[feature] Start implementing refetch of lost media files via /api/v1/admin/media_refetch (#1221)

* [chore] Move ShortcodeDomain to its own little util func

* [feature] Add RefetchEmojis function to media manager

* [feature] Expose admin media refresh via admin API

* update following review feedback

- change/fix log levels
- make sure not to try to refetch local emojis
- small style refactoring + comments

* log on emoji refetch start

Signed-off-by: kim <grufwub@gmail.com>
Co-authored-by: kim <grufwub@gmail.com>

internal/media/refetch_test.go

@@ -0,0 +1,85 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 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 media_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+)
+
+type RefetchTestSuite struct {
+	MediaStandardTestSuite
+}
+
+func (suite *RefetchTestSuite) TestRefetchEmojisNothingToDo() {
+	ctx := context.Background()
+
+	adminAccount := suite.testAccounts["admin_account"]
+	transport, err := suite.transportController.NewTransportForUsername(ctx, adminAccount.Username)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	refetched, err := suite.manager.RefetchEmojis(ctx, "", transport.DereferenceMedia)
+	suite.NoError(err)
+	suite.Equal(0, refetched)
+}
+
+func (suite *RefetchTestSuite) TestRefetchEmojis() {
+	ctx := context.Background()
+
+	if err := suite.storage.Delete(ctx, suite.testEmojis["yell"].ImagePath); err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	adminAccount := suite.testAccounts["admin_account"]
+	transport, err := suite.transportController.NewTransportForUsername(ctx, adminAccount.Username)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	refetched, err := suite.manager.RefetchEmojis(ctx, "", transport.DereferenceMedia)
+	suite.NoError(err)
+	suite.Equal(1, refetched)
+}
+
+func (suite *RefetchTestSuite) TestRefetchEmojisLocal() {
+	ctx := context.Background()
+
+	// delete the image for a LOCAL emoji
+	if err := suite.storage.Delete(ctx, suite.testEmojis["rainbow"].ImagePath); err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	adminAccount := suite.testAccounts["admin_account"]
+	transport, err := suite.transportController.NewTransportForUsername(ctx, adminAccount.Username)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	refetched, err := suite.manager.RefetchEmojis(ctx, "", transport.DereferenceMedia)
+	suite.NoError(err)
+	suite.Equal(0, refetched) // shouldn't refetch anything because local
+}
+
+func TestRefetchTestSuite(t *testing.T) {
+	suite.Run(t, &RefetchTestSuite{})
+}