ikiwiki/doc/plugins/comments/discussion.mdwn

## Why internal pages? (unresolved)

Comments are saved as internal pages, so they can never be edited through the CGI,
only by direct committers.

> So, why do it this way, instead of using regular wiki pages in a
> namespace, such as `$page/comments/*`? Then you could use [[plugins/lockedit]] to
> limit editing of comments in more powerful ways. --[[Joey]]

>> Er... I suppose so. I'd assumed that these pages ought to only exist as inlines
>> rather than as individual pages (same reasoning as aggregated posts), though.
>>
>> lockedit is actually somewhat insufficient, since `check_canedit()`
>> doesn't distinguish between creation and editing; I'd have to continue to use
>> some sort of odd hack to allow creation but not editing.
>>
>> I also can't think of any circumstance where you'd want a user other than
>> admins (~= git committers) and possibly the commenter (who we can't check for
>> at the moment anyway, I don't think?) to be able to edit comments - I think
>> user expectations for something that looks like ordinary blog comments are
>> likely to include "others can't put words into my mouth".
>>
>> My other objection to using a namespace is that I'm not particularly happy about
>> plugins consuming arbitrary pieces of the wiki namespace - /discussion is bad
>> enough already. Indeed, this very page would accidentally get matched by rules
>> aiming to control comment-posting... :-) --[[smcv]]

>>> Thinking about it, perhaps one way to address this would be to have the suffix
>>> (e.g. whether commenting on Sandbox creates sandbox/comment1 or sandbox/c1 or
>>> what) be configurable by the wiki admin, in the same way that recentchanges has
>>> recentchangespage => 'recentchanges'? I'd like to see fewer hard-coded page
>>> names in general, really - it seems odd to me that shortcuts and smileys
>>> hard-code the name of the page to look at. Perhaps I could add
>>> discussionpage => 'discussion' too? --[[smcv]]

>>> (I've now implemented this in my branch. --[[smcv]])

>> The best reason to keep the pages internal seems to me to be that you
>> don't want the overhead of every comment spawning its own wiki page. --[[Joey]]

## Formats (resolved)

The plugin now allows multiple comment formats while still using internal
pages; each comment is saved as a page containing one `\[[!comment]]` directive,
which has a superset of the functionality of [[ikiwiki/directives/format]].

## Access control (unresolved?)

By the way, I think that who can post comments should be controllable by
the existing plugins opendiscussion, anonok, signinedit, and lockedit. Allowing
posting comments w/o any login, while a nice capability, can lead to
spam problems. So, use `check_canedit` as at least a first-level check?
--[[Joey]]

> This plugin already uses `check_canedit`, but that function doesn't have a concept
> of different actions. The hack I use is that when a user comments on, say, sandbox,
> I call `check_canedit` for the pseudo-page "sandbox[postcomment]". The
> special `postcomment(glob)` [[ikiwiki/pagespec]] returns true if the page ends with
> "[postcomment]" and the part before (e.g. sandbox) matches the glob. So, you can
> have postcomment(blog/*) or something. (Perhaps instead of taking a glob, postcomment
> should take a pagespec, so you can have postcomment(link(tags/commentable))?)
>
> This is why `anonok_pagespec => 'postcomment(*)'` and `locked_pages => '!postcomment(*)'`
> are necessary to allow anonymous and logged-in editing (respectively).
>
>> I changed that to move the flag out of the page name, and into a variable that the `match_postcomment`
>> function checks for. Other ugliness still applies. :-) --[[Joey]] 
>
> This is ugly - one alternative would be to add `check_permission()` that takes a
> page and a verb (create, edit, rename, remove and maybe comment are the ones I
> can think of so far), use that, and port the plugins you mentioned to use that
> API too. This plugin could either call `check_can("$page/comment1", 'create')` or
> call `check_can($page, 'comment')`.
> 
> One odd effect of the code structure I've used is that we check for the ability to
> create the page before we actually know what page name we're going to use - when
> posting the comment I just increment a number until I reach an unused one - so
> either the code needs restructuring, or the permission check for 'create' would
> always be for 'comment1' and never 'comment123'. --[[smcv]]

