activitypub: implement /api/v1/activitypub/user/{username} (#14186)

Return informations regarding a Person (as defined in ActivityStreams
https://www.w3.org/TR/activitystreams-vocabulary/#dfn-person).

Refs: https://github.com/go-gitea/gitea/issues/14186

Signed-off-by: Loïc Dachary <loic@dachary.org>

6 files changed, 195 insertions, 0 deletions

diff --git a/integrations/api_activitypub_person_test.go b/integrations/api_activitypub_person_test.go
new file mode 100644
index 000000000..2efa82f02
--- /dev/null
+++ b/integrations/api_activitypub_person_test.go
@@ -0,0 +1,63 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package integrations
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"testing"
+
+	"code.gitea.io/gitea/modules/setting"
+	"github.com/go-fed/activity/streams"
+	"github.com/go-fed/activity/streams/vocab"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestActivityPubPerson(t *testing.T) {
+	onGiteaRun(t, func(*testing.T, *url.URL) {
+		setting.Federation.Enabled = true
+		defer func() {
+			setting.Federation.Enabled = false
+		}()
+
+		username := "user2"
+		req := NewRequestf(t, "GET", fmt.Sprintf("/api/v1/activitypub/user/%s", username))
+		resp := MakeRequest(t, req, http.StatusOK)
+		assert.Contains(t, string(resp.Body.Bytes()), "@context")
+		var m map[string]interface{}
+		_ = json.Unmarshal(resp.Body.Bytes(), &m)
+
+		var person vocab.ActivityStreamsPerson
+		resolver, _ := streams.NewJSONResolver(func(c context.Context, p vocab.ActivityStreamsPerson) error {
+			person = p
+			return nil
+		})
+		ctx := context.Background()
+		err := resolver.Resolve(ctx, m)
+		assert.Equal(t, err, nil)
+		assert.Equal(t, person.GetTypeName(), "Person")
+		assert.Equal(t, person.GetActivityStreamsName().Begin().GetXMLSchemaString(), username)
+		assert.Regexp(t, fmt.Sprintf("activitypub/user/%s$", username), person.GetJSONLDId().GetIRI().String())
+		assert.Regexp(t, fmt.Sprintf("activitypub/user/%s/outbox$", username), person.GetActivityStreamsOutbox().GetIRI().String())
+		assert.Regexp(t, fmt.Sprintf("activitypub/user/%s/inbox$", username), person.GetActivityStreamsInbox().GetIRI().String())
+	})
+}
+
+func TestActivityPubMissingPerson(t *testing.T) {
+	onGiteaRun(t, func(*testing.T, *url.URL) {
+		setting.Federation.Enabled = true
+		defer func() {
+			setting.Federation.Enabled = false
+		}()
+
+		req := NewRequestf(t, "GET", "/api/v1/activitypub/user/nonexistentuser")
+		resp := MakeRequest(t, req, http.StatusNotFound)
+		assert.Contains(t, string(resp.Body.Bytes()), "GetUserByName")
+	})
+}
diff --git a/modules/structs/activitypub.go b/modules/structs/activitypub.go
new file mode 100644
index 000000000..e1e2ec46a
--- /dev/null
+++ b/modules/structs/activitypub.go
@@ -0,0 +1,9 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package structs
+
+type ActivityPub struct {
+	Context string `json:"@context"`
+}
diff --git a/routers/api/v1/activitypub/person.go b/routers/api/v1/activitypub/person.go
new file mode 100644
index 000000000..ae1a8a7bb
--- /dev/null
+++ b/routers/api/v1/activitypub/person.go
@@ -0,0 +1,62 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package activitypub
+
+import (
+	"net/http"
+	"net/url"
+	"strings"
+
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/routers/api/v1/user"
+	"github.com/go-fed/activity/streams"
+)
+
+func Person(ctx *context.APIContext) {
+	// swagger:operation GET /activitypub/user/{username} information
+	// ---
+	// summary: Returns the person
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: username
+	//   in: path
+	//   description: username of the user
+	//   type: string
+	//   required: true
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/ActivityPub"
+
+	user.GetUserByParamsName(ctx, "username")
+	username := ctx.Params("username")
+
