view jamendo/sparql-archived/SeRQL/lib/http/html_head.pl @ 27:d95e683fbd35 tip

Enable CORS on urispace redirects as well

/*  This file is part of ClioPatria.

    Author:	Jan Wielemaker <[e-mail]>
    HTTP:	http://e-culture.multimedian.nl/
    GITWEB:	http://gollem.science.uva.nl/git/ClioPatria.git
    GIT:	git://gollem.science.uva.nl/home/git/ClioPatria.git
    GIT:	http://gollem.science.uva.nl/home/git/ClioPatria.git
    Copyright:  2007, E-Culture/MultimediaN

    ClioPatria is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 2 of the License, or
    (at your option) any later version.

    ClioPatria is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with ClioPatria.  If not, see <http://www.gnu.org/licenses/>.
*/

:- module(html_head,
	  [ html_resource/2,		% +Resource, +Attributes
	    html_requires//1,		% +Resource
	    absolute_http_location/2	% +Spec, -Path
	  ]).
:- use_module(library(http/html_write)).
:- use_module(library(http/mimetype)).
:- use_module(library(error)).
:- use_module(library(settings)).
:- use_module(library(lists)).
:- use_module(library(option)).
:- use_module(library(ordsets)).
:- use_module(library(assoc)).
:- use_module(library(ugraphs)).
:- use_module(library(broadcast)).
:- use_module(library(apply)).
:- use_module(library(debug)).


/** <module> Deal with CSS and scripts

This module is to clean up the   mess related to managing Javascript and
CSS files. It defines relations between scripts and style files.

Declarations  come  in  two   forms.   First    of   all,   clauses  for
http:location_path/2  define  HTTP  locations    globally,   similar  to
file_search_path/2. Second, html_resource/2 specifies  HTML resources to
be used in the =head= and   their  dependencies. Resources are currently
limited to Javascript files (.js) and style sheets (.css). It is trivial
to add support for other material in the head.  See html_include//1.

For usage in HTML generation, there is the DCG rule html_requires/1 that
demands named resources in the HTML head. For general purpose reasoning,
absolute_http_location/2  translates  a  path    specification  into  an
absolute HTTP location on the server.

---++ About resource ordering

All calls to html_requires//1 for the page are collected and duplicates
are removed.  Next, the following steps are taken:

    1. Add all dependencies to the set
    2. Replace multiple members by `aggregate' scripts or css files.
       see use_agregates/4.
    3. Order all resources by demanding that their dependencies
       preceede the resource itself.  Note that the ordering of
       resources in the dependency list is *ignored*.  This implies
       that if the order matters the dependency list must be split
       and only the primary dependency must be added.

---++ Debugging dependencies

Use ?- debug(html(script)). to  see  the   requested  and  final  set of
resources. All declared resources  are   in  html_resource/3. The edit/1
command recognises the names of HTML resources.

@see	For ClioPatria, the resources are defined in server/html_resource.pl
@tbd	Possibly we should add img//2 to include images from symbolic
	path notation.
@tbd	It would be nice if the HTTP file server could use our location
	declarations.
*/

:- dynamic
	html_resource/3.		% Resource, Source, Properties

%%	html_resource(+About, +Properties) is det.
%
%	Register an HTML head resource.  About   is  either an atom that
%	specifies an HTTP location or  a   term  Alias(Sub).  This works
%	similar to absolute_file_name/2.  See   http:location_path/2  for
%	details.  Recognised properties are:
%	
%		* requires(+Requirements)
%		Other required script and css files.  If this is a plain
%		file name, it is interpreted relative to the declared
%		resource.  Requirements can be a list, which is equivalent
%		to multiple requires properties.
%		
%		* virtual(+Bool)
%		If =true= (default =false=), do not include About itself,
%		but only its dependencies.  This allows for defining an
%		alias for one or more resources.
%		
%		* aggregate(+List)
%		States that About is an aggregate of the resources in
%		List.

html_resource(About, Properties) :-
	source_location(File, Line), !,
	retractall(html_resource(About, File:Line, _)),
	assert_resource(About, File:Line, Properties).
html_resource(About, Properties) :-
	assert_resource(About, -, Properties).

assert_resource(About, Location, Properties) :-
	assert(html_resource(About, Location, Properties)),
	clean_same_about_cache,
	(   memberchk(aggregate(_), Properties)
	->  clean_aggregate_cache
	;   true
	).


%%	html_requires(+ResourceOrList)// is det.
%
%	Include ResourceOrList and all dependencies  derived from it and
%	add them to the  HTML  =head=   using  html_post/2.  The  actual
%	dependencies are computed  during  the   HTML  output  phase  by
%	html_insert_resource//1.

html_requires(Required) -->
	html_post(head, 'html required'(Required)).

