# 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.

from __future__ import division
import os
import ruamel.yaml
import argparse
import tqdm
from tensorboardX import SummaryWriter
from paddle import fluid
import paddle.fluid.dygraph as dg

from parakeet.data import SliceDataset, TransformDataset, DataCargo, SequentialSampler, RandomSampler
from parakeet.models.wavenet import UpsampleNet, WaveNet, ConditionalWavenet
from parakeet.utils.layer_tools import summary
from parakeet.utils import io

from data import LJSpeechMetaData, Transform, DataCollector
from utils import make_output_tree, valid_model

if __name__ == "__main__":
    parser = argparse.ArgumentParser(
        description="Train a WaveNet model with LJSpeech.")
    parser.add_argument(
        "--data", type=str, help="path of the LJspeech dataset")
    parser.add_argument("--config", type=str, help="path of the config file")
    parser.add_argument("--device", type=int, default=-1, help="device to use")

    g = parser.add_mutually_exclusive_group()
    g.add_argument("--checkpoint", type=str, help="checkpoint to resume from")
    g.add_argument(
        "--iteration",
        type=int,
        help="the iteration of the checkpoint to load from output directory")

    parser.add_argument(
        "output", type=str, default="experiment", help="path to save results")

    args = parser.parse_args()
    with open(args.config, 'rt') as f:
        config = ruamel.yaml.safe_load(f)

    print("Command Line Args: ")
    for k, v in vars(args).items():
        print("{}: {}".format(k, v))

    ljspeech_meta = LJSpeechMetaData(args.data)

    data_config = config["data"]
    sample_rate = data_config["sample_rate"]
    n_fft = data_config["n_fft"]
    win_length = data_config["win_length"]
    hop_length = data_config["hop_length"]
    n_mels = data_config["n_mels"]
    train_clip_seconds = data_config["train_clip_seconds"]
    transform = Transform(sample_rate, n_fft, win_length, hop_length, n_mels)
    ljspeech = TransformDataset(ljspeech_meta, transform)

    valid_size = data_config["valid_size"]
    ljspeech_valid = SliceDataset(ljspeech, 0, valid_size)
    ljspeech_train = SliceDataset(ljspeech, valid_size, len(ljspeech))

    model_config = config["model"]
    n_loop = model_config["n_loop"]
    n_layer = model_config["n_layer"]
    filter_size = model_config["filter_size"]
    context_size = 1 + n_layer * sum([filter_size**i for i in range(n_loop)])
    print("context size is {} samples".format(context_size))
    train_batch_fn = DataCollector(context_size, sample_rate, hop_length,
                                   train_clip_seconds)
    valid_batch_fn = DataCollector(
        context_size, sample_rate, hop_length, train_clip_seconds, valid=True)

    batch_size = data_config["batch_size"]
    train_cargo = DataCargo(
        ljspeech_train,
        train_batch_fn,
        batch_size,
        sampler=RandomSampler(ljspeech_train))

    # only batch=1 for validation is enabled
    valid_cargo = DataCargo(
        ljspeech_valid,
        valid_batch_fn,
        batch_size=1,
        sampler=SequentialSampler(ljspeech_valid))

    make_output_tree(args.output)

    if args.device == -1:
        place = fluid.CPUPlace()
    else:
        place = fluid.CUDAPlace(args.device)

    with dg.guard(place):
        model_config = config["model"]
        upsampling_factors = model_config["upsampling_factors"]
        encoder = UpsampleNet(upsampling_factors)

        n_loop = model_config["n_loop"]
        n_layer = model_config["n_layer"]
        residual_channels = model_config["residual_channels"]
        output_dim = model_config["output_dim"]
        loss_type = model_config["loss_type"]
        log_scale_min = model_config["log_scale_min"]
        decoder = WaveNet(n_loop, n_layer, residual_channels, output_dim,
                          n_mels, filter_size, loss_type, log_scale_min)

        model = ConditionalWavenet(encoder, decoder)
        summary(model)

        train_config = config["train"]
        learning_rate = train_config["learning_rate"]
        anneal_rate = train_config["anneal_rate"]
        anneal_interval = train_config["anneal_interval"]
        lr_scheduler = dg.ExponentialDecay(
            learning_rate, anneal_interval, anneal_rate, staircase=True)
        optim = fluid.optimizer.Adam(
            lr_scheduler, parameter_list=model.parameters())

        gradiant_max_norm = train_config["gradient_max_norm"]
        clipper = fluid.dygraph_grad_clip.GradClipByGlobalNorm(
            gradiant_max_norm)

        train_loader = fluid.io.DataLoader.from_generator(
            capacity=10, return_list=True)
        train_loader.set_batch_generator(train_cargo, place)

        valid_loader = fluid.io.DataLoader.from_generator(
            capacity=10, return_list=True)
        valid_loader.set_batch_generator(valid_cargo, place)

        max_iterations = train_config["max_iterations"]
        checkpoint_interval = train_config["checkpoint_interval"]
        snap_interval = train_config["snap_interval"]
        eval_interval = train_config["eval_interval"]
        checkpoint_dir = os.path.join(args.output, "checkpoints")
        log_dir = os.path.join(args.output, "log")
        writer = SummaryWriter(log_dir)

        # load parameters and optimizer, and opdate iterations done sofar
        if args.checkpoint is not None:
            iteration = io.load_parameters(
                model, optim, checkpoint_path=args.checkpoint)
        else:
            iteration = io.load_parameters(
                model,
                optim,
                checkpoint_dir=checkpoint_dir,
                iteration=args.iteration)

        global_step = iteration + 1
        iterator = iter(tqdm.tqdm(train_loader))
        while global_step <= max_iterations:
            try:
                batch = next(iterator)
            except StopIteration as e:
                iterator = iter(tqdm.tqdm(train_loader))
                batch = next(iterator)

            audio_clips, mel_specs, audio_starts = batch

            model.train()
            y_var = model(audio_clips, mel_specs, audio_starts)
            loss_var = model.loss(y_var, audio_clips)
            loss_var.backward()
            loss_np = loss_var.numpy()

            writer.add_scalar("loss", loss_np[0], global_step)
            writer.add_scalar("learning_rate",
                              optim._learning_rate.step().numpy()[0],
                              global_step)
            optim.minimize(loss_var, grad_clip=clipper)
            optim.clear_gradients()
            print("global_step: {}\tloss: {:<8.6f}".format(global_step,
                                                           loss_np[0]))

            if global_step % snap_interval == 0:
                valid_model(model, valid_loader, writer, global_step,
                            sample_rate)

            if global_step % checkpoint_interval == 0:
                io.save_parameters(checkpoint_dir, global_step, model, optim)

            global_step += 1