#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Weighting and calibration filter in one
@author: J.A. de Jong - ASCEE
"""
from .lasp_common import FreqWeighting
from .filter import SPLFilterDesigner
from lasp.lasp_config import ones, empty
from .wrappers import FilterBank
import numpy as np

__all__ = ['WeighCal']


class WeighCal:
    """
    Frequency weighting and calibration FIR filter
    """

    def __init__(self, fw=FreqWeighting.default,
                 nchannels=1,
                 fs=48000.,
                 calfile=None):
        """
        Initialize the frequency weighting and calibration FIR filters.

        Args:
            fw: Frequency weighting to apply
            nchannels: Number of channels for the input data
            fs: Sampling frequency [Hz]
            calfile: Calibration file to load.
        """

        self.nchannels = nchannels
        self.fs = fs
        self.fw = fw

        self.calfile = calfile

        # Frequencies used for the filter design
        freq_design = np.linspace(0, 17e3, 3000)
        freq_design[-1] = fs/2

        # Objective function for the frequency response
        frp_obj = self.frpObj(freq_design)

        P = 2048 # Filter length (number of taps)

        self._firs = np.empty((P, self.nchannels))
        self._fbs = []
        for chan in range(self.nchannels):
            fir = arbitrary_fir_design(fs, P, freq_design,
                                       frp_obj[:, chan],
                                       window='rectangular')
            self._firs[:, chan] = fir

            self._fbs.append(FilterBank(fir[:, np.newaxis], 2*P))

        self._freq_design = freq_design

    def filter_(self, data):
        """
        Filter data using the calibration and frequency weighting filter.

        Args:
            data: (Weighted) raw time data that needs to be filtered, should
            have the same number of columns as the number of channels. First
            axis is assumed to be the time axis

        Retuns:
            Filtered data for each channel

        """
        nchan = self.nchannels
        assert data.ndim == 2
        assert data.shape[1] == nchan
        assert data.shape[0] > 0

        filtered = []
        for chan in range(nchan):
            filtered.append(self._fbs[chan].filter_(data[:, [chan]])[:, 0])
        filtered = np.asarray(filtered).transpose()
        if filtered.ndim == 1:
            filtered = filtered[:, np.newaxis]
        return filtered

    def frpCalObj(self, freq_design):
        """
        Computes the objective frequency response of the calibration filter
        """
        calfile = self.calfile
        if calfile is not None:
            cal = np.loadtxt(calfile, skiprows=2)
            freq = cal[:, 0]
            cal = cal[:, 1:]
            if cal.shape[1] != self.nchannels:
                raise ValueError('Number of channels in calibration file does'
                                 ' not equal to given number of channels')
            calfac = 10**(-cal/20)
            filter_calfac = empty((freq_design.shape[0], self.nchannels))

            for chan in range(self.nchannels):
                filter_calfac[:, chan] = np.interp(freq_design, freq,
                                                   calfac[:, chan])

        else:
            filter_calfac = ones((freq_design.shape[0], self.nchannels,))

        return filter_calfac

    def frpWeightingObj(self, freq_design):
        """
        Computes the objective frequency response of the frequency weighting
        filter.
        """
        fw = self.fw
        if fw == FreqWeighting.A:
            return A(freq_design)
        elif fw == FreqWeighting.C:
            return C(freq_design)
        elif fw == FreqWeighting.Z:
            return ones(freq_design.shape[0])
        else:
            raise ValueError('Invalid fw parameter')

    def frpObj(self, freq_design):
        """
        Combines the frequency weighting and the calibration filter into
        one frequency response objective function.
        """
        # Objective function for the frequency response
        frp_objective = self.frpCalObj(freq_design) * \
            self.frpWeightingObj(freq_design)[:, np.newaxis]
        frp_objective[-1] = 0.

        return frp_objective

    def freqResponse(self, chan=0, freq=None):
        """
        Returns the frequency response of the designed FIR filter
        """
        if freq is None:
            freq = np.logspace(1, np.log10(self.fs/2), 500)
        return (freq, frp(self.fs, freq, self._firs[chan]),
                self.frpObj(freq)[:, chan])