//
// Copyright(c) 2015 Gabi Melman.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
//

#pragma once

#include "spdlog/details/fmt_helper.h"
#include "spdlog/details/log_msg.h"
#include "spdlog/details/os.h"
#include "spdlog/fmt/fmt.h"
#include "spdlog/formatter.h"

#include <array>
#include <chrono>
#include <ctime>
#include <memory>
#include <mutex>
#include <string>
#include <thread>
#include <utility>
#include <vector>

namespace spdlog {
namespace details {

class flag_formatter
{
public:
    virtual ~flag_formatter() = default;
    virtual void format(const details::log_msg &msg, const std::tm &tm_time, fmt::memory_buffer &dest) = 0;
};

///////////////////////////////////////////////////////////////////////
// name & level pattern appender
///////////////////////////////////////////////////////////////////////
class name_formatter : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &, fmt::memory_buffer &dest) override
    {
        fmt_helper::append_string_view(*msg.logger_name, dest);
    }
};

// log level appender
class level_formatter : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &, fmt::memory_buffer &dest) override
    {
        fmt_helper::append_string_view(level::to_c_str(msg.level), dest);
    }
};

// short log level appender
class short_level_formatter : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &, fmt::memory_buffer &dest) override
    {
        fmt_helper::append_string_view(level::to_short_c_str(msg.level), dest);
    }
};

///////////////////////////////////////////////////////////////////////
// Date time pattern appenders
///////////////////////////////////////////////////////////////////////

static const char *ampm(const tm &t)
{
    return t.tm_hour >= 12 ? "PM" : "AM";
}

static int to12h(const tm &t)
{
    return t.tm_hour > 12 ? t.tm_hour - 12 : t.tm_hour;
}

// Abbreviated weekday name
static const char *days[]{"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
class a_formatter : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::append_string_view(days[tm_time.tm_wday], dest);
    }
};

// Full weekday name
static const char *full_days[]{"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
class A_formatter : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::append_string_view(full_days[tm_time.tm_wday], dest);
    }
};

// Abbreviated month
static const char *months[]{"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sept", "Oct", "Nov", "Dec"};
class b_formatter : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::append_string_view(months[tm_time.tm_mon], dest);
    }
};

// Full month name
static const char *full_months[]{
    "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
class B_formatter : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::append_string_view(full_months[tm_time.tm_mon], dest);
    }
};

// Date and time representation (Thu Aug 23 15:35:46 2014)
class c_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        // fmt::format_to(dest, "{} {} {} ", days[tm_time.tm_wday],
        // months[tm_time.tm_mon], tm_time.tm_mday);
        // date
        fmt_helper::append_string_view(days[tm_time.tm_wday], dest);
        dest.push_back(' ');
        fmt_helper::append_string_view(months[tm_time.tm_mon], dest);
        dest.push_back(' ');
        fmt_helper::append_int(tm_time.tm_mday, dest);
        dest.push_back(' ');
        // time

        fmt_helper::pad2(tm_time.tm_hour, dest);
        dest.push_back(':');
        fmt_helper::pad2(tm_time.tm_min, dest);
        dest.push_back(':');
        fmt_helper::pad2(tm_time.tm_sec, dest);
        dest.push_back(' ');
        fmt_helper::append_int(tm_time.tm_year + 1900, dest);
    }
};

// year - 2 digit
class C_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::pad2(tm_time.tm_year % 100, dest);
    }
};

// Short MM/DD/YY date, equivalent to %m/%d/%y 08/23/01
class D_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::pad2(tm_time.tm_mon + 1, dest);
        dest.push_back('/');
        fmt_helper::pad2(tm_time.tm_mday, dest);
        dest.push_back('/');
        fmt_helper::pad2(tm_time.tm_year % 100, dest);
    }
};

// year - 4 digit
class Y_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::append_int(tm_time.tm_year + 1900, dest);
    }
};

