[feature] Application creation + management via API + settings panel (#3906)

* [feature] Application creation + management via API + settings panel

* fix docs links

* add errnorows test

* use known application as shorter

* add comment about side effects

2 files changed, 172 insertions, 2 deletions

diff --git a/internal/typeutils/internaltofrontend.go b/internal/typeutils/internaltofrontend.go
index 537eeb6db..b0e137f75 100644
--- a/internal/typeutils/internaltofrontend.go
+++ b/internal/typeutils/internaltofrontend.go
@@ -623,8 +623,14 @@ func (c *Converter) AppToAPIAppSensitive(ctx context.Context, a *gtsmodel.Applic
 		return nil, gtserror.Newf("error getting VAPID public key: %w", err)
 	}
 
+	createdAt, err := id.TimeFromULID(a.ID)
+	if err != nil {
+		return nil, gtserror.Newf("error converting id to time: %w", err)
+	}
+
 	return &apimodel.Application{
 		ID:           a.ID,
+		CreatedAt:    util.FormatISO8601(createdAt),
 		Name:         a.Name,
 		Website:      a.Website,
 		RedirectURI:  strings.Join(a.RedirectURIs, "\n"),
@@ -1412,14 +1418,28 @@ func (c *Converter) baseStatusToFrontend(
 	apiStatus.InReplyToAccountID = util.PtrIf(s.InReplyToAccountID)
 	apiStatus.Language = util.PtrIf(s.Language)
 
-	if app := s.CreatedWithApplication; app != nil {
-		apiStatus.Application, err = c.AppToAPIAppPublic(ctx, app)
+	switch {
+	case s.CreatedWithApplication != nil:
+		// App exists for this status and is set.
+		apiStatus.Application, err = c.AppToAPIAppPublic(ctx, s.CreatedWithApplication)
 		if err != nil {
 			return nil, gtserror.Newf(
 				"error converting application %s: %w",
 				s.CreatedWithApplicationID, err,
 			)
 		}
+
+	case s.CreatedWithApplicationID != "":
+		// App existed for this status but not
+		// anymore, it's probably been cleaned up.
+		// Set a dummy application.
+		apiStatus.Application = &apimodel.Application{
+			Name: "unknown application",
+		}
+
+	default:
+		// No app stored for this (probably remote)
+		// status, so nothing to do (app is optional).
 	}
 
 	if s.Poll != nil {
diff --git a/internal/typeutils/internaltofrontend_test.go b/internal/typeutils/internaltofrontend_test.go
index 0b2c6ddfa..c94d4481a 100644
--- a/internal/typeutils/internaltofrontend_test.go
+++ b/internal/typeutils/internaltofrontend_test.go
@@ -753,6 +753,156 @@ func (suite *InternalToFrontendTestSuite) TestStatusToFrontendHTMLContentWarning
 }`, string(b))
 }
 
