/// Implementation of a Row of Cards on the Table (max 5)

// We use std::mem::take to do tricks with vector members and ownership.
use std::{collections::VecDeque, mem};

use crate::card::Card;

#[derive(Debug)]
/// A `Row` of [`Card`]s, in a two-ended vector (`VecDeque`).
/// A Row is smart and can do a few things on herself.
pub(crate) struct Row {
    cards: VecDeque<Card>,
}

impl Row {
    /// The maximum length of a Row. More cards cause overflow and force collection.
    const MAX_LEN: usize = 5;

    /// Create a new [`Row`] with capacity of 5 [`Card`]s.
    pub(crate) fn new() -> Self {
        Row {
            cards: VecDeque::with_capacity(5),
        }
    }

    /// Push a [`Card`] to the end of the Row.
    /// If it would make Row over maximum length the function 
    /// returns the content of the row, and then push the new
    /// Card as the new Row head.
    /// Otherwise return None.
    /// # Arguments
    /// - [`Card`] - the new card to put into the Row
    /// # Returns
    /// - `Option<VecDequeue<Card>>` - None or Some(cards) to be collected from Row
    pub(crate) fn push_or_collect( &mut self, card: Card ) -> Option<VecDeque<Card>> {
        trace!("Called push_or_collect on row {:?}", &self);
        if self.cards.len() < Self::MAX_LEN {
            trace!("Less than {} cards, putting at the end", Self::MAX_LEN);
            self.cards.push_back(card);
            None

        } else {
            trace!("Row is full, len {}, maxlen {}", self.cards.len(), Self::MAX_LEN);
            // Row overflow. We take out `cards` from `self` with its ownership and 
            // leave the default (empty VecDeque) in its place, without disturbing
            // `self` ownership.
            let row_cards = mem::take( &mut self.cards );
            // We put new card as new Row head.
            self.cards.push_back(card);
            if self.cards.len() != 1 {
                panic!("New row must have one card, not {}", self.cards.len());
            }
            // Return the collected old Row content
            Some(row_cards)
        }
    }

    /// Take out all `cards` (and their ownership) and return them.
    pub(crate) fn take_row( &mut self ) -> VecDeque<Card> {
        // take cards and empty the row
        mem::take( &mut self.cards )
    }

    /// Return the `value` of the last card in the Row.
    /// This is the largest value since the Row is always ordered.
    pub(crate) fn last_card_value(&self) -> i8 {
        // println!("last_card_value: cards {:?}, len {}", self.cards, self.cards.len());
        self.cards.get( self.cards.len()-1 ).unwrap().value
    }

    // sum of row card points
    pub(crate) fn sum(&self) -> i32 {
        let mut sum: i32 = 0;
        self.cards.iter().for_each(|card| {
            sum += card.points as i32;
        });
        sum
    }

    #[allow(dead_code)]
    /// We could use this, but... borrow checker, you know. Needs more love.
    /// I could have used `_len` to shut up the dead_code warning, so this is
    /// another example to do it the other way.
    pub fn len(&self) -> usize {
        self.cards.len()
    }
}