use crate::dynamic_data::choices::TurnChoice;
use crate::dynamic_data::script_handling::ScriptSource;
use crate::dynamic_data::Pokemon;
use crate::{script_hook, ValueIdentifiable};
use parking_lot::lock_api::MappedRwLockReadGuard;
use parking_lot::{RawRwLock, RwLock, RwLockReadGuard};

/// The ChoiceQueue is used to run choices one by one.
///
/// It functions internally by holding a vector of choices, and passing ownership of the turn choice
/// to the turn executor one by one, replacing it with empty spots at the start. It holds several
/// helper functions to change the turn order while doing the execution. This is needed, as several
/// moves in Pokemon actively mess with this order.
#[derive(Debug)]
#[cfg_attr(feature = "wasm", derive(unique_type_id_derive::UniqueTypeId))]
pub struct ChoiceQueue {
    /// Our storage of turn choices. Starts out completely filled, then slowly empties as turns get
    /// executed.
    queue: RwLock<Vec<Option<TurnChoice>>>,
    /// The current index of the turn we need to execute next.
    current: usize,
}

impl ChoiceQueue {
    /// Initializes a ChoiceQueue, and sort the choices.
    pub(crate) fn new(mut queue: Vec<Option<TurnChoice>>) -> Self {
        queue.sort_unstable_by(|a, b| b.cmp(a));
        Self {
            queue: RwLock::new(queue),
            current: 0,
        }
    }

    /// Dequeues the next turn choice to be executed. This gives ownership to the callee, and replaces
    /// our own reference to the turn choice with an empty spot. It also increments the current position
    /// by one.
    pub fn dequeue(&mut self) -> Option<TurnChoice> {
        let mut write_lock = self.queue.write();
        if self.current >= write_lock.len() {
            return None;
        }
        let c = write_lock[self.current].take();
        self.current += 1;
        c
    }

    /// This reads what the next choice to execute will be, without modifying state.
    pub fn peek(&self) -> Option<MappedRwLockReadGuard<'_, RawRwLock, TurnChoice>> {
        let read_lock = self.queue.read();
        if self.current >= read_lock.len() {
            None
        } else {
            Some(RwLockReadGuard::map(read_lock, |a| a[self.current].as_ref().unwrap()))
        }
    }

    /// Check if we have any choices remaining.
    pub fn has_next(&self) -> bool {
        self.current < self.queue.read().len()
    }

    /// This resorts the yet to be executed choices. This can be useful for dealing with situations
    /// such as Pokemon changing forms just after the very start of a turn, when turn order has
    /// technically already been decided.
    pub fn resort(&mut self) {
        let len = self.queue.read().len();
        let mut write_lock = self.queue.write();
        for index in self.current..len {
            let choice = &mut write_lock[index];
            if let Some(choice) = choice {
                let mut speed = choice.user().boosted_stats().speed();
                script_hook!(change_speed, (*choice), choice, &mut speed);
                *choice.speed_mut() = speed;
            }
        }

        write_lock[self.current..len].sort_unstable_by(|a, b| b.cmp(a));
    }

    /// This moves the choice of a specific Pokemon up to the next choice to be executed.
    pub fn move_pokemon_choice_next(&self, pokemon: &Pokemon) -> bool {
        let mut queue_lock = self.queue.write();
        let mut desired_index = None;
        // Find the index for the choice we want to move up.
        for index in self.current..queue_lock.len() {
            if let Some(choice) = &queue_lock[index] {
                if pokemon.value_identifier() == choice.user().value_identifier() {
                    desired_index = Some(index);
                    break;
                }
            }
        }
        // If we couldn't find a choice, we can't execute, return.
        if desired_index.is_none() {
            return false;
        }
        let desired_index = desired_index.unwrap();
        // If the choice we want to move up is already the next choice, just return.
        if desired_index == self.current {
            return true;
        }

        // Take the choice we want to move forward out of it's place.
        let choice = queue_lock[desired_index].take().unwrap();
        // Iterate backwards from the spot before the choice we want to move up, push them all back
        // by 1 spot.
        for index in (self.current..desired_index).rev() {
            queue_lock.swap(index, index + 1);
        }
        // Place the choice that needs to be next in the next to be executed position.
        let _ = queue_lock[self.current].insert(choice);
        true
    }

