X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/ba19f940bd071f7065246594751dd49041cbbaba..40be813b6ecdde2538b481b664e60505e76fd698:/doc/plugins/write.mdwn

diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index 07bfd72ac..9a5ca60a0 100644
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -1,24 +1,86 @@
-Ikiwiki's plugin interface allows all kinds of useful [[plugins]] to be
+lkiwiki's plugin interface allows all kinds of useful [[plugins]] to be
 written to extend ikiwiki in many ways. Despite the length of this page,
 it's not really hard. This page is a complete reference to everything a
 plugin might want to do. There is also a quick [[tutorial]].
 
-[[!template type="note" text="""
+[[!template id="note" text="""
 Ikiwiki is a compiler
 
 One thing to keep in mind when writing a plugin is that ikiwiki is a wiki
 *compiler*. So plugins influence pages when they are built, not when they
 are loaded. A plugin that inserts the current time into a page, for
-example, will insert the build time. Also, as a compiler, ikiwiki avoids
-rebuilding pages unless they have changed, so a plugin that prints some
-random or changing thing on a page will generate a static page that won't
-change until ikiwiki rebuilds the page for some other reason, like the page
-being edited. The [[tutorial]] has some other examples of ways that ikiwiki
-being a compiler may trip up the unwary.
+example, will insert the build time.
+
+Also, as a compiler, ikiwiki avoids rebuilding pages unless they have
+changed, so a plugin that prints some random or changing thing on a page
+will generate a static page that won't change until ikiwiki rebuilds the
+page for some other reason, like the page being edited.
+
+The [[tutorial]] has some other examples of ways that ikiwiki being a
+compiler may trip up the unwary.
 """]]
 
 [[!toc levels=2]]
 
+## Highlevel view of ikiwiki
+
+Ikiwiki mostly has two modes of operation. It can either be running
+as a compiler, building or updating a wiki; or as a cgi program, providing
+user interface for editing pages, etc. Almost everything ikiwiki does
+is accomplished by calling various hooks provided by plugins.
+
+### compiler
+
+As a compiler, ikiwiki starts by calling the `refresh` hook. Then it checks
+the wiki's source to find new or changed pages. The `needsbuild` hook is
+then called to allow manipulation of the list of pages that need to be
+built. 
+
+Now that it knows what pages it needs to build, ikiwiki runs two
+compile passes. First, it runs `scan` hooks, which collect metadata about
+the pages. Then it runs a page rendering pipeline, by calling in turn these
+hooks: `filter`, `preprocess`, `linkify`, `htmlize`, `indexhtml`,
+`pagetemplate`, `sanitize`, `format`.
+
+After all necessary pages are built, it calls the `change` hook. Finally,
+if a page is was deleted, the `delete` hook is called, and the files that
+page had previously produced are removed.
+
+### cgi
+
+The flow between hooks when ikiwiki is run as a cgi is best illustrated by
+an example.
+
+Alice browses to a page and clicks Edit.
+
+* Ikiwiki is run as a cgi. It assigns Alice a session cookie, and,
+  by calling the `auth` hooks, sees that she is not yet logged in.
+* The `sessioncgi` hooks are then called, and one of them,
+  from the [[editpage]] plugin, notices that the cgi has been told "do=edit".
+* The [[editpage]] plugin calls the `canedit` hook to check if this
+  page edit is allowed. The [[signinedit]] plugin has a hook that says not:
+  Alice is not signed in.
+* The [[signinedit]] plugin then launches the signin process. A signin
+  page is built by calling the `formbuilder_setup` hook.
+
+Alice signs in with her openid.
+
+* The [[openid]] plugin's `formbuilder` hook sees that an openid was
+  entered in the signin form, and redirects to Alice's openid provider.
+* Alice's openid provider calls back to ikiwiki. The [[openid]] plugin
+  has an `auth` hook that finishes the openid signin process.
+* Signin complete, ikiwiki returns to what Alice was doing before; editing
+  a page.
+* Now all the `canedit` hooks are happy. The [[editpage]] plugin calls
+  `formbuilder_setup` to display the page editing form.
+
+Alice saves her change to the page.
+
+* The [[editpage]] plugin's `formbuilder` hook sees that the Save button
+  was pressed, and calls the `checkcontent` and `editcontent` hooks.
+  Then it saves the page to disk, and branches into the compiler part
+  of ikiwiki to refresh the wiki.
+
 ## Types of plugins
 
