examples/testbed/scripts/test.lua

@@ -1,7 +1,25 @@
 print("Hello World")
 
-function update()
-    print("updated")
-    --printf("I love to eat formatted {}!", "food")
-    --printf("World is {}", world)
+function on_init()
+    print("Lua script was initialized!")
+end
+
+function on_first()
+    print("Lua's first function was called")
+end
+
+function on_pre_update()
+    print("Lua's pre-update function was called")
+end
+
+function on_update()
+    print("Lua's update function was called")
+end
+
+function on_post_update()
+    print("Lua's post-update function was called")
+end
+
+function on_last()
+    print("Lua's last function was called")
 end

lyra-scripting/src/host.rs

@@ -1,6 +1,6 @@
 use std::collections::HashMap;
 
-use lyra_ecs::ResourceObject;
+use lyra_ecs::{ResourceObject, Entity};
 
 use crate::ScriptWorldPtr;
 
@@ -29,8 +29,12 @@ impl From<anyhow::Error> for ScriptError {
 
 #[derive(Clone, Hash, PartialEq, Eq)]
 pub struct ScriptData {
+    /// The script id
     pub script_id: u64,
+    /// The name of the script
     pub name: String,
+    /// The entity that this script exists on
+    pub entity: Entity,
 }
 
 /// Provides an API to a scripting context.
@@ -41,9 +45,7 @@ pub trait ScriptApiProvider {
     /// Exposes an API in the provided script context.
     fn expose_api(&mut self, ctx: &mut Self::ScriptContext) -> Result<(), ScriptError>;
 
-    /// Create a script in the script host.
-    /// 
-    /// This only creates the script for the host, it does not setup the script for execution. See [`ScriptHostProvider::setup_script`].
+    /// Setup a script right before its 'init' method is called.
     fn setup_script(&mut self, data: &ScriptData, ctx: &mut Self::ScriptContext) -> Result<(), ScriptError>;
 
     /// A function that is used to update a script's environment.
@@ -74,13 +76,18 @@ pub trait ScriptHost: Default + ResourceObject {
     /// Loads a script and creates a context for it.
     /// 
     /// Before the script is executed, the API providers are exposed to the script.
-    fn load_script(&mut self, script: &[u8], script_data: &ScriptData, providers: &mut crate::ScriptApiProviders<Self>) -> Result<Self::ScriptContext, ScriptError>;
+    fn load_script(&mut self, script: &[u8], script_data: &ScriptData,
+        providers: &mut crate::ScriptApiProviders<Self>)
+        -> Result<Self::ScriptContext, ScriptError>;
 
     /// Setup a script for execution.
-    fn setup_script(&mut self, script_data: &ScriptData, ctx: &mut Self::ScriptContext, providers: &mut ScriptApiProviders<Self>) -> Result<(), ScriptError>;
+    fn setup_script(&mut self, script_data: &ScriptData, ctx: &mut Self::ScriptContext,
+        providers: &mut ScriptApiProviders<Self>) -> Result<(), ScriptError>;
 
     /// Executes the update step for the script.
-    fn update_script(&mut self, world: ScriptWorldPtr, script_data: &crate::ScriptData, ctx: &mut Self::ScriptContext, providers: &mut crate::ScriptApiProviders<Self>) -> Result<(), ScriptError>;
+    fn call_script(&mut self, world: ScriptWorldPtr, script_data: &crate::ScriptData,
+        ctx: &mut Self::ScriptContext, providers: &mut crate::ScriptApiProviders<Self>,
+        function_name: &str) -> Result<(), ScriptError>;
 }
 
 #[derive(Default)]

lyra-scripting/src/lua/mod.rs

@@ -2,7 +2,7 @@ pub mod dynamic_iter;
 pub use dynamic_iter::*;
 
 pub mod world;
-use lyra_game::plugin::Plugin;
+use lyra_game::{plugin::Plugin, game::GameStages};
 use lyra_resource::ResourceManager;
 use tracing::{debug, error};
 pub use world::*;
@@ -13,20 +13,25 @@ pub use script::*;
 pub mod loader;
 pub use loader::*;
 
+pub mod modules;
+pub use modules::*;
+
 #[cfg(test)]
 mod test;
 
 use std::{ptr::NonNull, sync::Mutex};
 
-use lyra_ecs::{DynamicBundle, World};
-use lyra_reflect::{Reflect, RegisteredType, FromType, AsRegisteredType};
+use lyra_ecs::{DynamicBundle, World, query::{ResMut, View, Entities}};
+use lyra_reflect::{Reflect, FromType};
 
 use mlua::{Lua, AnyUserDataExt};
 
