#![doc = include_str!("../README.md")]
#![warn(missing_docs)]
#![warn(clippy::missing_const_for_fn)]

use js_sys::JsString;
use wasm_bindgen::prelude::*;

mod de;
mod error;
mod ser;

pub use de::Deserializer;
pub use error::Error;
pub use ser::Serializer;

type Result<T> = std::result::Result<T, Error>;

fn static_str_to_js(s: &'static str) -> JsString {
    use std::cell::RefCell;
    use std::collections::HashMap;

    #[derive(Default)]
    struct PtrHasher {
        addr: usize,
    }

    impl std::hash::Hasher for PtrHasher {
        fn write(&mut self, _bytes: &[u8]) {
            unreachable!();
        }

        fn write_usize(&mut self, addr_or_len: usize) {
            if self.addr == 0 {
                self.addr = addr_or_len;
            }
        }

        fn finish(&self) -> u64 {
            self.addr as _
        }
    }

    type PtrBuildHasher = std::hash::BuildHasherDefault<PtrHasher>;

    thread_local! {
        // Since we're mainly optimising for converting the exact same string literal over and over again,
        // which will always have the same pointer, we can speed things up by indexing by the string's pointer
        // instead of its value.
        static CACHE: RefCell<HashMap<*const str, JsString, PtrBuildHasher>> = Default::default();
    }
    CACHE.with(|cache| {
        cache
            .borrow_mut()
            .entry(s)
            .or_insert_with(|| s.into())
            .clone()
    })
}

/// Custom bindings to avoid using fallible `Reflect` for plain objects.
#[wasm_bindgen]
extern "C" {
    type ObjectExt;

    #[wasm_bindgen(method, indexing_getter)]
    fn get_with_ref_key(this: &ObjectExt, key: &JsString) -> JsValue;

    #[wasm_bindgen(method, indexing_setter)]
    fn set(this: &ObjectExt, key: JsString, value: JsValue);
}

/// Converts [`JsValue`] into a Rust type.
pub fn from_value<T: serde::de::DeserializeOwned>(value: JsValue) -> Result<T> {
    T::deserialize(Deserializer::from(value))
}

/// Converts a Rust value into a [`JsValue`].
pub fn to_value<T: serde::ser::Serialize + ?Sized>(value: &T) -> Result<JsValue> {
    value.serialize(&Serializer::new())
}