database.rules.json

{
  "rules": {
    "data": {
      "$uid": {
        ".read": "$uid == auth.uid",
        ".write": "$uid == auth.uid"
      }
    },
    "groups": {
      "$group_id": {
        ".read": "root.child('groups').child($group_id).child('settings').child('members').child(auth.uid).exists()",
        "cards": {
          ".write": "root.child('groups').child($group_id).child('settings').child('permissions').child(root.child('groups').child($group_id).child('settings').child('members').child(auth.uid).child('role').val()).child('card').val() == true"
        },
        "tasks": {
          ".write": "root.child('groups').child($group_id).child('settings').child('permissions').child(root.child('groups').child($group_id).child('settings').child('members').child(auth.uid).child('role').val()).child('card').val() == true"
        },
        "settings": {
          "name": {
            ".write": "root.child('groups').child($group_id).child('settings').child('permissions').child(root.child('groups').child($group_id).child('settings').child('members').child(auth.uid).child('role').val()).child('settings').child('name').val() == true"
          },
          "note": {
            ".write": "root.child('groups').child($group_id).child('settings').child('permissions').child(root.child('groups').child($group_id).child('settings').child('members').child(auth.uid).child('role').val()).child('settings').child('note').val() == true"
          },
          "subjects": {
            ".write": "root.child('groups').child($group_id).child('settings').child('permissions').child(root.child('groups').child($group_id).child('settings').child('members').child(auth.uid).child('role').val()).child('settings').child('subjects').val() == true"
          },
          "permissions": {
            "admin": {
              ".write": "false"
            },
            "member": {
              ".write": "root.child('groups').child($group_id).child('settings').child('permissions').child(root.child('groups').child($group_id).child('settings').child('members').child(auth.uid).child('role').val()).child('settings').child('permissions').val() == true"
            }
          },
          "members": {
            ".write": "root.child('groups').child($group_id).child('settings').child('permissions').child(root.child('groups').child($group_id).child('settings').child('members').child(auth.uid).child('role').val()).child('members').val() == true",
            ".read": "auth != null && root.child('groups').child($group_id).child('settings').child('members').child(auth.uid).exists() == true",
            "$user": {
              "name": { ".write": "$user == auth.uid" },
							"icon": { ".write": "$user == auth.uid" },
              "role": {
                ".write": "root.child('groups').child($group_id).child('settings').child('permissions').child(root.child('groups').child($group_id).child('settings').child('members').child(auth.uid).child('role').val()).child('members').val() == true"
              }
            }
          },
          "invites": {
            ".read": "root
              					.child('groups')
              					.child($group_id)
              					.child('settings')
              					.child('members')
                        .child(auth.uid)
              					.exists()",
            "$inviteIndex": {
              ".read": "true"
            }
          } 
        }
      }
    }
  }
}