# -*- encoding: utf-8 -*-
from pathlib import Path
from typing import Any, Dict, Iterable, List, NamedTuple, Set, Tuple, Union

import numpy as np
from typeguard import check_argument_types
import kaldi_native_fbank as knf

root_dir = Path(__file__).resolve().parent

logger_initialized = {}


class WavFrontend():
    """Conventional frontend structure for ASR.
    """

    def __init__(
            self,
            cmvn_file: str = None,
            fs: int = 16000,
            window: str = 'hamming',
            n_mels: int = 80,
            frame_length: int = 25,
            frame_shift: int = 10,
            filter_length_min: int = -1,
            filter_length_max: float = -1,
            lfr_m: int = 1,
            lfr_n: int = 1,
            dither: float = 1.0
    ) -> None:
        check_argument_types()

        opts = knf.FbankOptions()
        opts.frame_opts.samp_freq = fs
        opts.frame_opts.dither = dither
        opts.frame_opts.window_type = window
        opts.frame_opts.frame_shift_ms = float(frame_shift)
        opts.frame_opts.frame_length_ms = float(frame_length)
        opts.mel_opts.num_bins = n_mels
        opts.energy_floor = 0
        opts.frame_opts.snip_edges = True
        opts.mel_opts.debug_mel = False
        self.opts = opts

        self.filter_length_min = filter_length_min
        self.filter_length_max = filter_length_max
        self.lfr_m = lfr_m
        self.lfr_n = lfr_n
        self.cmvn_file = cmvn_file

        if self.cmvn_file:
            self.cmvn = self.load_cmvn()

    def fbank(self,
              waveform: np.ndarray) -> Tuple[np.ndarray, np.ndarray]:
        waveform = waveform * (1 << 15)
        fbank_fn = knf.OnlineFbank(self.opts)
        fbank_fn.accept_waveform(self.opts.frame_opts.samp_freq, waveform.tolist())
        frames = fbank_fn.num_frames_ready
        mat = np.empty([frames, self.opts.mel_opts.num_bins])
        for i in range(frames):
            mat[i, :] = fbank_fn.get_frame(i)
        feat = mat.astype(np.float32)
        feat_len = np.array(mat.shape[0]).astype(np.int32)
        return feat, feat_len

    def lfr_cmvn(self, feat: np.ndarray) -> Tuple[np.ndarray, np.ndarray]:
        if self.lfr_m != 1 or self.lfr_n != 1:
            feat = self.apply_lfr(feat, self.lfr_m, self.lfr_n)

        if self.cmvn_file:
            feat = self.apply_cmvn(feat)

        feat_len = np.array(feat.shape[0]).astype(np.int32)
        return feat, feat_len

    @staticmethod
    def apply_lfr(inputs: np.ndarray, lfr_m: int, lfr_n: int) -> np.ndarray:
        LFR_inputs = []

        T = inputs.shape[0]
        T_lfr = int(np.ceil(T / lfr_n))
        left_padding = np.tile(inputs[0], ((lfr_m - 1) // 2, 1))
        inputs = np.vstack((left_padding, inputs))
        T = T + (lfr_m - 1) // 2
        for i in range(T_lfr):
            if lfr_m <= T - i * lfr_n:
                LFR_inputs.append(
                    (inputs[i * lfr_n:i * lfr_n + lfr_m]).reshape(1, -1))
            else:
                # process last LFR frame
                num_padding = lfr_m - (T - i * lfr_n)
                frame = inputs[i * lfr_n:].reshape(-1)
                for _ in range(num_padding):
                    frame = np.hstack((frame, inputs[-1]))

                LFR_inputs.append(frame)
        LFR_outputs = np.vstack(LFR_inputs).astype(np.float32)
        return LFR_outputs

    def apply_cmvn(self, inputs: np.ndarray) -> np.ndarray:
        """
        Apply CMVN with mvn data
        """
        frame, dim = inputs.shape
        means = np.tile(self.cmvn[0:1, :dim], (frame, 1))
        vars = np.tile(self.cmvn[1:2, :dim], (frame, 1))
        inputs = (inputs + means) * vars
        return inputs

    def load_cmvn(self,) -> np.ndarray:
        with open(self.cmvn_file, 'r', encoding='utf-8') as f:
            lines = f.readlines()

        means_list = []
        vars_list = []
        for i in range(len(lines)):
            line_item = lines[i].split()
            if line_item[0] == '<AddShift>':
                line_item = lines[i + 1].split()
                if line_item[0] == '<LearnRateCoef>':
                    add_shift_line = line_item[3:(len(line_item) - 1)]
                    means_list = list(add_shift_line)
                    continue
            elif line_item[0] == '<Rescale>':
                line_item = lines[i + 1].split()
                if line_item[0] == '<LearnRateCoef>':
                    rescale_line = line_item[3:(len(line_item) - 1)]
                    vars_list = list(rescale_line)
                    continue

        means = np.array(means_list).astype(np.float64)
        vars = np.array(vars_list).astype(np.float64)
        cmvn = np.array([means, vars])
        return cmvn