// month 1-12
class m_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::pad2(tm_time.tm_mon + 1, dest);
    }
};

// day of month 1-31
class d_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::pad2(tm_time.tm_mday, dest);
    }
};

// hours in 24 format 0-23
class H_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::pad2(tm_time.tm_hour, dest);
    }
};

// hours in 12 format 1-12
class I_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::pad2(to12h(tm_time), dest);
    }
};

// minutes 0-59
class M_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::pad2(tm_time.tm_min, dest);
    }
};

// seconds 0-59
class S_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::pad2(tm_time.tm_sec, dest);
    }
};

// milliseconds
class e_formatter final : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &, fmt::memory_buffer &dest) override
    {
        auto millis = fmt_helper::time_fraction<std::chrono::milliseconds>(msg.time);
        fmt_helper::pad3(static_cast<int>(millis.count()), dest);
    }
};

// microseconds
class f_formatter final : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &, fmt::memory_buffer &dest) override
    {
        auto micros = fmt_helper::time_fraction<std::chrono::microseconds>(msg.time);
        fmt_helper::pad6(static_cast<size_t>(micros.count()), dest);
    }
};

// nanoseconds
class F_formatter final : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &, fmt::memory_buffer &dest) override
    {
        auto ns = fmt_helper::time_fraction<std::chrono::nanoseconds>(msg.time);
        fmt::format_to(dest, "{:09}", ns.count());
    }
};

// seconds since epoch
class E_formatter final : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &, fmt::memory_buffer &dest) override
    {
        auto duration = msg.time.time_since_epoch();
        auto seconds = std::chrono::duration_cast<std::chrono::seconds>(duration).count();
        fmt_helper::append_int(seconds, dest);
    }
};

// AM/PM
class p_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::append_string_view(ampm(tm_time), dest);
    }
};

// 12 hour clock 02:55:02 pm
class r_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::pad2(to12h(tm_time), dest);
        dest.push_back(':');
        fmt_helper::pad2(tm_time.tm_min, dest);
        dest.push_back(':');
        fmt_helper::pad2(tm_time.tm_sec, dest);
        dest.push_back(' ');
        fmt_helper::append_string_view(ampm(tm_time), dest);
    }
};

// 24-hour HH:MM time, equivalent to %H:%M
class R_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        fmt_helper::pad2(tm_time.tm_hour, dest);
        dest.push_back(':');
        fmt_helper::pad2(tm_time.tm_min, dest);
    }
};

// ISO 8601 time format (HH:MM:SS), equivalent to %H:%M:%S
class T_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        // fmt::format_to(dest, "{:02}:{:02}:{:02}", tm_time.tm_hour,
        // tm_time.tm_min, tm_time.tm_sec);
        fmt_helper::pad2(tm_time.tm_hour, dest);
        dest.push_back(':');
        fmt_helper::pad2(tm_time.tm_min, dest);
        dest.push_back(':');
        fmt_helper::pad2(tm_time.tm_sec, dest);
    }
};

// ISO 8601 offset from UTC in timezone (+-HH:MM)
class z_formatter final : public flag_formatter
{
public:
    const std::chrono::seconds cache_refresh = std::chrono::seconds(5);

    z_formatter() = default;
    z_formatter(const z_formatter &) = delete;
    z_formatter &operator=(const z_formatter &) = delete;

    void format(const details::log_msg &msg, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
#ifdef _WIN32
        int total_minutes = get_cached_offset(msg, tm_time);
#else
        // No need to chache under gcc,
        // it is very fast (already stored in tm.tm_gmtoff)
        (void)(msg);
        int total_minutes = os::utc_minutes_offset(tm_time);
#endif
        bool is_negative = total_minutes < 0;
        if (is_negative)
        {
            total_minutes = -total_minutes;
            dest.push_back('-');
        }
        else
        {
            dest.push_back('+');
        }

