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/client/account/relationships.go

@@ -0,0 +1,46 @@
+package account
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+)
+
+// AccountRelationshipsGETHandler serves the relationship of the requesting account with one or more requested account IDs.
+func (m *Module) AccountRelationshipsGETHandler(c *gin.Context) {
+	l := m.log.WithField("func", "AccountRelationshipsGETHandler")
+
+	authed, err := oauth.Authed(c, true, true, true, true)
+	if err != nil {
+		l.Debugf("error authing: %s", err)
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "unauthorized"})
+		return
+	}
+
+	targetAccountIDs := c.QueryArray("id[]")
+	if len(targetAccountIDs) == 0 {
+		// check fallback -- let's be generous and see if maybe it's just set as 'id'?
+		id := c.Query("id")
+		if id == "" {
+			l.Debug("no account id specified in query")
+			c.JSON(http.StatusBadRequest, gin.H{"error": "no account id specified"})
+			return
+		}
+		targetAccountIDs = append(targetAccountIDs, id)
+	}
+
+	relationships := []model.Relationship{}
+
+	for _, targetAccountID := range targetAccountIDs {
+		r, errWithCode := m.processor.AccountRelationshipGet(authed, targetAccountID)
+		if err != nil {
+			c.JSON(errWithCode.Code(), gin.H{"error": errWithCode.Safe()})
+			return
+		}
+		relationships = append(relationships, *r)
+	}
+
+	c.JSON(http.StatusOK, relationships)
+}