//! Symmetric and asymmetric waku messages [decrypting](https://rfc.vac.dev/spec/36/#decrypting-messages) methods

// std
use std::ffi::{CStr, CString};
// crates
use aes_gcm::{Aes256Gcm, Key};
use secp256k1::SecretKey;
// internal
use crate::general::{DecodedPayload, JsonResponse, Result, WakuMessage};

/// Decrypt a message using a symmetric key
///
/// As per the [specification](https://rfc.vac.dev/spec/36/#extern-char-waku_decode_symmetricchar-messagejson-char-symmetrickey)
pub fn waku_decode_symmetric(
    message: &WakuMessage,
    symmetric_key: &Key<Aes256Gcm>,
) -> Result<DecodedPayload> {
    let symk = hex::encode(symmetric_key.as_slice());
    let result = unsafe {
        CStr::from_ptr(waku_sys::waku_decode_symmetric(
            CString::new(
                serde_json::to_string(&message)
                    .expect("WakuMessages should always be able to success serializing"),
            )
            .expect("CString should build properly from the serialized waku message")
            .into_raw(),
            CString::new(symk)
                .expect("CString should build properly from hex encoded symmetric key")
                .into_raw(),
        ))
    }
    .to_str()
    .expect("Response should always succeed to load to a &str");
    let response: JsonResponse<DecodedPayload> =
        serde_json::from_str(result).map_err(|e| format!("{e}"))?;
    response.into()
}

/// Decrypt a message using a symmetric key
///
/// As per the [specification](extern char* waku_decode_asymmetric(char* messageJson, char* privateKey))
pub fn waku_decode_asymmetric(
    message: &WakuMessage,
    asymmetric_key: &SecretKey,
) -> Result<DecodedPayload> {
    let sk = hex::encode(asymmetric_key.secret_bytes());
    let result = unsafe {
        CStr::from_ptr(waku_sys::waku_decode_asymmetric(
            CString::new(
                serde_json::to_string(&message)
                    .expect("WakuMessages should always be able to success serializing"),
            )
            .expect("CString should build properly from the serialized waku message")
            .into_raw(),
            CString::new(sk)
                .expect("CString should build properly from hex encoded symmetric key")
                .into_raw(),
        ))
    }
    .to_str()
    .expect("Response should always succeed to load to a &str");
    let response: JsonResponse<DecodedPayload> =
        serde_json::from_str(result).map_err(|e| format!("{e}"))?;
    response.into()
}