#ifndef _FORMAT_H
#define _FORMAT_H

#include <string.h>
#include <string>
#include <tuple>
#include <type_traits>
#include <iostream>

namespace detail
{

static void formatArg(char*& buf, int i)
{
 int size = sprintf(buf, "%d", i);
 buf += size;
}

static void formatArg(char*& buf, long i)
{
 int size = sprintf(buf, "%ld", i);
 buf += size;
}

static void formatArg(char*& buf, long long i)
{
 int size = sprintf(buf, "%lld", i);
 buf += size;
}

static void formatArg(char*& buf, double i)
{
 int size = sprintf(buf, "%.6f", i);
 buf += size;
}

static void formatArg(char*& buf, const char* p)
{
 int len = strlen(p);
 memcpy(buf, p, len);
 buf += len;
}

static void formatArg(char*& buf, const std::string& str)
{
 memcpy(buf, str.c_str(), str.size());
 buf += str.size();
}

template<std::size_t i, typename Tuple>
static typename std::enable_if<(i == std::tuple_size<Tuple>::value)>::type 
getArgByIndex(std::size_t, Tuple&, char*&)
{
 throw std::invalid_argument("Arg index out of range");
}

template<std::size_t i = 0, typename Tuple>
static typename std::enable_if<(i < std::tuple_size<Tuple>::value)>::type 
getArgByIndex(std::size_t index, Tuple& tp, char*& p)
{
 if (i == index)
 {
 formatArg(p, std::get<i>(tp));
 }
 else
 {
 getArgByIndex<i + 1>(index, tp, p);
 }
}

static int getIndex(char*& p)
{
 char temp[3] = {'0円'};
 int i = 0;
 while (*p != '}' && *p != '0円')
 {
 if (i >= 2)
 {
 throw std::invalid_argument("Index is out of range");
 }

 if (std::isdigit(*p))
 {
 // push digit
 temp[i++] = *p;
 char next = *(p + 1);
 if (std::isdigit(next))
 {
 temp[i++] = next;
 p += 2;
 continue;
 }

 // validate arg
 if (!std::isspace(next) && next != '}')
 {
 throw std::invalid_argument("Invaild argument");
 }
 }
 ++p;
 }
 return i == 0 ? -1 : std::atoi(temp);
}

}

template<typename... Args>
static std::string format(char* str, Args... args)
{
 char arr[4096] = {'0円'};
 char* buf = arr;
 auto tp = std::tuple<Args...>(args...);

 char* p = str;
 char* original = p;
 int last = 0;
 while (true)
 {
 if (*p == '{') 
 {
 // copy context before {
 last = p - original;
 memcpy(buf, original, last);
 buf += last;

 // format args
 int index = detail::getIndex(p);
 if (index >= 0)
 {
 detail::getArgByIndex<0>(index, tp, buf);
 }

 // skip }
 original = p + 1;
 }
 else if (*p == '0円')
 {
 last = p - original;
 memcpy(buf, original, last);
 break;
 }
 ++p;
 }

 return arr;
}

#endif