 Most ikiwiki [[plugins]] are written in perl, like ikiwiki. This gives the
@@ -115,10 +177,15 @@ function is passed no values.
 
 	hook(type => "needsbuild", id => "foo", call => \&needsbuild);
 
-This allows a plugin to manipulate the list of files that need to be
-built when the wiki is refreshed. The function is passed a reference to an
-array of files that will be rebuilt, and can modify the array, either
-adding or removing files from it.
+This allows a plugin to observe or even manipulate the list of files that
+need to be built when the wiki is refreshed. 
+
+As its first parameter, the function is passed a reference to an array of
+files that will be built. It should return an array reference that is a
+modified version of its input. It can add or remove files from it.
+
+The second parameter passed to the function is a reference to an array of
+files that have been deleted.
 
 ### scan
 
@@ -136,8 +203,8 @@ value is ignored.
 
 	hook(type => "filter", id => "foo", call => \&filter);
 
-Runs on the raw source of a page, before anything else touches it, and can
-make arbitrary changes. The function is passed named parameters "page",
+Runs on the full raw source of a page, before anything else touches it, and
+can make arbitrary changes. The function is passed named parameters "page",
 "destpage", and "content". It should return the filtered content.
 
 ### preprocess
@@ -220,22 +287,22 @@ like `Makefile` that have no extension.
 If `hook` is passed an optional "longname" parameter, this value is used
 when prompting a user to choose a page type on the edit page form.
 
-### postscan
+### indexhtml
 
-	hook(type => "postscan", id => "foo", call => \&postscan);
+	hook(type => "indexhtml", id => "foo", call => \&indexhtml);
 
 This hook is called once the page has been converted to html (but before
 the generated html is put in a template). The most common use is to
 update search indexes. Added in ikiwiki 2.54.
 
-The function is passed named parameters "page" and "content". Its return
-value is ignored.
+The function is passed named parameters "page", "destpage", and "content".
+Its return value is ignored.
 
 ### pagetemplate
 
 	hook(type => "pagetemplate", id => "foo", call => \&pagetemplate);
 
-[[Templates|wikitemplates]] are filled out for many different things in
+[[Templates]] are filled out for many different things in
 ikiwiki, like generating a page, or part of a blog page, or an rss feed, or
 a cgi. This hook allows modifying the variables available on those
 templates. The function is passed named parameters. The "page" and
@@ -251,11 +318,20 @@ a new custom parameter to the template.
 
 	hook(type => "templatefile", id => "foo", call => \&templatefile);
 
-This hook allows plugins to change the [[template|wikitemplates]] that is
+This hook allows plugins to change the [[template|templates]] that is
 used for a page in the wiki. The hook is passed a "page" parameter, and
-should return the name of the template file to use, or undef if it doesn't
-want to change the default ("page.tmpl"). Template files are looked for in
-/usr/share/ikiwiki/templates by default.
+should return the name of the template file to use (relative to the
+template directory), or undef if it doesn't want to change the default
+("page.tmpl").
+
+### pageactions
+
+	hook(type => "pageactions", id => "foo", call => \&pageactions);
+
+This hook allows plugins to add arbitrary actions to the action bar on a
+page (next to Edit, RecentChanges, etc). The hook is passed a "page"
+parameter, and can return a list of html fragments to add to the action
+bar.
 
