Because your neighbors keep defeating you in the holiday house decorating contest year after year, you've decided to deploy one million lights in a 1000x1000 grid.

Furthermore, because you've been especially nice this year, Santa has mailed you instructions on how to display the ideal lighting configuration.

Read the full puzzle.

using System;
using System.Linq;
using System.Text.RegularExpressions;

namespace AdventOfCode.Y2015.Day06;

[ProblemName("Probably a Fire Hazard")]
class Solution : Solver {

    public object PartOne(string input) => Run(input, _ => 1, _ => 0, v => 1 - v);
    public object PartTwo(string input) => Run(input, v => v + 1, v => v > 0 ? v - 1 : 0, v => v + 2);

    int Run(string input, Func<int, int> turnOn, Func<int, int> turnOff, Func<int, int> toggle) {
        int[] apply(int[] grid, string line, string pattern, Func<int, int> dg) {
            var match = Regex.Match(line, pattern);
            if (match.Success) {
                var rect = match.Groups.Cast<Group>().Skip(1).Select(g => int.Parse(g.Value)).ToArray();
                for (int irow = rect[0]; irow <= rect[2]; irow++) {
                    for (int icol = rect[1]; icol <= rect[3]; icol++) {
                        grid[irow * 1000 + icol] = dg(grid[irow * 1000 + icol]);
                    }
                }
                return grid;
            } else {
                return null;
            }
        }
        return input.Split('\n')
            .Aggregate(new int[1000 * 1000], (grid, line) =>
                apply(grid, line, @"turn on (\d+),(\d+) through (\d+),(\d+)", turnOn) ??
                apply(grid, line, @"turn off (\d+),(\d+) through (\d+),(\d+)", turnOff) ??
                apply(grid, line, @"toggle (\d+),(\d+) through (\d+),(\d+)", toggle) ??
                throw new Exception(line))
            .Sum();
    }
}

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