SocialPub/PrivaPub/Web/Pages/Pages.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;

using MongoDB.Entities;

using PrivaPub.Domain.Privacy;
using PrivaPub.Federation.Actors;
using PrivaPub.Federation.Rendering;
using PrivaPub.Models.Federation;
using PrivaPub.Models.Post;
using PrivaPub.StaticServices;

using PostEntity = PrivaPub.Models.Post.Post;

namespace PrivaPub.Web.Pages
{
	public sealed record PostView(string Title, string Warning, string ContentHtml, string Url, DateTime Published, bool Edited)
	{
		public static PostView From(PostEntity post, LocalActor author) => new(
			post.Title,
			post.SpoilerText ?? (post.HasContentWarning ? ActivityPubRenderer.ContentWarning : default),
			post.ContentHtml ?? ActivityPubRenderer.Html(post.Text),
			author.PostHtmlUrl(post.ID),
			DateTime.SpecifyKind(post.CreationDate, DateTimeKind.Utc),
			post.EditedAt.HasValue);
	}

	public abstract class PublicPageModel : PageModel
	{
		protected bool WantsActivityJson()
		{
			var accept = Request.Headers.Accept.ToString();
			return accept.Contains("activity+json", StringComparison.OrdinalIgnoreCase) || accept.Contains("ld+json", StringComparison.OrdinalIgnoreCase);
		}

		protected void Harden()
		{
			Response.Headers["Content-Security-Policy"] = "default-src 'none'; style-src 'unsafe-inline'; img-src https: data:; base-uri 'none'; form-action 'none'; frame-ancestors 'none'";
			Response.Headers["Referrer-Policy"] = "no-referrer";
			Response.Headers["X-Content-Type-Options"] = "nosniff";
		}
	}

	public class ProfileModel : PublicPageModel
	{
		const int PageSize = 20;

		readonly ILocalActorService _localActors;
		readonly DbEntities _dbEntities;

		public ProfileModel(ILocalActorService localActors, DbEntities dbEntities)
		{
			_localActors = localActors;
			_dbEntities = dbEntities;
		}

		public LocalActor Actor { get; private set; }
		public string BiographyHtml { get; private set; }
		public IReadOnlyList<PostView> Posts { get; private set; } = Array.Empty<PostView>();

		public async Task<IActionResult> OnGetAsync(string user, CancellationToken token)
		{
			Actor = await _localActors.FindByUserName(user, token);
			if (Actor is not { IsFederated: true, IsCircle: false, Suspended: false } || Actor.IsServerActor)
				return NotFound();
			if (WantsActivityJson())
				return Redirect(Actor.Uri);

			Harden();
			BiographyHtml = ActivityPubRenderer.Html(Actor.Summary);
			var posts = await (Actor.Kind == LocalActorKind.Group
					? _dbEntities.Posts.Match(p => p.GroupId == Actor.Id)
					: _dbEntities.Posts.Match(p => p.GroupUserId == Actor.Id && !p.IsFederatedCopy))
				.Match(VisibilityPolicy.IsPublic)
				.Match(p => p.ReblogOfPostId == null)
				.Sort(p => p.ID, Order.Descending)
				.Limit(PageSize)
				.ExecuteAsync(token);
			var authors = new Dictionary<string, LocalActor> { [Actor.Id] = Actor };
			var views = new List<PostView>();
			foreach (var post in posts)
			{
				if (post.IsFederatedCopy)
					continue;
				if (!authors.TryGetValue(post.GroupUserId, out var author))
					authors[post.GroupUserId] = author = await _localActors.FindById(LocalActorKind.Person, post.GroupUserId, token);
				if (author is { Suspended: false })
					views.Add(PostView.From(post, author));
			}
			Posts = views;
			return Page();
		}
	}

