updated branch; fold discussion of rejected version into a toggleable

doc/todo/want_to_avoid_ikiwiki_using_http_or_https_in_urls_to_allow_serving_both.mdwn

@@ -59,6 +59,9 @@ becoming a problem for me. Is there anything I can do here? --[[Perry]]
 
 ----
 
+[[!toggle id="smcv-https" text="Some discussion of a rejected implementation, smcv/https."]]
+[[!toggleable id="smcv-https" text="""
+
 [[!template id=gitbranch branch=smcv/https author="[[smcv]]"]]
 
 For a while I've been using a configuration where each wiki has a HTTP and
@@ -140,33 +143,61 @@ you don't like my approach:
 >> making it easier to run two mostly-synched copies like I was previously
 >> doing is the only solution... --s
 
+"""]]
+
 ----
 
-**warning: untested branch ** [[!template id=gitbranch branch=smcv/localurl author="[[smcv]]"]]
+[[!template id=gitbranch branch=smcv/localurl author="[[smcv]]"]]
 
 OK, here's an alternative approach, closer in spirit to what was initially
-requested. I haven't tested this at all (it's getting rather late in UK time)
+requested. I haven't tested this on a full website with the CGI yet.
-and it will probably be rebased later, but I've referenced it here as a proof of
-concept.
 
 The idea is that in the common case, the CGI and the pages will reside on the
 same server, so they can use "semi-absolute" URLs (`/ikiwiki.cgi`, `/style.css`,
-`/bugs/done`) to refer to each other. My branch adds config options which
+`/bugs/done`) to refer to each other. Most redirects, form actions, links etc.
-could be set as follows for ikiwiki.info or any branchable.com site:
+can safely use this form rather than the fully-absolute URL.
 
-* local_url: /
+The initial version of the branch had config options `local_url` and
-* local_cgiurl: /ikiwiki.cgi
+`local_cgiurl`, but they're now automatically computed by checking
-
+whether `url` and `cgiurl` are on the same server with the the same URL
-Most redirects, form actions, links etc. can safely use this form rather than
+scheme. In theory you could use things like `//static.example.com/wiki/`
-the fully-absolute URL. If not configured, these options default to the
+and `//dynamic.example.com/ikiwiki.cgi` to preserve choice of http/https
-corresponding absolute URL, which is would also be correct for unusual sites
-where the CGI and the pages aren't on the same server.
-
-(In theory you could use things like `//static.example.com/wiki/` and
-`//dynamic.example.com/ikiwiki.cgi` to preserve choice of http/https
 while switching server, but I don't know how consistently browsers
-suppot that.)
+suppot that.
 
 "local" here is short for "locally valid", because these URLs are neither
 fully relative nor fully absolute, and there doesn't seem to be a good name
 for them...
+
+New API added by this branch:
+
+* `urlto(x, y, 'local')` uses `$local_url` instead of `$config{url}`
+
+* `IkiWiki::baseurl` has a new second argument which works like the
+  third argument of `urlto`
+
+* `IkiWiki::cgiurl` uses `$local_cgiurl` if passed `local_cgiurl => 1`
+
+* `IkiWiki::cgiurl` omits the trailing `?` if given no named parameters
+  except `cgiurl` and/or `local_cgiurl`
+
+Bugs:
+
+* I don't think anything except `openid` calls `cgiurl` without also
+  passing in `local_cgiurl => 1`, so perhaps that should be the default;
+  `openid` uses `cgiurl` anyway, so there doesn't even necessarily need
+  to be a way to force absolute URLs? Any other module that really needs
+  an absolute URL could use `cgiurl(cgiurl => $config{cgiurl}, ...)`,
+  although that does look a bit strange
+
+* It occurs to me that `IkiWiki::cgiurl` could probably benefit from being
+  exported? Perhaps also `IkiWiki::baseurl`?
+
+* Or, to reduce use of the unexported `baseurl` function, it might make
+  sense to give `urlto` a special case that references the root of the wiki,
+  with a trailing slash ready to append stuff: perhaps `urlto('/')`,
+  with usage like this?
+
+      do_something(baseurl => urlto('/', undef, local)`);
+      do_something_else(urlto('/').'style.css');
+      IkiWiki::redirect(urlto('/', undef, 1));