use std::sync::atomic::{AtomicU8, Ordering};
use std::sync::Arc;

use crate::static_data::MoveData;
use crate::{ValueIdentifiable, ValueIdentifier};

/// A learned move is the data attached to a Pokemon for a move it has learned. It has information
/// such as the remaining amount of users, how it has been learned, etc.
#[derive(Debug)]
pub struct LearnedMove {
    /// A unique identifier so we know what value this is.
    identifier: ValueIdentifier,
    /// The immutable move information of the move.
    move_data: Arc<dyn MoveData>,
    /// The maximal power points for this move.
    max_pp: u8,
    /// The amount of remaining power points. If this is 0, we can not use the move anymore.
    remaining_pp: AtomicU8,
    /// The way the move was learned.
    learn_method: MoveLearnMethod,
}

/// The different ways a move can be learned.
#[derive(Copy, Clone, Debug, Default)]
#[repr(u8)]
pub enum MoveLearnMethod {
    /// We do not know the learn method.
    #[default]
    Unknown = 0,
    /// The move was learned through level up.
    Level = 1,
}

impl LearnedMove {
    /// Instantiate a new learned move.
    pub fn new(move_data: Arc<dyn MoveData>, learn_method: MoveLearnMethod) -> Self {
        let max_pp = move_data.base_usages();
        Self {
            identifier: Default::default(),
            move_data,
            max_pp,
            remaining_pp: AtomicU8::new(max_pp),
            learn_method,
        }
    }

    /// The immutable move information of the move.
    pub fn move_data(&self) -> &Arc<dyn MoveData> {
        &self.move_data
    }
    /// The maximal power points for this move.
    pub fn max_pp(&self) -> u8 {
        self.max_pp
    }
    /// The amount of remaining power points. If this is 0, we can not use the move anymore.
    pub fn remaining_pp(&self) -> u8 {
        self.remaining_pp.load(Ordering::Relaxed)
    }
    /// The way the move was learned.
    pub fn learn_method(&self) -> MoveLearnMethod {
        self.learn_method
    }

    /// Try and reduce the PP by a certain amount. If the amount is higher than the current uses,
    /// return false. Otherwise, reduce the PP, and return true.
    pub fn try_use(&self, amount: u8) -> bool {
        let res = self.remaining_pp.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |x| {
            if amount > x {
                None
            } else {
                Some(x - amount)
            }
        });
        res.is_ok()
    }

    /// Set the remaining PP to the max amount of PP.
    pub fn restore_all_uses(&self) {
        self.remaining_pp.store(self.max_pp, Ordering::SeqCst);
    }

    /// Restore the remaining PP by a certain amount. Will prevent it from going above max PP.
    pub fn restore_uses(&self, mut uses: u8) {
        self.remaining_pp
            .fetch_update(Ordering::SeqCst, Ordering::SeqCst, |x| {
                if x + uses > self.max_pp {
                    uses = self.max_pp - x;
                }
                Some(x + uses)
            })
            .ok();
    }
}

impl ValueIdentifiable for LearnedMove {
    fn value_identifier(&self) -> ValueIdentifier {
        self.identifier
    }
}

#[cfg(test)]
#[allow(clippy::unwrap_used)]
mod tests {
    use super::*;
    use crate::static_data::tests::MockMoveData;

    #[test]
    fn create_learned_move_restore_uses() {
        let mut mock = MockMoveData::new();
        mock.expect_base_usages().return_const(30);
        let data: Arc<dyn MoveData> = Arc::new(mock);
        let learned_move = LearnedMove::new(data, MoveLearnMethod::Level);
        assert!(learned_move.try_use(15));
        learned_move.restore_uses(5);
        assert_eq!(20, learned_move.remaining_pp());
    }
}