#include "Pch.h"
#include "Util.h"

typedef std::string Str;
typedef std::wstring WStr;

static void utf8toWStr(WStr& dest, const Str& src){
	dest.clear();
	wchar_t w = 0;
	int bytes = 0;
	wchar_t err = L'�';
	for (size_t i = 0; i < src.size(); i++){
		unsigned char c = (unsigned char)src[i];
		if (c <= 0x7f){//first byte
			if (bytes){
				dest.push_back(err);
				bytes = 0;
			}
			dest.push_back((wchar_t)c);
		}
		else if (c <= 0xbf){//second/third/etc byte
			if (bytes){
				w = ((w << 6)|(c & 0x3f));
				bytes--;
				if (bytes == 0)
					dest.push_back(w);
			}
			else
				dest.push_back(err);
		}
		else if (c <= 0xdf){//2byte sequence start
			bytes = 1;
			w = c & 0x1f;
		}
		else if (c <= 0xef){//3byte sequence start
			bytes = 2;
			w = c & 0x0f;
		}
		else if (c <= 0xf7){//3byte sequence start
			bytes = 3;
			w = c & 0x07;
		}
		else{
			dest.push_back(err);
			bytes = 0;
		}
	}
	if (bytes)
		dest.push_back(err);
}

static void wstrToUtf8(Str& dest, const WStr& src){
	dest.clear();
	for (size_t i = 0; i < src.size(); i++){
		wchar_t w = src[i];
		if (w <= 0x7f)
			dest.push_back((char)w);
		else if (w <= 0x7ff){
			dest.push_back(0xc0 | ((w >> 6)& 0x1f));
			dest.push_back(0x80| (w & 0x3f));
		}
		else if (w <= 0xffff){
			dest.push_back(0xe0 | ((w >> 12)& 0x0f));
			dest.push_back(0x80| ((w >> 6) & 0x3f));
			dest.push_back(0x80| (w & 0x3f));
		}
		else if (w <= 0x10ffff){
			dest.push_back(0xf0 | ((w >> 18)& 0x07));
			dest.push_back(0x80| ((w >> 12) & 0x3f));
			dest.push_back(0x80| ((w >> 6) & 0x3f));
			dest.push_back(0x80| (w & 0x3f));
		}
		else
			dest.push_back('?');
	}
}

Str wstrToUtf8(const WStr& str){
	Str result;
	wstrToUtf8(result, str);
	return result;
}

WStr utf8toWStr(const Str& str){
	WStr result;
	utf8toWStr(result, str);
	return result;
}