using Dpz.Core.Service.Mediator.Features.Media.Commands;

namespace Dpz.Core.Service.Mediator.Features.Markdown.Commands;

/// <summary>
/// 处理 Markdown 删除时的图片清理（兼容旧链路，已过时）。
/// </summary>
[Obsolete("已过时，改用消息队列处理，后续版本将会删除 ")]
public class DeleteMarkdownEvent(IMediator mediator) : IRequestHandler<DeleteMarkdownRequest>
{
    private readonly HtmlParser _htmlParse = new();

    /// <summary>
    /// 解析 Markdown 中的图片并触发删除请求。
    /// </summary>
    public async ValueTask<Unit> Handle(
        DeleteMarkdownRequest request,
        CancellationToken cancellationToken
    )
    {
        var images = new List<string>();
        foreach (var markdown in request.Markdown)
        {
            images.AddRange(await GetImagesByMarkdownAsync(markdown));
        }

        await mediator.Send(new RemoveImagesRequest { Images = images }, cancellationToken);
        return Unit.Value;
    }

    private async Task<List<string>> GetImagesByMarkdownAsync(string markdown)
    {
        var htmlContent = markdown.MarkdownToHtml();

        var document = await _htmlParse.ParseDocumentAsync(htmlContent);
        var imageElements = document.GetElementsByTagName("img");
        return GetElementImageUrls(imageElements);
    }

    private static List<string> GetElementImageUrls(IHtmlCollection<IElement> elements)
    {
        return elements
            .Select(x => x.Attributes["src"])
            .Where(x => x != null)
            .Select(x => x!.Value)
            .Where(x => !string.IsNullOrEmpty(x))
            .ToList();
    }
}