    /// Internal helper function to be easily able to iterate over the yet to be executed choices.
    pub(crate) fn get_queue(&self) -> MappedRwLockReadGuard<'_, RawRwLock, [Option<TurnChoice>]> {
        let read_lock = self.queue.read();
        RwLockReadGuard::map(read_lock, |a| &a[self.current..self.queue.read().len()])
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::defines::LevelInt;
    use crate::dynamic_data::PassChoice;
    use crate::static_data::{AbilityIndex, DataLibrary, Gender};
    use std::sync::Arc;

    #[test]
    fn create_empty_queue() {
        let queue = ChoiceQueue::new(Vec::new());
        assert!(!queue.has_next());
        assert!(queue.peek().is_none());
    }

    #[test]
    fn dequeue_from_empty_queue() {
        let mut queue = ChoiceQueue::new(Vec::new());
        assert!(queue.dequeue().is_none());
    }

    fn get_user(level: LevelInt) -> Pokemon {
        let lib = Arc::new(crate::dynamic_data::libraries::dynamic_library::test::build());
        let species = lib.static_data().species().get(&"foo".into()).unwrap().clone();
        let form = species.get_form(&"default".into()).unwrap();

        Pokemon::new(
            lib,
            species,
            &form,
            AbilityIndex {
                hidden: false,
                index: 0,
            },
            level,
            0,
            Gender::Male,
            0,
            &"test_nature".into(),
        )
    }

    #[test]
    fn create_queue_with_single_item() {
        let user = Arc::new(get_user(10));

        let queue = ChoiceQueue::new(vec![Some(TurnChoice::Pass(PassChoice::new(user)))]);
        assert!(queue.has_next());
        assert!(queue.peek().is_some());
        assert_eq!(7, queue.peek().unwrap().speed());
    }

    #[test]
    fn dequeue_from_queue_with_single_item() {
        let user = Arc::new(get_user(10));

        let mut queue = ChoiceQueue::new(vec![Some(TurnChoice::Pass(PassChoice::new(user)))]);
        assert!(queue.has_next());
        assert_eq!(7, queue.dequeue().unwrap().speed());
        assert!(!queue.has_next());
        assert!(queue.peek().is_none());
    }

    #[test]
    fn create_queue_with_two_items_with_equal_order() {
        let user1 = Arc::new(get_user(10));
        let user2 = Arc::new(get_user(10));

        let queue = ChoiceQueue::new(vec![
            Some(TurnChoice::Pass(PassChoice::new(user1))),
            Some(TurnChoice::Pass(PassChoice::new(user2))),
        ]);
        assert!(queue.has_next());
        assert!(queue.peek().is_some());
        assert_eq!(7, queue.peek().unwrap().speed());
    }

    #[test]
    fn create_queue_with_two_items_get_queue() {
        let user1 = Arc::new(get_user(10));
        let user2 = Arc::new(get_user(5));

        let queue = ChoiceQueue::new(vec![
            Some(TurnChoice::Pass(PassChoice::new(user1.clone()))),
            Some(TurnChoice::Pass(PassChoice::new(user2))),
        ]);
        let inner_queue = queue.get_queue();
        assert_eq!(
            inner_queue[0].as_ref().unwrap().user().value_identifier(),
            user1.value_identifier()
        );
    }

    #[test]
    fn create_queue_with_two_items_in_wrong_order_sorts_correctly() {
        let user1 = Arc::new(get_user(5));
        let user2 = Arc::new(get_user(100));

        let mut queue = ChoiceQueue::new(vec![
            Some(TurnChoice::Pass(PassChoice::new(user1))),
            Some(TurnChoice::Pass(PassChoice::new(user2))),
        ]);
        assert_eq!(25, queue.dequeue().unwrap().speed());
        assert_eq!(6, queue.dequeue().unwrap().speed());
    }

    #[test]
    fn resort_with_two_choices() {
        let user1 = Arc::new(get_user(50));
        let user2 = Arc::new(get_user(1));

        let mut queue = ChoiceQueue::new(vec![
            Some(TurnChoice::Pass(PassChoice::new(user1.clone()))),
            Some(TurnChoice::Pass(PassChoice::new(user2.clone()))),
        ]);

        user2.change_level_by(60);
        assert_eq!(
            user1.value_identifier(),
            queue.peek().unwrap().user().value_identifier()
        );
        queue.resort();
        assert_eq!(
            user2.value_identifier(),
            queue.peek().unwrap().user().value_identifier()
        );
    }

