#include <string>
#include <sstream>
#include <stdarg.h>
#include "UsefulException.hpp"
#include "../dependencies/kerep/src/base/base.h"

std::string _format(const std::string format_str, size_t args_count, ...){
    va_list vl;
    va_start(vl, args_count);
    std::stringstream ss;
    
    for(size_t i = 0; i < format_str.length(); i++){
        char c = format_str[i];

        // format specifier
        if(c == '%'){
            c = format_str[++i];
            bool l = false;
            while(c == 'l'){
                l = true;
                c = format_str[++i];
            }
            
            switch(c){
                case 'u':
                    if(l) ss<<(u64)va_arg(vl, u64);
                    else ss<<(u32)va_arg(vl, u32);
                    break;
                case 'i':
                case 'd':
                    if(l) ss<<(i64)va_arg(vl, i64);
                    else ss<<(i32)va_arg(vl, i32);
                    break;
                case 'f':
                    // f32 is promoted to f64 when passed through '...'
                    ss<<(f64)va_arg(vl, f64);
                    break;
                case 'p':
                    ss<<(void*)va_arg(vl, void*);
                    break;
                case 'x':
                    if(l) ss<<std::hex<<(u64)va_arg(vl, u64);
                    else ss<<std::hex<<(u32)va_arg(vl, u32);
                    break;
                case 's': {
                    const char* cptr = va_arg(vl,char*);
                    if(cptr != nullptr)
                        ss<<cptr;
                    else ss<<"<nullptr>";
                    break;
                }
                case 'c':
                    ss<<(char)va_arg(vl,int);
                    break;
                default:
                    throw UsefulException("invalid format cpecifier");
            }
        }

        // regular character
        else ss<<c;
    }

    va_end(vl);
    return ss.str();
}