 ### sanitize
 
@@ -474,7 +550,7 @@ The data returned is a list of `%config` options, followed by a hash
 describing the option. There can also be an item named "plugin", which
 describes the plugin as a whole. For example:
 
-                return
+		return
 			plugin => {
 				description => "description of this plugin",
 				safe => 1,
@@ -504,6 +580,7 @@ describes the plugin as a whole. For example:
 * `description` is a short description of the option.
 * `link` is a link to further information about the option. This can either
   be a [[ikiwiki/WikiLink]], or an url.
+* `htmldescription` is displayed instead of the description by websetup.
 * `advanced` can be set to true if the option is more suitable for advanced
   users.
 * `safe` should be false if the option should not be displayed in unsafe
@@ -524,19 +601,29 @@ describes the plugin as a whole. For example:
 	hook(type => "genwrapper", id => "foo", call => \&genwrapper);
 
 This hook is used to inject C code (which it returns) into the `main`
-function of the ikiwiki wrapper when it is being generated.
+function of the ikiwiki wrapper when it is being generated. 
+
+The code runs before anything else -- in particular it runs before
+the suid wrapper has sanitized its environment.
+
+### disable
+
+	hook(type => "disable", id => "foo", call => \&disable);
+
+This hook is only run when a previously enabled plugin gets disabled
+during ikiwiki setup. Plugins can use this to perform cleanups.
 
 ## Exported variables
 
 Several variables are exported to your plugin when you `use IkiWiki;`
 
-### %config
+### `%config`
 
 A plugin can access the wiki's configuration via the `%config`
 hash. The best way to understand the contents of the hash is to look at
 your ikiwiki setup file, which sets the hash content to configure the wiki.
 
-### %pagestate
+### `%pagestate`
 
 The `%pagestate` hash can be used by plugins to save state that they will need
 next time ikiwiki is run. The hash holds per-page state, so to set a value,
@@ -554,7 +641,7 @@ When pages are deleted, ikiwiki automatically deletes their pagestate too.
 Note that page state does not persist across wiki rebuilds, only across
 wiki updates.
 
-### %wikistate
+### `%wikistate`
 
 The `%wikistate` hash can be used by a plugin to store persistant state
 that is not bound to any one page. To set a value, use
@@ -563,28 +650,52 @@ serialize, `$key` is any string you like, and `$id` must be the same as the
 "id" parameter passed to `hook()` when registering the plugin, so that the
 state can be dropped if the plugin is no longer used.
 
-### %links
+### `%links`
 
 The `%links` hash can be used to look up the names of each page that
 a page links to. The name of the page is the key; the value is an array
 reference. Do not modify this hash directly; call `add_link()`.
 
-### %destsources
+	$links{"foo"} = ["bar", "baz"];
 
-The `%destsources` hash records the name of the source file used to
-create each destination file. The key is the output filename (ie,
-"foo/index.html"), and the value is the source filename that it was built
-from (eg, "foo.mdwn"). Note that a single source file may create multiple
-destination files. Do not modify this hash directly; call `will_render()`.
+### `%typedlinks`
+
+The `%typedlinks` hash records links of specific types. Do not modify this
+hash directly; call `add_link()`. The keys are page names, and the values
+are hash references. In each page's hash reference, the keys are link types
+defined by plugins, and the values are hash references with link targets
+as keys, and 1 as a dummy value, something like this:
+
+	$typedlinks{"foo"} = {
+		tag => { short_word => 1, metasyntactic_variable => 1 },
+		next_page => { bar => 1 },
+	};
+
+Ordinary [[WikiLinks|ikiwiki/WikiLink]] appear in `%links`, but not in
+`%typedlinks`.
 
-### %pagesources
+### `%pagesources`
 
 The `%pagesources` has can be used to look up the source filename
 of a page. So the key is the page name, and the value is the source
 filename. Do not modify this hash.
 