        fmt_helper::pad2(total_minutes / 60, dest); // hours
        dest.push_back(':');
        fmt_helper::pad2(total_minutes % 60, dest); // minutes
    }

private:
    log_clock::time_point last_update_{std::chrono::seconds(0)};
#ifdef _WIN32
    int offset_minutes_{0};

    int get_cached_offset(const log_msg &msg, const std::tm &tm_time)
    {
        if (msg.time - last_update_ >= cache_refresh)
        {
            offset_minutes_ = os::utc_minutes_offset(tm_time);
            last_update_ = msg.time;
        }
        return offset_minutes_;
    }
#endif
};

// Thread id
class t_formatter final : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &, fmt::memory_buffer &dest) override
    {
        fmt_helper::pad6(msg.thread_id, dest);
    }
};

// Current pid
class pid_formatter final : public flag_formatter
{
    void format(const details::log_msg &, const std::tm &, fmt::memory_buffer &dest) override
    {
        fmt_helper::append_int(details::os::pid(), dest);
    }
};

// message counter formatter
class i_formatter final : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &, fmt::memory_buffer &dest) override
    {
        fmt_helper::pad6(msg.msg_id, dest);
    }
};

class v_formatter final : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &, fmt::memory_buffer &dest) override
    {
        fmt_helper::append_string_view(msg.payload, dest);
    }
};

class ch_formatter final : public flag_formatter
{
public:
    explicit ch_formatter(char ch)
        : ch_(ch)
    {
    }
    void format(const details::log_msg &, const std::tm &, fmt::memory_buffer &dest) override
    {
        dest.push_back(ch_);
    }

private:
    char ch_;
};

// aggregate user chars to display as is
class aggregate_formatter final : public flag_formatter
{
public:
    aggregate_formatter() = default;

    void add_ch(char ch)
    {
        str_ += ch;
    }
    void format(const details::log_msg &, const std::tm &, fmt::memory_buffer &dest) override
    {
        fmt_helper::append_string_view(str_, dest);
    }

private:
    std::string str_;
};

// mark the color range. expect it to be in the form of "%^colored text%$"
class color_start_formatter final : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &, fmt::memory_buffer &dest) override
    {
        msg.color_range_start = dest.size();
    }
};
class color_stop_formatter final : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &, fmt::memory_buffer &dest) override
    {
        msg.color_range_end = dest.size();
    }
};

// Full info formatter
// pattern: [%Y-%m-%d %H:%M:%S.%e] [%n] [%l] %v
class full_formatter final : public flag_formatter
{
    void format(const details::log_msg &msg, const std::tm &tm_time, fmt::memory_buffer &dest) override
    {
        using std::chrono::duration_cast;
        using std::chrono::milliseconds;
        using std::chrono::seconds;

#ifndef SPDLOG_NO_DATETIME

        // cache the date/time part for the next second.
        auto duration = msg.time.time_since_epoch();
        auto secs = duration_cast<seconds>(duration);

        if (cache_timestamp_ != secs || cached_datetime_.size() == 0)
        {
            cached_datetime_.clear();
            cached_datetime_.push_back('[');
            fmt_helper::append_int(tm_time.tm_year + 1900, cached_datetime_);
            cached_datetime_.push_back('-');

            fmt_helper::pad2(tm_time.tm_mon + 1, cached_datetime_);
            cached_datetime_.push_back('-');

            fmt_helper::pad2(tm_time.tm_mday, cached_datetime_);
            cached_datetime_.push_back(' ');

            fmt_helper::pad2(tm_time.tm_hour, cached_datetime_);
            cached_datetime_.push_back(':');

            fmt_helper::pad2(tm_time.tm_min, cached_datetime_);
            cached_datetime_.push_back(':');

            fmt_helper::pad2(tm_time.tm_sec, cached_datetime_);
            cached_datetime_.push_back('.');

            cache_timestamp_ = secs;
        }
        fmt_helper::append_buf(cached_datetime_, dest);

        auto millis = fmt_helper::time_fraction<milliseconds>(msg.time);
        fmt_helper::pad3(static_cast<int>(millis.count()), dest);
        dest.push_back(']');
        dest.push_back(' ');