    #[test]
    fn move_pokemon_choice_first_with_two_choices() {
        let user1 = Arc::new(get_user(100));
        let user2 = Arc::new(get_user(1));

        let mut queue = ChoiceQueue::new(vec![
            Some(TurnChoice::Pass(PassChoice::new(user1.clone()))),
            Some(TurnChoice::Pass(PassChoice::new(user2.clone()))),
        ]);
        assert_eq!(
            user1.value_identifier(),
            queue.peek().unwrap().user().value_identifier()
        );
        assert!(queue.move_pokemon_choice_next(user2.as_ref()));

        assert_eq!(
            user2.value_identifier(),
            queue.dequeue().unwrap().user().value_identifier()
        );
        assert_eq!(
            user1.value_identifier(),
            queue.dequeue().unwrap().user().value_identifier()
        );
    }

    #[test]
    fn move_pokemon_choice_first_when_choice_has_already_been() {
        let user1 = Arc::new(get_user(10));
        let user2 = Arc::new(get_user(100));

        let mut queue = ChoiceQueue::new(vec![
            Some(TurnChoice::Pass(PassChoice::new(user1.clone()))),
            Some(TurnChoice::Pass(PassChoice::new(user2.clone()))),
        ]);
        assert_eq!(
            user2.value_identifier(),
            queue.dequeue().unwrap().user().value_identifier()
        );
        assert!(!queue.move_pokemon_choice_next(user2.as_ref()));

        assert_eq!(
            user1.value_identifier(),
            queue.dequeue().unwrap().user().value_identifier()
        );
        assert!(queue.peek().is_none())
    }

    #[test]
    fn move_pokemon_choice_first_when_choice_is_next() {
        let user1 = Arc::new(get_user(100));
        let user2 = Arc::new(get_user(10));

        let queue = ChoiceQueue::new(vec![
            Some(TurnChoice::Pass(PassChoice::new(user1.clone()))),
            Some(TurnChoice::Pass(PassChoice::new(user2.clone()))),
        ]);
        assert_eq!(
            user1.value_identifier(),
            queue.peek().unwrap().user().value_identifier()
        );
        assert!(queue.move_pokemon_choice_next(user1.as_ref()));
        assert_eq!(
            user1.value_identifier(),
            queue.peek().unwrap().user().value_identifier()
        );
    }

    #[test]
    fn move_pokemon_choice_first_with_seven_choices() {
        let users = [
            Arc::new(get_user(100)),
            Arc::new(get_user(90)),
            Arc::new(get_user(80)),
            Arc::new(get_user(70)),
            Arc::new(get_user(60)),
            Arc::new(get_user(50)),
            Arc::new(get_user(40)),
        ];

        let mut queue = ChoiceQueue::new(vec![
            Some(TurnChoice::Pass(PassChoice::new(users[0].clone()))),
            Some(TurnChoice::Pass(PassChoice::new(users[1].clone()))),
            Some(TurnChoice::Pass(PassChoice::new(users[2].clone()))),
            Some(TurnChoice::Pass(PassChoice::new(users[3].clone()))),
            Some(TurnChoice::Pass(PassChoice::new(users[4].clone()))),
            Some(TurnChoice::Pass(PassChoice::new(users[5].clone()))),
            Some(TurnChoice::Pass(PassChoice::new(users[6].clone()))),
        ]);
        assert_eq!(
            users[0].value_identifier(),
            queue.peek().unwrap().user().value_identifier()
        );
        assert!(queue.move_pokemon_choice_next(users[4].as_ref()));

        assert_eq!(
            users[4].value_identifier(),
            queue.dequeue().unwrap().user().value_identifier()
        );
        for index in 0..4 {
            assert_eq!(
                users[index].value_identifier(),
                queue.dequeue().unwrap().user().value_identifier()
            );
        }
        for index in 5..7 {
            assert_eq!(
                users[index].value_identifier(),
                queue.dequeue().unwrap().user().value_identifier()
            );
        }
    }
}