DiscordClient/DiscordClient/DiscordUserClient.cs

using System.Net.Http.Headers;
using System.Net.Http.Json;
using System.Text.Json.Serialization;
using DiscordClient.Data;

namespace DiscordClient;

public class DiscordUserClient
{
    private readonly HttpClient _httpClient;

    public DiscordUserClient(string authorizationToken)
    {
        _httpClient = new HttpClient();
        _httpClient.DefaultRequestHeaders.Host = "discord.com";
        _httpClient.DefaultRequestHeaders.Authorization = AuthenticationHeaderValue.Parse(
            authorizationToken
        );
    }

    public async Task<ChannelMessagesResponse[]?> GetChannelMessages(
        string channelId,
        int offset = 0,
        string? authorId = null,
        int limit = 50
    )
    {
        string authorQuery = authorId is not null ? $"&author_id={authorId}" : "";
        string url =
            $"https://discord.com/api/v9/channels/{channelId}/messages?limit={limit}&offset={offset}{authorQuery}";
        HttpResponseMessage response = await _httpClient.GetAsync(url);
        return await response.Content.ReadFromJsonAsync<ChannelMessagesResponse[]>();
    }

    sealed class MessageContent
    {
        [JsonPropertyName("content")]
        public string? Content { get; set; }
    }

    /// <summary>
    /// This method does NOT work yet.
    /// </summary>
    /// <param name="channelId"></param>
    /// <param name="message"></param>
    /// <returns></returns>
    public async Task<HttpResponseMessage> SendMessage(string channelId, string message)
    {
        throw new NotImplementedException();
        string url = $"https://discord.com/api/v9/channels/{channelId}/messages";
        HttpContent httpContent = JsonContent.Create(new MessageContent { Content = message });
        return await _httpClient.PostAsync(url, httpContent);
    }

    public async Task<HttpResponseMessage> DeleteMessage(string channelId, string messageId)
    {
        string url = $"https://discord.com/api/v9/channels/{channelId}/messages/{messageId}";
        return await _httpClient.DeleteAsync(url);
    }

    /// <summary>
    /// This method returns some of most recent messages, sent to a guild.
    /// </summary>
    /// <param name="guildId">Guild ID from which we're gathering messages.</param>
    /// <param name="authorId">
    /// Optional author ID. If specified, gather only
    /// recent messages from this particular author.
    /// </param>
    /// <returns></returns>
    public async Task<GuildMessageSearchResponse?> SearchGuildMessages(
        string guildId,
        ulong offset,
        string? authorId = null
    )
    {
        string authorQuery = authorId is not null ? $"&author_id={authorId}" : "";
        string url =
            $"https://discord.com/api/v9/guilds/{guildId}/messages/search?offset={offset}{authorQuery}";
        HttpResponseMessage response = await _httpClient.GetAsync(url);
        return await response.Content.ReadFromJsonAsync<GuildMessageSearchResponse>();
    }
}