#else // no datetime needed
        (void)tm_time;
#endif

#ifndef SPDLOG_NO_NAME
        if (!msg.logger_name->empty())
        {
            dest.push_back('[');
            // fmt_helper::append_str(*msg.logger_name, dest);
            fmt_helper::append_string_view(*msg.logger_name, dest);
            dest.push_back(']');
            dest.push_back(' ');
        }
#endif

        dest.push_back('[');
        // wrap the level name with color
        msg.color_range_start = dest.size();
        // fmt_helper::append_string_view(level::to_c_str(msg.level), dest);
        fmt_helper::append_string_view(level::to_c_str(msg.level), dest);
        msg.color_range_end = dest.size();
        dest.push_back(']');
        dest.push_back(' ');
        // fmt_helper::append_string_view(msg.msg(), dest);
        fmt_helper::append_string_view(msg.payload, dest);
    }

private:
    std::chrono::seconds cache_timestamp_{0};
    fmt::basic_memory_buffer<char, 128> cached_datetime_;
};

} // namespace details

class pattern_formatter final : public formatter
{
public:
    explicit pattern_formatter(
        std::string pattern, pattern_time_type time_type = pattern_time_type::local, std::string eol = spdlog::details::os::default_eol)
        : pattern_(std::move(pattern))
        , eol_(std::move(eol))
        , pattern_time_type_(time_type)
        , last_log_secs_(0)
    {
        std::memset(&cached_tm_, 0, sizeof(cached_tm_));
        compile_pattern_(pattern_);
    }

    pattern_formatter(const pattern_formatter &other) = delete;
    pattern_formatter &operator=(const pattern_formatter &other) = delete;

    std::unique_ptr<formatter> clone() const override
    {
        return details::make_unique<pattern_formatter>(pattern_, pattern_time_type_, eol_);
    }

    void format(const details::log_msg &msg, fmt::memory_buffer &dest) override
    {
#ifndef SPDLOG_NO_DATETIME
        auto secs = std::chrono::duration_cast<std::chrono::seconds>(msg.time.time_since_epoch());
        if (secs != last_log_secs_)
        {
            cached_tm_ = get_time_(msg);
            last_log_secs_ = secs;
        }
#endif
        for (auto &f : formatters_)
        {
            f->format(msg, cached_tm_, dest);
        }
        // write eol
        details::fmt_helper::append_string_view(eol_, dest);
    }

private:
    std::string pattern_;
    std::string eol_;
    pattern_time_type pattern_time_type_;
    std::tm cached_tm_;
    std::chrono::seconds last_log_secs_;

    std::vector<std::unique_ptr<details::flag_formatter>> formatters_;

    std::tm get_time_(const details::log_msg &msg)
    {
        if (pattern_time_type_ == pattern_time_type::local)
        {
            return details::os::localtime(log_clock::to_time_t(msg.time));
        }
        return details::os::gmtime(log_clock::to_time_t(msg.time));
    }

    void handle_flag_(char flag)
    {
        switch (flag)
        {
        // logger name
        case 'n':
            formatters_.push_back(details::make_unique<details::name_formatter>());
            break;

        case 'l':
            formatters_.push_back(details::make_unique<details::level_formatter>());
            break;

        case 'L':
            formatters_.push_back(details::make_unique<details::short_level_formatter>());
            break;

        case ('t'):
            formatters_.push_back(details::make_unique<details::t_formatter>());
            break;

        case ('v'):
            formatters_.push_back(details::make_unique<details::v_formatter>());
            break;

        case ('a'):
            formatters_.push_back(details::make_unique<details::a_formatter>());
            break;

