[feature] Add `/api/v1/admin/custom_emojis` endpoint (#902)

* add admin emojis get path + model + docs

* stub admin emojis get processor function

* add id + disabled fields to admin emoji

* add emoji -> api admin emoji converter

* tidy up a bit

* add GetEmojis function

* finish up get emojis function

* order by shortcodedomain

* ASC

* tidy up + explain

* update to allow paging

* make admin emojis pageable

* fix mixed case paging

* normalize emoji queries a bit better

* test emoji get paging

* make limit optional

* fix incorrect path in media cleanup tests

* i have bad coder syndrome

* don't trimspace

* rename -> GetUseableEmojis

* wrap emoji query in subquery
avoid selecting more than we need

* fix a bit of sillyness teehee

* fix subquery postgres woes

3 files changed, 102 insertions, 0 deletions

diff --git a/internal/processing/admin/admin.go b/internal/processing/admin/admin.go
index c528f0fb8..0de165fb9 100644
--- a/internal/processing/admin/admin.go
+++ b/internal/processing/admin/admin.go
@@ -41,6 +41,7 @@ type Processor interface {
 	DomainBlockDelete(ctx context.Context, account *gtsmodel.Account, id string) (*apimodel.DomainBlock, gtserror.WithCode)
 	AccountAction(ctx context.Context, account *gtsmodel.Account, form *apimodel.AdminAccountActionRequest) gtserror.WithCode
 	EmojiCreate(ctx context.Context, account *gtsmodel.Account, user *gtsmodel.User, form *apimodel.EmojiCreateRequest) (*apimodel.Emoji, gtserror.WithCode)
+	EmojisGet(ctx context.Context, account *gtsmodel.Account, user *gtsmodel.User, domain string, includeDisabled bool, includeEnabled bool, shortcode string, maxShortcodeDomain string, minShortcodeDomain string, limit int) (*apimodel.PageableResponse, gtserror.WithCode)
 	MediaPrune(ctx context.Context, mediaRemoteCacheDays int) gtserror.WithCode
 }
 
diff --git a/internal/processing/admin/emoji.go b/internal/processing/admin/createemoji.go
index 50399279c..50399279c 100644
--- a/internal/processing/admin/emoji.go
+++ b/internal/processing/admin/createemoji.go
diff --git a/internal/processing/admin/getemojis.go b/internal/processing/admin/getemojis.go
new file mode 100644
index 000000000..d44b4d250
--- /dev/null
+++ b/internal/processing/admin/getemojis.go
@@ -0,0 +1,101 @@
+/*
+   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 admin
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
+)
+
+func (p *processor) EmojisGet(ctx context.Context, account *gtsmodel.Account, user *gtsmodel.User, domain string, includeDisabled bool, includeEnabled bool, shortcode string, maxShortcodeDomain string, minShortcodeDomain string, limit int) (*apimodel.PageableResponse, gtserror.WithCode) {
+	if !*user.Admin {
+		return nil, gtserror.NewErrorUnauthorized(fmt.Errorf("user %s not an admin", user.ID), "user is not an admin")
+	}
+
+	emojis, err := p.db.GetEmojis(ctx, domain, includeDisabled, includeEnabled, shortcode, maxShortcodeDomain, minShortcodeDomain, limit)
+	if err != nil && !errors.Is(err, db.ErrNoEntries) {
+		err := fmt.Errorf("EmojisGet: db error: %s", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	count := len(emojis)
+	if count == 0 {
+		return util.EmptyPageableResponse(), nil
+	}
+
+	items := make([]interface{}, 0, count)
+	for _, emoji := range emojis {
+		adminEmoji, err := p.tc.EmojiToAdminAPIEmoji(ctx, emoji)
+		if err != nil {
+			err := fmt.Errorf("EmojisGet: error converting emoji to admin model emoji: %s", err)
+			return nil, gtserror.NewErrorInternalError(err)
+		}
+		items = append(items, adminEmoji)
+	}
+
+	filterBuilder := strings.Builder{}
+	filterBuilder.WriteString("filter=")
+
+	switch domain {
+	case "", "local":
+		filterBuilder.WriteString("domain:local")
+	case db.EmojiAllDomains:
+		filterBuilder.WriteString("domain:all")
+	default:
+		filterBuilder.WriteString("domain:")
+		filterBuilder.WriteString(domain)
+	}
+
+	if includeDisabled != includeEnabled {
+		if includeDisabled {
+			filterBuilder.WriteString(",disabled")
+		}
+		if includeEnabled {
+			filterBuilder.WriteString(",enabled")
+		}
+	}
+
+	if shortcode != "" {
+		filterBuilder.WriteString(",shortcode:")
+		filterBuilder.WriteString(shortcode)
+	}
+
+	return util.PackagePageableResponse(util.PageableResponseParams{
+		Items:            items,
+		Path:             "api/v1/admin/custom_emojis",
+		NextMaxIDKey:     "max_shortcode_domain",
+		NextMaxIDValue:   shortcodeDomain(emojis[count-1]),
+		PrevMinIDKey:     "min_shortcode_domain",
+		PrevMinIDValue:   shortcodeDomain(emojis[0]),
+		Limit:            limit,
+		ExtraQueryParams: []string{filterBuilder.String()},
+	})
+}
+
+func shortcodeDomain(emoji *gtsmodel.Emoji) string {
+	return emoji.Shortcode + "@" + emoji.Domain
+}