:- multifile
	html_write:html_head_expansion/2.

html_write:html_head_expansion(In, Out) :-
	require_commands(In, Required, Rest),
	Required \== [], !,
	flatten(Required, Plain),
	Out = [ html_head:(\html_insert_resource(Plain))
	      | Rest
	      ].

require_commands([], [], []).
require_commands([_:('html required'(Required))|T0], [Required|TR], R) :- !,
	require_commands(T0, TR, R).
require_commands([R|T0], TR, [R|T]) :- !,
	require_commands(T0, TR, T).


%%	html_insert_resource(+ResourceOrList)// is det.
%
%	Actually   include   HTML   head   resources.   Called   through
%	html_post//2   from   html_requires//1   after     rewrite    by
%	html_head_expansion/2. We are guaranteed we   will  only get one
%	call that is passed a flat   list  of requested requirements. We
%	have three jobs:
%	
%	    1. Figure out all indirect requirements
%	    2. See whether we can use any `aggregate' resources
%	    3. Put required resources before their requiree.

html_insert_resource(Required) -->
	{ requirements(Required, Paths),
	  debug(html(script), 'Requirements: ~q~nFinal: ~q', [Required, Paths])
	},
	html_include(Paths).
	
requirements(Required, Paths) :-
	phrase(requires(Required), List),
	sort(List, Paths0),		% remove duplicates
	use_agregates(Paths0, Paths1, AggregatedBy),
	order_html_resources(Paths1, AggregatedBy, Paths).

%%	use_agregates(+Paths, -Aggregated, -AggregatedBy) is det.
%
%	Try to replace sets of  resources   by  an  `aggregate', a large
%	javascript or css file that  combines   the  content of multiple
%	small  ones  to  reduce  the  number   of  files  that  must  be
%	transferred to the server. The current rule says that aggregates
%	are used if at least half of the members are used.

use_agregates(Paths, Aggregated, AggregatedBy) :-
	empty_assoc(AggregatedBy0),
	use_agregates(Paths, Aggregated, AggregatedBy0, AggregatedBy).

use_agregates(Paths, Aggregated, AggregatedBy0, AggregatedBy) :-
	aggregate(Aggregate, Parts, Size),
	ord_subtract(Paths, Parts, NotCovered),
	length(Paths, Len0),
	length(NotCovered, Len1),
	Covered is Len0-Len1,
	Covered >= Size/2, !,
	ord_add_element(NotCovered, Aggregate, NewPaths),
	add_aggregated_by(Parts, AggregatedBy0, Aggregate, AggregatedBy1),
	use_agregates(NewPaths, Aggregated, AggregatedBy1, AggregatedBy).
use_agregates(Paths, Paths, AggregatedBy, AggregatedBy).

add_aggregated_by([], Assoc, _, Assoc).
add_aggregated_by([H|T], Assoc0, V, Assoc) :-
	put_assoc(H, Assoc0, V, Assoc1),
	add_aggregated_by(T, Assoc1, V, Assoc).


:- dynamic
	aggregate_cache_filled/0,
	aggregate_cache/3.
:- volatile
	aggregate_cache_filled/0,
	aggregate_cache/3.

clean_aggregate_cache :-
	retractall(aggregate_cache_filled).

%%	aggregate(-Aggregate, -Parts, -Size) is nondet.
%
%	True if Aggregate is a defined   aggregate  with Size Parts. All
%	parts are canonical absolute HTTP locations  and Parts is sorted
%	to allow for processing using ordered set predicates.

aggregate(Path, Parts, Size) :-
	aggregate_cache_filled, !,
	aggregate_cache(Path, Parts, Size).
aggregate(Path, Parts, Size) :-
	retractall(aggregate_cache(_,_, _)),
	forall(uncached_aggregate(Path, Parts, Size),
	       assert(aggregate_cache(Path, Parts, Size))),
	assert(aggregate_cache_filled),
	aggregate_cache(Path, Parts, Size).

uncached_aggregate(Path, APartsS, Size) :-
	html_resource(Aggregate, _, Properties),
	memberchk(aggregate(Parts), Properties),
	absolute_http_location(Aggregate, Path),
	absolute_paths(Parts, Path, AParts),
	sort(AParts, APartsS),
	length(APartsS, Size).

absolute_paths([], _, []).
absolute_paths([H0|T0], Base, [H|T]) :-
	absolute_http_location(H0, Base, H),
	absolute_paths(T0, Base, T).


