console_integration.rs

use bevy::{ecs::event::Events, prelude::*};
use bevy_console::{AddConsoleCommand, ConsoleCommand, ConsolePlugin, PrintConsoleLine};
use bevy_mod_scripting::prelude::*;
use bevy_script_api::common::bevy::ScriptWorld;
use clap::Parser;
/// custom Rhai API, world is provided as a usize (by the script this time), since
/// Rhai does not allow global/local variable access from a callback
#[derive(Default)]
pub struct RhaiAPI;

impl APIProvider for RhaiAPI {
    type APITarget = Engine;
    type DocTarget = RhaiDocFragment;
    type ScriptContext = RhaiContext;

    fn attach_api(&mut self, engine: &mut Self::APITarget) -> Result<(), ScriptError> {
        // rhai allows us to decouple the api from the script context,
        // so here we do not have access to the script scope, but the advantage is that
        // this single engine is shared with all of our scripts.
        // we can also set script wide settings here like this one for all our scripts.

        engine.set_max_expr_depths(0, 0);

        engine.register_fn(
            "print_to_console",
            |world: &mut ScriptWorld, msg: String| {
                let mut world = world.write();

                let mut events: Mut<Events<PrintConsoleLine>> = world.get_resource_mut().unwrap();
                events.send(PrintConsoleLine { line: msg });
            },
        );

        engine.register_fn("entity_id", |entity: Entity| entity.index());

        Ok(())
    }

    fn setup_script(
        &mut self,
        _: &ScriptData,
        _: &mut Self::ScriptContext,
    ) -> Result<(), ScriptError> {
        Ok(())
    }
}

// sends updates to script host which are then handled by the scripts
// in the designated system sets
pub fn trigger_on_update_rhai(mut w: PriorityEventWriter<RhaiEvent<()>>) {
    let event = RhaiEvent {
        hook_name: "on_update".to_string(),
        args: (),
        recipients: Recipients::All,
    };

    w.send(event, 0);
}

pub fn forward_script_err_to_console(
    mut r: EventReader<ScriptErrorEvent>,
    mut w: EventWriter<PrintConsoleLine>,
) {
    for e in r.read() {
        w.send(PrintConsoleLine {
            line: format!("ERROR:{}", e.error),
        });
    }
}

// we use bevy-debug-console to demonstrate how this can fit in in the runtime of a game
// note that using just the entity id instead of the full Entity has issues,
// but since we aren't despawning/spawning entities this works in our case
#[derive(Parser, ConsoleCommand)]
#[command(name = "run_script")]
///Runs a Lua script from the `assets/scripts` directory
pub struct RunScriptCmd {
    /// the relative path to the script, e.g.: `/hello.lua` for a script located in `assets/scripts/hello.lua`
    pub path: String,

    /// the entity id to attach this script to
    pub entity: Option<u32>,
}

pub fn run_script_cmd(
    mut log: ConsoleCommand<RunScriptCmd>,
    server: Res<AssetServer>,
    mut commands: Commands,
    mut existing_scripts: Query<&mut ScriptCollection<RhaiFile>>,
) {
    if let Some(Ok(RunScriptCmd { path, entity })) = log.take() {
        let handle = server.load::<RhaiFile>(&format!("scripts/{}", &path));

        match entity {
            Some(e) => {
                if let Ok(mut scripts) = existing_scripts.get_mut(Entity::from_raw(e)) {
                    info!("Creating script: scripts/{} {:?}", &path, e);

                    scripts.scripts.push(Script::<RhaiFile>::new(path, handle));
                } else {
                    log.reply_failed("Something went wrong".to_string());
                };
            }
            None => {
                info!("Creating script: scripts/{}", &path);

                commands.spawn(()).insert(ScriptCollection::<RhaiFile> {
                    scripts: vec![Script::<RhaiFile>::new(path, handle)],
                });
            }
        };
    }
}

pub fn delete_script_cmd(
    mut log: ConsoleCommand<DeleteScriptCmd>,
    mut scripts: Query<(Entity, &mut ScriptCollection<RhaiFile>)>,
) {
    if let Some(Ok(DeleteScriptCmd { name, entity_id })) = log.take() {
        for (e, mut s) in scripts.iter_mut() {
            if e.index() == entity_id {
                let old_len = s.scripts.len();
                s.scripts.retain(|s| s.name() != name);

                if old_len > s.scripts.len() {
                    log.reply_ok(format!("Deleted script {}, on entity: {}", name, entity_id));
                } else {
                    log.reply_failed(format!(
                        "Entity {} did own a script named: {}",
                        entity_id, name
                    ))
                };
                return;
            }
        }

        log.reply_failed("Could not find given entity ID with a script")
    }
}

#[derive(Parser, ConsoleCommand)]
#[command(name = "delete_script")]
///Runs a Lua script from the `assets/scripts` directory
pub struct DeleteScriptCmd {
    ///the name of the script
    pub name: String,

    ///the entity the script is attached to
    pub entity_id: u32,
}

fn main() -> std::io::Result<()> {
    let mut app = App::new();
    app.add_plugins(DefaultPlugins)
        .add_plugins(ScriptingPlugin)
        .add_plugins(ConsolePlugin)
        // register bevy_console commands
        .add_console_command::<RunScriptCmd, _>(run_script_cmd)
        .add_console_command::<DeleteScriptCmd, _>(delete_script_cmd)
        // choose and register the script hosts you want to use
        .add_script_host::<RhaiScriptHost<()>>(PostUpdate)
        .add_api_provider::<RhaiScriptHost<()>>(Box::new(RhaiAPI))
        .add_api_provider::<RhaiScriptHost<()>>(Box::new(RhaiBevyAPIProvider))
        .add_script_handler::<RhaiScriptHost<()>, 0, 0>(PostUpdate)
        // add your systems
        .add_systems(Update, trigger_on_update_rhai)
        .add_systems(Update, forward_script_err_to_console);

    info!("press '~' to open the console. Type in `run_script \"console_integration.rhai\"` to run example script!");

    app.run();

    Ok(())
}