SocialPub/PrivaPub/Api/Mastodon/Controllers/MediaController.cs

using Microsoft.AspNetCore.RateLimiting;
using PrivaPub.Infrastructure.Statistics;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;

using MongoDB.Entities;

using PrivaPub.Api.Mastodon.Infrastructure;
using PrivaPub.Domain.Media;
using PrivaPub.Models.Media;
using PrivaPub.Infrastructure;
using PrivaPub.Infrastructure.Jobs;

using System.Globalization;

namespace PrivaPub.Api.Mastodon.Controllers
{
	public class MediaController : MastodonController
	{
		const long UploadLimit = 100L * 1024 * 1024;

		readonly IMediaService _media;
		readonly IMediaProxy _proxy;
		readonly IJobQueue _jobs;

		readonly IInteractionLedger _ledger;

		public MediaController(IMediaService media, IMediaProxy proxy, IJobQueue jobs, IInteractionLedger ledger = default)
		{
			_media = media;
			_proxy = proxy;
			_jobs = jobs;
			_ledger = ledger;
		}

		[HttpPost("/api/v1/media"), HttpPost("/api/v2/media"), Scope("write:media"), EnableRateLimiting(RateLimiting.Uploads), RequestSizeLimit(UploadLimit),
			RequestFormLimits(MultipartBodyLengthLimit = UploadLimit)]
		public async Task<IActionResult> Upload(CancellationToken token)
		{
			if (!Request.HasFormContentType)
				return Error(StatusCodes.Status422UnprocessableEntity, "Validation failed: File can't be blank");
			var form = await Request.ReadFormAsync(token);
			// v2 may answer before audio or video is processed (202, its url null until then), as Mastodon does; v1 waits
			var later = Request.Path.StartsWithSegments("/api/v2/media");
			var outcome = await _media.Upload(Me, form.Files["file"], form["description"], form["focus"], later, token);
			if (!outcome.Ok)
				return Error(outcome.Status, outcome.Error);
			if (outcome.Attachment.ProcessingState != "pending")
				return Json(View(outcome.Attachment));
			await _jobs.EnqueueMany(new[] { ProcessMediaJob.JobFor(outcome.Attachment, new Uri(Me.BaseAddress).Host) }, token);
			return new JsonResult(View(outcome.Attachment)) { StatusCode = StatusCodes.Status202Accepted };
		}

		[HttpGet("/api/v1/media/{id}"), Scope("write:media")]
		public async Task<IActionResult> Get(string id, CancellationToken token)
		{
			var attachment = await DB.Default.Find<MediaAttachment>().Match(m => m.ID == id && m.OwnerAvatarId == MyId && m.TrashedAt == null && m.ProfileOfAvatarId == null).ExecuteFirstAsync(token);
			return attachment?.ProcessingState switch
			{
				null when attachment == default => NotFoundError(),
				"pending" => new JsonResult(View(attachment)) { StatusCode = StatusCodes.Status206PartialContent },
				"failed" => Error(StatusCodes.Status422UnprocessableEntity, attachment.ProcessingError ?? "Validation failed: The file could not be processed"),
				_ => Json(View(attachment))
			};
		}

		// Mastodon 4.4: a persona's own upload, while nothing holds it (not posted, not scheduled, not a profile picture), goes to
		// the trash as the janitor would take it
		[HttpDelete("/api/v1/media/{id}"), Scope("write:media")]
		public async Task<IActionResult> Delete(string id, CancellationToken token)
		{
			var attachment = await DB.Default.Find<MediaAttachment>().Match(m => m.ID == id && m.OwnerAvatarId == MyId && m.TrashedAt == null && m.ProfileOfAvatarId == null).ExecuteFirstAsync(token);
			if (attachment == default)
				return NotFoundError();
			if (attachment.PostId != null || attachment.ScheduledStatusId != null)
				return Error(StatusCodes.Status422UnprocessableEntity, "Media attachment is currently used by a status");
			await _media.Trash(m => m.ID == attachment.ID && m.PostId == null && m.ScheduledStatusId == null, "deleted by its owner", token);
			return Json(new { });
		}

