#include <filesystem>
#include <fstream>
#include <iostream>
#include <string>

using namespace std;

namespace {

string
read_line(const filesystem::path& filename)
{
	ifstream file{ filename };
	string   line;
	getline(file, line);
	return line;
}

bool
xorEqual(char lhs, char rhs)
{
	return (lhs ^ (1 << 5)) == rhs;
}

#if 0
void
part1(string str)
{
	size_t idx = 1;
	while ( idx < str.length() ) {
		if ( xorEqual(str[idx - 1], str[idx]) ) {
			str.erase(idx - 1, 2);
			idx = 1;
		}
		else {
			++idx;
		}
	}

	cout << "Part 1: " << str.length() << '\n';
}
#endif

void
part1_opti(string_view str)
{
	string result;

	for ( const auto chr: str ) {
		if ( !result.empty() && xorEqual(result.back(), chr) ) {
			result.pop_back();
		}
		else {
			result.push_back(chr);
		}
	}

	cout << "Part 1: " << result.length() << '\n';
}

void
part2(string_view str)
{
	size_t min_length = str.size();
	for ( auto ch = 'a'; ch != 'z'; ++ch ) {
		string result;

		for ( const auto chr: str ) {
			if ( tolower(chr) == ch ) {
				// nichts
			}
			else if ( !result.empty() && xorEqual(result.back(), chr) ) {
				result.pop_back();
			}
			else {
				result.push_back(chr);
			}
		}
		min_length = min(min_length, result.length());
	}

	cout << "Part 2: " << min_length << '\n';
}

} // namespace

int
main()
{
	auto line = read_line("data/day05.txt");
	// part1(line);
	part1_opti(line);
	part2(line);
	/*
	cout << reduce("aA") << '\n';
	cout << reduce("abBA") << '\n';
	cout << reduce("abAB") << '\n';
	cout << reduce("aabAAB") << '\n';
	cout << reduce("dabAcCaCBAcCcaDA") << '\n';
	*/
}