[feature] Custom emoji updates (serve emoji via s2s api, tune db models) (#805)

* migrate emojis

* add get emoji to s2s (federation) API

* add new emoji db + cache functions

* add shortcodeDomain lookup for emojis

* check existing emojis w/cache, not w/constraints

* go fmt

* add putEmoji func

* use new db emoji funcs instead of where

* remove emojistringstotags func

* add unique constraint back in

* fix up broken migration

* update index

2 files changed, 62 insertions, 0 deletions

diff --git a/internal/processing/federation/federation.go b/internal/processing/federation/federation.go
index adf7b0437..c79baec3c 100644
--- a/internal/processing/federation/federation.go
+++ b/internal/processing/federation/federation.go
@@ -56,6 +56,9 @@ type Processor interface {
 	// GetWebfingerAccount handles the GET for a webfinger resource. Most commonly, it will be used for returning account lookups.
 	GetWebfingerAccount(ctx context.Context, requestedUsername string) (*apimodel.WellKnownResponse, gtserror.WithCode)
 
+	// GetFediEmoji handles the GET for a federated emoji originating from this instance.
+	GetEmoji(ctx context.Context, requestedEmojiID string, requestURL *url.URL) (interface{}, gtserror.WithCode)
+
 	// GetNodeInfoRel returns a well known response giving the path to node info.
 	GetNodeInfoRel(ctx context.Context, request *http.Request) (*apimodel.WellKnownResponse, gtserror.WithCode)
 
diff --git a/internal/processing/federation/getemoji.go b/internal/processing/federation/getemoji.go
new file mode 100644
index 000000000..a6d76deee
--- /dev/null
+++ b/internal/processing/federation/getemoji.go
@@ -0,0 +1,59 @@
+/*
+   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 federation
+
+import (
+	"context"
+	"fmt"
+	"net/url"
+
+	"github.com/superseriousbusiness/activity/streams"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+)
+
+func (p *processor) GetEmoji(ctx context.Context, requestedEmojiID string, requestURL *url.URL) (interface{}, gtserror.WithCode) {
+	if _, errWithCode := p.federator.AuthenticateFederatedRequest(ctx, ""); errWithCode != nil {
+		return nil, errWithCode
+	}
+
+	requestedEmoji, err := p.db.GetEmojiByID(ctx, requestedEmojiID)
+	if err != nil {
+		return nil, gtserror.NewErrorNotFound(fmt.Errorf("database error getting emoji with id %s: %s", requestedEmojiID, err))
+	}
+
+	if requestedEmoji.Domain != "" {
+		return nil, gtserror.NewErrorNotFound(fmt.Errorf("emoji with id %s doesn't belong to this instance (domain %s)", requestedEmojiID, requestedEmoji.Domain))
+	}
+
+	if *requestedEmoji.Disabled {
+		return nil, gtserror.NewErrorNotFound(fmt.Errorf("emoji with id %s has been disabled", requestedEmojiID))
+	}
+
+	apEmoji, err := p.tc.EmojiToAS(ctx, requestedEmoji)
+	if err != nil {
+		return nil, gtserror.NewErrorInternalError(fmt.Errorf("error converting gtsmodel emoji with id %s to ap emoji: %s", requestedEmojiID, err))
+	}
+
+	data, err := streams.Serialize(apEmoji)
+	if err != nil {
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	return data, nil
+}