use std::cell::RefCell;

pub struct Ctxt {
    errors: RefCell<Option<Vec<syn::Error>>>,
}

impl Ctxt {
    pub fn new() -> Self {
        Self {
            errors: RefCell::new(Some(Vec::new())),
        }
    }

    pub fn syn_error(&self, err: syn::Error) {
        self.errors.borrow_mut().as_mut().unwrap().push(err)
    }

    pub fn check(self) -> syn::Result<()> {
        let mut errors = self.errors.take().unwrap().into_iter();

        let mut combined = match errors.next() {
            Some(first) => first,
            None => return Ok(()),
        };

        for rest in errors {
            combined.combine(rest);
        }

        Err(combined)
    }
}

impl Drop for Ctxt {
    fn drop(&mut self) {
        if !std::thread::panicking() && self.errors.borrow().is_some() {
            panic!("forgot to check for errors");
        }
    }
}