var lines = File.ReadAllLines("input.txt");

var pageOrderingRules = new List<(int, int)>();
var pageNumbersUpdates = new List<List<int>>();

var separatorIndex = lines.ToList().IndexOf(string.Empty);
for (var i = 0; i < separatorIndex; i++)
{
    var parts = lines[i].Split('|');
    pageOrderingRules.Add((int.Parse(parts[0]), int.Parse(parts[1])));
}

for (var i = separatorIndex + 1; i < lines.Length; i++)
{
    var currentList = lines[i].Split(',')
        .Select(int.Parse)
        .ToList();
    pageNumbersUpdates.Add(currentList);
}

var part1 = 0;
var part2 = 0;

foreach (var pageNumberUpdate in pageNumbersUpdates)
{
    var isInRightOder = true;

    for (var i = 0; i < pageNumberUpdate.Count; i++)
    {
        var rules = pageOrderingRules
            .Where(rule => rule.Item1 == pageNumberUpdate[i])
            .ToList();

        if (!IsPageInRightOrder(i, rules, pageNumberUpdate))
        {
            isInRightOder = false;
            break;
        }
    }

    if (isInRightOder)
    {
        part1 += pageNumberUpdate[pageNumberUpdate.Count / 2];
    }
    else
    {
        var orderedPages = OrderPages(pageNumberUpdate, pageOrderingRules);
        part2 += orderedPages[orderedPages.Count / 2];
    }
}

Console.WriteLine($"Part1: {part1}\nPart2: {part2}");

List<int> OrderPages( List<int> pageNumberUpdate, List<(int, int)> rules)
{
    var orderedPages = new List<int>(pageNumberUpdate);
    bool changesMade;
    
    do 
    {
        changesMade = false;
        
        foreach (var rule in rules)
        {
            if (!orderedPages.Contains(rule.Item1) || !orderedPages.Contains(rule.Item2)) continue;
            
            var index1 = orderedPages.IndexOf(rule.Item1);
            var index2 = orderedPages.IndexOf(rule.Item2);

            if (index1 <= index2) continue;
                
            orderedPages.RemoveAt(index1);
            orderedPages.Insert(index2, rule.Item1);
            changesMade = true;
            break;
        }
    } 
    while (changesMade);

    return orderedPages;
}

bool IsPageInRightOrder(int pageIndex, List<(int, int)> rules, List<int> pageNumberUpdate)
{
    return rules.Select(rule => pageNumberUpdate.IndexOf(rule.Item2)).Where(indexOfRuleSecondPart => indexOfRuleSecondPart != -1).All(indexOfRuleSecondPart => pageIndex < indexOfRuleSecondPart);
}