// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
#pragma once

#include <chrono>
#include <type_traits>
#include <iterator>
#include <spdlog/fmt/fmt.h>
#include <spdlog/common.h>

// Some fmt helpers to efficiently format and pad ints and strings
namespace spdlog {
namespace details {
namespace fmt_helper {

inline spdlog::string_view_t to_string_view(const memory_buf_t &buf) SPDLOG_NOEXCEPT
{
    return spdlog::string_view_t{buf.data(), buf.size()};
}

inline void append_string_view(spdlog::string_view_t view, memory_buf_t &dest)
{
    auto *buf_ptr = view.data();
    dest.append(buf_ptr, buf_ptr + view.size());
}

template<typename T>
inline void append_int(T n, memory_buf_t &dest)
{
    fmt::format_int i(n);
    dest.append(i.data(), i.data() + i.size());
}

template<typename T>
inline unsigned int count_digits(T n)
{
    using count_type = typename std::conditional<(sizeof(T) > sizeof(uint32_t)), uint64_t, uint32_t>::type;
    return static_cast<unsigned int>(fmt::
// fmt 7.0.0 renamed the internal namespace to detail.
// See: https://github.com/fmtlib/fmt/issues/1538
#if FMT_VERSION < 70000
            internal
#else
            detail
#endif
        ::count_digits(static_cast<count_type>(n)));
}

inline void pad2(int n, memory_buf_t &dest)
{
    if (n >= 0 && n < 100) // 0-99
    {
        dest.push_back(static_cast<char>('0' + n / 10));
        dest.push_back(static_cast<char>('0' + n % 10));
    }
    else // unlikely, but just in case, let fmt deal with it
    {
        fmt::format_to(std::back_inserter(dest), SPDLOG_FMT_RUNTIME("{:02}"), n);
    }
}

template<typename T>
inline void pad_uint(T n, unsigned int width, memory_buf_t &dest)
{
    static_assert(std::is_unsigned<T>::value, "pad_uint must get unsigned T");
    for (auto digits = count_digits(n); digits < width; digits++)
    {
        dest.push_back('0');
    }
    append_int(n, dest);
}

template<typename T>
inline void pad3(T n, memory_buf_t &dest)
{
    static_assert(std::is_unsigned<T>::value, "pad3 must get unsigned T");
    if (n < 1000)
    {
        dest.push_back(static_cast<char>(n / 100 + '0'));
        n = n % 100;
        dest.push_back(static_cast<char>((n / 10) + '0'));
        dest.push_back(static_cast<char>((n % 10) + '0'));
    }
    else
    {
        append_int(n, dest);
    }
}

template<typename T>
inline void pad6(T n, memory_buf_t &dest)
{
    pad_uint(n, 6, dest);
}

template<typename T>
inline void pad9(T n, memory_buf_t &dest)
{
    pad_uint(n, 9, dest);
}

// return fraction of a second of the given time_point.
// e.g.
// fraction<std::milliseconds>(tp) -> will return the millis part of the second
template<typename ToDuration>
inline ToDuration time_fraction(log_clock::time_point tp)
{
    using std::chrono::duration_cast;
    using std::chrono::seconds;
    auto duration = tp.time_since_epoch();
    auto secs = duration_cast<seconds>(duration);
    return duration_cast<ToDuration>(duration) - duration_cast<ToDuration>(secs);
}

} // namespace fmt_helper
} // namespace details
} // namespace spdlog
