use anyhow::bail;

pub struct Ruleset {
    pub n_slots: u8,
    pub n_suits: u8,
    pub n_cards_per_suit: u8,
    pub n_arcana: u8,
}

pub struct Deck {
    pub aces: Vec<Card>,
    pub suits: Vec<u8>,
    pub cards: Vec<CardMetadata>,
}

pub struct Setup {
    pub ruleset: Ruleset,
    pub deck: Deck
}


#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub struct Card(pub u8);


#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub struct CardMetadata { pub suit: u8, pub rank: u8 }

impl Ruleset {
    fn usable_slots(&self) -> u8 { self.n_slots - 1 }
    fn total_n_cards(&self) -> u8 {
        self.n_arcana + self.n_suits * self.n_cards_per_suit
    }
    fn usable_n_cards(&self) -> u8 {
        self.total_n_cards() - self.n_suits
    }

    pub fn compile(self) -> anyhow::Result<Setup> {
        self.validate()?;
        let deck = self.create_deck();
        Ok(Setup {
            ruleset: self,
            deck
        })
    }
    fn validate(&self) -> anyhow::Result<()> {
        if self.n_slots > 11 { bail!("max 11 slots") }
        if self.n_suits > 5 { bail!("max 5 suits") }
        if self.n_cards_per_suit > 13 { bail!("max 13 cards per suit") }
        if self.n_arcana > 99 { bail!("max 99 arcana") }
        if self.usable_slots() % 2 != 0 {
            bail!("must have even number of usable slots")
        }
        if self.usable_n_cards() % self.usable_slots() != 0 {
            bail!(
                "needs {} more cards for an even deal", 
                self.usable_slots() - (self.usable_n_cards() % self.usable_slots())
            )
        }
        let instantly_placed_cards = self.n_suits + 
            if self.n_arcana == 0 { 0 }
            else if self.n_arcana == 1 { 1 }
            else { 2 };
        if self.total_n_cards() - instantly_placed_cards < self.usable_slots() {
            bail!("can't place all cards without automoves");
        }
        Ok(())
    }

    fn create_deck(&self) -> Deck {
        let possible_suits = b"pscwb";
        let mut aces = vec![];
        let mut suits: Vec<u8> = vec![];
        suits.extend(possible_suits[..self.n_suits as usize].into_iter());
        let mut cards = vec![];

        // suited cards
        for &suit in &suits {
            for rank in 1..=self.n_cards_per_suit {
                if rank == 1 {
                    aces.push(Card(cards.len() as u8))
                }
                cards.push(CardMetadata { suit, rank: rank as u8 })
            }
        }

        // arcana
        for rank in 0..self.n_arcana {
            cards.push(CardMetadata {suit: b'a', rank});
        }

        Deck { aces, suits, cards }
    }
}