//-----------------------------------------------------------------------------
//     ___                      __ _       _
//    / _ \__ _ _ __ ___  ___  / /(_)_ __ | | __
//   / /_)/ _` | '__/ __|/ _ \/ / | | '_ \| |/ /
//  / ___/ (_| | |  \__ \  __/ /__| | | | |   <
//  \/    \__,_|_|  |___/\___\____/_|_| |_|_|\_\ .
//
//-----------------------------------------------------------------------------
// Author: Kurt Sassenrath
// Module: Proto
//
// Parser implementations for various msgpack messages.
//
// Copyright (c) 2023 Kurt Sassenrath.
//
// License TBD.
//-----------------------------------------------------------------------------

#include "parselink/proto/parser.h"
#include "parselink/logging.h"

#include "parselink/msgpack/core/unpacker.h"

namespace parselink {
namespace proto {

namespace {

logging::logger logger{"parser"};

constexpr auto assign(auto& param, msgpack::unpacker& unpacker) noexcept
        -> tl::expected<void, error> {
    auto do_assign = [&param](auto&& v) { param = v; };
    return unpacker.unpack<std::decay_t<decltype(param)>>()
            .map(do_assign)
            .map_error([](auto) { return error::bad_data; });
}

} // anonymous namespace

tl::expected<connect_message, error> parse_connect_message(
        std::span<std::byte const> data) noexcept {
    msgpack::unpacker unpacker(data);
    connect_message msg;

    constexpr static tl::unexpected<error> bad_data(error::bad_data);

    auto type = unpacker.unpack<std::string_view>();
    if (!type || type != "connect") return bad_data;

    auto entries = unpacker.unpack<msgpack::map_desc>();
    if (!entries) return bad_data;

    for (auto i = entries->count; i != 0; --i) {
        auto key = unpacker.unpack<std::string_view>();
        if (!key) return bad_data;
        if (key == "version") {
            if (auto val = assign(msg.version, unpacker)) continue;
        } else if (key == "user_id") {
            if (auto val = assign(msg.user_id, unpacker)) continue;
        }
        logger.debug("Unknown key: {}", *key);
        return bad_data;
    }

    return msg;
}

} // namespace proto
} // namespace parselink