		// as on Mastodon, only media not posted yet: a posted one's description and focus change by editing its post (media_attributes)
		[HttpPut("/api/v1/media/{id}"), Scope("write:media")]
		public async Task<IActionResult> Update(string id, CancellationToken token)
		{
			var attachment = await DB.Default.Find<MediaAttachment>().Match(m => m.ID == id && m.OwnerAvatarId == MyId && m.TrashedAt == null && m.ProfileOfAvatarId == null && m.PostId == null).ExecuteFirstAsync(token);
			if (attachment == default)
				return NotFoundError();
			if (Params.Has("description"))
				attachment.Description = Params.Get("description")?.Trim() is { Length: > 0 } description ? description[..Math.Min(description.Length, 1500)] : default;
			if (FocalPoint.Parse(Params.Get("focus")) is { } focus)
				attachment.Focus = focus;
			await DB.Default.SaveAsync(attachment, token);
			return Json(View(attachment));
		}

		[HttpGet("/media/proxy/{signature}/{encoded}"), AllowAnonymous, EnableRateLimiting(RateLimiting.Proxy), ApiExplorerSettings(IgnoreApi = true)]
		public async Task<IActionResult> Proxy(string signature, string encoded, CancellationToken token)
		{
			var url = _proxy.Verified(signature, encoded);
			if (url == default || _proxy.Refuses(url))
				return NotFound();
			Response.Headers["X-Content-Type-Options"] = "nosniff";
			Response.Headers["Content-Security-Policy"] = "default-src 'none'; sandbox";
			if (_proxy.Cached(url) is { Path: not null } cached && Serve(cached.Path, cached.ContentType) is { } hit)
			{
				_ledger?.Count(Interactions.HostOf(url), "media:hit");
				return hit;
			}
			if (Request.Headers.Range.Count == 0)
			{
				var (outcome, path, contentType) = await _proxy.Download(url, token);
				if (outcome == ProxyOutcome.Cached && Serve(path, contentType) is { } fetched)
					return fetched;
				if (outcome == ProxyOutcome.Failed)
					return NotFound();
			}
			return await Stream(url, token);
		}

		// a cached file, opened before it is answered: trimmed meanwhile, what is open still reads; cached by browsers only
		// once there is something to cache
		IActionResult Serve(string path, string contentType)
		{
			FileStream file;
			try
			{
				file = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete, 64 * 1024, useAsync: true);
			}
			catch (IOException)
			{
				return default;
			}
			Response.Headers["Cache-Control"] = "public, max-age=604800";
			return File(file, contentType, enableRangeProcessing: true);
		}

		async Task<IActionResult> Stream(string url, CancellationToken token)
		{
			var range = System.Net.Http.Headers.RangeHeaderValue.TryParse(Request.Headers.Range.ToString(), out var asked) ? asked : default;
			using var upstream = await _proxy.Open(url, range, token);
			if (upstream == default)
				return NotFound();
			if (upstream.IsSuccessStatusCode)
				Response.Headers["Cache-Control"] = "public, max-age=604800";
			Response.StatusCode = (int)upstream.StatusCode;
			Response.ContentType = upstream.Content.Headers.ContentType?.ToString() ?? "application/octet-stream";
			if (upstream.Content.Headers.ContentLength is { } length)
				Response.ContentLength = length;
			if (upstream.Content.Headers.ContentRange is { } contentRange)
				Response.Headers.ContentRange = contentRange.ToString();
			Response.Headers.AcceptRanges = "bytes";
			await upstream.Content.CopyToAsync(Response.Body, token);
			return new EmptyResult();
		}

		object View(MediaAttachment attachment) => View(_media, attachment);

		internal static object View(IMediaService media, MediaAttachment attachment) => new
		{
			id = attachment.ID,
			type = attachment.Kind,
			url = media.Url(attachment.FilePath),
			preview_url = media.Url(attachment.PreviewPath ?? attachment.FilePath),
			remote_url = default(string),
			text_url = default(string),
			meta = new
			{
				original = attachment.Width.HasValue && attachment.Height > 0
					? new { width = attachment.Width, height = attachment.Height, size = $"{attachment.Width}x{attachment.Height}", aspect = (double)attachment.Width / attachment.Height.Value }
					: default,
				focus = attachment.Focus is { Length: 2 } ? new { x = attachment.Focus[0], y = attachment.Focus[1] } : default
			},
			description = attachment.Description,
			blurhash = attachment.Blurhash
		};
	}
}