[backend/masto-client] Add tag timeline endpoint (ISH-115)

Iceshrimp.Backend/Controllers/Mastodon/Schemas/TimelineSchemas.cs

@@ -10,4 +10,11 @@ public abstract class TimelineSchemas
 		[FromQuery(Name = "remote")]     public bool OnlyRemote { get; set; } = false;
 		[FromQuery(Name = "only_media")] public bool OnlyMedia  { get; set; } = false;
 	}
+
+	public class HashtagTimelineRequest : PublicTimelineRequest
+	{
+		[FromQuery(Name = "any")]  public List<string> Any  { get; set; } = [];
+		[FromQuery(Name = "all")]  public List<string> All  { get; set; } = [];
+		[FromQuery(Name = "none")] public List<string> None { get; set; } = [];
+	}
 }

Iceshrimp.Backend/Controllers/Mastodon/TimelineController.cs

@@ -69,6 +69,28 @@ public class TimelineController(DatabaseContext db, NoteRenderer noteRenderer, I
 		return Ok(res);
 	}
 
+	[Authorize("read:statuses")]
+	[HttpGet("tag/{hashtag}")]
+	[ProducesResponseType(StatusCodes.Status200OK, Type = typeof(IEnumerable<StatusEntity>))]
+	public async Task<IActionResult> GetHashtagTimeline(
+		string hashtag, MastodonPaginationQuery query, TimelineSchemas.HashtagTimelineRequest request
+	)
+	{
+		var user = HttpContext.GetUserOrFail();
+
+		var res = await db.Notes
+		                  .IncludeCommonProperties()
+		                  .Where(p => p.Tags.Contains(hashtag.ToLowerInvariant()))
+		                  .FilterByHashtagTimelineRequest(request)
+		                  .FilterBlocked(user)
+		                  .FilterMuted(user)
+		                  .Paginate(query, ControllerContext)
+		                  .PrecomputeVisibilities(user)
+		                  .RenderAllForMastodonAsync(noteRenderer, user);
+
+		return Ok(res);
+	}
+
 	[Authorize("read:lists")]
 	[HttpGet("list/{id}")]
 	[ProducesResponseType(StatusCodes.Status200OK, Type = typeof(IEnumerable<StatusEntity>))]

Iceshrimp.Backend/Core/Extensions/QueryableExtensions.cs

@@ -408,6 +408,20 @@ public static class QueryableExtensions
 		return query;
 	}
 
+	public static IQueryable<Note> FilterByHashtagTimelineRequest(
+		this IQueryable<Note> query, TimelineSchemas.HashtagTimelineRequest request
+	)
+	{
+		if (request.Any.Count > 0)
+			query = query.Where(p => request.Any.Any(t => p.Tags.Contains(t)));
+		if (request.All.Count > 0)
+			query = query.Where(p => request.All.All(t => p.Tags.Contains(t)));
+		if (request.None.Count > 0)
+			query = query.Where(p => request.None.All(t => !p.Tags.Contains(t)));
+
+		return query.FilterByPublicTimelineRequest(request);
+	}
+
 #pragma warning disable CS8602 // Dereference of a possibly null reference.
 // Justification: in the context of nullable EF navigation properties, null values are ignored and therefore irrelevant.
 // Source: https://learn.microsoft.com/en-us/ef/core/miscellaneous/nullable-reference-types#navigating-and-including-nullable-relationships