feat: emoji reactions for tasks and comments (#2196)

This PR adds reactions for tasks and comments, similar to what you can do on Gitea, GitHub, Slack and plenty of other tools.

Reviewed-on: https://kolaente.dev/vikunja/vikunja/pulls/2196
Co-authored-by: kolaente <k@knt.li>
Co-committed-by: kolaente <k@knt.li>

pkg/models/reaction_rights.go

@@ -0,0 +1,81 @@
+// Vikunja is a to-do list application to facilitate your life.
+// Copyright 2018-present Vikunja and contributors. All rights reserved.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public Licensee 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 Licensee for more details.
+//
+// You should have received a copy of the GNU Affero General Public Licensee
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package models
+
+import (
+	"code.vikunja.io/web"
+	"xorm.io/xorm"
+)
+
+func (r *Reaction) setEntityKindFromString() (err error) {
+	switch r.EntityKindString {
+	case "tasks":
+		r.EntityKind = ReactionKindTask
+		return
+	case "comments":
+		r.EntityKind = ReactionKindComment
+		return
+	}
+
+	return ErrInvalidReactionEntityKind{
+		Kind: r.EntityKindString,
+	}
+}
+
+func (r *Reaction) CanRead(s *xorm.Session, a web.Auth) (bool, int, error) {
+	t, err := r.getTask(s)
+	if err != nil {
+		return false, 0, err
+	}
+	return t.CanRead(s, a)
+}
+
+func (r *Reaction) CanDelete(s *xorm.Session, a web.Auth) (bool, error) {
+	t, err := r.getTask(s)
+	if err != nil {
+		return false, err
+	}
+	return t.CanUpdate(s, a)
+}
+
+func (r *Reaction) CanCreate(s *xorm.Session, a web.Auth) (bool, error) {
+	t, err := r.getTask(s)
+	if err != nil {
+		return false, err
+	}
+	return t.CanUpdate(s, a)
+}
+
+func (r *Reaction) getTask(s *xorm.Session) (t *Task, err error) {
+	err = r.setEntityKindFromString()
+	if err != nil {
+		return
+	}
+
+	t = &Task{ID: r.EntityID}
+
+	if r.EntityKind == ReactionKindComment {
+		tc := &TaskComment{ID: r.EntityID}
+		err = getTaskCommentSimple(s, tc)
+		if err != nil {
+			return
+		}
+		t.ID = tc.TaskID
+	}
+
+	return
+}