Parallel.ForEach version #4

class Program
{
    private static readonly ConcurrentDictionary<string, int> wordCounts = new ConcurrentDictionary<string, int>();

    static void Main(string[] args)
    {
        if (args.Length < 2)
        {
            Console.WriteLine("Usage: <path> <minWordLength>");
            return;
        }

        string path = args[0];
        if (!int.TryParse(args[1], out int minWordLength) || minWordLength <= 0)
        {
            Console.WriteLine("Invalid minimum word length.");
            return;
        }

        if (!Directory.Exists(path))
        {
            Console.WriteLine("Directory does not exist.");
            return;
        }

        var files = Directory.GetFiles(path, "*.txt", SearchOption.AllDirectories);

        // Process files using Parallel.ForEach
        Parallel.ForEach(files, (filePath) =>
        {
            ProcessFile(filePath, minWordLength);
        });

        // Get top-10 most frequent words
        var topWords = wordCounts
            .OrderByDescending(kv => kv.Value)
            .Take(10)
            .ToList();

        Console.WriteLine("Top 10 most used words:");
        foreach (var word in topWords)
        {
            Console.WriteLine($"{word.Key}: {word.Value}");
        }
    }

    private static void ProcessFile(string filePath, int minWordLength)
    {
        try
        {
            var text = File.ReadAllText(filePath);
            var words = text.Split(new[] { ' ', '\r', '\n', '\t', '.', ',', ';', '!', '?' }, StringSplitOptions.RemoveEmptyEntries);

            foreach (var word in words)
            {
                if (word.Length >= minWordLength)
                {
                    var normalizedWord = word.ToLowerInvariant();
                    wordCounts.AddOrUpdate(normalizedWord, 1, (key, oldValue) => oldValue + 1);
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error processing file {filePath}: {ex.Message}");
        }
    }
}