//          Copyright Johannes Kapfhammer 2019.
// Distributed under the Boost Software License, Version 1.0.
//    (See accompanying file LICENSE_1_0.txt or copy at
//          http://www.boost.org/LICENSE_1_0.txt)
//
// A debug macro: allows debugging with dbg(<expression>);
// initialize with dbg_init() to enable colorized output
//

#ifndef SOI_DBG
#define SOI_DBG

#include <cstddef>
#include <stdexcept>
#include <cstring>
#include <ostream>
#include <iostream>
#include <sstream>

#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
#include <unistd.h>
#endif

#include "soi-pretty.hpp"

namespace soi_h {

namespace detail {

// ----------------------------------------------------------------------------
// detecting the type name: https://stackoverflow.com/a/20170989

#ifndef _MSC_VER
#  if __cplusplus < 201103
#    define CONSTEXPR11_TN
#    define CONSTEXPR14_TN
#    define NOEXCEPT_TN
#  elif __cplusplus < 201402
#    define CONSTEXPR11_TN constexpr
#    define CONSTEXPR14_TN
#    define NOEXCEPT_TN noexcept
#  else
#    define CONSTEXPR11_TN constexpr
#    define CONSTEXPR14_TN constexpr
#    define NOEXCEPT_TN noexcept
#  endif
#else  // _MSC_VER
#  if _MSC_VER < 1900
#    define CONSTEXPR11_TN
#    define CONSTEXPR14_TN
#    define NOEXCEPT_TN
#  elif _MSC_VER < 2000
#    define CONSTEXPR11_TN constexpr
#    define CONSTEXPR14_TN
#    define NOEXCEPT_TN noexcept
#  else
#    define CONSTEXPR11_TN constexpr
#    define CONSTEXPR14_TN constexpr
#    define NOEXCEPT_TN noexcept
#  endif
#endif  // _MSC_VER

class static_string {
    const char* const p_;
    const std::size_t sz_;

public:
    typedef const char* const_iterator;

    template <std::size_t N>
    CONSTEXPR11_TN static_string(const char(&a)[N]) NOEXCEPT_TN
        : p_(a)
        , sz_(N-1)
        {}

    CONSTEXPR11_TN static_string(const char* p, std::size_t N) NOEXCEPT_TN
        : p_(p)
        , sz_(N)
        {}

    CONSTEXPR11_TN const char* data() const NOEXCEPT_TN {return p_;}
    CONSTEXPR11_TN std::size_t size() const NOEXCEPT_TN {return sz_;}

    CONSTEXPR11_TN const_iterator begin() const NOEXCEPT_TN {return p_;}
    CONSTEXPR11_TN const_iterator end()   const NOEXCEPT_TN {return p_ + sz_;}

    CONSTEXPR11_TN char operator[](std::size_t n) const
    {
        return n < sz_ ? p_[n] : throw std::out_of_range("static_string");
    }
};

inline
std::ostream&
operator<<(std::ostream& os, static_string const& s)
{
    return os.write(s.data(), s.size());
}

template <class T>
CONSTEXPR14_TN
static_string
type_name()
{
  const int k = sizeof("constexpr soi_h::detail:: T =")/sizeof(char);
#ifdef __clang__
    static_string p = __PRETTY_FUNCTION__;
    return static_string(p.data() + 31 + k, p.size() - 31 - k - 1);
#elif defined(__GNUC__)
    static_string p = __PRETTY_FUNCTION__;
#  if __cplusplus < 201402
    return static_string(p.data() + 36 + k, p.size() - 36 - k - 1);
#  else
    return static_string(p.data() + 46 + k, p.size() - 46 - k - 1);
#  endif
#elif defined(_MSC_VER)
    static_string p = __FUNCSIG__;
    return static_string(p.data() + 38 + k, p.size() - 38 - k - 7);
#endif
}

constexpr bool is_prefix_of(char const *suffix, char const *s) {
  return suffix[0]=='\0' || (suffix[0] == s[0] && is_prefix_of(suffix + 1, s + 1));
}

static char const* const type_string = "string";

template <class T>
CONSTEXPR14_TN
static_string
sanitized_type_name() {
  CONSTEXPR14_TN static_string t = type_name<T>();
  CONSTEXPR14_TN std::size_t offset =
    is_prefix_of("std::__debug::", t.data()) ? sizeof("std::__debug::")-1 :
    is_prefix_of("std::", t.data()) ? sizeof("std::")-1 :
    0;
  return
    is_prefix_of("std::__cxx11::basic_string<char>", t.data()) ?
    static_string(type_string, sizeof(type_string)-2) :
    static_string(t.data()+offset, t.size()-offset);
}

