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use self::Letter::{Ab, Ash, Bb, Csh, Db, Dsh, Eb, Fsh, Gb, Gsh, A, B, C, D, E, F, G};
use crate::utils::modulo;
use num::PrimInt as Int;
use num::{FromPrimitive, ToPrimitive};
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
use std::cmp::Ordering;

pub const TOTAL_LETTERS: u8 = 12;

/// The letter representation for each step in the 12-tone, equal temperament, chromatic scale.
#[derive(Copy, Clone, Debug)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum Letter {
    C,
    Csh,
    Db,
    D,
    Dsh,
    Eb,
    E,
    F,
    Fsh,
    Gb,
    G,
    Gsh,
    Ab,
    A,
    Ash,
    Bb,
    B,
}

impl PartialOrd for Letter {
    fn partial_cmp(&self, other: &Letter) -> Option<Ordering> {
        let other_u8 = other.to_u8().unwrap();
        self.to_u8().unwrap().partial_cmp(&other_u8)
    }
}

impl Ord for Letter {
    fn cmp(&self, other: &Letter) -> Ordering {
        let other_u8 = other.to_u8().unwrap();
        self.to_u8().unwrap().cmp(&other_u8)
    }
}

impl PartialEq for Letter {
    fn eq(&self, other: &Letter) -> bool {
        self.to_u8().unwrap() == other.to_u8().unwrap()
    }
}

impl Eq for Letter {}

impl Letter {
    /// Returns whether or not the note would be a black key on a standard piano or keyboard.
    pub fn is_black_key(self) -> bool {
        use self::Letter::*;
        match self {
            Csh | Db | Dsh | Eb | Fsh | Gb | Gsh | Ab | Ash | Bb => true,
            C | D | E | F | G | A | B => false,
        }
    }
}

impl FromPrimitive for Letter {
    fn from_i64(n: i64) -> Option<Letter> {
        match modulo(n, 12) {
            0 => Some(C),
            1 => Some(Csh),
            2 => Some(D),
            3 => Some(Dsh),
            4 => Some(E),
            5 => Some(F),
            6 => Some(Fsh),
            7 => Some(G),
            8 => Some(Gsh),
            9 => Some(A),
            10 => Some(Ash),
            11 => Some(B),
            _ => None,
        }
    }
    fn from_u64(n: u64) -> Option<Letter> {
        match modulo(n, 12) {
            0 => Some(C),
            1 => Some(Csh),
            2 => Some(D),
            3 => Some(Dsh),
            4 => Some(E),
            5 => Some(F),
            6 => Some(Fsh),
            7 => Some(G),
            8 => Some(Gsh),
            9 => Some(A),
            10 => Some(Ash),
            11 => Some(B),
            _ => None,
        }
    }
}

impl ToPrimitive for Letter {
    fn to_i64(&self) -> Option<i64> {
        match *self {
            C => Some(0),
            Csh | Db => Some(1),
            D => Some(2),
            Dsh | Eb => Some(3),
            E => Some(4),
            F => Some(5),
            Fsh | Gb => Some(6),
            G => Some(7),
            Gsh | Ab => Some(8),
            A => Some(9),
            Ash | Bb => Some(10),
            B => Some(11),
        }
    }
    fn to_u64(&self) -> Option<u64> {
        match *self {
            C => Some(0),
            Csh | Db => Some(1),
            D => Some(2),
            Dsh | Eb => Some(3),
            E => Some(4),
            F => Some(5),
            Fsh | Gb => Some(6),
            G => Some(7),
            Gsh | Ab => Some(8),
            A => Some(9),
            Ash | Bb => Some(10),
            B => Some(11),
        }
    }
}

impl ::rand::Rand for Letter {
    fn rand<R: ::rand::Rng>(rng: &mut R) -> Letter {
        rng.gen_range(0, 12).to_letter()
    }
}

/// A trait to be implemented for all primitives for easy conversion to the Letter type.
pub trait ToLetter {
    /// Cast a primitive type to a Letter.
    fn to_letter(&self) -> Letter;
}

impl<T: Int> ToLetter for T {
    fn to_letter(&self) -> Letter {
        FromPrimitive::from_i64(self.to_i64().unwrap()).unwrap()
    }
}

impl<T: Int> ::std::ops::Add<T> for Letter {
    type Output = Letter;
    fn add(self, rhs: T) -> Letter {
        let semitones = modulo(rhs.to_i64().unwrap(), 12).to_i16().unwrap();
        FromPrimitive::from_i16(modulo(self.to_i16().unwrap() + semitones, 12)).unwrap()
    }
}

impl<T: Int> ::std::ops::Sub<T> for Letter {
    type Output = Letter;
    fn sub(self, rhs: T) -> Letter {
        let semitones = modulo(rhs.to_i64().unwrap(), 12).to_i16().unwrap();
        FromPrimitive::from_i16(modulo(self.to_i16().unwrap() - semitones, 12)).unwrap()
    }
}

impl ::std::ops::Add for Letter {
    type Output = Letter;
    fn add(self, rhs: Letter) -> Letter {
        self + rhs.to_u8().unwrap()
    }
}

impl ::std::ops::Sub for Letter {
    type Output = Letter;
    fn sub(self, rhs: Letter) -> Letter {
        self - rhs.to_i16().unwrap()
    }
}