use std::{
    collections::HashMap,
    path::Path,
    sync::{Mutex, MutexGuard},
};

use lazy_static::lazy_static;
use mlua::{Lua, UserData};

use crate::lua::{ownedfunction::OwnedFunction, runnable::Runnable};

use super::{register::SheetId, tablized::Tablized};

lazy_static! {
    static ref GLOBAL_LOADER: Mutex<Loader> = Mutex::new(Loader::new());
}

#[derive(Default)]
pub struct Loader {
    loaders: HashMap<String, Box<dyn Runnable<String, Tablized>>>,
}

impl Loader {
    pub fn new() -> Self {
        Self {
            loaders: HashMap::new(),
        }
    }

    pub fn load_sheet(&self, path: String, lua: &Lua) -> Option<SheetId> {
        let p = Path::new(&path);
        let loader = self.loaders.get(p.extension()?.to_str()?)?;
        match loader.run(path, lua) {
            Ok(table) => table.to_sheet(lua).ok(),
            Err(_) => None,
        }
    }

    pub fn add(&mut self, extension: String, func: Box<dyn Runnable<String, Tablized>>) {
        self.loaders.insert(extension, func);
    }

    pub fn get() -> MutexGuard<'static, Loader> {
        GLOBAL_LOADER.lock().unwrap()
    }
}

impl UserData for Loader {
    fn add_methods<'lua, M: mlua::prelude::LuaUserDataMethods<'lua, Self>>(methods: &mut M) {
        methods.add_function("add", |_, (extension, func): (String, OwnedFunction)| {
            GLOBAL_LOADER.lock().unwrap().add(extension, Box::new(func));
            Ok(())
        });
    }
}