[feature] Add emoji DELETE handler at `/api/v1/admin/custom_emojis` (#913)

* add emoji DELETE handler

* no need to process error (thanks kim)

* don't double check if user is admin

* add missing security annotation

4 files changed, 52 insertions, 0 deletions

diff --git a/internal/db/bundb/bundb_test.go b/internal/db/bundb/bundb_test.go
index 2af6cf122..b05df8b74 100644
--- a/internal/db/bundb/bundb_test.go
+++ b/internal/db/bundb/bundb_test.go
@@ -41,6 +41,7 @@ type BunDBStandardTestSuite struct {
 	testTags         map[string]*gtsmodel.Tag
 	testMentions     map[string]*gtsmodel.Mention
 	testFollows      map[string]*gtsmodel.Follow
+	testEmojis       map[string]*gtsmodel.Emoji
 }
 
 func (suite *BunDBStandardTestSuite) SetupSuite() {
@@ -54,6 +55,7 @@ func (suite *BunDBStandardTestSuite) SetupSuite() {
 	suite.testTags = testrig.NewTestTags()
 	suite.testMentions = testrig.NewTestMentions()
 	suite.testFollows = testrig.NewTestFollows()
+	suite.testEmojis = testrig.NewTestEmojis()
 }
 
 func (suite *BunDBStandardTestSuite) SetupTest() {
diff --git a/internal/db/bundb/emoji.go b/internal/db/bundb/emoji.go
index 4fb4f0ce6..51d767a7b 100644
--- a/internal/db/bundb/emoji.go
+++ b/internal/db/bundb/emoji.go
@@ -68,6 +68,43 @@ func (e *emojiDB) UpdateEmoji(ctx context.Context, emoji *gtsmodel.Emoji, column
 	return emoji, nil
 }
 
+func (e *emojiDB) DeleteEmojiByID(ctx context.Context, id string) db.Error {
+	if err := e.conn.RunInTx(ctx, func(tx bun.Tx) error {
+		// delete links between this emoji and any statuses that use it
+		if _, err := tx.
+			NewDelete().
+			TableExpr("? AS ?", bun.Ident("status_to_emojis"), bun.Ident("status_to_emoji")).
+			Where("? = ?", bun.Ident("status_to_emoji.emoji_id"), id).
+			Exec(ctx); err != nil {
+			return err
+		}
+
+		// delete links between this emoji and any accounts that use it
+		if _, err := tx.
+			NewDelete().
+			TableExpr("? AS ?", bun.Ident("account_to_emojis"), bun.Ident("account_to_emoji")).
+			Where("? = ?", bun.Ident("account_to_emoji.emoji_id"), id).
+			Exec(ctx); err != nil {
+			return err
+		}
+
+		if _, err := tx.
+			NewDelete().
+			TableExpr("? AS ?", bun.Ident("emojis"), bun.Ident("emoji")).
+			Where("? = ?", bun.Ident("emoji.id"), id).
+			Exec(ctx); err != nil {
+			return e.conn.ProcessError(err)
+		}
+
+		return nil
+	}); err != nil {
+		return err
+	}
+
+	e.cache.Invalidate(id)
+	return nil
+}
+
 func (e *emojiDB) GetEmojis(ctx context.Context, domain string, includeDisabled bool, includeEnabled bool, shortcode string, maxShortcodeDomain string, minShortcodeDomain string, limit int) ([]*gtsmodel.Emoji, db.Error) {
 	emojiIDs := []string{}
 
diff --git a/internal/db/bundb/emoji_test.go b/internal/db/bundb/emoji_test.go
index c6577a721..b542f9b67 100644
--- a/internal/db/bundb/emoji_test.go
+++ b/internal/db/bundb/emoji_test.go
@@ -38,6 +38,17 @@ func (suite *EmojiTestSuite) TestGetUseableEmojis() {
 	suite.Equal("rainbow", emojis[0].Shortcode)
 }
 
+func (suite *EmojiTestSuite) TestDeleteEmojiByID() {
+	testEmoji := suite.testEmojis["rainbow"]
+
+	err := suite.db.DeleteEmojiByID(context.Background(), testEmoji.ID)
+	suite.NoError(err)
+
+	dbEmoji, err := suite.db.GetEmojiByID(context.Background(), testEmoji.ID)
+	suite.Nil(dbEmoji)
+	suite.ErrorIs(err, db.ErrNoEntries)
+}
+
 func (suite *EmojiTestSuite) TestGetEmojiByStaticURL() {
 	emoji, err := suite.db.GetEmojiByStaticURL(context.Background(), "http://localhost:8080/fileserver/01F8MH17FWEB39HZJ76B6VXSKF/emoji/static/01F8MH9H8E4VG3KDYJR9EGPXCQ.png")
 	suite.NoError(err)
diff --git a/internal/db/emoji.go b/internal/db/emoji.go
index 831629232..d2f66a377 100644
--- a/internal/db/emoji.go
+++ b/internal/db/emoji.go
@@ -35,6 +35,8 @@ type Emoji interface {
 	// UpdateEmoji updates the given columns of one emoji.
 	// If no columns are specified, every column is updated.
 	UpdateEmoji(ctx context.Context, emoji *gtsmodel.Emoji, columns ...string) (*gtsmodel.Emoji, Error)
+	// DeleteEmojiByID deletes one emoji by its database ID.
+	DeleteEmojiByID(ctx context.Context, id string) Error
 	// GetUseableEmojis gets all emojis which are useable by accounts on this instance.
 	GetUseableEmojis(ctx context.Context) ([]*gtsmodel.Emoji, Error)
 	// GetEmojis gets emojis based on given parameters. Useful for admin actions.