bevy_ecs_tiled 0.12.0

//! Asset loader for Tiled worlds.
//!
//! This module defines the asset loader implementation for importing Tiled worlds into Bevy's asset system.

use crate::{
    prelude::*,
    tiled::{cache::TiledResourceCache, reader::BytesResourceReader},
};
use bevy::{
    asset::{io::Reader, AssetLoader, AssetPath, LoadContext},
    prelude::*,
};

/// [`TiledWorldAsset`] loading error.
#[derive(Debug, thiserror::Error)]
pub enum TiledWorldLoaderError {
    /// An [`IO`](std::io) Error
    #[error("Could not load Tiled file: {0}")]
    Io(#[from] std::io::Error),
    /// No map was found in this world
    #[error("No map found in this world")]
    EmptyWorld,
    /// Found an infinite map in this world which is not supported
    #[error("Infinite map found in this world (not supported)")]
    WorldWithInfiniteMap,
}

#[derive(TypePath)]
pub(crate) struct TiledWorldLoader {
    cache: TiledResourceCache,
}

impl FromWorld for TiledWorldLoader {
    fn from_world(world: &mut World) -> Self {
        Self {
            cache: world.resource::<TiledResourceCache>().clone(),
        }
    }
}

impl AssetLoader for TiledWorldLoader {
    type Asset = TiledWorldAsset;
    type Settings = ();
    type Error = TiledWorldLoaderError;

    async fn load(
        &self,
        reader: &mut dyn Reader,
        _settings: &Self::Settings,
        load_context: &mut LoadContext<'_>,
    ) -> Result<Self::Asset, Self::Error> {
        let mut bytes = Vec::new();
        reader.read_to_end(&mut bytes).await?;

        debug!("Start loading world '{}'", load_context.path());

        let world_path = load_context.path().path().to_path_buf();

        let world = {
            let mut loader = tiled::Loader::with_cache_and_reader(
                self.cache.clone(),
                BytesResourceReader::new(&bytes, load_context),
            );
            loader
                .load_world(&world_path)
                .map_err(|e| std::io::Error::other(format!("Could not load Tiled world: {e}")))?
        };

        if world.maps.is_empty() {
            return Err(TiledWorldLoaderError::EmptyWorld);
        }

        // Calculate the full rect of the world
        let mut world_rect = Rect::new(0.0, 0.0, 0.0, 0.0);
        for map in world.maps.iter() {
            let (Some(map_width), Some(map_height)) = (map.width, map.height) else {
                // Assume that we cannot get map width / map height because it's an infinite map
                return Err(TiledWorldLoaderError::WorldWithInfiniteMap);
            };
            let map_rect = Rect::new(
                map.x as f32,
                map.y as f32, // Invert for Tiled to Bevy Y axis
                map.x as f32 + map_width as f32,
                map.y as f32 + map_height as f32,
            );

            world_rect = world_rect.union(map_rect);
        }

        // Load all maps
        let mut maps = Vec::new();
        for map in world.maps.iter() {
            // Seems safe to unwrap() here since we do it on the world path (which should always have a parent)
            let map_path = world_path.parent().unwrap().join(map.filename.clone());

            let (Some(map_width), Some(map_height)) = (map.width, map.height) else {
                // Assume that we cannot get map width / map height because it's an infinite map
                return Err(TiledWorldLoaderError::WorldWithInfiniteMap);
            };

            maps.push((
                Rect::new(
                    map.x as f32,
                    world_rect.max.y - map_height as f32 - map.y as f32, // Invert for Tiled to Bevy Y axis
                    map.x as f32 + map_width as f32,
                    world_rect.max.y - map.y as f32,
                ),
                load_context.load(AssetPath::from(map_path)),
            ));
        }

        trace!(?maps, "maps");

        let world = TiledWorldAsset {
            world,
            rect: world_rect,
            maps,
        };
        debug!("Loaded world '{}': {:?}", load_context.path(), world);
        Ok(world)
    }

    fn extensions(&self) -> &[&str] {
        static EXTENSIONS: &[&str] = &["world"];
        EXTENSIONS
    }
}

pub(crate) fn plugin(app: &mut App) {
    app.init_asset_loader::<TiledWorldLoader>();
}