+	person := streams.NewActivityStreamsPerson()
+
+	id := streams.NewJSONLDIdProperty()
+	link := strings.TrimSuffix(setting.AppURL, "/") + strings.TrimSuffix(ctx.Req.URL.EscapedPath(), "/")
+	url_object, _ := url.Parse(link)
+	id.SetIRI(url_object)
+	person.SetJSONLDId(id)
+
+	name := streams.NewActivityStreamsNameProperty()
+	name.AppendXMLSchemaString(username)
+	person.SetActivityStreamsName(name)
+
+	ibox := streams.NewActivityStreamsInboxProperty()
+	url_object, _ = url.Parse(link + "/inbox")
+	ibox.SetIRI(url_object)
+	person.SetActivityStreamsInbox(ibox)
+
+	obox := streams.NewActivityStreamsOutboxProperty()
+	url_object, _ = url.Parse(link + "/outbox")
+	obox.SetIRI(url_object)
+	person.SetActivityStreamsOutbox(obox)
+
+	var jsonmap map[string]interface{}
+	jsonmap, _ = streams.Serialize(person)
+	ctx.JSON(http.StatusOK, jsonmap)
+}
diff --git a/routers/api/v1/api.go b/routers/api/v1/api.go
index d4891daef..3fde7c34e 100644
--- a/routers/api/v1/api.go
+++ b/routers/api/v1/api.go
@@ -79,6 +79,7 @@ import (
 	"code.gitea.io/gitea/modules/setting"
 	api "code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/web"
+	"code.gitea.io/gitea/routers/api/v1/activitypub"
 	"code.gitea.io/gitea/routers/api/v1/admin"
 	"code.gitea.io/gitea/routers/api/v1/misc"
 	"code.gitea.io/gitea/routers/api/v1/notify"
@@ -597,6 +598,11 @@ func Routes(sessioner func(http.Handler) http.Handler) *web.Route {
 		m.Get("/version", misc.Version)
 		if setting.Federation.Enabled {
 			m.Get("/nodeinfo", misc.NodeInfo)
+			m.Group("/activitypub", func() {
+				m.Group("/user/{username}", func() {
+					m.Get("", activitypub.Person)
+				})
+			})
 		}
 		m.Get("/signing-key.gpg", misc.SigningKey)
 		m.Post("/markdown", bind(api.MarkdownOption{}), misc.Markdown)
diff --git a/routers/api/v1/swagger/activitypub.go b/routers/api/v1/swagger/activitypub.go
new file mode 100644
index 000000000..3576439f4
--- /dev/null
+++ b/routers/api/v1/swagger/activitypub.go
@@ -0,0 +1,16 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package swagger
+
+import (
+	api "code.gitea.io/gitea/modules/structs"
+)
+
+// ActivityPub
+// swagger:response ActivityPub
+type swaggerResponseActivityPub struct {
+	// in:body
+	Body api.ActivityPub `json:"body"`
+}
diff --git a/templates/swagger/v1_json.tmpl b/templates/swagger/v1_json.tmpl
index 3bc615818..c4ecf0f2e 100644
--- a/templates/swagger/v1_json.tmpl
+++ b/templates/swagger/v1_json.tmpl
@@ -23,6 +23,29 @@
   },
   "basePath": "{{AppSubUrl | JSEscape | Safe}}/api/v1",
   "paths": {
+    "/activitypub/user/{username}": {
+      "get": {
+        "produces": [
+          "application/json"
+        ],
+        "summary": "Returns the person",
+        "operationId": "information",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "username of the user",
+            "name": "username",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "200": {
+            "$ref": "#/responses/ActivityPub"
+          }
+        }
+      }
+    },
     "/admin/cron": {
       "get": {
         "produces": [
@@ -12700,6 +12723,16 @@
       },
       "x-go-package": "code.gitea.io/gitea/modules/structs"
     },
+    "ActivityPub": {
+      "type": "object",
+      "properties": {
+        "@context": {
+          "type": "string",
+          "x-go-name": "Context"
+        }
+      },
+      "x-go-package": "code.gitea.io/gitea/modules/structs"
+    },
     "AddCollaboratorOption": {
       "description": "AddCollaboratorOption options when adding a user as a collaborator of a repository",
       "type": "object",
@@ -18235,6 +18268,12 @@
         }
       }
     },
+    "ActivityPub": {
+      "description": "ActivityPub",
+      "schema": {
+        "$ref": "#/definitions/ActivityPub"
+      }
+    },
     "AnnotatedTag": {
       "description": "AnnotatedTag",
       "schema": {