// Copyright (c) 2024-present The Bitcoin Core developers

// Distributed under the MIT software license, see the accompanying

// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <musig.h>

#include <secp256k1_musig.h>

bool GetMuSig2KeyAggCache(const std::vector<CPubKey>& pubkeys, secp256k1_musig_keyagg_cache& keyagg_cache)

{

    // Parse the pubkeys

    std::vector<secp256k1_pubkey> secp_pubkeys;

    std::vector<const secp256k1_pubkey*> pubkey_ptrs;

    for (const CPubKey& pubkey : pubkeys) {

        if (!secp256k1_ec_pubkey_parse(secp256k1_context_static, &secp_pubkeys.emplace_back(), pubkey.data(), pubkey.size())) {

            return false;

        }

    }

    pubkey_ptrs.reserve(secp_pubkeys.size());

    for (const secp256k1_pubkey& p : secp_pubkeys) {

        pubkey_ptrs.push_back(&p);

    }

    // Aggregate the pubkey

    if (!secp256k1_musig_pubkey_agg(secp256k1_context_static, nullptr, &keyagg_cache, pubkey_ptrs.data(), pubkey_ptrs.size())) {

        return false;

    }

    return true;

}

std::optional<CPubKey> GetCPubKeyFromMuSig2KeyAggCache(secp256k1_musig_keyagg_cache& keyagg_cache)

{

    // Get the plain aggregated pubkey

    secp256k1_pubkey agg_pubkey;

    if (!secp256k1_musig_pubkey_get(secp256k1_context_static, &agg_pubkey, &keyagg_cache)) {

        return std::nullopt;

    }

    // Turn into CPubKey

    unsigned char ser_agg_pubkey[CPubKey::COMPRESSED_SIZE];

    size_t ser_agg_pubkey_len = CPubKey::COMPRESSED_SIZE;

    secp256k1_ec_pubkey_serialize(secp256k1_context_static, ser_agg_pubkey, &ser_agg_pubkey_len, &agg_pubkey, SECP256K1_EC_COMPRESSED);

    return CPubKey(ser_agg_pubkey, ser_agg_pubkey + ser_agg_pubkey_len);

}

std::optional<CPubKey> MuSig2AggregatePubkeys(const std::vector<CPubKey>& pubkeys)

{

    secp256k1_musig_keyagg_cache keyagg_cache;

    if (!GetMuSig2KeyAggCache(pubkeys, keyagg_cache)) {

        return std::nullopt;

    }

    return GetCPubKeyFromMuSig2KeyAggCache(keyagg_cache);

}