use specs::prelude::*;
use super::{WantsToPickupItem, Name, InBackpack, Position, gamelog::GameLog};

pub struct ItemCollectionSystem {}

impl<'a> System<'a> for ItemCollectionSystem {
    #[allow(clippy::type_complexity)]
    type SystemData = ( ReadExpect<'a, Entity>,
                        WriteExpect<'a, GameLog>,
                        WriteStorage<'a, WantsToPickupItem>,
                        WriteStorage<'a, Position>,
                        ReadStorage<'a, Name>,
                        WriteStorage<'a, InBackpack>                        
                    );

    fn run (&mut self, data : Self::SystemData) {
        let (player_entity, mut log, mut wants_pickup, mut positions, names, mut backpack) = data;

        for pickup in wants_pickup.join() {
            positions.remove(pickup.item);
            backpack.insert(pickup.item, InBackpack{ owner: pickup.collected_by }).expect("Unable to insert item");

            if pickup.collected_by == *player_entity {
                log.entries.push(format!("You pick up the {}.", names.get(pickup.item).unwrap().name));
            }
        }

        wants_pickup.clear();
    }
}