[bugfix] Fix 404 on status delete redraft (#668)

* add unattach function to media processor

* call delete or unattach appropriately
unattach from client api, delete from federated api

* typo fix

internal/processing/media/unattach.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 media
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	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"
+)
+
+func (p *processor) Unattach(ctx context.Context, account *gtsmodel.Account, mediaAttachmentID string) (*apimodel.Attachment, gtserror.WithCode) {
+	attachment, err := p.db.GetAttachmentByID(ctx, mediaAttachmentID)
+	if err != nil {
+		if err == db.ErrNoEntries {
+			return nil, gtserror.NewErrorNotFound(errors.New("attachment doesn't exist in the db"))
+		}
+		return nil, gtserror.NewErrorNotFound(fmt.Errorf("db error getting attachment: %s", err))
+	}
+
+	if attachment.AccountID != account.ID {
+		return nil, gtserror.NewErrorNotFound(errors.New("attachment not owned by requesting account"))
+	}
+
+	attachment.UpdatedAt = time.Now()
+	attachment.StatusID = ""
+
+	if err := p.db.UpdateByPrimaryKey(ctx, attachment); err != nil {
+		return nil, gtserror.NewErrorNotFound(fmt.Errorf("db error updating attachment: %s", err))
+	}
+
+	a, err := p.tc.AttachmentToAPIAttachment(ctx, attachment)
+	if err != nil {
+		return nil, gtserror.NewErrorNotFound(fmt.Errorf("error converting attachment: %s", err))
+	}
+
+	return &a, nil
+}