bevy-expedition-demo/src/ui/inventory/systems.rs

use bevy::prelude::*;

use crate::{
    inventory::ActiveInventory,
    player::Player,
    ui::UiRoot,
};

use super::{*, bundles::*, observers::*};

const UI_SLOT_ASSET_PATH: &'static str = "sprites/ui/inventory_slot.png";
const TEMP_ITEM_PATH: &'static str = "sprites/items/choco_bar.png";

pub fn setup_ui_inventory(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
    inventory_query: Query<(Option<&ChildOf>, Entity, &Inventory, Option<&Children>)>,
    player_query: Query<(), With<Player>>,
    active_inventory_query: Query<Entity, With<ActiveInventory>>,
    item_query: Query<&Item>,
    root_query: Query<Entity, With<UiRoot>>,
) {
    let Ok(root) = root_query.single() else {
        error!("Query contains more than one UiRoot");
        return;
    };
    let ui_slot_image: Handle<Image> = asset_server.load(UI_SLOT_ASSET_PATH);
    let temp_item_image: Handle<Image> = asset_server.load(TEMP_ITEM_PATH);
    let (mut player_inventory_ids, mut active_inventory_ids) = (Vec::new(), Vec::new());
    for (inventory_parent, inventory_entity, inventory, children) in inventory_query.iter().sort::<Entity>() {
        let is_player = match inventory_parent {
            Some(parent) => {
                if player_query.get(parent.0)
                    .is_ok() { true }
                else {
                    if active_inventory_query.get(inventory_entity)
                        .is_ok() { false }
                    else { continue; }
                }
            },
            None => {
                if active_inventory_query.get(inventory_entity)
                    .is_ok() { false }
                else { continue; }
            },
        };
        let items = match children {
            Some(children) => {
                children.iter().filter_map(|item_entity| {
                    match item_query.get(item_entity) {
                        Ok(item) => Some((item, item_entity)),
                        Err(_) => None,
                    }
                }).collect::<Vec<(&Item, Entity)>>()
            }
            None => Vec::new(),
        };
        let inventory_id = commands.spawn(ui_inventory_bundle(inventory, inventory_entity))
            .with_children(|commands| {
                for x in 0..inventory.size.x { for y in 0..inventory.size.y {
                    let mut slot_commands = commands.spawn(inventory_slot_bundle(x, y, ui_slot_image.clone()));
                    slot_commands.observe(on_slot_over)
                        .observe(on_slot_out)
                        .observe(on_item_drag_drop);
                    if let Some((item, entity)) = items.iter()
                        .find(|(i, _)| i.position.unwrap_or_default() == UVec2::new(x, y)) {
                        slot_commands.with_children(|commands| {
                            commands.spawn(ui_item_bundle(item, *entity, temp_item_image.clone()))
                                .observe(on_item_over)
                                .observe(on_item_out)
                                .observe(on_item_drag_start)
                                .observe(on_item_drag)
                                .observe(on_item_drag_end);
                        });
                    }
                } }
            }).id();
        if is_player {
            player_inventory_ids.push(inventory_id);
        } else {
            active_inventory_ids.push(inventory_id);
        }
    }
    let player_inventory_manager = commands.spawn(ui_manager_bundle(player_inventory_ids, true)).id();
    let active_inventory_manager = commands.spawn(ui_manager_bundle(active_inventory_ids, false)).id();
    for entity in active_inventory_query {
        commands.entity(entity).remove::<ActiveInventory>();
    }
    commands.entity(root).add_children(&[player_inventory_manager, active_inventory_manager]);
}

pub fn clear_ui_inventory(
    mut commands: Commands,
    inventory_query: Query<Entity, With<UiInventoryManager>>,
) {
    for entity in inventory_query {
        commands.entity(entity).despawn();
    }
}