        case ('A'):
            formatters_.push_back(details::make_unique<details::A_formatter>());
            break;

        case ('b'):
        case ('h'):
            formatters_.push_back(details::make_unique<details::b_formatter>());
            break;

        case ('B'):
            formatters_.push_back(details::make_unique<details::B_formatter>());
            break;
        case ('c'):
            formatters_.push_back(details::make_unique<details::c_formatter>());
            break;

        case ('C'):
            formatters_.push_back(details::make_unique<details::C_formatter>());
            break;

        case ('Y'):
            formatters_.push_back(details::make_unique<details::Y_formatter>());
            break;

        case ('D'):
        case ('x'):
            formatters_.push_back(details::make_unique<details::D_formatter>());
            break;

        case ('m'):
            formatters_.push_back(details::make_unique<details::m_formatter>());
            break;

        case ('d'):
            formatters_.push_back(details::make_unique<details::d_formatter>());
            break;

        case ('H'):
            formatters_.push_back(details::make_unique<details::H_formatter>());
            break;

        case ('I'):
            formatters_.push_back(details::make_unique<details::I_formatter>());
            break;

        case ('M'):
            formatters_.push_back(details::make_unique<details::M_formatter>());
            break;

        case ('S'):
            formatters_.push_back(details::make_unique<details::S_formatter>());
            break;

        case ('e'):
            formatters_.push_back(details::make_unique<details::e_formatter>());
            break;

        case ('f'):
            formatters_.push_back(details::make_unique<details::f_formatter>());
            break;
        case ('F'):
            formatters_.push_back(details::make_unique<details::F_formatter>());
            break;

        case ('E'):
            formatters_.push_back(details::make_unique<details::E_formatter>());
            break;

        case ('p'):
            formatters_.push_back(details::make_unique<details::p_formatter>());
            break;

        case ('r'):
            formatters_.push_back(details::make_unique<details::r_formatter>());
            break;

        case ('R'):
            formatters_.push_back(details::make_unique<details::R_formatter>());
            break;

        case ('T'):
        case ('X'):
            formatters_.push_back(details::make_unique<details::T_formatter>());
            break;

        case ('z'):
            formatters_.push_back(details::make_unique<details::z_formatter>());
            break;

        case ('+'):
            formatters_.push_back(details::make_unique<details::full_formatter>());
            break;

        case ('P'):
            formatters_.push_back(details::make_unique<details::pid_formatter>());
            break;
#ifdef SPDLOG_ENABLE_MESSAGE_COUNTER
        case ('i'):
            formatters_.push_back(details::make_unique<details::i_formatter>());
            break;
#endif
        case ('^'):
            formatters_.push_back(details::make_unique<details::color_start_formatter>());
            break;

        case ('$'):
            formatters_.push_back(details::make_unique<details::color_stop_formatter>());
            break;

        default: // Unknown flag appears as is
            formatters_.push_back(details::make_unique<details::ch_formatter>('%'));
            formatters_.push_back(details::make_unique<details::ch_formatter>(flag));
            break;
        }
    }

    void compile_pattern_(const std::string &pattern)
    {
        auto end = pattern.end();
        std::unique_ptr<details::aggregate_formatter> user_chars;
        formatters_.clear();
        for (auto it = pattern.begin(); it != end; ++it)
        {
            if (*it == '%')
            {
                if (user_chars) // append user chars found so far
                {
                    formatters_.push_back(std::move(user_chars));
                }
                if (++it != end)
                {
                    handle_flag_(*it);
                }
                else
                {
                    break;
                }
            }
            else // chars not following the % sign should be displayed as is
            {
                if (!user_chars)
                {
                    user_chars = details::make_unique<details::aggregate_formatter>();
                }
                user_chars->add_ch(*it);
            }
        }
        if (user_chars) // append raw chars found so far
        {
            formatters_.push_back(std::move(user_chars));
        }
    }
};
} // namespace spdlog