generator = models['generator']
        self.discriminator = models['discriminator']

        self.criterions = criterions
        self.criterion_stft = criterions['stft']
        self.criterion_mse = criterions['mse']

        self.dataloader = dataloader

        self.lambda_adv = lambda_adv
        self.lambda_aux = lambda_aux

        log_file = output_dir / 'worker_{}.log'.format(dist.get_rank())
        self.filehandler = logging.FileHandler(str(log_file))
        logger.addHandler(self.filehandler)
        self.logger = logger
        self.msg = ""

    def evaluate_core(self, batch):
        # logging.debug("Evaluate: ")
        self.msg = "Evaluate: "
        losses_dict = {}
        wav, mel = batch
        noise = paddle.randn(wav.shape)

        # Generator
        wav_ = self.generator(noise, mel)

        # initialize
        gen_loss = 0.0
        aux_loss = 0.0

        # adversarial loss
        p_ = self.discriminator(wav_)
        adv_loss = self.criterion_mse(p_, paddle.ones_like(p_))
        report("eval/adversarial_loss", float(adv_loss))
        losses_dict["adversarial_loss"] = float(adv_loss)

        gen_loss += self.lambda_adv * adv_loss

        # multi-resolution stft loss
        sc_loss, mag_loss = self.criterion_stft(wav_, wav)
        report("eval/spectral_convergence_loss", float(sc_loss))
        report("eval/log_stft_magnitude_loss", float(mag_loss))
        losses_dict["spectral_convergence_loss"] = float(sc_loss)
        losses_dict["log_stft_magnitude_loss"] = float(mag_loss)
        aux_loss += sc_loss + mag_loss

        gen_loss += aux_loss * self.lambda_aux

        report("eval/generator_loss", float(gen_loss))
        losses_dict["generator_loss"] = float(gen_loss)

        # Disctiminator
        p = self.discriminator(wav)
        real_loss = self.criterion_mse(p, paddle.ones_like(p))
        fake_loss = self.criterion_mse(p_, paddle.zeros_like(p_))
        dis_loss = real_loss + fake_loss
        report("eval/real_loss", float(real_loss))
        report("eval/fake_loss", float(fake_loss))
        report("eval/discriminator_loss", float(dis_loss))

        losses_dict["real_loss"] = float(real_loss)
        losses_dict["fake_loss"] = float(fake_loss)
        losses_dict["discriminator_loss"] = float(dis_loss)

        self.msg += ', '.join('{}: {:>.6f}'.format(k, v)
                              for k, v in losses_dict.items())
        self.logger.info(self.msg)
