Do not warn agents about empty article subjects by default (#88).

[reneeb]

Proposed change

When an agent wants to reply to a ticket, they get a warning about empty article subjects when the mail only contains the ticket hook. This is annoying as the subject usually doesn't contain only the ticket hook.

This change implements a new subaction for AgentTicketCompose where the subject is checked. And in the JavaScript code this subaction is called when the dialog is opened and when the subject is changed. And the warning is shown when TicketSubjectClean() returns an empty subject (and the new subaction returns a value that the subject would be empty).

This new subaction has the nice effect, that a solution for znuny/znuny-feature-requests#19 would be recognized as well without any further code change.

Type of change

• '1 - 🐞 bug 🐞' - Bugfix (non-breaking change which fixes an issue)

Additional information

• This PR is related to issue: Warning is shown with no need. - Proposal for fix #34

Checklist

• The code change is tested and works locally.(❗)
• There is no commented out code in this PR.(❕)
• You improved or added new unit tests.(❕)
• Local ZnunyCodePolicy run passes successfully.(❕)
• Local unit tests pass.(❕)
• GitHub workflow ZnunyCodePolicy passes.(❗)
• GitHub workflow unit tests pass.(❗)

[eyazi]

1. I would suggest changing CheckSubject to:

function CheckSubject() {
    $('#SubjectWarning').remove();

    Core.AJAX.FunctionCall(
        Core.Config.Get('CGIHandle'),
        {
            Action: 'AgentTicketCompose',
            Subaction: 'CheckSubject',
            Subject: $('#Subject').val(),
            TicketID: $('input[name=TicketID]').val(),
        },
        function (Response) {
            if (Response.Empty) {
                $('#AppWrapper').prepend('<div class="MessageBox Notice" id="SubjectWarning"><p>' + Response.Message + '</div>');
            }
        }
    );
}

2. There is still one notification left here https://github.com/znuny/Znuny/blob/rel-6_1-dev/Kernel/Modules/AgentTicketCompose.pm#L896 ($Error{LoadedFormDraft}).

3. It's not that great to make an AJAX call on page load up. To fix that, however, there needs to be a way to add HTML classes or IDs to $LayoutObject->Notify() to distinguish between difference notifications.