+pub type LuaContext = Mutex<mlua::Lua>;
+
 pub const FN_NAME_INTERNAL_REFLECT_TYPE: &str = "__lyra_internal_reflect_type";
 pub const FN_NAME_INTERNAL_REFLECT: &str = "__lyra_internal_reflect";
 
-use crate::{ScriptBorrow, ScriptDynamicBundle, ScriptApiProviders, ScriptContexts, ScriptWorldPtr, ScriptList, ScriptData, ScriptHost, ScriptError};
+use crate::{ScriptBorrow, ScriptDynamicBundle, ScriptApiProviders, ScriptContexts, ScriptWorldPtr, ScriptList, ScriptData, ScriptHost, ScriptError, GameScriptExt};
 
 impl<'lua> mlua::FromLua<'lua> for ScriptBorrow {
     fn from_lua(value: mlua::Value<'lua>, _lua: &'lua Lua) -> mlua::Result<Self> {
@@ -115,18 +120,24 @@ impl mlua::UserData for ScriptDynamicBundle {
     }
 }
 
-/// A system that updates the scripts that exist in the world
-pub fn lua_update_scripts(world: &mut World) -> anyhow::Result<()> {
-    let world_ptr = ScriptWorldPtr::from_ref(&world);
-    let mut host = world.get_resource_mut::<LuaHost>();
-    let mut contexts = world.get_resource_mut::<ScriptContexts<Mutex<mlua::Lua>>>();
-    let mut providers = world.get_resource_mut::<ScriptApiProviders<LuaHost>>();
+/// 
+/* fn lua_script_run_func(world: &mut World, function_name: &str) -> anyhow::Result<()> {
 
-    for scripts in world.view_iter::<&ScriptList<LuaScript>>() {
+} */
+
+/// A system that creates the script contexts in the world as new scripts are found
+pub fn lua_scripts_create_contexts(mut host: ResMut<LuaHost>,
+        mut contexts: ResMut<ScriptContexts<LuaContext>>,
+        mut providers: ResMut<ScriptApiProviders<LuaHost>>,
+        view: View<(Entities, &ScriptList<LuaScript>)>,
+    ) -> anyhow::Result<()> {
+
+    for (en, scripts) in view.into_iter() {
         for script in scripts.iter() {
             let script_data = ScriptData {
                 name: script.name().to_string(),
                 script_id: script.id(),
+                entity: en,
             };
 
             if !contexts.has_context(script.id()) {
@@ -144,11 +155,29 @@ pub fn lua_update_scripts(world: &mut World) -> anyhow::Result<()> {
                     debug!("Script '{}' is not yet loaded, skipping", script.name());
                 }
             }
+        }
+    }
     
-            let ctx = contexts.get_context_mut(script.id()).unwrap();
+    Ok(())
+}
 
-            debug!("Running 'update' function in script '{}'", script.name());
-            match host.update_script(world_ptr.clone(), &script_data, ctx, &mut providers) {
+fn lua_call_script_function(world: &mut World, stage_name: &str) -> anyhow::Result<()> {
+    let world_ptr = ScriptWorldPtr::from_ref(&world);
+    let mut host = world.get_resource_mut::<LuaHost>();
+    let mut contexts = world.get_resource_mut::<ScriptContexts<LuaContext>>();
+    let mut providers = world.get_resource_mut::<ScriptApiProviders<LuaHost>>();
+
+    for (en, scripts) in world.view_iter::<(Entities, &ScriptList<LuaScript>)>() {
+        for script in scripts.iter() {
+            let script_data = ScriptData {
+                name: script.name().to_string(),
+                script_id: script.id(),
+                entity: en,
+            };
+
+            if let Some(ctx) = contexts.get_context_mut(script.id()) {
+                debug!("Running '{}' function in script '{}'", stage_name, script.name());
+                match host.call_script(world_ptr.clone(), &script_data, ctx, &mut providers, stage_name) {
                     Ok(()) => {},
                     Err(e) => match e {
                         ScriptError::MluaError(m) => {
@@ -159,10 +188,41 @@ pub fn lua_update_scripts(world: &mut World) -> anyhow::Result<()> {
                 }
             }
         }
+    }
     
