ImageGrouper.cs

using System.Text.RegularExpressions;

namespace ImageHelper.Shared;

public class ImageGrouper
{
    private string _parentFolder;
    private SearchOption _option;

    private readonly List<string> _imageExtensions = new List<string> { ".jpg", ".jpeg", ".png", ".gif" };

    public ImageGrouper(string parentFolder, SearchOption option = SearchOption.TopDirectoryOnly)
    {
        _parentFolder = parentFolder;
        _option = option;
    }

    public void GroupImagesByCreateTime()
    {
        var imageFiles = GetAllImages();

        foreach (var imageFile in imageFiles)
        {
            var createTime = GetImageCreationTime(imageFile);
            var year = createTime.Year;
            var month = createTime.Month;

            var newFolder = Path.Combine(_parentFolder, year.ToString(), month.ToString().PadLeft(2, '0'));

            MoveFileToNewFolder(newFolder, imageFile);
        }
    }

    public void GroupImagesByFileName()
    {
        var imageFiles = GetAllImages();

        foreach (var imageFile in imageFiles)
        {
            var yearAndMonth = ExtractYearAndMonthFromFileName(imageFile);

            if (yearAndMonth != null)
            {
                var newFolder = Path.Combine(_parentFolder, yearAndMonth.Item1, yearAndMonth.Item2);

                MoveFileToNewFolder(imageFile, newFolder);
            }
        }
    }

    public void GroupScreenshots()
    {
        var imageFiles = GetAllImages();

        foreach (var imageFile in imageFiles)
        {
            if (IsScreenshotImage(imageFile))
            {
                var newFolder = Path.Combine(_parentFolder, "Screenshots");

                MoveFileToNewFolder(imageFile, newFolder);
            }
        }
    }

    private void MoveFileToNewFolder(string imageFile, string newFolder)
    {
        if (!Directory.Exists(newFolder))
        {
            Directory.CreateDirectory(newFolder);
        }

        var newFileName = Path.Combine(newFolder, Path.GetFileName(imageFile));

        if (!string.Equals(imageFile, newFileName))
        {
            File.Move(imageFile, newFileName);
        }
    }

    private IEnumerable<string> GetAllImages()
    {
        return Directory.GetFiles(_parentFolder, "*", _option)
            .Where(file => _imageExtensions.Any(ext => file.EndsWith(ext)));
    }

    private Tuple<string, string>? ExtractYearAndMonthFromFileName(string imageFile)
    {
        string? date = null;

        var fileName = Path.GetFileName(imageFile);
        var regex1 = new Regex(@"^(\d{8})_\d*_(iOS|Android)");
        var regex2 = new Regex(@"^IMG_(\d{8})_\d*");

        var match1 = regex1.Match(fileName);
        var match2 = regex2.Match(fileName);

        if (match1.Success)
        {
            date = match1.Groups[1].Value;
        }
        else if (match2.Success)
        {
            date = match2.Groups[1].Value;
        }

        if (!string.IsNullOrEmpty(date))
        {
            var year = date[0..4];
            var month = date[4..6];

            return new Tuple<string, string>(year, month);
        }

        return null;
    }

    private DateTime GetImageCreationTime(string imageFile)
    {
        var fileInfo = new FileInfo(imageFile);
        return fileInfo.CreationTime;
    }

    private bool IsScreenshotImage(string imageFile)
    {
        var fileName = Path.GetFileName(imageFile);
        var regex = new Regex(@"^Screenshot");

        return regex.IsMatch(fileName);
    }
}