"""Parameters tuning for DeepSpeech2 model."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import numpy as np
import distutils.util
import argparse
import multiprocessing
import paddle.v2 as paddle
from data_utils.data import DataGenerator
from model import DeepSpeech2Model
from error_rate import wer
import utils

parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument(
    "--num_samples",
    default=100,
    type=int,
    help="Number of samples for parameters tuning. (default: %(default)s)")
parser.add_argument(
    "--num_conv_layers",
    default=2,
    type=int,
    help="Convolution layer number. (default: %(default)s)")
parser.add_argument(
    "--num_rnn_layers",
    default=3,
    type=int,
    help="RNN layer number. (default: %(default)s)")
parser.add_argument(
    "--rnn_layer_size",
    default=512,
    type=int,
    help="RNN layer cell number. (default: %(default)s)")
parser.add_argument(
    "--use_gpu",
    default=True,
    type=distutils.util.strtobool,
    help="Use gpu or not. (default: %(default)s)")
parser.add_argument(
    "--trainer_count",
    default=8,
    type=int,
    help="Trainer number. (default: %(default)s)")
parser.add_argument(
    "--num_threads_data",
    default=1,
    type=int,
    help="Number of cpu threads for preprocessing data. (default: %(default)s)")
parser.add_argument(
    "--num_processes_beam_search",
    default=multiprocessing.cpu_count() // 2,
    type=int,
    help="Number of cpu processes for beam search. (default: %(default)s)")
parser.add_argument(
    "--specgram_type",
    default='linear',
    type=str,
    help="Feature type of audio data: 'linear' (power spectrum)"
    " or 'mfcc'. (default: %(default)s)")
parser.add_argument(
    "--mean_std_filepath",
    default='mean_std.npz',
    type=str,
    help="Manifest path for normalizer. (default: %(default)s)")
parser.add_argument(
    "--tune_manifest_path",
    default='datasets/manifest.dev',
    type=str,
    help="Manifest path for tuning. (default: %(default)s)")
parser.add_argument(
    "--model_filepath",
    default='checkpoints/params.latest.tar.gz',
    type=str,
    help="Model filepath. (default: %(default)s)")
parser.add_argument(
    "--vocab_filepath",
    default='datasets/vocab/eng_vocab.txt',
    type=str,
    help="Vocabulary filepath. (default: %(default)s)")
parser.add_argument(
    "--beam_size",
    default=500,
    type=int,
    help="Width for beam search decoding. (default: %(default)d)")
parser.add_argument(
    "--language_model_path",
    default="lm/data/common_crawl_00.prune01111.trie.klm",
    type=str,
    help="Path for language model. (default: %(default)s)")
parser.add_argument(
    "--alpha_from",
    default=0.1,
    type=float,
    help="Where alpha starts from. (default: %(default)f)")
parser.add_argument(
    "--num_alphas",
    default=14,
    type=int,
    help="Number of candidate alphas. (default: %(default)d)")
parser.add_argument(
    "--alpha_to",
    default=0.36,
    type=float,
    help="Where alpha ends with. (default: %(default)f)")
parser.add_argument(
    "--beta_from",
    default=0.05,
    type=float,
    help="Where beta starts from. (default: %(default)f)")
parser.add_argument(
    "--num_betas",
    default=20,
    type=float,
    help="Number of candidate betas. (default: %(default)d)")
parser.add_argument(
    "--beta_to",
    default=1.0,
    type=float,
    help="Where beta ends with. (default: %(default)f)")
parser.add_argument(
    "--cutoff_prob",
    default=0.99,
    type=float,
    help="The cutoff probability of pruning"
    "in beam search. (default: %(default)f)")
args = parser.parse_args()


def tune():
    """Tune parameters alpha and beta on one minibatch."""
    if not args.num_alphas >= 0:
        raise ValueError("num_alphas must be non-negative!")
    if not args.num_betas >= 0:
        raise ValueError("num_betas must be non-negative!")

    data_generator = DataGenerator(
        vocab_filepath=args.vocab_filepath,
        mean_std_filepath=args.mean_std_filepath,
        augmentation_config='{}',
        specgram_type=args.specgram_type,
        num_threads=args.num_threads_data)
    batch_reader = data_generator.batch_reader_creator(
        manifest_path=args.tune_manifest_path,
        batch_size=args.num_samples,
        sortagrad=False,
        shuffle_method=None)
    tune_data = batch_reader().next()
    target_transcripts = [
        ''.join([data_generator.vocab_list[token] for token in transcript])
        for _, transcript in tune_data
    ]

    ds2_model = DeepSpeech2Model(
        vocab_size=data_generator.vocab_size,
        num_conv_layers=args.num_conv_layers,
        num_rnn_layers=args.num_rnn_layers,
        rnn_layer_size=args.rnn_layer_size,
        pretrained_model_path=args.model_filepath)

    # create grid for search
    cand_alphas = np.linspace(args.alpha_from, args.alpha_to, args.num_alphas)
    cand_betas = np.linspace(args.beta_from, args.beta_to, args.num_betas)
    params_grid = [(alpha, beta) for alpha in cand_alphas
                   for beta in cand_betas]

    ## tune parameters in loop
    for alpha, beta in params_grid:
        result_transcripts = ds2_model.infer_batch(
            infer_data=tune_data,
            decode_method='beam_search',
            beam_alpha=alpha,
            beam_beta=beta,
            beam_size=args.beam_size,
            cutoff_prob=args.cutoff_prob,
            vocab_list=data_generator.vocab_list,
            language_model_path=args.language_model_path,
            num_processes=args.num_processes_beam_search)
        wer_sum, num_ins = 0.0, 0
        for target, result in zip(target_transcripts, result_transcripts):
            wer_sum += wer(target, result)
            num_ins += 1
        print("alpha = %f\tbeta = %f\tWER = %f" %
              (alpha, beta, wer_sum / num_ins))


def main():
    utils.print_arguments(args)
    paddle.init(use_gpu=args.use_gpu, trainer_count=args.trainer_count)
    tune()


if __name__ == '__main__':
    main()