     Ok(())
 }
 
+/// This system executes the 'on_update' function of lua scripts in the world. It is meant to run
+/// during the 'GameStages::Update' stage.
+pub fn lua_script_update_stage_system(world: &mut World) -> anyhow::Result<()> {
+    lua_call_script_function(world, "on_update")
+}
+
+/// This system executes the 'on_pre_update' function of lua scripts in the world. It is meant to run
+/// during the 'GameStages::PreUpdate' stage.
+pub fn lua_script_pre_update_stage_system(world: &mut World) -> anyhow::Result<()> {
+    lua_call_script_function(world, "on_pre_update")
+}
+
+/// This system executes the 'on_post_update' function of lua scripts in the world. It is meant to run
+/// during the 'GameStages::PostUpdate' stage.
+pub fn lua_script_post_update_stage_system(world: &mut World) -> anyhow::Result<()> {
+    lua_call_script_function(world, "on_post_update")
+}
+
+/// This system executes the 'on_first' function of lua scripts in the world. It is meant to run
+/// during the 'GameStages::First' stage.
+pub fn lua_script_first_stage_system(world: &mut World) -> anyhow::Result<()> {
+    lua_call_script_function(world, "on_first")
+}
+
+/// This system executes the 'on_last' function of lua scripts in the world. It is meant to run
+/// during the 'GameStages::Last' stage.
+pub fn lua_script_last_stage_system(world: &mut World) -> anyhow::Result<()> {
+    lua_call_script_function(world, "on_last")
+}
+
 #[derive(Default)]
 pub struct LuaScriptingPlugin;
 
@@ -172,13 +232,24 @@ impl Plugin for LuaScriptingPlugin {
 
         world.add_resource_default::<LuaHost>();
         world.add_resource_default::<ScriptApiProviders<LuaHost>>();
-        world.add_resource_default::<ScriptContexts<Mutex<mlua::Lua>>>();
+        world.add_resource_default::<ScriptContexts<LuaContext>>();
 
         let mut loader = world.try_get_resource_mut::<ResourceManager>()
             .expect("Add 'ResourceManager' to the world before trying to add this plugin");
         loader.register_loader::<LuaLoader>();
         drop(loader);
 
-        game.with_system("lua_update", lua_update_scripts, &[]);
+        game.add_script_api_provider::<LuaHost, _>(UtilityApiProvider);
+
+        game
+            .add_system_to_stage(GameStages::First, "lua_create_contexts", lua_scripts_create_contexts, &[])
+            .add_system_to_stage(GameStages::First, "lua_first_stage", lua_script_first_stage_system, &["lua_create_contexts"])
+            // cannot depend on 'lua_create_contexts' since it will cause a panic.
+            // the staged executor separates the executor of a single stage so this system
+            // cannot depend on the other one.
+            .add_system_to_stage(GameStages::PreUpdate, "lua_pre_update", lua_script_pre_update_stage_system, &[])
+            .add_system_to_stage(GameStages::Update, "lua_update", lua_script_update_stage_system, &[])
+            .add_system_to_stage(GameStages::PostUpdate, "lua_post_update", lua_script_post_update_stage_system, &[])
+            .add_system_to_stage(GameStages::Last, "lua_last_stage", lua_script_last_stage_system, &[]);
     }
 }