+func (suite *InternalToFrontendTestSuite) TestStatusToFrontendApplicationDeleted() {
+	ctx := context.Background()
+	testStatus := suite.testStatuses["admin_account_status_1"]
+
+	// Delete the application this status was created with.
+	if err := suite.state.DB.DeleteApplicationByID(ctx, testStatus.CreatedWithApplicationID); err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	requestingAccount := suite.testAccounts["local_account_1"]
+	apiStatus, err := suite.typeconverter.StatusToAPIStatus(ctx, testStatus, requestingAccount, statusfilter.FilterContextNone, nil, nil)
+	suite.NoError(err)
+
+	b, err := json.MarshalIndent(apiStatus, "", "  ")
+	suite.NoError(err)
+
+	suite.Equal(`{
+  "id": "01F8MH75CBF9JFX4ZAD54N0W0R",
+  "created_at": "2021-10-20T11:36:45.000Z",
+  "edited_at": null,
+  "in_reply_to_id": null,
+  "in_reply_to_account_id": null,
+  "sensitive": false,
+  "spoiler_text": "",
+  "visibility": "public",
+  "language": "en",
+  "uri": "http://localhost:8080/users/admin/statuses/01F8MH75CBF9JFX4ZAD54N0W0R",
+  "url": "http://localhost:8080/@admin/statuses/01F8MH75CBF9JFX4ZAD54N0W0R",
+  "replies_count": 1,
+  "reblogs_count": 0,
+  "favourites_count": 1,
+  "favourited": true,
+  "reblogged": false,
+  "muted": false,
+  "bookmarked": true,
+  "pinned": false,
+  "content": "\u003cp\u003ehello world! \u003ca href=\"http://localhost:8080/tags/welcome\" class=\"mention hashtag\" rel=\"tag nofollow noreferrer noopener\" target=\"_blank\"\u003e#\u003cspan\u003ewelcome\u003c/span\u003e\u003c/a\u003e ! first post on the instance :rainbow: !\u003c/p\u003e",
+  "reblog": null,
+  "application": {
+    "name": "unknown application"
+  },
+  "account": {
+    "id": "01F8MH17FWEB39HZJ76B6VXSKF",
+    "username": "admin",
+    "acct": "admin",
+    "display_name": "",
+    "locked": false,
+    "discoverable": true,
+    "bot": false,
+    "created_at": "2022-05-17T13:10:59.000Z",
+    "note": "",
+    "url": "http://localhost:8080/@admin",
+    "avatar": "",
+    "avatar_static": "",
+    "header": "http://localhost:8080/assets/default_header.webp",
+    "header_static": "http://localhost:8080/assets/default_header.webp",
+    "header_description": "Flat gray background (default header).",
+    "followers_count": 1,
+    "following_count": 1,
+    "statuses_count": 4,
+    "last_status_at": "2021-10-20",
+    "emojis": [],
+    "fields": [],
+    "enable_rss": true,
+    "roles": [
+      {
+        "id": "admin",
+        "name": "admin",
+        "color": ""
+      }
+    ],
+    "group": false
+  },
+  "media_attachments": [
+    {
+      "id": "01F8MH6NEM8D7527KZAECTCR76",
+      "type": "image",
+      "url": "http://localhost:8080/fileserver/01F8MH17FWEB39HZJ76B6VXSKF/attachment/original/01F8MH6NEM8D7527KZAECTCR76.jpg",
+      "text_url": "http://localhost:8080/fileserver/01F8MH17FWEB39HZJ76B6VXSKF/attachment/original/01F8MH6NEM8D7527KZAECTCR76.jpg",
+      "preview_url": "http://localhost:8080/fileserver/01F8MH17FWEB39HZJ76B6VXSKF/attachment/small/01F8MH6NEM8D7527KZAECTCR76.webp",
+      "remote_url": null,
+      "preview_remote_url": null,
+      "meta": {
+        "original": {
+          "width": 1200,
+          "height": 630,
+          "size": "1200x630",
+          "aspect": 1.9047619
+        },
+        "small": {
+          "width": 512,
+          "height": 268,
+          "size": "512x268",
+          "aspect": 1.9104477
+        },
+        "focus": {
+          "x": 0,
+          "y": 0
+        }
+      },
+      "description": "Black and white image of some 50's style text saying: Welcome On Board",
+      "blurhash": "LIIE|gRj00WB-;j[t7j[4nWBj[Rj"
+    }
+  ],
+  "mentions": [],
+  "tags": [
+    {
+      "name": "welcome",
+      "url": "http://localhost:8080/tags/welcome"
+    }
+  ],
+  "emojis": [
+    {
+      "shortcode": "rainbow",
+      "url": "http://localhost:8080/fileserver/01AY6P665V14JJR0AFVRT7311Y/emoji/original/01F8MH9H8E4VG3KDYJR9EGPXCQ.png",
+      "static_url": "http://localhost:8080/fileserver/01AY6P665V14JJR0AFVRT7311Y/emoji/static/01F8MH9H8E4VG3KDYJR9EGPXCQ.png",
+      "visible_in_picker": true,
+      "category": "reactions"
+    }
+  ],
+  "card": null,
+  "poll": null,
+  "text": "hello world! #welcome ! first post on the instance :rainbow: !",
+  "content_type": "text/plain",
+  "interaction_policy": {
+    "can_favourite": {
+      "always": [
+        "public",
+        "me"
+      ],
+      "with_approval": []
+    },
+    "can_reply": {
+      "always": [
+        "public",
+        "me"
+      ],
+      "with_approval": []
+    },
+    "can_reblog": {
+      "always": [
+        "public",
+        "me"
+      ],
+      "with_approval": []
+    }
+  }
+}`, string(b))
+}
+
 // Modify a fixture status into a status that should be filtered,
 // and then filter it, returning the API status or any error from converting it.
 func (suite *InternalToFrontendTestSuite) filteredStatusToFrontend(action gtsmodel.FilterAction, boost bool) (*apimodel.Status, error) {