[feature] Fetch + display custom emoji in statuses from remote instances (#807)

* start implementing remote emoji fetcher

* update status where pk

* aaa

* tidy up a little

* check size limits for emojis

* thank you linter, i love you <3

* update swagger docs

* add emoji dereference test

* make emoji max sizes configurable

* normalize db.ErrAlreadyExists

internal/db/bundb/errors.go

@@ -19,7 +19,7 @@ func processPostgresError(err error) db.Error {
 	// (https://www.postgresql.org/docs/10/errcodes-appendix.html)
 	switch pgErr.Code {
 	case "23505" /* unique_violation */ :
-		return db.NewErrAlreadyExists(pgErr.Message)
+		return db.ErrAlreadyExists
 	default:
 		return err
 	}
@@ -36,7 +36,7 @@ func processSQLiteError(err error) db.Error {
 	// Handle supplied error code:
 	switch sqliteErr.Code() {
 	case sqlite3.SQLITE_CONSTRAINT_UNIQUE, sqlite3.SQLITE_CONSTRAINT_PRIMARYKEY:
-		return db.NewErrAlreadyExists(err.Error())
+		return db.ErrAlreadyExists
 	default:
 		return err
 	}

internal/db/bundb/status.go

@@ -22,6 +22,7 @@ import (
 	"container/list"
 	"context"
 	"database/sql"
+	"errors"
 	"time"
 
 	"github.com/superseriousbusiness/gotosocial/internal/cache"
@@ -175,6 +176,57 @@ func (s *statusDB) PutStatus(ctx context.Context, status *gtsmodel.Status) db.Er
 	})
 }
 
+func (s *statusDB) UpdateStatus(ctx context.Context, status *gtsmodel.Status) (*gtsmodel.Status, db.Error) {
+	err := s.conn.RunInTx(ctx, func(tx bun.Tx) error {
+		// create links between this status and any emojis it uses
+		for _, i := range status.EmojiIDs {
+			if _, err := tx.NewInsert().Model(&gtsmodel.StatusToEmoji{
+				StatusID: status.ID,
+				EmojiID:  i,
+			}).Exec(ctx); err != nil {
+				err = s.conn.errProc(err)
+				if !errors.Is(err, db.ErrAlreadyExists) {
+					return err
+				}
+			}
+		}
+
+		// create links between this status and any tags it uses
+		for _, i := range status.TagIDs {
+			if _, err := tx.NewInsert().Model(&gtsmodel.StatusToTag{
+				StatusID: status.ID,
+				TagID:    i,
+			}).Exec(ctx); err != nil {
+				err = s.conn.errProc(err)
+				if !errors.Is(err, db.ErrAlreadyExists) {
+					return err
+				}
+			}
+		}
+
+		// change the status ID of the media attachments to this status
+		for _, a := range status.Attachments {
+			a.StatusID = status.ID
+			a.UpdatedAt = time.Now()
+			if _, err := tx.NewUpdate().Model(a).
+				Where("id = ?", a.ID).
+				Exec(ctx); err != nil {
+				return err
+			}
+		}
+
+		// Finally, update the status itself
+		if _, err := tx.NewUpdate().Model(status).WherePK().Exec(ctx); err != nil {
+			return err
+		}
+
+		s.cache.Put(status)
+		return nil
+	})
+
+	return status, err
+}
+
 func (s *statusDB) GetStatusParents(ctx context.Context, status *gtsmodel.Status, onlyDirect bool) ([]*gtsmodel.Status, db.Error) {
 	parents := []*gtsmodel.Status{}
 	s.statusParent(ctx, status, &parents, onlyDirect)