// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.

///////////////////////////////////////////////////////////////////////////////
//
// util/util.h
//

size_t
ircd::util::size(std::ostream &s)
{
	const auto cur(s.tellp());
	s.seekp(0, std::ios::end);
	const auto ret(s.tellp());
	s.seekp(cur, std::ios::beg);
	return ret;
}

///////////////////////////////////////////////////////////////////////////////
//
// util/fpe.h
//

#ifndef __GNUC__
#pragma STDC FENV_ACCESS on
#endif

std::fexcept_t
ircd::util::fpe::set(const ushort &flags)
{
	std::fexcept_t theirs;
	syscall(std::fesetexceptflag, &theirs, flags);
	return theirs;
}

void
ircd::util::fpe::throw_errors(const ushort &flags)
{
	if(!flags)
		return;

	thread_local char buf[128];
	throw std::domain_error
	{
		reflect(buf, flags)
	};
}

ircd::string_view
ircd::util::fpe::reflect(const mutable_buffer &buf,
                         const ushort &flags)
{
	window_buffer wb{buf};
	const auto append{[&wb](const auto &flag)
	{
		wb([&flag](const mutable_buffer &buf)
		{
			return strlcpy(buf, reflect(flag));
		});
	}};

	for(size_t i(0); i < sizeof(flags) * 8; ++i)
		if(flags & (1 << i))
			append(1 << i);

	return wb.completed();
}

ircd::string_view
ircd::util::fpe::reflect(const ushort &flag)
{
	switch(flag)
	{
		case 0:             return "";
		case FE_INVALID:    return "INVALID";
		case FE_DIVBYZERO:  return "DIVBYZERO";
		case FE_UNDERFLOW:  return "UNDERFLOW";
		case FE_OVERFLOW:   return "OVERFLOW";
		case FE_INEXACT:    return "INEXACT";
	}

	return "?????";
}

ircd::string_view
ircd::util::fpe::reflect_sicode(const int &code)
{
	switch(code)
	{
		#if defined(HAVE_SIGNAL_H) && defined(FPE_INTDIV)
		case FPE_INTDIV:  return "INTDIV";
		case FPE_INTOVF:  return "INTOVF";
		case FPE_FLTDIV:  return "FLTDIV";
		case FPE_FLTOVF:  return "FLTOVF";
		case FPE_FLTUND:  return "FLTUND";
		case FPE_FLTRES:  return "FLTRES";
		case FPE_FLTINV:  return "FLTINV";
		case FPE_FLTSUB:  return "FLTSUB";
		#endif // HAVE_SIGNAL_H
	}

	return "?????";
}

//
// errors_handle
//

ircd::util::fpe::errors_handle::errors_handle()
{
	syscall(std::fegetexceptflag, &theirs, FE_ALL_EXCEPT);
	clear_pending();
}

ircd::util::fpe::errors_handle::~errors_handle()
noexcept(false)
{
	const auto pending(this->pending());
	syscall(std::fesetexceptflag, &theirs, FE_ALL_EXCEPT);
	throw_errors(pending);
}

void
ircd::util::fpe::errors_handle::clear_pending()
{
	syscall(std::feclearexcept, FE_ALL_EXCEPT);
}

void
ircd::util::fpe::errors_handle::throw_pending()
const
{
	throw_errors(pending());
}

ushort
ircd::util::fpe::errors_handle::pending()
const
{
	return std::fetestexcept(FE_ALL_EXCEPT);
}

#ifndef __GNUC__
#pragma STDC FENV_ACCESS off
#endif

///////////////////////////////////////////////////////////////////////////////
//
// util/env.h
//

ircd::string_view
ircd::util::getenv(const string_view &key)
{
	thread_local char keystr[128];
	if(unlikely(size(key) >= sizeof(keystr)))
		throw error
		{
			"getenv(): variable key is too long."
		};

	// Ensure the key is null terminated for the std:: call.
	const size_t len
	{
		strlcpy(keystr, key)
	};

	const string_view var
	{
		std::getenv(keystr)
	};

	return var;
}

///////////////////////////////////////////////////////////////////////////////
//
// util/pretty.h
//

