From 813d2eaaf08efcb7aa87f6270e98c760b0b60b99 Mon Sep 17 00:00:00 2001
From: eal <eal@waifu.club>
Date: Wed, 25 Oct 2017 21:02:42 +0300
Subject: [PATCH 1/3] Add mastodon API endpoint for follow

---
 .../mastodon_api/mastodon_api_controller.ex   | 31 ++++++++++++++++---
 lib/pleroma/web/router.ex                     |  2 ++
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/lib/pleroma/web/mastodon_api/mastodon_api_controller.ex b/lib/pleroma/web/mastodon_api/mastodon_api_controller.ex
index a01a199fb..ea85e5bce 100644
--- a/lib/pleroma/web/mastodon_api/mastodon_api_controller.ex
+++ b/lib/pleroma/web/mastodon_api/mastodon_api_controller.ex
@@ -269,11 +269,13 @@ defmodule Pleroma.Web.MastodonAPI.MastodonAPIController do
     end
   end
 
-  def follow(%{assigns: %{user: follower}} = conn, %{"id" => id}) do
-    with %User{} = followed <- Repo.get(User, id),
-       {:ok, follower} <- User.follow(follower, followed),
-       {:ok, activity} <- ActivityPub.follow(follower, followed) do
+  def follow(%{assigns: %{user: follower}} = conn, params) do
+    with {:ok, %User{} = followed} <- get_user(params),
+         {:ok, follower} <- User.follow(follower, followed),
+         {:ok, activity} <- ActivityPub.follow(follower, followed) do
       render conn, AccountView, "relationship.json", %{user: follower, target: followed}
+    else
+      err -> err
     end
   end
 
@@ -338,4 +340,25 @@ defmodule Pleroma.Web.MastodonAPI.MastodonAPIController do
     Logger.debug("Unimplemented, returning an empty array")
     json(conn, [])
   end
+
+  defp get_user(params) do
+    case params do
+      %{"uri" => uri} ->
+        case target = Repo.get_by(User, nickname: uri) do
+          nil ->
+            {:error, "No user with such nickname"}
+          _ ->
+            {:ok, target}
+        end
+      %{"id" => id} ->
+        case target = Repo.get(User, id) do
+          nil ->
+            {:error, "No user with such id"}
+          _ ->
+            {:ok, target}
+        end
+      _ ->
+        {:error, "You need to specify uri or id"}
+    end
+  end
 end
diff --git a/lib/pleroma/web/router.ex b/lib/pleroma/web/router.ex
index cb818b3cc..45c47eefb 100644
--- a/lib/pleroma/web/router.ex
+++ b/lib/pleroma/web/router.ex
@@ -62,6 +62,8 @@ defmodule Pleroma.Web.Router do
     post "/accounts/:id/mute", MastodonAPIController, :relationship_noop
     post "/accounts/:id/unmute", MastodonAPIController, :relationship_noop
 
+    post "/follows", MastodonAPIController, :follow
+
     get "/blocks", MastodonAPIController, :empty_array
     get "/domain_blocks", MastodonAPIController, :empty_array
     get "/follow_requests", MastodonAPIController, :empty_array

From 11d2287476fe9518cd0a3721a0fe7a0a1fd937fd Mon Sep 17 00:00:00 2001
From: eal <eal@waifu.club>
Date: Wed, 25 Oct 2017 21:25:37 +0300
Subject: [PATCH 2/3] Return error message on errors

---
 lib/pleroma/web/mastodon_api/mastodon_api_controller.ex | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/pleroma/web/mastodon_api/mastodon_api_controller.ex b/lib/pleroma/web/mastodon_api/mastodon_api_controller.ex
index ea85e5bce..5032c735d 100644
--- a/lib/pleroma/web/mastodon_api/mastodon_api_controller.ex
+++ b/lib/pleroma/web/mastodon_api/mastodon_api_controller.ex
@@ -275,7 +275,10 @@ defmodule Pleroma.Web.MastodonAPI.MastodonAPIController do
          {:ok, activity} <- ActivityPub.follow(follower, followed) do
       render conn, AccountView, "relationship.json", %{user: follower, target: followed}
     else
-      err -> err
+      {:error, message} = err ->
+        conn
+        |> put_resp_content_type("application/json")
+        |> send_resp(403, Poison.encode!(%{"error" => message}))
     end
   end
 

From 8e94936553c978e5f0d3bb802a1932a6b505f86e Mon Sep 17 00:00:00 2001
From: eal <eal@waifu.club>
Date: Fri, 27 Oct 2017 13:55:36 +0300
Subject: [PATCH 3/3] Add tests.

---
 test/web/mastodon_api/mastodon_api_controller_test.exs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/test/web/mastodon_api/mastodon_api_controller_test.exs b/test/web/mastodon_api/mastodon_api_controller_test.exs
index 56888140d..af2351706 100644
--- a/test/web/mastodon_api/mastodon_api_controller_test.exs
+++ b/test/web/mastodon_api/mastodon_api_controller_test.exs
@@ -281,6 +281,13 @@ defmodule Pleroma.Web.MastodonAPI.MastodonAPIControllerTest do
     |> post("/api/v1/accounts/#{other_user.id}/unfollow")
 
     assert %{"id" => id, "following" => false} = json_response(conn, 200)
+
+    user = Repo.get(User, user.id)
+    conn = build_conn()
+    |> assign(:user, user)
+    |> post("/api/v1/follows", %{"uri" => other_user.nickname})
+
+    assert %{"id" => id, "following" => true} = json_response(conn, 200)
   end
 
   test "unimplemented block/mute endpoints" do