archived-discord-bot/CompatBot/EventHandlers/LogParsing/SourceHandlers/FileSourceHandler.cs

using System.IO;
using System.IO.Pipelines;
using CompatBot.EventHandlers.LogParsing.ArchiveHandlers;
using ResultNet;

namespace CompatBot.EventHandlers.LogParsing.SourceHandlers;

internal class FileSource : ISource
{
    private readonly string path;
    private readonly IArchiveHandler handler;

    public FileSource(string path, IArchiveHandler handler)
    {
        this.path = path;
        this.handler = handler;
        var fileInfo = new FileInfo(path);
        SourceFileSize = fileInfo.Length;
        FileName = fileInfo.Name;
    }

    public string SourceType => "File";
    public string FileName { get; }
    public long SourceFileSize { get; }
    public long SourceFilePosition { get; }
    public long LogFileSize { get; }

    public async Task FillPipeAsync(PipeWriter writer, CancellationToken cancellationToken)
    {
        await using var stream = File.Open(path, FileMode.Open, FileAccess.Read, FileShare.Read);
        await handler.FillPipeAsync(stream, writer, cancellationToken).ConfigureAwait(false);
    }

    public static async Task<ISource> DetectArchiveHandlerAsync(string path, ICollection<IArchiveHandler> handlers)
    {
        var buf = new byte[4096];
        await using var stream = File.Open(path, FileMode.Open, FileAccess.Read, FileShare.Read);
        var read = await stream.ReadBytesAsync(buf).ConfigureAwait(false);
        foreach (var handler in handlers)
        {
            var result = handler.CanHandle(Path.GetFileName(path), (int)stream.Length, buf.AsSpan(0, read));
            if (result.IsSuccess())
                return new FileSource(path, handler);
                
            if (result.Message is {Length: >0} reason)
                throw new InvalidOperationException(reason);
        }
        throw new InvalidOperationException("Unknown source type");
    }

    public void Dispose() { }
}