use crate::*;
use rand::prelude::*;
use std::{
    ops::{Add, Sub},
    str::FromStr,
};

pub const AMOUNT_OF_LETTERS: usize = 26;

#[derive(Debug, PartialEq, Eq, Hash, Copy, Clone, PartialOrd, Ord)]
pub enum Letter {
    A = 0,
    B = 1,
    C = 2,
    D = 3,
    E = 4,
    F = 5,
    G = 6,
    H = 7,
    I = 8,
    J = 9,
    K = 10,
    L = 11,
    M = 12,
    N = 13,
    O = 14,
    P = 15,
    Q = 16,
    R = 17,
    S = 18,
    T = 19,
    U = 20,
    V = 21,
    W = 22,
    X = 23,
    Y = 24,
    Z = 25,
}

impl Letter {
    pub fn all() -> Vec<Letter> {
        use Letter::*;

        vec![
            A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z,
        ]
    }
}

impl Add for Letter {
    type Output = Letter;

    fn add(self, rhs: Self) -> Self::Output {
        Letter::from((self as usize + rhs as usize) % 26)
    }
}

impl Sub for Letter {
    type Output = Letter;

    fn sub(self, rhs: Self) -> Self::Output {
        let sum = (self as isize - rhs as isize).rem_euclid(26);
        Letter::from(sum as usize)
    }
}

impl Random for Letter {
    fn random() -> Self {
        let mut rng = rand::thread_rng();
        let num = rng.gen_range(0..AMOUNT_OF_LETTERS);
        Letter::from(num)
    }
}

impl From<usize> for Letter {
    fn from(n: usize) -> Self {
        let index = n % 26;

        match index {
            0 => Letter::A,
            1 => Letter::B,
            2 => Letter::C,
            3 => Letter::D,
            4 => Letter::E,
            5 => Letter::F,
            6 => Letter::G,
            7 => Letter::H,
            8 => Letter::I,
            9 => Letter::J,
            10 => Letter::K,
            11 => Letter::L,
            12 => Letter::M,
            13 => Letter::N,
            14 => Letter::O,
            15 => Letter::P,
            16 => Letter::Q,
            17 => Letter::R,
            18 => Letter::S,
            19 => Letter::T,
            20 => Letter::U,
            21 => Letter::V,
            22 => Letter::W,
            23 => Letter::X,
            24 => Letter::Y,
            25 => Letter::Z,
            _ => unreachable!(),
        }
    }
}

impl From<char> for Letter {
    fn from(c: char) -> Self {
        match c {
            'A' => Letter::A,
            'B' => Letter::B,
            'C' => Letter::C,
            'D' => Letter::D,
            'E' => Letter::E,
            'F' => Letter::F,
            'G' => Letter::G,
            'H' => Letter::H,
            'I' => Letter::I,
            'J' => Letter::J,
            'K' => Letter::K,
            'L' => Letter::L,
            'M' => Letter::M,
            'N' => Letter::N,
            'O' => Letter::O,
            'P' => Letter::P,
            'Q' => Letter::Q,
            'R' => Letter::R,
            'S' => Letter::S,
            'T' => Letter::T,
            'U' => Letter::U,
            'V' => Letter::V,
            'W' => Letter::W,
            'X' => Letter::X,
            'Y' => Letter::Y,
            'Z' => Letter::Z,
            _ => panic!("Tried to parse unknown letter: '{}'", c),
        }
    }
}

impl FromStr for Letter {
    type Err = &'static str;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "A" => Ok(Letter::A),
            "B" => Ok(Letter::B),
            "C" => Ok(Letter::C),
            "D" => Ok(Letter::D),
            "E" => Ok(Letter::E),
            "F" => Ok(Letter::F),
            "G" => Ok(Letter::G),
            "H" => Ok(Letter::H),
            "I" => Ok(Letter::I),
            "J" => Ok(Letter::J),
            "K" => Ok(Letter::K),
            "L" => Ok(Letter::L),
            "M" => Ok(Letter::M),
            "N" => Ok(Letter::N),
            "O" => Ok(Letter::O),
            "P" => Ok(Letter::P),
            "Q" => Ok(Letter::Q),
            "R" => Ok(Letter::R),
            "S" => Ok(Letter::S),
            "T" => Ok(Letter::T),
            "U" => Ok(Letter::U),
            "V" => Ok(Letter::V),
            "W" => Ok(Letter::W),
            "X" => Ok(Letter::X),
            "Y" => Ok(Letter::Y),
            "Z" => Ok(Letter::Z),
            _ => Err("Failed to parse string as letter"),
        }
    }
}

impl From<Letter> for char {
    fn from(letter: Letter) -> Self {
        match letter {
            Letter::A => 'A',
            Letter::B => 'B',
            Letter::C => 'C',
            Letter::D => 'D',
            Letter::E => 'E',
            Letter::F => 'F',
            Letter::G => 'G',
            Letter::H => 'H',
            Letter::I => 'I',
            Letter::J => 'J',
            Letter::K => 'K',
            Letter::L => 'L',
            Letter::M => 'M',
            Letter::N => 'N',
            Letter::O => 'O',
            Letter::P => 'P',
            Letter::Q => 'Q',
            Letter::R => 'R',
            Letter::S => 'S',
            Letter::T => 'T',
            Letter::U => 'U',
            Letter::V => 'V',
            Letter::W => 'W',
            Letter::X => 'X',
            Letter::Y => 'Y',
            Letter::Z => 'Z',
        }
    }
}