// ----------------------------------------------------------------------------
// colorized output

bool tty_supports_colors() {
#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
  return isatty(STDERR_FILENO);
#else
  return true;
#endif
}

int has_environment_color_overwrite() {
  if (const char* color_enabled = std::getenv("SOI_COLOR")) {
    if (!std::strcmp(color_enabled, "1"))
      return 1;
    if (!std::strcmp(color_enabled, "0"))
      return 0;
  }
  return -1;
}

bool are_colors_enabled() {
  int c = has_environment_color_overwrite();
  if (c == -1)
    return tty_supports_colors();
  return static_cast<bool>(c);
}

// ----------------------------------------------------------------------------
// init and static variables

static bool colors_enabled = false;
static const char* ANSI_DEBUG = "";
static const char* ANSI_EXPRESSION = "";
static const char* ANSI_VALUE = "";
static const char* ANSI_TYPE = "";
static const char* ANSI_MESSAGE = "";
static const char* ANSI_RESET = "";

void dbg_init(bool with_colors) {
  if (with_colors) {
    bool colors_enabled = true;
    ANSI_DEBUG = "\x1b[37m";
    ANSI_EXPRESSION = "\x1b[36m";
    ANSI_VALUE = "\x1b[01m";
    ANSI_TYPE = "\x1b[32m";
    ANSI_MESSAGE = "\x1b[31;01m";
    ANSI_RESET = "\x1b[0m";
  } else {
    bool colors_enabled = false;
    ANSI_DEBUG = "";
    ANSI_EXPRESSION = "";
    ANSI_VALUE = "";
    ANSI_TYPE = "";
    ANSI_MESSAGE = "";
    ANSI_RESET = "";
  }
}

void dbg_init() {
  dbg_init(are_colors_enabled());
}

// ----------------------------------------------------------------------------
// printer

template <typename T>
T&& dbg_print(T&& value,
              static_string const& type,
              char const* file,
              int line,
              char const* function_name,
              char const* expression) {
  const T& ref = value;
  std::stringstream value_buffer; // avoid nesting of dbg macros within print functinos
  soi_h::pretty_print(value_buffer, ref);

  std::cerr << ANSI_DEBUG
            << "[" << file << ":" << line
            << " (" << function_name << ")] " << ANSI_RESET
            << ANSI_EXPRESSION << expression << ANSI_RESET
            << " = "
            << ANSI_VALUE << value_buffer.rdbuf() << ANSI_RESET
            << " (" << ANSI_TYPE << type << ANSI_RESET << ")"
            << '\n';

  return std::forward<T>(value);
}

template<unsigned int N>
auto dbg_print(const char (&msg)[N],
               static_string const&,
               char const* file,
               int line,
               char const* function_name,
               char const* expression) -> decltype(msg) {
  std::cerr << ANSI_DEBUG
            << "[" << file << ":" << line
            << " (" << function_name << ")] " << ANSI_RESET
            << ANSI_MESSAGE << msg << ANSI_RESET
            << '\n';
  return msg;
}

template <typename T>
T&& identity(T&& t) {
  return std::forward<T>(t);
}

} // end namespace detail

} // end namespace dbg_macro

#ifdef SOI_RELEASE
#define dbg(...) dbg_macro::identity(__VA_ARGS__)
#else
#define dbg(...)                                                        \
  soi_h::detail::dbg_print((__VA_ARGS__),                               \
                           soi_h::detail::sanitized_type_name<decltype(__VA_ARGS__)>(), \
                           __FILE__,                                    \
                           __LINE__,                                    \
                           __func__,                                    \
                           #__VA_ARGS__)
#endif

#endif  // SOI_DBG