using Spectre.Console;

namespace AdventOfCode.Days;

public class Day5 : Day
{
    public override int Number => 5;
    public override string Name => "Print Queue";

    public override void RunPart1(bool display = true)
    {
        var result = 0;

        var precedences = new HashSet<int>?[100];

        var readingPrecedences = true;
        foreach (var line in Input.AsSpan().EnumerateLines())
        {
            if (line.IsWhiteSpace())
            {
                readingPrecedences = false;

                continue;
            }

            if (readingPrecedences)
            {
                var split = line.Split('|');
                split.MoveNext();

                var ruleTarget = int.Parse(line[split.Current]);

                split.MoveNext();

                var ruleNumber = int.Parse(line[split.Current]);

                if (precedences[ruleTarget] is not { } precedenceSet)
                {
                    precedenceSet = [ ruleNumber ];
                    precedences[ruleTarget] = precedenceSet;
                }
                else
                {
                    precedenceSet.Add(ruleNumber);
                }
            }
            else
            {
                result += CheckLine(line);
            }
        }

        if (display)
        {
            AnsiConsole.MarkupLine($"[green]Sum of middle page numbers: [yellow]{result}[/][/]");
        }

        return;

        int CheckLine(ReadOnlySpan<char> line)
        {
            Span<int> positions = stackalloc int[100];

            // Read line to get positions
            var position = 1;
            foreach (var range in line.Split(','))
            {
                var number = int.Parse(line[range]);

                positions[number] = position;

                position++;
            }

            var middlePosition = (position - 1) / 2;
            var middleNumber = 0;

            var index = 0;
            // Check if positions respect precedence rules
            foreach (var range in line.Split(','))
            {
                var number = int.Parse(line[range]);

                // Fetch middle number
                if (index == middlePosition)
                {
                    middleNumber = number;
                }
                index++;

                if (precedences[number] is not { } precedenceSet)
                {
                    continue;
                }

                var numberPosition = positions[number];

                // Check all precedence rules for numbers in the list
                foreach (var nextNumber in precedenceSet)
                {
                    var nextNumberPosition = positions[nextNumber];

                    if (nextNumberPosition != 0 && numberPosition >= nextNumberPosition)
                    {
                        return 0;
                    }
                }
            }

            return middleNumber;
        }
    }

    public override void RunPart2(bool display = true)
    {
        // if (display)
        // {
        //     AnsiConsole.MarkupLine($"[green]Number of safe reports: [yellow]{xmasCount}[/][/]");
        // }
    }
}