Mention fixup (#167)

* rework mention creation a bit

* rework mention creation a bit

* tidy up status dereferencing

* start adding tests for dereferencing

* fixups

* fix

* review changes

internal/federation/dereferencing/attachment.go

@@ -0,0 +1,84 @@
+/*
+   GoToSocial
+   Copyright (C) 2021 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 dereferencing
+
+import (
+	"context"
+	"fmt"
+	"net/url"
+
+	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+func (d *deref) GetRemoteAttachment(ctx context.Context, requestingUsername string, remoteAttachmentURI *url.URL, ownerAccountID string, statusID string, expectedContentType string) (*gtsmodel.MediaAttachment, error) {
+	l := d.log.WithFields(logrus.Fields{
+		"username":            requestingUsername,
+		"remoteAttachmentURI": remoteAttachmentURI,
+	})
+
+	maybeAttachment := &gtsmodel.MediaAttachment{}
+	where := []db.Where{
+		{
+			Key:   "remote_url",
+			Value: remoteAttachmentURI.String(),
+		},
+	}
+
+	if err := d.db.GetWhere(ctx, where, maybeAttachment); err == nil {
+		// we already the attachment in the database
+		l.Debugf("GetRemoteAttachment: attachment already exists with id %s", maybeAttachment.ID)
+		return maybeAttachment, nil
+	}
+
+	a, err := d.RefreshAttachment(ctx, requestingUsername, remoteAttachmentURI, ownerAccountID, expectedContentType)
+	if err != nil {
+		return nil, fmt.Errorf("GetRemoteAttachment: error refreshing attachment: %s", err)
+	}
+
+	a.StatusID = statusID
+	if err := d.db.Put(ctx, a); err != nil {
+		if err != db.ErrAlreadyExists {
+			return nil, fmt.Errorf("GetRemoteAttachment: error inserting attachment: %s", err)
+		}
+	}
+
+	return a, nil
+}
+
+func (d *deref) RefreshAttachment(ctx context.Context, requestingUsername string, remoteAttachmentURI *url.URL, ownerAccountID string, expectedContentType string) (*gtsmodel.MediaAttachment, error) {
+	// it just doesn't exist or we have to refresh
+	t, err := d.transportController.NewTransportForUsername(ctx, requestingUsername)
+	if err != nil {
+		return nil, fmt.Errorf("RefreshAttachment: error creating transport: %s", err)
+	}
+
+	attachmentBytes, err := t.DereferenceMedia(ctx, remoteAttachmentURI, expectedContentType)
+	if err != nil {
+		return nil, fmt.Errorf("RefreshAttachment: error dereferencing media: %s", err)
+	}
+
+	a, err := d.mediaHandler.ProcessAttachment(ctx, attachmentBytes, ownerAccountID, remoteAttachmentURI.String())
+	if err != nil {
+		return nil, fmt.Errorf("RefreshAttachment: error processing attachment: %s", err)
+	}
+
+	return a, nil
+}