nadekobot/src/NadekoBot/Modules/Nsfw/Common/Downloaders/GelbooruImageDownloader.cs

using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Text.Json;
using System.Text.Json.Serialization;
using System.Threading;
using System.Threading.Tasks;

namespace NadekoBot.Modules.Nsfw.Common
{
    public class GelbooruImageDownloader : ImageDownloader<DapiImageObject>
    {
        public GelbooruImageDownloader(HttpClient http) : base(Booru.Gelbooru, http)
        {
        }

        public override async Task<List<DapiImageObject>> DownloadImagesAsync(string[] tags, int page,
            bool isExplicit = false, CancellationToken cancel = default)
        {
            var tagString = ImageDownloaderHelper.GetTagString(tags, isExplicit);
            var uri = $"https://gelbooru.com/index.php?page=dapi&s=post&json=1&q=index&limit=100" +
                      $"&tags={tagString}&pid={page}";
            using var req = new HttpRequestMessage(HttpMethod.Get, uri);
            using var res = await _http.SendAsync(req, cancel).ConfigureAwait(false);
            res.EnsureSuccessStatusCode();
            var resString = await res.Content.ReadAsStringAsync(cancel);
            if (string.IsNullOrWhiteSpace(resString))
                return new();

            var images = JsonSerializer.Deserialize<GelbooruResponse>(resString, _serializerOptions);
            if (images is null or { Post: null })
                return new();

            return images.Post.Where(x => x.FileUrl is not null).ToList();
        }
    }

    public class GelbooruResponse
    {
        [JsonPropertyName("post")]
        public List<DapiImageObject> Post { get; set; }
    }
}