1from functools import cmp_to_key
  2
  3
  4TONES = (
  5    "A",
  6    "A#",
  7    "B",
  8    "C",
  9    "C#",
 10    "D",
 11    "D#",
 12    "E",
 13    "F",
 14    "F#",
 15    "G",
 16    "G#",
 17)
 18INTERVALS = [
 19    "unison",
 20    "minor 2nd",
 21    "major 2nd",
 22    "minor 3rd",
 23    "major 3rd",
 24    "perfect 4th",
 25    "diminished 5th",
 26    "perfect 5th",
 27    "minor 6th",
 28    "major 6th",
 29    "minor 7th",
 30    "major 7th",
 31]
 32
 33
 34class Tone:
 35    def __init__(self, tone_literal):
 36        assert tone_literal in TONES
 37        self.tone_literal = tone_literal
 38
 39    def __str__(self):
 40        return self.tone_literal
 41
 42    def __add__(self, other):
 43        if isinstance(other, Tone):
 44            return Chord(self, other)
 45        elif isinstance(other, Interval):
 46            return Tone(TONES[(TONES.index(self.tone_literal) + other.interval_length) % 12])
 47
 48    def __sub__(self, other):
 49        if isinstance(other, Tone):
 50            return Interval(Tone.get_tone_gap(other, self))
 51        elif isinstance(other, Interval):
 52            return Tone(TONES[(TONES.index(self.tone_literal) - other.interval_length) % 12])
 53
 54    @staticmethod
 55    def get_tone_gap(a, b):
 56        start_index = TONES.index(str(a))
 57        end_index = TONES.index(str(b))
 58        gap = 0
 59        while TONES[start_index % 12] != TONES[end_index]:
 60            start_index += 1
 61            gap += 1
 62        return gap
 63
 64
 65class Interval:
 66    def __init__(self, interval_length):
 67        assert isinstance(interval_length, int)
 68        self.interval_length = interval_length % 12
 69
 70    def __str__(self):
 71        return INTERVALS[self.interval_length]
 72
 73    def __add__(self, other):
 74        if isinstance(other, Tone):
 75            raise TypeError("Invalid operation")
 76        elif isinstance(other, Interval):
 77            return Interval(self.interval_length + other.interval_length)
 78
 79    def __sub__(self, other):
 80        if isinstance(other, Tone):
 81            raise TypeError("Invalid operation")
 82
 83    def __neg__(self):
 84        return Interval(-self.interval_length)
 85
 86
 87class Chord:
 88    def __init__(self, main_tone, *rest_tones):
 89        if len(set([str(main_tone), *[str(tone) for tone in rest_tones]])) == 1:
 90            raise TypeError("Cannot have a chord made of only 1 unique tone")
 91
 92        self.main_tone = main_tone
 93        self.rest_tones = [Tone(tone) for tone in sorted(set([str(tone) for tone in rest_tones if str(tone) != str(
 94            main_tone)]), key=cmp_to_key(lambda a, b: Tone.get_tone_gap(main_tone, Tone(a)) - Tone.get_tone_gap(main_tone, Tone(b))))]
 95
 96    def __str__(self):
 97        return "-".join([str(self.main_tone), *[str(tone) for tone in self.rest_tones]])
 98
 99    def __add__(self, other):
100        if isinstance(other, Tone):
101            return Chord(self.main_tone, *self.rest_tones, other)
102        if isinstance(other, Chord):
103            return Chord(self.main_tone, *self.rest_tones, other.main_tone, *other.rest_tones)
104
105    def __sub__(self, other):
106        if isinstance(other, Tone):
107            if not any((str(tone) == str(other) for tone in [self.main_tone, *self.rest_tones])):
108                raise TypeError(f"Cannot remove tone {
109                                str(other)} from chord {str(self)}")
110            return Chord(*[tone for tone in [self.main_tone, *self.rest_tones] if str(tone) != str(other)])
111
112    def transposed(self, interval):
113        assert isinstance(interval, Interval)
114        return Chord(self.main_tone + interval, *[tone + interval for tone in self.rest_tones])
115
116    def is_minor(self):
117        return any([INTERVALS[Tone.get_tone_gap(self.main_tone, tone)] == "minor 3rd" for tone in self.rest_tones])
118
119    def is_major(self):
120        return any([INTERVALS[Tone.get_tone_gap(self.main_tone, tone)] == "major 3rd" for tone in self.rest_tones])
121
122    def is_power_chord(self):
123        return not self.is_minor() and not self.is_major()