[chore] Deinterface processor and subprocessors (#1501)

* [chore] Deinterface processor and subprocessors

* expose subprocessors via function calls

* missing license header

internal/processing/fedi/user.go

@@ -0,0 +1,88 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2023 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 fedi
+
+import (
+	"context"
+	"fmt"
+	"net/url"
+
+	"github.com/superseriousbusiness/activity/streams"
+	"github.com/superseriousbusiness/activity/streams/vocab"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/transport"
+	"github.com/superseriousbusiness/gotosocial/internal/uris"
+)
+
+// UserGet handles the getting of a fedi/activitypub representation of a user/account, performing appropriate authentication
+// before returning a JSON serializable interface to the caller.
+func (p *Processor) UserGet(ctx context.Context, requestedUsername string, requestURL *url.URL) (interface{}, gtserror.WithCode) {
+	// Get the instance-local account the request is referring to.
+	requestedAccount, err := p.db.GetAccountByUsernameDomain(ctx, requestedUsername, "")
+	if err != nil {
+		return nil, gtserror.NewErrorNotFound(fmt.Errorf("database error getting account with username %s: %s", requestedUsername, err))
+	}
+
+	var requestedPerson vocab.ActivityStreamsPerson
+
+	if uris.IsPublicKeyPath(requestURL) {
+		// if it's a public key path, we don't need to authenticate but we'll only serve the bare minimum user profile needed for the public key
+		requestedPerson, err = p.tc.AccountToASMinimal(ctx, requestedAccount)
+		if err != nil {
+			return nil, gtserror.NewErrorInternalError(err)
+		}
+	} else {
+		// if it's any other path, we want to fully authenticate the request before we serve any data, and then we can serve a more complete profile
+		requestingAccountURI, errWithCode := p.federator.AuthenticateFederatedRequest(ctx, requestedUsername)
+		if errWithCode != nil {
+			return nil, errWithCode
+		}
+
+		// if we're not already handshaking/dereferencing a remote account, dereference it now
+		if !p.federator.Handshaking(requestedUsername, requestingAccountURI) {
+			requestingAccount, err := p.federator.GetAccountByURI(
+				transport.WithFastfail(ctx), requestedUsername, requestingAccountURI, false,
+			)
+			if err != nil {
+				return nil, gtserror.NewErrorUnauthorized(err)
+			}
+
+			blocked, err := p.db.IsBlocked(ctx, requestedAccount.ID, requestingAccount.ID, true)
+			if err != nil {
+				return nil, gtserror.NewErrorInternalError(err)
+			}
+
+			if blocked {
+				return nil, gtserror.NewErrorUnauthorized(fmt.Errorf("block exists between accounts %s and %s", requestedAccount.ID, requestingAccount.ID))
+			}
+		}
+
+		requestedPerson, err = p.tc.AccountToAS(ctx, requestedAccount)
+		if err != nil {
+			return nil, gtserror.NewErrorInternalError(err)
+		}
+	}
+
+	data, err := streams.Serialize(requestedPerson)
+	if err != nil {
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	return data, nil
+}