Ferrous-Solitaire/solitaire_core/src/pile.rs

use crate::card::{Card, Suit};
use klondike::KlondikePile;

/// A named collection of cards in a specific board position.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Pile {
    /// Which logical Klondike pile this is.
    pub pile_type: KlondikePile,
    /// Cards in the pile, bottom-to-top stacking order. Last element is the top card.
    pub cards: Vec<Card>,
}

impl Pile {
    /// Creates a new empty pile of the given type.
    pub fn new(pile_type: KlondikePile) -> Self {
        Self {
            pile_type,
            cards: Vec::new(),
        }
    }

    /// Returns a reference to the top (last) card, or `None` if empty.
    pub fn top(&self) -> Option<&Card> {
        self.cards.last()
    }

    /// For foundation piles: returns `Some(suit)` once at least one card has
    /// landed (the bottom card is always an Ace of the claimed suit).
    /// Returns `None` for empty foundations or non-foundation piles.
    pub fn claimed_suit(&self) -> Option<Suit> {
        match self.pile_type {
            KlondikePile::Foundation(_) => self.cards.first().map(|c| c.suit),
            _ => None,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::card::{Card, Rank, Suit};

    #[test]
    fn new_pile_is_empty() {
        let pile = Pile::new(KlondikePile::Stock);
        assert!(pile.cards.is_empty());
    }

    #[test]
    fn pile_top_returns_last_card() {
        let mut pile = Pile::new(KlondikePile::Stock);
        pile.cards.push(Card {
            id: 0,
            suit: Suit::Hearts,
            rank: Rank::Ace,
            face_up: true,
        });
        pile.cards.push(Card {
            id: 1,
            suit: Suit::Clubs,
            rank: Rank::Two,
            face_up: true,
        });
        assert_eq!(pile.top().unwrap().id, 1);
    }

    #[test]
    fn pile_top_on_empty_is_none() {
        let pile = Pile::new(KlondikePile::Stock);
        assert!(pile.top().is_none());
    }

    #[test]
    fn claimed_suit_is_none_for_empty_foundation() {
        let pile = Pile::new(KlondikePile::Foundation(klondike::Foundation::Foundation1));
        assert!(pile.claimed_suit().is_none());
    }

    #[test]
    fn claimed_suit_is_none_for_non_foundation() {
        let mut pile = Pile::new(KlondikePile::Tableau(klondike::Tableau::Tableau1));
        pile.cards.push(Card {
            id: 0,
            suit: Suit::Hearts,
            rank: Rank::Ace,
            face_up: true,
        });
        assert!(pile.claimed_suit().is_none());
    }

    #[test]
    fn claimed_suit_returns_bottom_card_suit() {
        let mut pile = Pile::new(KlondikePile::Foundation(klondike::Foundation::Foundation3));
        pile.cards.push(Card {
            id: 0,
            suit: Suit::Hearts,
            rank: Rank::Ace,
            face_up: true,
        });
        pile.cards.push(Card {
            id: 1,
            suit: Suit::Hearts,
            rank: Rank::Two,
            face_up: true,
        });
        assert_eq!(pile.claimed_suit(), Some(Suit::Hearts));
    }
}