Masuit.Tools/Masuit.Tools.Abstractions/Files/FileDetector/AbstractFullRegexDetector.cs

using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Text.RegularExpressions;
using Masuit.Tools.AspNetCore.Mime;

namespace Masuit.Tools.Files.FileDetector;

public abstract class AbstractFullRegexDetector : IDetector
{
    public abstract string Extension { get; }

    public virtual string Precondition => "txt";

    protected abstract Regex Pattern { get; }

    public virtual string MimeType => new MimeMapper().GetMimeFromExtension("." + Extension);

    public virtual List<FormatCategory> FormatCategories => GetType().GetCustomAttributes<FormatCategoryAttribute>().Select(a => a.Category).ToList();

    public virtual bool Detect(Stream stream)
    {
        var encodings = new[]
        {
            Encoding.UTF8,
            Encoding.Unicode,
            Encoding.GetEncoding ( "utf-7" ),
            Encoding.GetEncoding ( "utf-32" ),
            Encoding.BigEndianUnicode,
            Encoding.GetEncoding ( "ascii" ),
            Encoding.GetEncoding ( "ks_c_5601-1987" ),
            Encoding.GetEncoding ( "iso-2022-kr" ),
            Encoding.GetEncoding ( "shift_jis" ),
            Encoding.GetEncoding ( "csISO2022JP" ),
            Encoding.GetEncoding ( "windows-1250" ),
            Encoding.GetEncoding ( "windows-1251" ),
            Encoding.GetEncoding ( "windows-1252" ),
            Encoding.GetEncoding ( "windows-1253" ),
            Encoding.GetEncoding ( "windows-1254" ),
        };
        foreach (var encoding in encodings)
        {
            stream.Position = 0;
            using var reader = new StreamReader(stream, encoding, true, 4096, true);
            string buffer = reader.ReadToEnd();
            if (Pattern.Replace(buffer, "") == string.Empty)
            {
                return true;
            }
        }

        return false;
    }
}