+	$pagesources{"foo"} = "foo.mdwn";
+
+### `%destsources`
+
+The `%destsources` hash records the name of the source file used to
+create each destination file. The key is the output filename (ie,
+"foo/index.html"), and the value is the source filename that it was built
+from (eg, "foo.mdwn"). Note that a single source file may create multiple
+destination files. Do not modify this hash directly; call `will_render()`.
+	
+	$destsources{"foo/index.html"} = "foo.mdwn";
+
 ## Library functions
 
+Several functions are exported to your plugin when you `use IkiWiki;`
+
 ### `hook(@)`
 
 Hook into ikiwiki's processing. See the discussion of hooks above.
@@ -615,10 +726,31 @@ the entire wiki build and make the wiki unusable.
 
 ### `template($;@)`
 
-Creates and returns a [[!cpan HTML::Template]] object. The first parameter
-is the name of the file in the template directory. The optional remaining
+Creates and returns a [[!cpan HTML::Template]] object. (In a list context,
+returns the parameters needed to construct the obhect.) 
+
+The first parameter is the name of the template file. The optional remaining
 parameters are passed to `HTML::Template->new`.
 
+Normally, the template file is first looked for in the templates/ subdirectory
+of the srcdir. Failing that, it is looked for in the templatedir.
+
+Wiki pages can be used as templates. This should be done only for templates
+which it is safe to let wiki users edit. Enable it by passing a filename
+with no ".tmpl" extension. Template pages are normally looked for in
+the templates/ directory. If the page name starts with "/", a page
+elsewhere in the wiki can be used.
+
+If the template is not found, or contains a syntax error, an error is thrown.
+
+### `template_depends($$;@)`
+
+Use this instead of `template()` if the content of a template is being
+included into a page. This causes the page to depend on the template,
+so it will be updated if the template is modified.
+
+Like `template()`, except the second parameter is the page.
+
 ### `htmlpage($)`
 
 Passed a page name, returns the base name that will be used for a the html
@@ -648,7 +780,10 @@ Additional named parameters can be specified:
 * `filter` is a reference to a function, that is called and passed a page,
   and returns true if the page should be filtered out of the list.
 * `sort` specifies a sort order for the list. See
-  [[ikiwiki/PageSpec/sorting]] for the avilable sort methods.
+  [[ikiwiki/PageSpec/sorting]] for the avilable sort methods. Note that
+  if a sort method is specified that depends on the
+  page content (such as 'meta(foo)'), the deptype needs to be set to
+  a content dependency.
 * `reverse` if true, sorts in reverse.
 * `num` if nonzero, specifies the maximum number of matching pages that
   will be returned.
@@ -666,7 +801,7 @@ By default, dependencies are full content dependencies, meaning that the
 page will be updated whenever anything matching the PageSpec is modified.
 This can be overridden by passing a `deptype` value as the third parameter.
 
-#### `pagespec_match($$;@)`
+### `pagespec_match($$;@)`
 
 Passed a page name, and [[ikiwiki/PageSpec]], returns a true value if the
 [[ikiwiki/PageSpec]] matches the page.
@@ -696,7 +831,7 @@ dependency type from one or more of these keywords:
 
 If multiple types are specified, they are combined.
 
-#### `bestlink($$)`
+### `bestlink($$)`
 
 Given a page and the text of a link on the page, determine which
 existing page that link best points to. Prefers pages under a
@@ -704,7 +839,7 @@ subdirectory with the same name as the source page, failing that
 goes down the directory tree to the base looking for matching
 pages, as described in [[ikiwiki/SubPage/LinkingRules]].
 
-#### `htmllink($$$;@)`
+### `htmllink($$$;@)`
 
 Many plugins need to generate html links and add them to a page. This is
 done by using the `htmllink` function. The usual way to call
@@ -830,25 +965,40 @@ search for files.
 If the directory name is not absolute, ikiwiki will assume it is in
 the parent directory of the configured underlaydir.
 
