#!/usr/bin/env python3
#
# Music - an utility class to deal with musical details
#
# Copyright (C) 2016  Antonio Ospite <ao2@ao2.it>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# The 88 piano keyboard goes from A0 (-39) to C8 (+48), see:
# https://en.wikipedia.org/wiki/Piano_key_frequencies
PIANO_88_KEYS_RANGE = range(-39, 48 + 1)


class SpnNote(object):
    def __init__(self, note_number):
        # Scientific Pitch Notation values are from -48 to +83
        # https://en.wikipedia.org/wiki/Scientific_pitch_notation
        if note_number < -48 or note_number > 83:
            raise ValueError("Invalid Scientific Pitch Notation number")

        self.note_number = note_number
        self.name = self._name()
        self.frequency = self._frequency()

    def _name(self):
        note_names = ["C", "C#", "D", "Eb", "E", "F", "F#", "G", "Ab", "A", "Bb", "B"]

        note_offset = self.note_number % 12
        name = note_names[note_offset]
        octave = (self.note_number + 48 - note_offset) // 12
        note_name = "%s%d" % (name, octave)
        return note_name

    def _frequency(self):
        # https://en.wikipedia.org/wiki/A440_(pitch_standard)
        return round(440 * pow(2, (self.note_number - 9) / 12), 4)

    def __repr__(self):
        return "(%+3d): %-3s frequency: %9.4f" % (self.note_number,
                                                  self.name,
                                                  self.frequency)


class MidiNote(SpnNote):
    def __init__(self, note_number):
        # midi notes go from 0 to 127
        if note_number < 0 or note_number > 127:
            raise ValueError("Invalid midi note")

        # In Scientific Pitch Notation C4 is 0
        # In MIDI it's 60
        SpnNote.__init__(self, note_number - 60)


def test():
    A0 = SpnNote(-39)
    print("Note A0? %s" % A0)
    del A0

    C4 = SpnNote(0)
    print("Note C4? %s" % C4)
    del C4

    A4 = SpnNote(9)
    print("Note A4? %s" % A4)
    del A4

    C8 = SpnNote(+48)
    print("Note C8? %s" % C8)
    del C8

    print()

    midi_C4 = MidiNote(60)
    print("Midi C4? %s" % midi_C4)
    del midi_C4



if __name__ == "__main__":
    test()