use crate::{
    types::{FuncSig, Map, SigIndex, MapIndex},
    vm,
};
use hashbrown::HashMap;

pub struct SigRegistry {
    func_table: HashMap<FuncSig, SigIndex>,
    sig_assoc: Map<SigIndex, FuncSig>,
}

impl SigRegistry {
    pub fn new() -> Self {
        Self {
            func_table: HashMap::new(),
            sig_assoc: Map::new(),
        }
    }
    
    pub fn register(&mut self, func_sig: FuncSig) -> SigIndex {
        let func_table = &mut self.func_table;
        let sig_assoc = &mut self.sig_assoc;
        *func_table.entry(func_sig.clone()).or_insert_with(|| {
            sig_assoc.push(func_sig)
        })
    }

    pub fn lookup_func_sig(&self, sig_index: SigIndex) -> &FuncSig {
        &self.sig_assoc[sig_index]
    }

    pub(crate) fn into_vm_sigid(&self) -> Box<[vm::SigId]> {
        let v: Vec<_> = self.sig_assoc.iter().map(|(sig_index, _)| vm::SigId(sig_index.index() as u32)).collect();
        v.into_boxed_slice()
    }
}