lyra-scripting/src/lua/modules/mod.rs

@@ -0,0 +1,120 @@
+use std::sync::{Mutex, Arc};
+
+use crate::{ScriptApiProvider, ScriptData};
+
+/// This Api provider provides some nice utility functions.
+/// 
+/// Functions:
+/// ```lua
+/// ---@param str (string) A format string.
+/// ---@param ... (any varargs) The variables to format into the string. These values must be
+///     primitives, or if UserData, have the '__tostring' meta method
+/// function printf(str, ...)
+/// ```
+#[derive(Default)]
+pub struct UtilityApiProvider;
+
+impl ScriptApiProvider for UtilityApiProvider {
+    type ScriptContext = Mutex<mlua::Lua>;
+
+    fn expose_api(&mut self, ctx: &mut Self::ScriptContext) -> Result<(), crate::ScriptError> {
+        let ctx = ctx.lock().unwrap();
+
+        fn printf(lua: &mlua::Lua, (mut text, formats): (String, mlua::Variadic<mlua::Value>)) -> mlua::Result<()> {
+            let mut formatted = String::new();
+            let mut arg_num = 0;
+
+            while let Some(start) = text.find("{}") {
+                let val_str = match formats.get(arg_num) {
+                    Some(v) => match v {
+                        mlua::Value::Nil => "nil".to_string(),
+                        mlua::Value::Boolean(b) => b.to_string(),
+                        mlua::Value::LightUserData(_) => {
+                            return Err(mlua::Error::RuntimeError(format!("unable to get string representation of LightUserData")));
+                        },
+                        mlua::Value::Integer(i) => i.to_string(),
+                        mlua::Value::Number(n) => n.to_string(),
+                        mlua::Value::String(s) => s.to_str().unwrap().to_string(),
+                        mlua::Value::Table(_) => {
+                            return Err(mlua::Error::RuntimeError(format!("unable to get string representation of Table")));
+                        },
+                        mlua::Value::Function(_) => {
+                            return Err(mlua::Error::RuntimeError(format!("unable to get string representation of Function")));
+                        },
+                        mlua::Value::Thread(_) => {
+                            return Err(mlua::Error::RuntimeError(format!("unable to get string representation of Thread")));
+                        },
+                        mlua::Value::UserData(ud) => {
+                            let metatable = ud.get_metatable()?;
+                            if let Ok(tos) = metatable.get::<mlua::Function>(mlua::MetaMethod::ToString) {
+                                tos.call::<_, String>((ud.clone(),))?
+                            } else {
+                                return Err(mlua::Error::RuntimeError(format!("UserData does not implement MetaMethod '__tostring'")));
+                            }
+                        },
+                        mlua::Value::Error(e) => e.to_string(),
+                    },
+                    None => {
+                        let got_args = arg_num;
+
+                        // continue searching for {} to get the number of format spots for the error message.
+                        while let Some(start) = text.find("{}") {
+                            text = text[start + 2..].to_string();
+                            arg_num += 1;
+                        }
+
+                        return Err(mlua::Error::BadArgument {
+                            to: Some("printf".to_string()),
+                            pos: 2,
+                            name: Some("...".to_string()),
+                            cause: Arc::new(mlua::Error::RuntimeError(format!("not enough args \
+                                given for the amount of format areas in the string. Expected {}, \
+                                got {}.", arg_num, got_args)))
+                        })
+                    },
+                };
+
+                formatted = format!("{}{}{}", formatted, &text[0..start], val_str);
+
+                text = text[start + 2..].to_string();
+
+                arg_num += 1;
+            }
+
+            if arg_num < formats.len() {
+                return Err(mlua::Error::BadArgument {
+                    to: Some("printf".to_string()),
+                    pos: 2,
+                    name: Some("...".to_string()),
+                    cause: Arc::new(mlua::Error::RuntimeError(format!("got more args \
+                        than format areas in the string. Expected {}, got {}.", formats.len(), arg_num)))
+                })
+            }
+            
+            formatted = format!("{}{}", formatted, text);
+
+            lua.globals()
+                .get::<_, mlua::Function>("print")
+                .unwrap()
+                .call::<_, ()>(formatted)
+                .unwrap();
+
+            Ok(())
+        }
+        
+        let printf_func = ctx.create_function(printf).unwrap();
+
+        let globals = ctx.globals();
+        globals.set("printf", printf_func).unwrap();
+        
+        Ok(())
+    }
+
+    fn setup_script(&mut self, _data: &ScriptData, _ctx: &mut Self::ScriptContext) -> Result<(), crate::ScriptError> {
+        Ok(())
+    }
+
+    fn update_script_environment(&mut self, _world: crate::ScriptWorldPtr, _data: &ScriptData, _ctx: &mut Self::ScriptContext) -> Result<(), crate::ScriptError> {
+        Ok(())
+    }
+}

lyra-scripting/src/lua/script.rs

@@ -1,8 +1,9 @@
 use std::sync::Mutex;
 
+use mlua::IntoLua;
 use tracing::debug;
 
-use crate::{ScriptHost, ScriptError, ScriptWorldPtr};
+use crate::{ScriptHost, ScriptError, ScriptWorldPtr, ScriptEntity};
 
 #[derive(Default)]
 pub struct LuaHost;
@@ -53,7 +54,7 @@ impl ScriptHost for LuaHost {
         }
 
         let ctx = ctx.lock().expect("Failure to get Lua ScriptContext");
-        try_call_lua_function(&ctx, "init")?;
+        try_call_lua_function(&ctx, "on_init")?;
 
         Ok(())
     }
@@ -61,13 +62,20 @@ impl ScriptHost for LuaHost {
     /// Runs the update step of the lua script.
     /// 
     /// It looks for an `update` function with zero parameters in [`the ScriptContext`] and executes it.
-    fn update_script(&mut self, world: ScriptWorldPtr, script_data: &crate::ScriptData, ctx: &mut Self::ScriptContext, providers: &mut crate::ScriptApiProviders<Self>) -> Result<(), ScriptError> {
+    fn call_script(&mut self, world: ScriptWorldPtr, script_data: &crate::ScriptData,
+            ctx: &mut Self::ScriptContext, providers: &mut crate::ScriptApiProviders<Self>,
+            function_name: &str) -> Result<(), ScriptError> {
         for provider in providers.apis.iter_mut() {
             provider.update_script_environment(world.clone(), script_data, ctx)?;
         }
 
         let ctx = ctx.lock().expect("Failure to get Lua ScriptContext");
-        try_call_lua_function(&ctx, "update")?;
+        
+        let globals = ctx.globals();
+        globals.set("world", world.into_lua(&ctx)?)?;
+        globals.set("entity", ScriptEntity(script_data.entity).into_lua(&ctx)?)?;
+        
+        try_call_lua_function(&ctx, function_name)?;
 
