Add bare bones user API (#1127)

* Add bare bones user API

with tests!

* linting

userapi/internal/api.go

@@ -0,0 +1,53 @@
+// Copyright 2020 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package internal
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+
+	"github.com/matrix-org/dendrite/clientapi/auth/storage/accounts"
+	"github.com/matrix-org/dendrite/clientapi/auth/storage/devices"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+type UserInternalAPI struct {
+	AccountDB  accounts.Database
+	DeviceDB   devices.Database
+	ServerName gomatrixserverlib.ServerName
+}
+
+func (a *UserInternalAPI) QueryProfile(ctx context.Context, req *api.QueryProfileRequest, res *api.QueryProfileResponse) error {
+	local, domain, err := gomatrixserverlib.SplitID('@', req.UserID)
+	if err != nil {
+		return err
+	}
+	if domain != a.ServerName {
+		return fmt.Errorf("cannot query profile of remote users: got %s want %s", domain, a.ServerName)
+	}
+	prof, err := a.AccountDB.GetProfileByLocalpart(ctx, local)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return nil
+		}
+		return err
+	}
+	res.UserExists = true
+	res.AvatarURL = prof.AvatarURL
+	res.DisplayName = prof.DisplayName
+	return nil
+}