use crate::context::Context;

pub struct Runner{
	lua:mlua::Lua,
}
#[derive(Debug)]
pub enum Error{
	Lua{
		source:String,
		error:mlua::Error
	},
	RustLua(mlua::Error),
	Script(super::instance::GetScriptError),
}
impl std::fmt::Display for Error{
	fn fmt(&self,f:&mut std::fmt::Formatter<'_>)->std::fmt::Result{
		match self{
			Self::Lua{source,error:mlua::Error::RuntimeError(s)}=>write!(f,"lua error: {s}\nsource:{source}"),
			Self::RustLua(mlua::Error::RuntimeError(s))=>write!(f,"rust-side lua error: {s}"),
			other=>write!(f,"{other:?}"),
		}
	}
}

fn init(lua:&mlua::Lua)->mlua::Result<()>{
	lua.sandbox(true)?;

	//global environment
	let globals=lua.globals();

	super::vector3::set_globals(lua,&globals)?;
	super::cframe::set_globals(lua,&globals)?;

	Ok(())
}

impl Runner{
	pub fn new()->Result<Self,Error>{
		let runner=Self{
			lua:mlua::Lua::new(),
		};
		init(&runner.lua).map_err(Error::RustLua)?;
		Ok(runner)
	}
	pub fn run_script(&self,script:super::instance::Script,context:&mut Context)->Result<(),Error>{
		let (name,source)=script.get_name_source(context).map_err(Error::Script)?;
		self.lua.globals().set("script",script).map_err(Error::RustLua)?;
		//this makes set_app_data shut up about the lifetime
		self.lua.set_app_data::<&'static mut rbx_dom_weak::WeakDom>(unsafe{core::mem::transmute(&mut context.dom)});
		let r=self.lua.load(source.as_str())
		.set_name(name)
		.exec().map_err(|error|Error::Lua{source,error});
		self.lua.remove_app_data::<&'static mut rbx_dom_weak::WeakDom>();
		r?;
		Ok(())
	}
}