         Ok(())
     }

lyra-scripting/src/lua/test.rs

@@ -1,16 +1,13 @@
-use std::{sync::{Mutex, Arc}, alloc::Layout, ptr::NonNull};
+use std::{sync::{Mutex, Arc}, ptr::NonNull};
 
-use lyra_ecs::{World, query::{Res, View, Entities, ResMut}, Component, system::{GraphExecutor, IntoSystem}};
+use lyra_ecs::{World, system::{GraphExecutor, IntoSystem}};
 use lyra_resource::ResourceManager;
 use mlua::{IntoLua, AnyUserDataExt};
-use tracing::{debug, error};
-use tracing_subscriber::{layer::SubscriberExt, fmt, filter, util::SubscriberInitExt};
+use tracing_subscriber::{layer::SubscriberExt, fmt, util::SubscriberInitExt};
 
-use crate::{ScriptHost, ScriptData, ScriptApiProvider, ScriptApiProviders, ScriptError, ScriptWorldPtr, ScriptList, Script, ScriptContexts};
+use crate::{ScriptData, ScriptApiProvider, ScriptApiProviders, ScriptError, ScriptList, Script, ScriptContexts};
 
-use super::{LuaHost, LuaLoader, LuaScript, lua_update_scripts};
-
-use crate::lyra_engine;
+use super::{LuaHost, LuaLoader, LuaScript, lua_script_update_stage_system, lua_scripts_create_contexts, LuaContext};
 
 fn enable_tracing() {
     tracing_subscriber::registry()
@@ -148,7 +145,7 @@ pub fn lua_print() {
 
     world.add_resource(host);
     world.add_resource(providers);
-    world.add_resource(ScriptContexts::<Mutex<mlua::Lua>>::default());
+    world.add_resource(ScriptContexts::<LuaContext>::default());
 
     let mut res_loader = ResourceManager::new();
     res_loader.register_loader::<LuaLoader>();
@@ -174,6 +171,7 @@ pub fn lua_print() {
     world.spawn((scripts,));
 
     let mut exec = GraphExecutor::new();
-    exec.insert_system("lua_update_scripts", lua_update_scripts.into_system(), &[]);
+    exec.insert_system("lua_create_contexts", lua_scripts_create_contexts.into_system(), &[]);
+    exec.insert_system("lua_update_scripts", lua_script_update_stage_system.into_system(), &["lua_create_contexts"]);
     exec.execute(NonNull::from(&world), true).unwrap();
 }

lyra-scripting/src/lua/world.rs

@@ -16,7 +16,13 @@ impl<'lua> mlua::FromLua<'lua> for ScriptEntity {
     }
 }
 
-impl mlua::UserData for ScriptEntity {}
+impl mlua::UserData for ScriptEntity {
+    fn add_methods<'lua, M: mlua::prelude::LuaUserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_meta_method(mlua::MetaMethod::ToString, |_, this, ()| {
+            Ok(format!("{:?}", this.0))
+        })
+    }
+}
 
 #[derive(thiserror::Error, Debug, Clone)]
 pub enum WorldError {

lyra-scripting/src/script.rs

@@ -1,8 +1,12 @@
+use std::sync::atomic::{AtomicU64, Ordering};
+
 use lyra_ecs::Component;
 use lyra_resource::ResHandle;
 
 use crate::lyra_engine;
 
+static SCRIPT_ID_COUNTER: AtomicU64 = AtomicU64::new(0);
+
 #[derive(Clone)]
 pub struct Script<T> {
     res: ResHandle<T>,
@@ -15,7 +19,7 @@ impl<T> Script<T> {
         Self {
             res: script,
             name: name.to_string(),
-            id: 0 // TODO: make a counter
+            id: SCRIPT_ID_COUNTER.fetch_add(1, Ordering::AcqRel)
         }
     }
 

lyra-scripting/src/world.rs

@@ -5,6 +5,14 @@ use lyra_ecs::{world::World, Entity};
 #[derive(Clone)]
 pub struct ScriptEntity(pub Entity);
 
+impl std::ops::Deref for ScriptEntity {
+    type Target = Entity;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
 #[derive(Clone)]
 pub struct ScriptWorldPtr {
     pub inner: NonNull<World>,