//
// Human readable time suite
//

ircd::string_view
ircd::util::pretty_nanoseconds(const mutable_buffer &out,
                               const long double &ns,
                               const uint &fmt)
{
	using formats = std::array<string_view, 2>;
	using element = std::tuple<formats, double>;
	static const std::array<element, 9> unit
	{{
		//  fmt=0              fmt=1
		{ { "nanoseconds",     "ns" },     1000.0  },
		{ { "microseconds",    "us" },     1000.0  },
		{ { "milliseconds",    "ms" },     1000.0  },
		{ { "seconds",         "s"  },       60.0  },
		{ { "minutes",         "m"  },       60.0  },
		{ { "hours",           "h"  },       24.0  },
		{ { "days",            "d"  },        7.0  },
		{ { "weeks",           "w"  },       30.0  },
		{ { "months",          "M"  },       12.0  },
	}};

	const string_view &fmtstr
	{
		fmt == 1?
			"%.2lf%s"_sv:
			"%.2lf %s"_sv
	};

	size_t i(0), pos(0);
	long double val(ns);
	for(; val > std::get<1>(unit.at(pos)) && pos < unit.size() - 1; ++pos)
		val /= std::get<1>(unit.at(pos));

	return fmt::sprintf
	{
		out, fmtstr, val, std::get<0>(unit.at(pos)).at(fmt)
	};
}

//
// Human readable space suite
//

decltype(ircd::util::pretty_size_fmt)
ircd::util::pretty_size_fmt
{
	"%.2lf %s (%lu)"
};

decltype(ircd::util::pretty_only_size_fmt)
ircd::util::pretty_only_size_fmt
{
	"%.2lf %s",
};

std::string
ircd::util::pretty_only(const human_readable_size &value)
{
	return util::string(32, [&value]
	(const mutable_buffer &out)
	{
		return pretty_only(out, value);
	});
}

ircd::string_view
ircd::util::pretty_only(const mutable_buffer &out,
                        const human_readable_size &value)
try
{
	return fmt::sprintf
	{
		out, pretty_only_size_fmt,
		std::get<long double>(value),
		std::get<const string_view &>(value)
	};
}
catch(const std::out_of_range &e)
{
	return fmt::sprintf
	{
		out, "%lu B",
		std::get<uint64_t>(value)
	};
}

std::string
ircd::util::pretty(const human_readable_size &value)
{
	return pretty(value, pretty_size_fmt);
}

ircd::string_view
ircd::util::pretty(const mutable_buffer &out,
                   const human_readable_size &value)
{
	return pretty(out, pretty_size_fmt, value);
}

std::string
ircd::util::pretty(const human_readable_size &value,
                   const string_view &fmt)
{
	return util::string(64, [&value, &fmt]
	(const mutable_buffer &out)
	{
		return pretty(out, fmt, value);
	});
}

ircd::string_view
ircd::util::pretty(const mutable_buffer &out,
                   const string_view &fmt,
                   const human_readable_size &value)
try
{
	return fmt::sprintf
	{
		out, fmt,
		std::get<long double>(value),
		std::get<const string_view &>(value),
		std::get<uint64_t>(value)
	};
}
catch(const std::out_of_range &e)
{
	return fmt::sprintf
	{
		out, "%lu B",
		std::get<uint64_t>(value)
	};
}

ircd::human_readable_size
ircd::util::iec(const uint64_t &value)
{
	static const std::array<string_view, 7> unit
	{
		"B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB"
	};

	auto pos(0);
	long double v(value);
	for(; v > 1024.0; v /= 1024.0, ++pos);
	return
	{
		value, v, unit.at(pos)
	};
}

ircd::human_readable_size
ircd::util::si(const uint64_t &value)
{
	static const std::array<string_view, 7> unit
	{
		"B", "KB", "MB", "GB", "TB", "PB", "EB"
	};

	auto pos(0);
	long double v(value);
	for(; v > 1000.0; v /= 1000.0, ++pos);
	return
	{
		value, v, unit.at(pos)
	};
}

///////////////////////////////////////////////////////////////////////////////
//
// util/string.h
//

