use super::*;
use core::hash::Hash;
use std::hash::Hasher;

// Types implementing this trait can be stored in the internpool.
trait KeyTrait: Hash + Eq {
    const TAG: Tag;
    fn serialise(self, pool: &mut InternPool);
    fn deserialise(index: Index, pool: &mut InternPool) -> Self;
}

impl KeyTrait for String {
    const TAG: Tag = Tag::String;
    fn serialise(self, pool: &mut InternPool) {
        todo!()
    }

    fn deserialise(index: Index, pool: &mut InternPool) -> Self {
        // let mut hasher = std::hash::DefaultHasher::new();
        // core::any::TypeId::of::<Self>().hash(&mut hasher);
        // let tag = hasher.finish() as u32;
        let item = pool.get_item(index).unwrap();
        assert_eq!(item.tag, Self::TAG);

        let start = pool.words[item.idx()] as usize;
        let len = pool.words[item.idx() + 1] as usize;
        let str = unsafe {
            let bytes = &pool.strings[start..start + len];
            std::str::from_utf8_unchecked(bytes)
        };

        str.to_owned()
    }
}