/*
 * Copyright (C) 2018 ScyllaDB
 */

/*
 * This file is part of Scylla.
 *
 * Scylla is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Scylla is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Scylla.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "vint-serialization.hh"
#include "sstables/types.hh"
#include "sstables/m_format_read_helpers.hh"
#include "sstables/exceptions.hh"
#include "sstables/random_access_reader.hh"

namespace sstables {

static void check_buf_size(temporary_buffer<char>& buf, size_t expected) {
    if (buf.size() < expected) {
        throw bufsize_mismatch_exception(buf.size(), expected);
    }
}

template <typename T>
inline future<T> read_vint_impl(random_access_reader& in) {
    using vint_type = std::conditional_t<std::is_unsigned_v<T>, unsigned_vint, signed_vint>;
    return in.read_exactly(1).then([&in] (auto&& buf) {
        check_buf_size(buf, 1);
        vint_size_type len = vint_type::serialized_size_from_first_byte(*buf.begin());
        temporary_buffer<char> bytes(len);
        std::copy_n(buf.begin(), 1, bytes.get_write());
        return in.read_exactly(len - 1).then([len, bytes = std::move(bytes)] (temporary_buffer<char> buf) mutable {
            check_buf_size(buf, len - 1);
            std::copy_n(buf.begin(), len - 1, bytes.get_write() + 1);
            return vint_type::deserialize(
                bytes_view(reinterpret_cast<bytes::value_type*>(bytes.get_write()), len));
        });
    });
}

future<uint64_t> read_unsigned_vint(random_access_reader& in) {
    return read_vint_impl<uint64_t>(in);
}

future<int64_t> read_signed_vint(random_access_reader& in) {
    return read_vint_impl<int64_t>(in);
}

}  // namespace sstables
