using AdventOfCode.Core;
using AdventOfCode.Core.Shared.Grid;
using System.Linq;
using System.Text.RegularExpressions;

namespace AdventOfCode.Solutions._2023
{
    public partial class Day03(InputReader reader) : IChallange
    {
        private InputReader _inputReader = reader;

        private class PartNumber
        {
            public int X { get; set; }

            public int Y { get; set; }

            public string Section { get; set; } = string.Empty;

            public int Length => Section.Length;

            public bool IsDigit() => Section.All(char.IsDigit);

            public bool IsPartSymbol() => !IsDigit();
        }

        public async Task<string> GetSolutionPart1()
        {
            List<PartNumber> parts = [];
            int row = 0;
            await foreach (string line in _inputReader.ReadAsStringLine())
            {
                row++;
                MatchCollection matchCollection = FindPartItems().Matches(line);
                parts.AddRange(matchCollection.Select(match => new PartNumber { X = match.Index + 1, Y = row, Section = match.Value }));
            }

            List<Rectangle> numbers = parts.Where(p => p.IsDigit()).Select(number => new Rectangle(new Point(number.X - 1, number.Y - 1), new Point(number.X + number.Length, number.Y + 1), number.Section)).ToList();
            List<Point> symbols = parts.Where(p => p.IsPartSymbol()).Select(symbol => new Point(symbol.X, symbol.Y,  symbol.Section)).ToList();
            return numbers.Where(number => symbols.Any(s => number.Intersect(s))).Select(num => int.Parse(num.Value)).Sum().ToString();
        }

        public async Task<string> GetSolutionPart2()
        {
            List<PartNumber> parts = [];
            int row = 0;
            await foreach (string line in _inputReader.ReadAsStringLine())
            {
                row++;
                MatchCollection matchCollection = FindPartItems().Matches(line);
                parts.AddRange(matchCollection.Select(match => new PartNumber { X = match.Index + 1, Y = row, Section = match.Value }));
            }

            List<Rectangle> numbers = parts.Where(p => p.IsDigit()).Select(number => new Rectangle(new Point(number.X - 1, number.Y - 1), new Point(number.X + number.Length, number.Y + 1), number.Section)).ToList();
            List<Point> gears = parts.Where(p => p.IsPartSymbol() && p.Section == "*").Select(symbol => new Point(symbol.X, symbol.Y,  symbol.Section)).ToList();

            return gears.Select(g => numbers.Where(n => n.Intersect(g)))
                .Where(n => n.Count() == 2)
                .Select(num => int.Parse(num.First().Value) * int.Parse(num.Last().Value))
                .Sum()
                .ToString();
        }

        [GeneratedRegex("(\\d+)", RegexOptions.Compiled)]
        private static partial Regex FindDigits();

        [GeneratedRegex("(\\d+)|([^.])", RegexOptions.Compiled)]
        private static partial Regex FindPartItems();
    }
}