/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Copyright 2012-2016 Danny Robson <danny@nerdcruft.net>
 */


#include "log.hpp"

#include "../term.hpp"
#include "../time.hpp"
#include "../cast.hpp"
#include "../string.hpp"

#include <cstring>
#include <ctime>
#include <iomanip>
#include <iostream>
#include <map>
#include <string>

///////////////////////////////////////////////////////////////////////////////
static constexpr
cruft::log::level_t
ALL_LEVELS[] = {
    cruft::log::EMERGENCY,
    cruft::log::ALERT,
    cruft::log::CRITICAL,
    cruft::log::ERROR,
    cruft::log::WARN,
    cruft::log::NOTICE,
    cruft::log::INFO,
    cruft::log::DEBUG,
};


///////////////////////////////////////////////////////////////////////////////
/// convert a string representation of a log-level into an enumeration value.
///
/// conversion is case insensitive
/// throws std::range_error if unable to convert
cruft::log::level_t
cruft::log::to_level (std::string_view name)
{
    if (std::empty (name))
        return cruft::log::EMERGENCY;

    std::string upper (name.size (), char{});
    std::transform (
        name.cbegin (),
        name.cend   (),
        upper.begin (),
        ::toupper
    );

    static constexpr struct {
        char const *name;
        cruft::log::level_t value;
    } VALUES[] = {
        { "EMERGENCY",     cruft::log::EMERGENCY },
        { "ALERT",         cruft::log::ALERT },
        { "CRITICAL",      cruft::log::CRITICAL },
        { "ERROR",         cruft::log::ERROR },
        { "WARN",          cruft::log::WARN },
        { "WARNING",       cruft::log::WARN },
        { "NOTICE",        cruft::log::NOTICE },
        { "INFO",          cruft::log::INFO },
        { "INFORMATIONAL", cruft::log::INFO },
        { "DEBUG",         cruft::log::DEBUG }
    };

    for (auto const [key, val]: VALUES)
        if (!strcmp (upper.data (), key))
            return val;

    throw std::invalid_argument (std::string (name));
}


///////////////////////////////////////////////////////////////////////////////
const std::string&
cruft::log::to_string (level_t l)
{
    switch (l) {
    #define CASE(L)                             \
        case cruft::log::L: {                   \
            static const std::string STR = #L;  \
            return STR;                         \
        }

    MAP_LEVEL_T(CASE)

    #undef CASE
    }

    unreachable ();
}


//-----------------------------------------------------------------------------
std::ostream&
cruft::log::operator<< (std::ostream& os, level_t l)
{
    return os << to_string (l);
}


///////////////////////////////////////////////////////////////////////////////
// Determine what the value for LOG_LEVEL should be at the beginning of
// execution given the system environment.
//
// Note that the LOG macros _cannot_ be used from within this function as it
// will likely result in infinite recursion.
static cruft::log::level_t
initial_log_level (void)
{
    const char *env = getenv ("LOG_LEVEL");
    if (!env)
        return cruft::log::DEFAULT_LOG_LEVEL;

    try {
        return cruft::log::to_level (env);
    } catch (...) {
        std::clog << "Invalid environment LOG_LEVEL: '" << env << "'\n";
        return cruft::log::DEFAULT_LOG_LEVEL;
    }
}


//-----------------------------------------------------------------------------
// We shouldn't ever actually get to use the default value, but we set it to
// the most verbose option just in case we've made a mistake elsewhere.

static bool                s_log_level_done;
static cruft::log::level_t s_log_level_value;

//-----------------------------------------------------------------------------
cruft::log::level_t
cruft::log::log_level (level_t _level)
{
    s_log_level_value = _level;
    s_log_level_done  = true;
    return s_log_level_value;
}


//-----------------------------------------------------------------------------
cruft::log::level_t
cruft::log::log_level (void)
{
    if (!s_log_level_done) {
        s_log_level_value = initial_log_level ();
        s_log_level_done  = true;
    }

    return s_log_level_value;
}


//-----------------------------------------------------------------------------
static bool
needs_break (cruft::log::level_t level)
{
    static cruft::log::level_t break_level;
    static bool has_level = [&] (void) {
        const char *env = getenv ("BREAK_LEVEL");
        if (!env)
            return false;

        try {
            break_level = cruft::log::to_level (env);
            return true;
        } catch (...) {
            return false;
        }
    } ();

    return has_level && level <= break_level;
}


//-----------------------------------------------------------------------------
static
cruft::term::csi::graphics
level_colour (cruft::log::level_t level)
{
    using cruft::term::csi::graphics;

    switch (level) {
    case cruft::log::EMERGENCY:
    case cruft::log::ALERT:
    case cruft::log::CRITICAL:
    case cruft::log::ERROR:
        return graphics (graphics::FOREGROUND, graphics::RED);

    case cruft::log::WARNING:
        return graphics (graphics::FOREGROUND, graphics::YELLOW);

    case cruft::log::NOTICE:
    case cruft::log::INFORMATIONAL:
        return graphics (graphics::FOREGROUND, graphics::GREEN);

    case cruft::log::DEBUG:
        return graphics (graphics::FOREGROUND, graphics::WHITE);
    }

    unreachable ();
}


//-----------------------------------------------------------------------------
static
size_t
level_width (void)
{
    static size_t width = [] {
        size_t hi = 0;

        for (auto i: ALL_LEVELS)
            hi = cruft::max (to_string (i).size (), hi);

        return hi;
    } ();

    return width;
}


///////////////////////////////////////////////////////////////////////////////
void
cruft::log::write (level_t level, const std::string &msg)
{
    return write (level, std::string_view (msg));
}


//-----------------------------------------------------------------------------
void
cruft::log::write (level_t level, char const *msg)
{
    return write (level, std::string_view (msg));
}


//-----------------------------------------------------------------------------
void
cruft::log::write (level_t level, std::string_view msg)
{
    if (level <= log_level ()) {
        static const size_t time_len = strlen("YYYY-mm-dd HHMMhSS") + 1;
        std::string time_string (time_len - 1, '\0');
        time_t unix_time = time (nullptr);

        if (0 == strftime (&time_string[0],
                    time_len,
                    "%Y-%m-%d %H%Mh%S",
                    localtime (&unix_time))) {
            warn ("failed to log time");
            return;
        }

        std::clog << time_string << " ["
            << level_colour (level)
            << std::setw (cruft::cast::lossless<int> (level_width ()))
            << std::left
            << level
            << std::setw (0)
            << cruft::term::csi::graphics::RESET
        << "] " << msg << std::endl;
    }

    if (needs_break (level))
        breakpoint ();
}


///////////////////////////////////////////////////////////////////////////////
cruft::log::scoped_logger::scoped_logger (
    level_t _level,
    std::string   _message
):
    m_level   (_level),
    m_message (std::move (_message))
{ ; }


//-----------------------------------------------------------------------------
cruft::log::scoped_logger::~scoped_logger ()
{
    write (m_level, m_message);
}


///////////////////////////////////////////////////////////////////////////////
cruft::log::scoped_timer::scoped_timer (
    cruft::log::level_t _level,
    std::string   _message
):
    m_level (_level),
    m_message (std::move (_message)),
    m_start (cruft::nanoseconds ())
{ ; }


//-----------------------------------------------------------------------------
cruft::log::scoped_timer::~scoped_timer ()
{
    auto finish = cruft::nanoseconds ();
    auto duration = finish - m_start;

    write (
        m_level,
        "%fs, %s",
        float (duration) / 1'000'000'000.f,
        m_message
    );
}