#
# Copyright 2005,2006,2012-2013,2020 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
#


import math

from gnuradio import gr
from gnuradio import blocks
from gnuradio import filter, fft

from . import analog_python as analog
from .fm_emph import fm_deemph


class wfm_rcv_fmdet(gr.hier_block2):
    def __init__(self, demod_rate, audio_decimation):
        """
        Hierarchical block for demodulating a broadcast FM signal.

        The input is the downconverted complex baseband signal
        (gr_complex).  The output is two streams of the demodulated
        audio (float) 0=Left, 1=Right.

        Args:
            demod_rate: input sample rate of complex baseband input. (float)
            audio_decimation: how much to decimate demod_rate to get to audio. (integer)
        """
        gr.hier_block2.__init__(self, "wfm_rcv_fmdet",
                                # Input signature
                                gr.io_signature(1, 1, gr.sizeof_gr_complex),
                                gr.io_signature(2, 2, gr.sizeof_float))      # Output signature

        if audio_decimation != int(audio_decimation):
            raise ValueError("audio_decimation needs to be an integer")
        audio_decimation = int(audio_decimation)

        lowfreq = -125e3 / demod_rate
        highfreq = 125e3 / demod_rate
        audio_rate = demod_rate / audio_decimation

        # We assign to self so that outsiders can grab the demodulator
        # if they need to.  E.g., to plot its output.
        #
        # input: complex; output: float

        self.fm_demod = analog.fmdet_cf(demod_rate, lowfreq, highfreq, 0.05)

        # input: float; output: float
        self.deemph_Left = fm_deemph(audio_rate)
        self.deemph_Right = fm_deemph(audio_rate)

        # compute FIR filter taps for audio filter
        width_of_transition_band = audio_rate / 32
        audio_coeffs = filter.firdes.low_pass(1.0,         # gain
                                              demod_rate,   # sampling rate
                                              15000,
                                              width_of_transition_band,
                                              fft.window.WIN_HAMMING)

        # input: float; output: float
        self.audio_filter = filter.fir_filter_fff(
            audio_decimation, audio_coeffs)
        if 1:
            # Pick off the stereo carrier/2 with this filter. It
            # attenuated 10 dB so apply 10 dB gain We pick off the
            # negative frequency half because we want to base band by
            # it!
            # NOTE THIS WAS HACKED TO OFFSET INSERTION LOSS DUE TO
            # DEEMPHASIS

            stereo_carrier_filter_coeffs = \
                filter.firdes.complex_band_pass(10.0,
                                                demod_rate,
                                                -19020,
                                                -18980,
                                                width_of_transition_band,
                                                fft.window.WIN_HAMMING)

            # print "len stereo carrier filter = ",len(stereo_carrier_filter_coeffs)
            # print "stereo carrier filter ", stereo_carrier_filter_coeffs
            # print "width of transition band = ",width_of_transition_band, " audio rate = ", audio_rate

            # Pick off the double side band suppressed carrier
            # Left-Right audio. It is attenuated 10 dB so apply 10 dB
            # gain

            stereo_dsbsc_filter_coeffs = \
                filter.firdes.complex_band_pass(20.0,
                                                demod_rate,
                                                38000 - 15000 / 2,
                                                38000 + 15000 / 2,
                                                width_of_transition_band,
                                                fft.window.WIN_HAMMING)
            # print "len stereo dsbsc filter = ",len(stereo_dsbsc_filter_coeffs)
            # print "stereo dsbsc filter ", stereo_dsbsc_filter_coeffs

            # construct overlap add filter system from coefficients
            # for stereo carrier
            self.stereo_carrier_filter = \
                filter.fir_filter_fcc(audio_decimation,
                                      stereo_carrier_filter_coeffs)

            # carrier is twice the picked off carrier so arrange to do
            # a complex multiply
            self.stereo_carrier_generator = blocks.multiply_cc()