/// Close over the common pattern to write directly into a post-C++11 standard
/// string through the data() member requiring a const_cast. Closure returns
/// a view of the data actually written to the buffer.
std::string
ircd::util::string(const size_t &size,
                   const string_closure_view &closure)
{
	return string(size, [&closure]
	(const mutable_buffer &buffer)
	{
		return ircd::size(closure(buffer));
	});
}

/// Close over the common pattern to write directly into a post-C++11 standard
/// string through the data() member requiring a const_cast. Closure returns
/// the final size of the data written into the buffer.
std::string
ircd::util::string(const size_t &size,
                   const string_closure_size &closure)
{
	const size_t alloc_size
	{
		size & ~SHRINK_TO_FIT
	};

	std::string ret(alloc_size, char{});
	const mutable_buffer buf
	{
		const_cast<char *>(ret.data()), ret.size()
	};

	const size_t consumed
	{
		closure(buf)
	};

	assert(consumed <= buffer::size(buf));
	data(buf)[consumed] = '\0';
	ret.resize(consumed);

	if(size & SHRINK_TO_FIT)
		ret.shrink_to_fit();

	return ret;
}

std::string
ircd::util::string(const const_buffer &buf)
{
	return string(data(buf), size(buf));
}

std::string
ircd::util::string(const char *const &buf,
                   const size_t &size)
{
	return std::string{buf, size};
}

std::string
ircd::util::string(const uint8_t *const &buf,
                   const size_t &size)
{
	return string(reinterpret_cast<const char *>(buf), size);
}

///////////////////////////////////////////////////////////////////////////////
//
// util/timer.h
//

ircd::util::timer::timer(const std::function<void ()> &func)
:timer{}
{
	func();
	stop();
}

void
ircd::util::timer::stop()
{
	if(stopped())
		return;

	const auto now(clock::now());
	accumulator += std::chrono::duration_cast<decltype(accumulator)>(now - start);
	start = clock::time_point::min();
}

void
ircd::util::timer::cont()
{
	if(!stopped())
	{
		const auto now(clock::now());
		accumulator += std::chrono::duration_cast<decltype(accumulator)>(now - start);
	}

	start = clock::now();
}

std::string
ircd::util::timer::pretty(const int &fmt)
const
{
	return util::pretty(at(), fmt);
}

ircd::string_view
ircd::util::timer::pretty(const mutable_buffer &out,
                          const int &fmt)
const
{
	return util::pretty(out, at(), fmt);
}

bool
ircd::util::timer::stopped()
const
{
	return start == clock::time_point::min();
}

///////////////////////////////////////////////////////////////////////////////
//
// util/u2a.h
//

std::string
ircd::util::u2a(const const_buffer &in)
{
	return string(size(in) * 2, [&in]
	(const mutable_buffer &out)
	{
		return u2a(out, in);
	});
}

ircd::string_view
ircd::util::u2a(const mutable_buffer &out,
                const const_buffer &in)
{
	char *p(data(out));
	for(size_t i(0); i < size(in) && p + 2 <= end(out); ++i)
	{
		char tmp[3];
		::snprintf(tmp, sizeof(tmp), "%02x", uint8_t(in[i]));
		*p++ = tmp[0];
		*p++ = tmp[1];
	}

	return { data(out), p };
}

ircd::const_buffer
ircd::util::a2u(const mutable_buffer &out,
                const const_buffer &in)
{
	const size_t len{size(in) / 2};
	for(size_t i(0); i < len; ++i)
	{
		const char gl[3]
		{
			in[i * 2],
			in[i * 2 + 1],
			'\0'
		};

		out[i] = strtol(gl, nullptr, 16);
	}

	return { data(out), len };
}

///////////////////////////////////////////////////////////////////////////////
//
// util/unwind.h
//

ircd::util::unwind::defer::~defer()
noexcept
{
	ircd::defer
	{
		std::move(func)
	};
}

///////////////////////////////////////////////////////////////////////////////
//
// util/what.h
//

/// Get what() from exception_ptr
///
ircd::string_view
ircd::util::what(const std::exception_ptr eptr)
noexcept try
{
	if(likely(eptr))
		std::rethrow_exception(eptr);

	return {};
}
catch(const std::exception &e)
{
	return e.what();
}
catch(...)
{
	return {};
}