use std::sync::{Arc, RwLock};

use mlua::{UserData, Value};

use super::{Sheet, SheetLuaRef};

static REGISTER: RwLock<Vec<Arc<RwLock<Sheet>>>> = RwLock::new(Vec::new());

pub type SheetId = usize;

#[derive(Debug)]
pub struct Register;

impl Register {
    pub fn create(width: usize, height: usize) -> SheetId {
        let mut register = REGISTER.write().unwrap();

        let id = register.len();
        let sheet = Sheet::new(width, height, id);
        register.push(Arc::new(RwLock::new(sheet)));
        id
    }

    pub fn get<'a>(id: SheetId) -> Option<Arc<RwLock<Sheet>>> {
        let register = REGISTER.read().unwrap();

        if id < register.len() {
            Some(Arc::clone(&register[id]))
        } else {
            None
        }
    }
}

impl UserData for Register {
    fn add_methods<'lua, M: mlua::UserDataMethods<'lua, Self>>(methods: &mut M) {
        methods.add_function_mut("create", |lua, (width, height): (usize, usize)| {
            let id = Register::create(width, height);
            let luaref = SheetLuaRef::new(id);
            if let Ok(ud) = lua.create_userdata(luaref) {
                Ok(Value::UserData(ud))
            } else {
                Ok(Value::Nil)
            }
        });

        methods.add_function_mut("get", |lua, id: SheetId| {
            if let Some(_) = Register::get(id) {
                let luaref = SheetLuaRef::new(id);
                if let Ok(ud) = lua.create_userdata(luaref) {
                    Ok(Value::UserData(ud))
                } else {
                    Ok(Value::Nil)
                }
            } else {
                Ok(Value::Nil)
            }
        })
    }
}