Follows and relationships (#27)

* Follows -- create and undo, both remote and local
* Statuses -- federate new posts, including media, attachments, CWs and image descriptions.

internal/api/s2s/user/followers.go

@@ -0,0 +1,58 @@
+/*
+   GoToSocial
+   Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package user
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	"github.com/sirupsen/logrus"
+)
+
+func (m *Module) FollowersGETHandler(c *gin.Context) {
+	l := m.log.WithFields(logrus.Fields{
+		"func": "FollowersGETHandler",
+		"url":  c.Request.RequestURI,
+	})
+
+	requestedUsername := c.Param(UsernameKey)
+	if requestedUsername == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "no username specified in request"})
+		return
+	}
+
+	// make sure this actually an AP request
+	format := c.NegotiateFormat(ActivityPubAcceptHeaders...)
+	if format == "" {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": "could not negotiate format with given Accept header(s)"})
+		return
+	}
+	l.Tracef("negotiated format: %s", format)
+
+	// make a copy of the context to pass along so we don't break anything
+	cp := c.Copy()
+	user, err := m.processor.GetFediFollowers(requestedUsername, cp.Request) // GetFediUser handles auth as well
+	if err != nil {
+		l.Info(err.Error())
+		c.JSON(err.Code(), gin.H{"error": err.Safe()})
+		return
+	}
+
+	c.JSON(http.StatusOK, user)
+}

internal/api/s2s/user/statusget.go

@@ -0,0 +1,46 @@
+package user
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	"github.com/sirupsen/logrus"
+)
+
+func (m *Module) StatusGETHandler(c *gin.Context) {
+	l := m.log.WithFields(logrus.Fields{
+		"func": "StatusGETHandler",
+		"url":  c.Request.RequestURI,
+	})
+
+	requestedUsername := c.Param(UsernameKey)
+	if requestedUsername == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "no username specified in request"})
+		return
+	}
+
+	requestedStatusID := c.Param(StatusIDKey)
+	if requestedStatusID == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "no status id specified in request"})
+		return
+	}
+
+	// make sure this actually an AP request
+	format := c.NegotiateFormat(ActivityPubAcceptHeaders...)
+	if format == "" {
+		c.JSON(http.StatusNotAcceptable, gin.H{"error": "could not negotiate format with given Accept header(s)"})
+		return
+	}
+	l.Tracef("negotiated format: %s", format)
+
+	// make a copy of the context to pass along so we don't break anything
+	cp := c.Copy()
+	status, err := m.processor.GetFediStatus(requestedUsername, requestedStatusID, cp.Request) // handles auth as well
+	if err != nil {
+		l.Info(err.Error())
+		c.JSON(err.Code(), gin.H{"error": err.Safe()})
+		return
+	}
+
+	c.JSON(http.StatusOK, status)
+}

internal/api/s2s/user/user.go

@@ -32,6 +32,8 @@ import (
 const (
 	// UsernameKey is for account usernames.
 	UsernameKey = "username"
+	// StatusIDKey is for status IDs
+	StatusIDKey = "status"
 	// UsersBasePath is the base path for serving information about Users eg https://example.org/users
 	UsersBasePath = "/" + util.UsersPath
 	// UsersBasePathWithUsername is just the users base path with the Username key in it.
@@ -40,6 +42,10 @@ const (
 	UsersBasePathWithUsername = UsersBasePath + "/:" + UsernameKey
 	// UsersInboxPath is for serving POST requests to a user's inbox with the given username key.
 	UsersInboxPath = UsersBasePathWithUsername + "/" + util.InboxPath
+	// UsersFollowersPath is for serving GET request's to a user's followers list, with the given username key.
+	UsersFollowersPath = UsersBasePathWithUsername + "/" + util.FollowersPath
+	// UsersStatusPath is for serving GET requests to a particular status by a user, with the given username key and status ID
+	UsersStatusPath = UsersBasePathWithUsername + "/" + util.StatusesPath + "/:" + StatusIDKey
 )
 
 // ActivityPubAcceptHeaders represents the Accept headers mentioned here:
@@ -69,5 +75,7 @@ func New(config *config.Config, processor message.Processor, log *logrus.Logger)
 func (m *Module) Route(s router.Router) error {
 	s.AttachHandler(http.MethodGet, UsersBasePathWithUsername, m.UsersGETHandler)
 	s.AttachHandler(http.MethodPost, UsersInboxPath, m.InboxPOSTHandler)
+	s.AttachHandler(http.MethodGet, UsersFollowersPath, m.FollowersGETHandler)
+	s.AttachHandler(http.MethodGet, UsersStatusPath, m.StatusGETHandler)
 	return nil
 }