            # Pick off the rds signal
            stereo_rds_filter_coeffs = \
                filter.firdes.complex_band_pass(30.0,
                                                demod_rate,
                                                57000 - 1500,
                                                57000 + 1500,
                                                width_of_transition_band,
                                                fft.window.WIN_HAMMING)
            # print "len stereo dsbsc filter = ",len(stereo_dsbsc_filter_coeffs)
            # print "stereo dsbsc filter ", stereo_dsbsc_filter_coeffs
            # construct overlap add filter system from coefficients for stereo carrier

            self.rds_signal_filter = \
                filter.fir_filter_fcc(audio_decimation,
                                      stereo_rds_filter_coeffs)
            self.rds_carrier_generator = blocks.multiply_cc()
            self.rds_signal_generator = blocks.multiply_cc()
            self_rds_signal_processor = blocks.null_sink(gr.sizeof_gr_complex)

            loop_bw = 2 * math.pi / 100.0
            max_freq = -2.0 * math.pi * 18990 / audio_rate
            min_freq = -2.0 * math.pi * 19010 / audio_rate
            self.stereo_carrier_pll_recovery = analog.pll_refout_cc(loop_bw,
                                                                    max_freq,
                                                                    min_freq)

            # self.stereo_carrier_pll_recovery.squelch_enable(False)
            # pll_refout does not have squelch yet, so disabled for
            # now

            # set up mixer (multiplier) to get the L-R signal at
            # baseband

            self.stereo_basebander = blocks.multiply_cc()

            # pick off the real component of the basebanded L-R
            # signal.  The imaginary SHOULD be zero

            self.LmR_real = blocks.complex_to_real()
            self.Make_Left = blocks.add_ff()
            self.Make_Right = blocks.sub_ff()

            self.stereo_dsbsc_filter = \
                filter.fir_filter_fcc(audio_decimation,
                                      stereo_dsbsc_filter_coeffs)

        if 1:

            # send the real signal to complex filter to pick off the
            # carrier and then to one side of a multiplier
            self.connect(self, self.fm_demod, self.stereo_carrier_filter,
                         self.stereo_carrier_pll_recovery,
                         (self.stereo_carrier_generator, 0))

            # send the already filtered carrier to the otherside of the carrier
            # the resulting signal from this multiplier is the carrier
            # with correct phase but at -38000 Hz.
            self.connect(self.stereo_carrier_pll_recovery,
                         (self.stereo_carrier_generator, 1))

            # send the new carrier to one side of the mixer (multiplier)
            self.connect(self.stereo_carrier_generator,
                         (self.stereo_basebander, 0))

            # send the demphasized audio to the DSBSC pick off filter,  the complex
            # DSBSC signal at +38000 Hz is sent to the other side of the mixer/multiplier
            # the result is BASEBANDED DSBSC with phase zero!
            self.connect(self.fm_demod, self.stereo_dsbsc_filter,
                         (self.stereo_basebander, 1))

            # Pick off the real part since the imaginary is
            # theoretically zero and then to one side of a summer
            self.connect(self.stereo_basebander,
                         self.LmR_real, (self.Make_Left, 0))

            # take the same real part of the DSBSC baseband signal and
            # send it to negative side of a subtracter
            self.connect(self.LmR_real, (self.Make_Right, 1))

            # Make rds carrier by taking the squared pilot tone and
            # multiplying by pilot tone
            self.connect(self.stereo_basebander,
                         (self.rds_carrier_generator, 0))
            self.connect(self.stereo_carrier_pll_recovery,
                         (self.rds_carrier_generator, 1))

            # take signal, filter off rds, send into mixer 0 channel
            self.connect(self.fm_demod, self.rds_signal_filter,
                         (self.rds_signal_generator, 0))

            # take rds_carrier_generator output and send into mixer 1
            # channel
            self.connect(self.rds_carrier_generator,
                         (self.rds_signal_generator, 1))

            # send basebanded rds signal and send into "processor"
            # which for now is a null sink
            self.connect(self.rds_signal_generator, self_rds_signal_processor)

        if 1:
            # pick off the audio, L+R that is what we used to have and
            # send it to the summer
            self.connect(self.fm_demod, self.audio_filter, (self.Make_Left, 1))

            # take the picked off L+R audio and send it to the PLUS
            # side of the subtractor
            self.connect(self.audio_filter, (self.Make_Right, 0))

            # The result of  Make_Left  gets    (L+R) +  (L-R) and results in 2*L
            # The result of Make_Right gets  (L+R) - (L-R) and results in 2*R
            self.connect(self.Make_Left, self.deemph_Left, (self, 0))
            self.connect(self.Make_Right, self.deemph_Right, (self, 1))

        # NOTE: mono support will require variable number of outputs in hier_block2s
        # See ticket:174 in Trac database
        # else:
        #    self.connect (self.fm_demod, self.audio_filter, self)
