// Solutions to the Advent Of Code 2024.
// Copyright (C) 2025  Stefan Müller
//
// This program is free software: you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free Software
// Foundation, either version 3 of the License, or (at your option) any later
// version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along with
// this program.  If not, see <http://www.gnu.org/licenses/>.

#include <aoc/ResonantCollinearity.hpp>

const std::string ResonantCollinearity::getPuzzleName() const
{
    return "Resonant Collinearity";
}

const int ResonantCollinearity::getPuzzleDay() const
{
    return 8;
}

void ResonantCollinearity::finish()
{
    Grid<bool> antinodeGrid1{ lines.size(), lines[0].size() };
    antinodeGrid1.fill(false);
    Grid<bool> antinodeGrid2{ lines.size(), lines[0].size() };
    antinodeGrid2.fill(false);

    for (int j = 0; j < lines.size(); j++)
    {
        for (int i = 0; i < lines[j].size(); i++)
        {
            if (lines[j][i] != getEmptyChar())
            {
                addNewAntenna(antinodeGrid1, antinodeGrid2, { i, j });
            }
        }
    }
}

constexpr char ResonantCollinearity::getEmptyChar()
{
    return '.';
}

void ResonantCollinearity::addNewAntenna(Grid<bool>& antinodeGrid1, Grid<bool>& antinodeGrid2, Point2&& newPosition)
{
    const auto [it, success] = antennas_.insert({ getCharAt(newPosition), { newPosition } });
    if (!success)
    {
        // Adds the new antenna position itself as an antinode for part 2.
        if (it->second.size() == 1)
        {
            addNewAntinode(antinodeGrid2, it->second.front(), part2);
        }
        addNewAntinode(antinodeGrid2, newPosition, part2);

        // Adds antinodes for all pairs of the new antenna position and each of the already processed other antenna
        // positions with the same frequency.
        for (const auto& other : it->second)
        {
            Point2 diff = newPosition - other;
            findNewAntinodes(antinodeGrid1, antinodeGrid2, newPosition + diff, diff);
            diff = -diff;
            findNewAntinodes(antinodeGrid1, antinodeGrid2, other + diff, diff);
        }

        it->second.push_back(newPosition);
    }
}

void ResonantCollinearity::findNewAntinodes(Grid<bool>& antinodeGrid1, Grid<bool>& antinodeGrid2, Point2&& start,
    const Point2& increment)
{
    if (isInBounds(start))
    {
        addNewAntinode(antinodeGrid1, start, part1);
        addNewAntinode(antinodeGrid2, start, part2);
        start += increment;
        while (isInBounds(start))
        {
            addNewAntinode(antinodeGrid2, start, part2);
            start += increment;
        }
    }
}

void ResonantCollinearity::addNewAntinode(Grid<bool>& antinodeGrid, Point2& newPosition, long long int& count)
{
    if (!antinodeGrid[newPosition.y][newPosition.x])
    {
        antinodeGrid[newPosition.y][newPosition.x] = true;
        count++;
    }
}