	// The hashtag links our posts carry (/tags/{tag}): this server's public posts with that tag, as a page like a profile's.
	public class TagModel : PublicPageModel
	{
		const int PageSize = 20;

		readonly ILocalActorService _localActors;
		readonly DbEntities _dbEntities;

		public TagModel(ILocalActorService localActors, DbEntities dbEntities)
		{
			_localActors = localActors;
			_dbEntities = dbEntities;
		}

		public string Tag { get; private set; }
		public IReadOnlyList<PostView> Posts { get; private set; } = Array.Empty<PostView>();

		public async Task<IActionResult> OnGetAsync(string tag, CancellationToken token)
		{
			Tag = tag?.TrimStart('#').ToLowerInvariant();
			if (string.IsNullOrEmpty(Tag) || Tag.Length > 100)
				return NotFound();
			Harden();
			var posts = await _dbEntities.Posts
				.Match(p => p.Tags.Contains(Tag) && !p.IsFederatedCopy && p.ReblogOfPostId == null && p.Visibility == PostVisibility.Public)
				.Match(VisibilityPolicy.IsPublic)
				.Match(VisibilityPolicy.IsListed)
				.Sort(p => p.ID, Order.Descending)
				.Limit(PageSize)
				.ExecuteAsync(token);
			var authors = new Dictionary<string, LocalActor>();
			var views = new List<PostView>();
			foreach (var post in posts)
			{
				if (!authors.TryGetValue(post.GroupUserId, out var author))
					authors[post.GroupUserId] = author = await _localActors.FindById(LocalActorKind.Person, post.GroupUserId, token);
				if (author is { IsFederated: true, Suspended: false })
					views.Add(PostView.From(post, author));
			}
			Posts = views;
			return Page();
		}
	}

	public class StatusModel : PublicPageModel
	{
		readonly ILocalActorService _localActors;
		readonly DbEntities _dbEntities;

		public StatusModel(ILocalActorService localActors, DbEntities dbEntities)
		{
			_localActors = localActors;
			_dbEntities = dbEntities;
		}

		public LocalActor Actor { get; private set; }
		public PostView Post { get; private set; }
		public string ObjectUri { get; private set; }

		public async Task<IActionResult> OnGetAsync(string user, string id, CancellationToken token)
		{
			Actor = await _localActors.FindByUserName(user, token);
			if (Actor is not { IsFederated: true, Kind: LocalActorKind.Person, Suspended: false })
				return NotFound();
			var post = await _dbEntities.Posts
				.Match(p => p.ID == id && p.GroupUserId == Actor.Id && !p.IsFederatedCopy && p.ReblogOfPostId == null)
				.Match(VisibilityPolicy.IsPublic)
				.ExecuteFirstAsync(token);
			if (post == default)
				return NotFound();
			ObjectUri = Actor.PostUri(post.ID);
			if (WantsActivityJson())
				return Redirect(ObjectUri);

			Harden();
			Post = PostView.From(post, Actor);
			return Page();
		}
	}

	public class StargazingModel : PublicPageModel
	{
		readonly Microsoft.Extensions.Options.IOptionsMonitor<Infrastructure.Statistics.StatisticsOptions> _options;
		readonly Microsoft.Extensions.Options.IOptionsMonitor<Models.AppConfiguration> _app;

		readonly Infrastructure.Geo.IGeoLocator _geo;

		public StargazingModel(Microsoft.Extensions.Options.IOptionsMonitor<Infrastructure.Statistics.StatisticsOptions> options,
			Microsoft.Extensions.Options.IOptionsMonitor<Models.AppConfiguration> app, Infrastructure.Geo.IGeoLocator geo)
		{
			_options = options;
			_app = app;
			_geo = geo;
		}

		public bool CrawlerEnabled => _options.CurrentValue.Crawler.Enabled;
		public string GeoSource => _geo.Source;
		public string UserAgent => Federation.Crawler.Stargazer.UserAgent(_app.CurrentValue.BackendBaseAddress);

		public void OnGet() => Harden();
	}
}