using System;
using System.Collections.Generic;
using System.IO.Pipelines;
using System.Net.Http;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using CompatBot.EventHandlers.LogParsing.ArchiveHandlers;
using CompatBot.Utils;
using DSharpPlus.Entities;
using OneDriveClient;
using OneDriveClient.POCOs;

namespace CompatBot.EventHandlers.LogParsing.SourceHandlers;

internal sealed class OneDriveSourceHandler : BaseSourceHandler
{
    private static readonly Regex ExternalLink = new(@"(?<onedrive_link>(https?://)?(1drv\.ms|onedrive\.live\.com)/[^>\s]+)", DefaultOptions);
    private static readonly Client Client = new();

    public override async Task<(ISource? source, string? failReason)> FindHandlerAsync(DiscordMessage message, ICollection<IArchiveHandler> handlers)
    {
        if (string.IsNullOrEmpty(message.Content))
            return (null, null);

        var matches = ExternalLink.Matches(message.Content);
        if (matches.Count == 0)
            return (null, null);

        using var httpClient = HttpClientFactory.Create();
        foreach (Match m in matches)
        {
            try
            {
                if (m.Groups["onedrive_link"].Value is not { Length: > 0 } lnk
                    || !Uri.TryCreate(lnk, UriKind.Absolute, out var uri)
                    || await Client.ResolveContentLinkAsync(uri, Config.Cts.Token).ConfigureAwait(false) is not { ContentDownloadUrl: { Length: > 0 } downloadUrl } itemMeta)
                    continue;
                try
                {
                    var filename = itemMeta.Name ?? "";
                    var filesize = itemMeta.Size;
                    uri = new(downloadUrl);

                    await using var stream = await httpClient.GetStreamAsync(uri).ConfigureAwait(false);
                    var buf = BufferPool.Rent(SnoopBufferSize);
                    try
                    {
                        var read = await stream.ReadBytesAsync(buf).ConfigureAwait(false);
                        foreach (var handler in handlers)
                        {
                            var (canHandle, reason) = handler.CanHandle(filename, filesize, buf.AsSpan(0, read));
                            if (canHandle)
                                return (new OneDriveSource(uri, handler, filename, filesize), null);
                            else if (!string.IsNullOrEmpty(reason))
                                return (null, reason);
                        }
                    }
                    finally
                    {
                        BufferPool.Return(buf);
                    }
                }
                catch (Exception e)
                {
                    Config.Log.Warn(e, $"Error sniffing {m.Groups["link"].Value}");
                }
            }
            catch (Exception e)
            {
                Config.Log.Warn(e, $"Error sniffing {m.Groups["mega_link"].Value}");
            }
        }
        return (null, null);
    }


    private sealed class OneDriveSource : ISource
    {
        private readonly Uri uri;
        private readonly IArchiveHandler handler;

        public string SourceType => "OneDrive";
        public string FileName { get; }
        public long SourceFileSize { get; }
        public long SourceFilePosition => handler.SourcePosition;
        public long LogFileSize => handler.LogSize;

        internal OneDriveSource(Uri uri, IArchiveHandler handler, string fileName, int fileSize)
        {
            this.uri = uri;
            this.handler = handler;
            FileName = fileName;
            SourceFileSize = fileSize;
        }

        public async Task FillPipeAsync(PipeWriter writer, CancellationToken cancellationToken)
        {
            using var client = HttpClientFactory.Create();
            await using var stream = await client.GetStreamAsync(uri, cancellationToken).ConfigureAwait(false);
            await handler.FillPipeAsync(stream, writer, cancellationToken).ConfigureAwait(false);
        }

        public void Dispose() { }
    }
}