>> Now resolved, in fact --[[smcv]]

> Another possibility is to just check for permission to edit (e.g.) `sandbox/comment1`.
> However, this makes the "comments can only be created, not edited" feature completely
> reliant on the fact that internal pages can't be edited. Perhaps there should be a
> `editable_pages` pagespec, defaulting to `'*'`? --[[smcv]]

## comments directive vs global setting (resolved?)

When comments have been enabled generally, you still need to mark which pages
can have comments, by including the `\[[!comments]]` directive in them. By default,
this directive expands to a "post a comment" link plus an `\[[!inline]]` with
the comments. [This requirement has now been removed --[[smcv]]]

> I don't like this, because it's hard to explain to someone why they have
> to insert this into every post to their blog. Seems that the model used
> for discussion pages could work -- if comments are enabled, automatically
> add the comment posting form and comments to the end of each page.
> --[[Joey]]

>> I don't think I'd want comments on *every* page (particularly, not the
>> front page). Perhaps a pagespec in the setup file, where the default is "*"?
>> Then control freaks like me could use "link(tags/comments)" and tag pages
>> as allowing comments.
>>
>>> Yes, I think a pagespec is the way to go. --[[Joey]]

>>>> Implemented --[[smcv]]

>> 
>> The model used for discussion pages does require patching the existing
>> page template, which I was trying to avoid - I'm not convinced that having
>> every possible feature hard-coded there really scales (and obviously it's
>> rather annoying while this plugin is on a branch). --[[smcv]]

>>> Using the template would allow customising the html around the comments
>>> which seems like a good thing? --[[Joey]]

>>>> The \[[!comments]] directive is already template-friendly - it expands to
>>>> the contents of the template `comments_embed.tmpl`, possibly with the
>>>> result of an \[[!inline]] appended. I should change `comments_embed.tmpl`
>>>> so it uses a template variable `INLINE` for the inline result rather than
>>>> having the perl code concatenate it, which would allow a bit more
>>>> customization (whether the "post" link was before or after the inline).
>>>> Even if you want comments in page.tmpl, keeping the separate comments_embed.tmpl
>>>> and having a `COMMENTS` variable in page.tmpl might be the way forward,
>>>> since the smaller each templates is, the easier it will be for users
>>>> to maintain a patched set of templates. (I think so, anyway, based on what happens
>>>> with dpkg prompts in Debian packages with monolithic vs split
>>>> conffiles.) --[[smcv]]

>>>>> I've switched my branch to use page.tmpl instead; see what you think? --[[smcv]]

## Raw HTML (resolved?)

Raw HTML was not initially allowed by default (this was configurable).

> I'm not sure that raw html should be a problem, as long as the
> htmlsanitizer and htmlbalanced plugins are enabled. I can see filtering
> out directives, as a special case. --[[Joey]]

>> Right, if I sanitize each post individually, with htmlscrubber and either htmltidy
>> or htmlbalance turned on, then there should be no way the user can forge a comment;
>> I was initially wary of allowing meta directives, but I think those are OK, as long
>> as the comment template puts the \[[!meta author]] at the *end*. Disallowing
>> directives is more a way to avoid commenters causing expensive processing than
>> anything else, at this point.
>>
>> I've rebased the plugin on master, made it sanitize individual posts' content
>> and removed the option to disallow raw HTML. Sanitizing individual posts before
>> they've been htmlized required me to preserve whitespace in the htmlbalance
>> plugin, so I did that. Alternatively, we could htmlize immediately and always
>> save out raw HTML? --[[smcv]]

>>> There might be some use cases for other directives, such as img, in
>>> comments.
>>> 
>>> I don't know if meta is "safe" (ie, guaranteed to be inexpensive and not
>>> allow users to do annoying things) or if it will continue to be in the
>>> future. Hard to predict really, all that can be said with certainty is
>>> all directives will contine to be inexpensive and safe enough that it's
>>> sensible to allow users to (ab)use them on open wikis.
>>> --[[Joey]]