[feature] Push notifications (#3587)

* Update push subscription API model to be Mastodon 4.0 compatible

* Add webpush-go dependency

# Conflicts:
#	go.sum

* Single-row table for storing instance's VAPID key pair

* Generate VAPID key pair during startup

* Add VAPID public key to instance info API

* Return VAPID public key when registering an app

* Store Web Push subscriptions in DB

* Add Web Push sender (similar to email sender)

* Add no-op push senders to most processor tests

* Test Web Push notifications from workers

* Delete Web Push subscriptions when account is deleted

* Implement push subscription API

* Linter fixes

* Update Swagger

* Fix enum to int migration

* Fix GetVAPIDKeyPair

* Create web push subscriptions table with indexes

* Log Web Push server error messages

* Send instance URL as Web Push JWT subject

* Accept any 2xx code as a success

* Fix malformed VAPID sub claim

* Use packed notification flags

* Remove unused date columns

* Add notification type for update notifications

Not used yet

* Make GetVAPIDKeyPair idempotent

and remove PutVAPIDKeyPair

* Post-rebase fixes

* go mod tidy

* Special-case 400 errors other than 408/429

Most client errors should remove the subscription.

* Improve titles, trim body to reasonable length

* Disallow cleartext HTTP for Web Push servers

* Fix lint

* Remove redundant index on unique column

Also removes redundant unique and notnull tags on ID column since these are implied by pk

* Make realsender.go more readable

* Use Tobi's style for wrapping errors

* Restore treating all 5xx codes as temporary problems

* Always load target account settings

* Stub `policy` and `standard`

* webpush.Sender: take type converter as ctor param

* Move webpush.MockSender and noopSender into testrig

internal/api/client/push/pushsubscriptiondelete_test.go

@@ -0,0 +1,83 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// 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 push_test
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+
+	"github.com/superseriousbusiness/gotosocial/internal/api/client/push"
+	"github.com/superseriousbusiness/gotosocial/internal/config"
+	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+	"github.com/superseriousbusiness/gotosocial/testrig"
+)
+
+// deleteSubscription deletes the push subscription for the named account and token.
+func (suite *PushTestSuite) deleteSubscription(
+	accountFixtureName string,
+	tokenFixtureName string,
+	expectedHTTPStatus int,
+) error {
+	// instantiate recorder + test context
+	recorder := httptest.NewRecorder()
+	ctx, _ := testrig.CreateGinTestContext(recorder, nil)
+	ctx.Set(oauth.SessionAuthorizedAccount, suite.testAccounts[accountFixtureName])
+	ctx.Set(oauth.SessionAuthorizedToken, oauth.DBTokenToToken(suite.testTokens[tokenFixtureName]))
+	ctx.Set(oauth.SessionAuthorizedApplication, suite.testApplications["application_1"])
+	ctx.Set(oauth.SessionAuthorizedUser, suite.testUsers[accountFixtureName])
+
+	// create the request
+	requestUrl := config.GetProtocol() + "://" + config.GetHost() + "/api" + push.SubscriptionPath
+	ctx.Request = httptest.NewRequest(http.MethodDelete, requestUrl, nil)
+
+	// trigger the handler
+	suite.pushModule.PushSubscriptionDELETEHandler(ctx)
+
+	// read the response
+	result := recorder.Result()
+	defer func() {
+		_ = result.Body.Close()
+	}()
+
+	if resultCode := recorder.Code; expectedHTTPStatus != resultCode {
+		return fmt.Errorf("expected %d got %d", expectedHTTPStatus, resultCode)
+	}
+
+	return nil
+}
+
+// Delete a subscription that should exist.
+func (suite *PushTestSuite) TestDeleteSubscription() {
+	accountFixtureName := "local_account_1"
+	// This token should have a subscription associated with it already.
+	tokenFixtureName := "local_account_1"
+
+	err := suite.deleteSubscription(accountFixtureName, tokenFixtureName, 200)
+	suite.NoError(err)
+}
+
+// Delete a subscription that should not exist, which should succeed anyway.
+func (suite *PushTestSuite) TestDeleteMissingSubscription() {
+	accountFixtureName := "local_account_1"
+	// This token should not have a subscription.
+	tokenFixtureName := "local_account_1_user_authorization_token"
+
+	err := suite.deleteSubscription(accountFixtureName, tokenFixtureName, 200)
+	suite.NoError(err)
+}