-### `displaytime($;$)`
+### `displaytime($;$$)`
 
 Given a time, formats it for display.
 
 The optional second parameter is a strftime format to use to format the
 time.
 
+If the third parameter is true, this is the publication time of a page.
+(Ie, set the html5 pubdate attribute.)
+
 ### `gettext`
 
 This is the standard gettext function, although slightly optimised.
 
-### `urlto($$;$)`
+### `ngettext`
+
+This is the standard ngettext function, although slightly optimised.
+
+### `urlto($;$$)`
 
 Construct a relative url to the first parameter from the page named by the
 second. The first parameter can be either a page name, or some other
 destination file, as registered by `will_render`.
 
-If the third parameter is passed and is true, an absolute url will be
-constructed instead of the default relative url.
+Provide a second parameter whenever possible, since this leads to better
+behaviour for the [[plugins/po]] plugin and `file:///` URLs.
+
+If the second parameter is not specified (or `undef`), the URL will be
+valid from any page on the wiki, or from the CGI; if possible it'll
+be a path starting with `/`, but an absolute URL will be used if
+the wiki and the CGI are on different domains.
+
+If the third parameter is passed and is true, the url will be a fully
+absolute url. This is useful when generating an url to publish elsewhere.
 
 ### `newpagefile($$)`
 
@@ -865,11 +1015,31 @@ Optionally, a third parameter can be passed, to specify the preferred
 filename of the page. For example, `targetpage("foo", "rss", "feed")`
 will yield something like `foo/feed.rss`.
 
-### `add_link($$)`
+### `add_link($$;$)`
 
 This adds a link to `%links`, ensuring that duplicate links are not
 added. Pass it the page that contains the link, and the link text.
 
+An optional third parameter sets the link type. If not specified,
+it is an ordinary [[ikiwiki/WikiLink]].
+
+### `add_autofile($$$)`
+
+Sometimes you may want to add a file to the `srcdir` as a result of content
+of other pages. For example, [[plugins/tag]] pages can be automatically
+created as needed. This function can be used to do that. 
+
+The three parameters are the filename to create (relative to the `srcdir`),
+the name of the plugin, and a callback function. The callback will be
+called if it is appropriate to automatically add the file, and should then
+take care of creating it, and doing anything else it needs to (such as
+checking it into revision control). Note that the callback may not always
+be called. For example, if an automatically added file is deleted by the
+user, ikiwiki will avoid re-adding it again.
+
+This function needs to be called during the scan hook, or earlier in the
+build process, in order to add the file early enough for it to be built.
+
 ## Miscellaneous
 
 ### Internal use pages
@@ -907,16 +1077,20 @@ token, that will be passed into `rcs_commit` when committing. For example,
 it might return the current revision ID of the file, and use that
 information later when merging changes.
 
-#### `rcs_commit($$$;$$)`
+#### `rcs_commit(@)`
+
+Passed named parameters: `file`, `message`, `token` (from `rcs_prepedit`),
+and `session` (optional).
 
-Passed a file, message, token (from `rcs_prepedit`), user, and ip address.
 Should try to commit the file. Returns `undef` on *success* and a version
 of the page with the rcs's conflict markers on failure.
 
-#### `rcs_commit_staged($$$)`
+#### `rcs_commit_staged(@)`
 
-Passed a message, user, and ip address. Should commit all staged changes.
-Returns undef on success, and an error message on failure.
+Passed named parameters: `message`, and `session` (optional).
+
+Should commit all staged changes. Returns undef on success, and an
+error message on failure.
 
 Changes can be staged by calls to `rcs_add`, `rcs_remove`, and
 `rcs_rename`.
@@ -959,7 +1133,9 @@ The data structure returned for each change is:
 
 	{
 		rev => # the RCSs id for this commit
-		user => # name of user who made the change,
+		user => # user who made the change (may be an openid),
+		nickname => # short name for user (optional; not an openid),
+		
 		committype => # either "web" or the name of the rcs,
 		when => # time when the change was made,
 		message => [
@@ -976,19 +1152,30 @@ The data structure returned for each change is:
 		],
 	}
 
-#### `rcs_diff($)`
+#### `rcs_diff($;$)`
+
+The first parameter is the rev from `rcs_recentchanges`.
+The optional second parameter is how many lines to return (default: all).
 
