//----------------------------------------------------------------------------- 
//     ___                      __ _       _
//    / _ \__ _ _ __ ___  ___  / /(_)_ __ | | __
//   / /_)/ _` | '__/ __|/ _ \/ / | | '_ \| |/ /
//  / ___/ (_| | |  \__ \  __/ /__| | | | |   <
//  \/    \__,_|_|  |___/\___\____/_|_| |_|_|\_\ .
//
//----------------------------------------------------------------------------- 
// Author: Kurt Sassenrath
// Module: Server
//
// Server implementation. Currently, a monolithic server which:
//     * Communicates with users via TCP (msgpack).
//     * Runs the websocket server for overlays to read.
//
// Copyright (c) 2023 Kurt Sassenrath.
//
// License TBD.
//----------------------------------------------------------------------------- 

#include "parselink/proto/session.h"

#include "parselink/logging.h"
#include "parselink/msgpack/token.h"

using namespace parselink;
using namespace parselink::proto;

namespace {
logging::logger logger("session");
}

tl::expected<header_info, error> session::parse_header(
        std::span<std::byte const> buffer) noexcept {
    auto reader = msgpack::token_reader(buffer);
    auto magic = reader.read_one();
    if (!magic || *magic != "prs") {
        logger.error("Failed to parse magic");
        return tl::unexpected(magic ? error::bad_data : error::incomplete);
    }

    auto size = reader.read_one().and_then(
            [](auto t){ return t.template get<std::uint32_t>(); });

    if (!size || !*size) {
        logger.error("Failed to get valid message size");
        return tl::unexpected(magic ? error::bad_data : error::incomplete);
    }

    if (*size > max_message_size) {
        logger.error("Message {} exceeds max size {}", *size, max_message_size);
        return tl::unexpected(error::too_large);
    }

    std::uint32_t amt = std::distance(buffer.begin(), reader.current());
    return tl::expected<header_info, error>(tl::in_place, *size, amt);
}