#
# Copyright 2005,2007,2012 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


class standard_squelch(gr.hier_block2):
    def __init__(self, audio_rate):
        gr.hier_block2.__init__(self, "standard_squelch",
                                # Input signature
                                gr.io_signature(1, 1, gr.sizeof_float),
                                gr.io_signature(1, 1, gr.sizeof_float))  # Output signature

        self.input_node = blocks.add_const_ff(0)          # FIXME kludge

        self.low_iir = filter.iir_filter_ffd(
            (0.0193, 0, -0.0193), (1, 1.9524, -0.9615))
        self.low_square = blocks.multiply_ff()
        self.low_smooth = filter.single_pole_iir_filter_ff(
            1 / (0.01 * audio_rate))   # 100ms time constant

        self.hi_iir = filter.iir_filter_ffd(
            (0.0193, 0, -0.0193), (1, 1.3597, -0.9615))
        self.hi_square = blocks.multiply_ff()
        self.hi_smooth = filter.single_pole_iir_filter_ff(
            1 / (0.01 * audio_rate))

        self.sub = blocks.sub_ff()
        self.add = blocks.add_ff()
        self.gate = blocks.threshold_ff(0.3, 0.43, 0)
        self.squelch_lpf = filter.single_pole_iir_filter_ff(
            1 / (0.01 * audio_rate))

        self.div = blocks.divide_ff()
        self.squelch_mult = blocks.multiply_ff()

        self.connect(self, self.input_node)
        self.connect(self.input_node, (self.squelch_mult, 0))

        self.connect(self.input_node, self.low_iir)
        self.connect(self.low_iir, (self.low_square, 0))
        self.connect(self.low_iir, (self.low_square, 1))
        self.connect(self.low_square, self.low_smooth, (self.sub, 0))
        self.connect(self.low_smooth, (self.add, 0))

        self.connect(self.input_node, self.hi_iir)
        self.connect(self.hi_iir, (self.hi_square, 0))
        self.connect(self.hi_iir, (self.hi_square, 1))
        self.connect(self.hi_square, self.hi_smooth, (self.sub, 1))
        self.connect(self.hi_smooth, (self.add, 1))

        self.connect(self.sub, (self.div, 0))
        self.connect(self.add, (self.div, 1))
        self.connect(self.div, self.gate, self.squelch_lpf,
                     (self.squelch_mult, 1))
        self.connect(self.squelch_mult, self)

    def set_threshold(self, threshold):
        self.gate.set_hi(threshold)

    def threshold(self):
        return self.gate.hi()

    def squelch_range(self):
        return (0.0, 1.0, 1.0 / 100)