-The parameter is the rev from `rcs_recentchanges`.
 Should return a list of lines of the diff (including \n) in list
-context, and the whole diff in scalar context.
+context, and a string containing the whole diff in scalar context.
 
 #### `rcs_getctime($)`
 
 This is used to get the page creation time for a file from the RCS, by looking
 it up in the history.
 
+If the RCS cannot determine a ctime for the file, return 0.
+
+#### `rcs_getmtime($)`
+
+This is used to get the page modification time for a file from the RCS, by
+looking it up in the history.
+
 It's ok if this is not implemented, and throws an error.
 
+If the RCS cannot determine a mtime for the file, return 0.
+
 #### `rcs_receive()`
 
 This is called when ikiwiki is running as a pre-receive hook (or
@@ -998,9 +1185,9 @@ sense to implement for all RCSs.
 
 It should examine the incoming changes, and do any sanity 
 checks that are appropriate for the RCS to limit changes to safe file adds,
-removes, and changes. If something bad is found, it should exit
-nonzero, to abort the push. Otherwise, it should return a list of
-files that were changed, in the form:
+removes, and changes. If something bad is found, it should die, to abort
+the push. Otherwise, it should return a list of files that were changed,
+in the form:
 
 	{
 		file => # name of file that was changed
@@ -1013,6 +1200,28 @@ files that were changed, in the form:
 The list will then be checked to make sure that each change is one that
 is allowed to be made via the web interface.
 
+#### `rcs_preprevert($)`
+
+This is called by the revert web interface. It is passed a RCS-specific
+change ID, and should determine what the effects would be of reverting
+that change, and return the same data structure as `rcs_receive`.
+
+Like `rcs_receive`, it should do whatever sanity checks are appropriate
+for the RCS to limit changes to safe changes, and die if a change would
+be unsafe to revert.
+
+#### `rcs_revert($)`
+
+This is called by the revert web interface. It is passed a named
+parameter rev that is the RCS-specific change ID to revert.
+
+It should try to revert the specified rev, and leave the reversion staged
+so `rcs_commit_staged` will complete it. It should return undef on _success_
+and an error message on failure.
+
+This hook and `rcs_preprevert` are optional, if not implemented, no revert
+web interface will be available.
+
 ### PageSpec plugins
 
 It's also possible to write plugins that add new functions to
@@ -1036,6 +1245,24 @@ For example, "backlink(foo)" is influenced by the contents of page foo;
 they match; "created_before(foo)" is influenced by the metadata of foo;
 while "glob(*)" is not influenced by the contents of any page.
 
+### Sorting plugins
+
+Similarly, it's possible to write plugins that add new functions as
+[[ikiwiki/pagespec/sorting]] methods. To achieve this, add a function to
+the IkiWiki::SortSpec package named `cmp_foo`, which will be used when sorting
+by `foo` or `foo(...)` is requested.
+
+The names of pages to be compared are in the global variables `$a` and `$b`
+in the IkiWiki::SortSpec package. The function should return the same thing
+as Perl's `cmp` and `<=>` operators: negative if `$a` is less than `$b`,
+positive if `$a` is greater, or zero if they are considered equal. It may
+also raise an error using `error`, for instance if it needs a parameter but
+one isn't provided.
+
+The function will also be passed one or more parameters. The first is
+`undef` if invoked as `foo`, or the parameter `"bar"` if invoked as `foo(bar)`;
+it may also be passed additional, named parameters.
+
 ### Setup plugins
 
 The ikiwiki setup file is loaded using a pluggable mechanism. If you look