decePubClient/Services/ListService.cs

using System.Net;

using decePubClient.Extensions;
using decePubClient.Models;
using decePubClient.Models.Mastodon;

using PrivaPub.ClientModels;

namespace decePubClient.Services
{
	/// <summary>
	/// The current persona's lists (Mastodon's /api/v1/lists): made, renamed and deleted, their members (only accounts the
	/// persona follows; PrivaPub drops a member when the follow ends), and the lists an account is in. A list's posts are a
	/// feed of their own (TimelineService, TimelineType.Lists). Lists come back empty on failure; nothing throws.
	/// </summary>
	public class ListService(IHttpService httpService, ILoggingService logger, CoalescingStringLocalizer localizer)
	{
		/// <summary>The most members PrivaPub keeps in one list, and so the most read back.</summary>
		public const int MaxMembers = 500;
		const int MembersPerPage = 80;

		public async Task<List<MastodonList>> All(CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Get(APIs.Mastodon.GET_Lists, cancellationToken: cancellationToken);
			if (response.IsSuccessStatusCode)
				return await response.MastodonReadFromJsonAsync<List<MastodonList>>(cancellationToken) ?? [];

			await LogFailure(response, nameof(All), cancellationToken);
			return [];
		}

		/// <summary>Makes the list when it has no id yet, or saves its title, replies policy and exclusivity; Data is the list.</summary>
		public async Task<WebResult> Save(MastodonList list, CancellationToken cancellationToken = default)
		{
			var form = new MastodonList { Title = list.Title?.Trim(), RepliesPolicy = list.RepliesPolicy, Exclusive = list.Exclusive };
			using var response = list.Id is null
				? await httpService.Post(APIs.Mastodon.POST_List, form, cancellationToken: cancellationToken)
				: await httpService.Put(APIs.Mastodon.PUT_M_List(list.Id), form, cancellationToken: cancellationToken);
			if (!response.IsSuccessStatusCode)
				return await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);

			return new WebResult { Data = await response.MastodonReadFromJsonAsync<MastodonList>(cancellationToken) };
		}

		public async Task<WebResult> Delete(string listId, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Delete(APIs.Mastodon.DELETE_M_List(listId), cancellationToken: cancellationToken);
			if (!response.IsSuccessStatusCode)
				return await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);

			return new WebResult();
		}

		/// <summary>Every member of the list, page by page, up to MaxMembers.</summary>
		public async Task<List<Account>> Members(string listId, CancellationToken cancellationToken = default)
		{
			var members = new List<Account>();
			var maxId = default(string);
			while (members.Count < MaxMembers)
			{
				string[] parameters = maxId is null ? [$"limit={MembersPerPage}"] : [$"limit={MembersPerPage}", $"max_id={Uri.EscapeDataString(maxId)}"];
				using var response = await httpService.Get(APIs.Mastodon.M_ListAccounts(listId), parameters, cancellationToken: cancellationToken);
				if (!response.IsSuccessStatusCode)
				{
					await LogFailure(response, nameof(Members), cancellationToken);
					return members;
				}

				var page = await response.MastodonReadFromJsonAsync<List<Account>>(cancellationToken) ?? [];
				members.AddRange(page);
				maxId = response.PageCursors().MaxId;
				if (page.Count < MembersPerPage || maxId is null)
					return members;
			}
			return members;
		}

		/// <summary>Adds (or removes) an account the persona follows to (from) the list.</summary>
		public async Task<WebResult> SetMember(string listId, string accountId, bool member, CancellationToken cancellationToken = default)
		{
			using var response = member
				? await httpService.Post(APIs.Mastodon.M_ListAccounts(listId), new ListAccountsForm { AccountIds = [accountId] },
					cancellationToken: cancellationToken)
				: await httpService.Delete(APIs.Mastodon.M_ListAccounts(listId), [$"account_ids[]={Uri.EscapeDataString(accountId)}"],
					cancellationToken: cancellationToken);
			if (!response.IsSuccessStatusCode)
				return await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);

			return new WebResult();
		}

		/// <summary>The persona's lists the account is in.</summary>
		public async Task<List<MastodonList>> Of(string accountId, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Get(APIs.Mastodon.GET_M_AccountLists(accountId), cancellationToken: cancellationToken);
			if (response.IsSuccessStatusCode)
				return await response.MastodonReadFromJsonAsync<List<MastodonList>>(cancellationToken) ?? [];

			await LogFailure(response, nameof(Of), cancellationToken);
			return [];
		}

		/// <summary>Accounts the persona follows whose name, display name or server starts with the query (PrivaPub's
		/// following=true; nothing is resolved).</summary>
		public async Task<List<Account>> FindFollowed(string query, CancellationToken cancellationToken = default)
		{
			if (string.IsNullOrWhiteSpace(query))
				return [];
			using var response = await httpService.Get(APIs.Mastodon.GET_AccountSearch,
				[$"q={Uri.EscapeDataString(query.Trim())}", "following=true", "resolve=false", "limit=20"], cancellationToken: cancellationToken);
			if (response.IsSuccessStatusCode)
				return await response.MastodonReadFromJsonAsync<List<Account>>(cancellationToken) ?? [];

			await LogFailure(response, nameof(FindFollowed), cancellationToken);
			return [];
		}

		async Task LogFailure(HttpResponseMessage response, string caller, CancellationToken cancellationToken)
		{
			var result = await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);
			if (result.StatusCode is not ((int)HttpStatusCode.Gone or (int)HttpStatusCode.NotFound))
				await logger.ProcessWarning(result.ToString(localizer), $"{nameof(ListService)}.{caller}", cancellationToken);
		}
	}
}