Here is a patch that makes [[ikiwiki-calendar]] almost useless.

It adds some options, the main one being `calendar_autocreate`, which is
similar to the `tag_autocreate` option of the [[tag|plugins/tag]]: it create
archive pages when needed.

The documentation is updated as well (but as a non-native English speaker, I
won't be offended if you correct stuff you consider awkward):

- [[plugin|https://github.com/paternal/ikiwiki/blob/calendar-autocreate/doc/plugins/calendar.mdwn]]
- [[directive|https://github.com/paternal/ikiwiki/blob/calendar-autocreate/doc/ikiwiki/directive/calendar.mdwn]]

[[!tag patch]]
[[!template  id=gitbranch branch=spalax/calendar-autocreate browse="https://github.com/paternal/ikiwiki/tree/calendar-autocreate" author="[[Louis|spalax]]"]]

--[[Louis|spalax]]

> An attempt at a review (although note that I don't have commit access,
> so my opinion is not final):
>
> Should `calendar_autocreate_commit` really default to 1? I would personally
> expect that any new features that synthesize new pages should not commit
> them by default - I'd prefer to avoid cluttering git history with generated
> pages. (Indeed, should the option even exist?)
>
> > I copied those options from the [[plugins/tag]] plugin: the
> > `tag_autocreate_commit` option exists and default to 1.
> >
> > It should definitely exists: suppose a calendar page is created and not
> > commited, and later, someone tries to push some changes where a page with
> > the same name has been created. This would result in a conflict. The
> > `calendar_autocreate_commit` prevents this.
>
> > > `tag_autocreate_commit` exists because when tag autocreation
> > > was introduced, they were always in the `$srcdir` and committed.
> > > I changed it so that it was possible to put them in the [[plugins/transient]]
> > > underlay and not commit them. It defaults to 1 to preserve existing
> > > functionality.
> > >
> > > When automatic tag pages (or autoindex pages) are not committed, they
> > > go in the transient underlay, which means they can't cause conflicts:
> > > independent page creation will simply mask them (a page in the
> > > `$srcdir` hides a page of the same name in an underlay). I thought
> > > this implementation did the same when not committing? --[[smcv]]
>
> I'd personally do the conditional in gencalendaryear more like:
>
> [[!format perl """
return unless $config{calendar_autocreate};
"""]]
>
> to reduce the indentation depth of the more interesting code.
>
> > [[I agree|https://github.com/paternal/ikiwiki/commit/7f18c1ce48630507b744fa56b83999e8ca684606]]
>
> The recursion to generate missing years:
>
> [[!format perl """
if (not exists $wikistate{calendar}{minyear}) {
        $wikistate{calendar}{minyear} = $year;
} elsif ($wikistate{calendar}{minyear} > $year) {
        gencalendaryear($year + 1);
        $wikistate{calendar}{minyear} -= 1;
}
"""]]
>
> does seem to be correct on closer examination, but it took me a while
> to work out that it would actually do the right thing by recursing:
>
> * generate 2005
>   * recurse to generate 2006
>     * recurse to generate 2007
>       * recurse to generate 2008
>         * recurse to generate 2009
>           * recurse to try to generate 2010 (no effect)
>         * minyear = minyear - 1 = 2010 - 1 = 2009
>       * minyear = minyear - 1 = 2009 - 1 = 2008
>     * minyear = minyear - 1 = 2008 - 1 = 2007
>   * minyear = minyear - 1 = 2007 - 1 = 2006
> * minyear = minyear - 1 = 2006 - 1 = 2005
>
> I think it might be clearer (as well as less
> recursion-happy) to use iteration:
>
> * generate 2005
>   * recurse to generate 2006
>   * ...
>   * recurse to generate 2009
> * minyear = 2005
>
> something like this:
>
> [[!format perl """
sub gencalendaryear {
        my $year = shift;
        my %params = @_;
        ...
        # generate this year
        ...
        # Filling potential gaps in years [...] years 2006 to 2009.
        return if $params{norecurse};
        if (not exists $wikistate{calendar}{minyear}) {
                $wikistate{calendar}{minyear} = $year;
        } elsif ($wikistate{calendar}{minyear} > $year) {
                foreach my $other ($year + 1 .. $wikistate{calendar}{minyear} - 1) {
                        gencalendar($year, norecurse => 1);
                }
                $wikistate{calendar}{minyear} = $year;
        }
        # ... and the opposite for maxyear
}
"""]]
>
>
> > [[I agree|https://github.com/paternal/ikiwiki/commit/7f18c1ce48630507b744fa56b83999e8ca684606]]
>
> I'm not sure about generating missing years at all, though: if the
> generation is entirely dynamic, and there were no posts at all during
> a particular year (or month for that matter), shouldn't we just skip
> the year/month? That seems to be what e.g. Wordpress does.
>
> > [[Done|https://github.com/paternal/ikiwiki/commit/59b46942e01b32138d056381249effbbaf773892]].
> > I added an option `calendar_fill_gaps` to chose between the two
> > alternatives (since skipping empty months and years would change the
> > default behaviour of this plugin).
> >
> > I think the code is a bit ugly at some places. Perl is not one the the
> > programming languages I am fluent into. Sorry.
> >
> > PS: Good idea, thought. I now have to implement a similar thing for
> > [[plugins/contrib/jscalendar]].
>
> This piece of ikiwiki-calendar functionality is lost:
>
> [[!format diff """
- ... It also refreshes the wiki, updating the calendars to
-highlight the current day. This command is typically run at midnight from
-cron.
"""]]
>
> If I understand correctly, the highlight will be on the day at which
> the wiki was last refreshed, which seems arbitrary and confusing.
> If ikiwiki-calendar is not used, I'd say there should just not be a
> highlight for today (although I'm not sure how best to implement that -
> perhaps a config option representing "I am going to use ikiwiki-calendar").
>
> > This is not lost. What ikiwiki-calendar do is simply: build the missing
> > `archive/year/month` pages, and run `ikiwiki -refresh`. With my patch, the
> > `ikiwiki -refresh` includes:
> >
> > - the build of missing `archive/year/month` pages;
> > - highlighting the current day (this was already the case).
> >
> > So one can simply drop the `ikiwiki-calendar ...` for `ikiwiki --refresh
> > ...` in cron to get the same result.
> >
> > I
> > [[tried|https://github.com/paternal/ikiwiki/commit/7a92444e56fe023cea3b074dc5e6b5c4acdb6114]]
> > to make the documentation clearer.
>
> [[!format diff """
-\[[!template id=plugin name=calendar author="\[[ManojSrivastava]]"]]
-\[[!tag type/widget]]
"""]]
>
> Why did you remove that? It's useful information about the plugin
> which I think ought to stay.
>
> > Oops! It was a mistake.
> > [[Corrected|https://github.com/paternal/ikiwiki/commit/de9842ecc8914e11e73148dae78cd6909b535262]].
>
> --[[smcv]]
>
> > Thank you for this review. -- [[Louis|spalax]]