%%	requires(+Spec)// is det.
%%	requires(+Spec, +Base)// is det.
%
%	True if Files is the set of  files   that  need to be loaded for
%	Spec. Note that Spec normally appears in  Files, but this is not
%	necessary (i.e. virtual resources  or   the  usage  of aggregate
%	resources).

requires(Spec) -->
	requires(Spec, /).

requires([], _) --> !,
	[].
requires([H|T], Base) --> !,
	requires(H, Base),
	requires(T, Base).
requires(Spec, Base) -->
	requires(Spec, Base, true).

requires(Spec, Base, Virtual) -->
	{ res_properties(Spec, Properties),
	  absolute_http_location(Spec, Base, File)
	},
	(   { option(virtual(true), Properties)
	    ; Virtual == false
	    }
	->  []
	;   [File]
	),
	requires_from_properties(Properties, File).


requires_from_properties([], _) --> 
	[].
requires_from_properties([H|T], Base) -->
	requires_from_property(H, Base),
	requires_from_properties(T, Base).

requires_from_property(requires(What), Base) --> !,
	requires(What, Base).
requires_from_property(_, _) -->
	[].


% %	order_html_resources(+Requirements, +AggregatedBy, -Ordered) is det.
%
%	Establish a proper order for the   collected (sorted and unique)
%	list of Requirements. 

order_html_resources(Requirements, AggregatedBy, Ordered) :-
	requirements_graph(Requirements, AggregatedBy, Graph),
	(   top_sort(Graph, Ordered)
	->  true
	;   connect_graph(Graph, Start, Connected),
	    top_sort(Connected, Ordered0),
	    Ordered0 = [Start|Ordered]
	).

%%	requirements_graph(+Requirements, +AggregatedBy, -Graph) is det.
%
%	Produce an S-graph (see library(ugraphs))   that  represents the
%	dependencies  in  the  list  of  Requirements.  Edges  run  from
%	required to requirer.

requirements_graph(Requirements, AggregatedBy, Graph) :-
	phrase(prerequisites(Requirements, AggregatedBy, Vertices, []), Edges),
	vertices_edges_to_ugraph(Vertices, Edges, Graph).

prerequisites([], _, Vs, Vs) -->
	[].
prerequisites([R|T], AggregatedBy, Vs, Vt) -->
	prerequisites_for(R, AggregatedBy, Vs, Vt0),
	prerequisites(T, AggregatedBy, Vt0, Vt).

prerequisites_for(R, AggregatedBy, Vs, Vt) -->
	{ phrase(requires(R, /, false), Req) },
	(   {Req == []}
	->  {Vs = [R|Vt]}
	;   req_edges(Req, AggregatedBy, R),
	    {Vs = Vt}
	).

req_edges([], _, _) -->
	[].
req_edges([H|T], AggregatedBy, R) -->
	(   { get_assoc(H, AggregatedBy, Aggregate) }
	->  [Aggregate-R]
	;   [H-R]
	),
	req_edges(T, AggregatedBy, R).
	

%%	connect_graph(+Graph, -Connected) is det.
%	
%	Turn Graph into a connected graph   by putting a shared starting
%	point before all vertices.

connect_graph([], 0, []) :- !.
connect_graph(Graph, Start, [Start-Vertices|Graph]) :-
	vertices(Graph, Vertices),
	Vertices = [First|_],
	before(First, Start).
	
%%	before(+Term, -Before) is det.
%
%	Unify Before to a term that comes   before  Term in the standard
%	order of terms.
%	
%	@error instantiation_error if Term is unbound.

before(X, _) :-
	var(X), !,
	instantiation_error(X).
before(Number, Start) :-
	number(Number), !,
	Start is Number - 1.
before(_, 0).


%%	res_properties(+Spec, -Properties) is det.
%
%	True if Properties is the set of defined properties on Spec.

res_properties(Spec, Properties) :-
	findall(P, res_property(Spec, P), Properties0),
	list_to_set(Properties0, Properties).

res_property(Spec, Property) :-
	same_about(Spec, About),
	html_resource(About, _, Properties),
	member(Property, Properties).

:- dynamic
	same_about_cache/2.
:- volatile
	same_about_cache/2.

clean_same_about_cache :-
	retractall(same_about_cache(_,_)).

same_about(Spec, About) :-
	same_about_cache(Spec, Same), !,
	member(About, Same).
same_about(Spec, About) :-
	findall(A, uncached_same_about(Spec, A), List),
	assert(same_about_cache(Spec, List)),
	member(About, List).

uncached_same_about(Spec, About) :-
	html_resource(About, _, _),
	same_resource(Spec, About).


%%	same_resource(+R1, +R2) is semidet.
%
%	True if R1 an R2 represent the same resource.  R1 and R2 are
%	resource specifications are defined by absolute_http_location/2.

same_resource(R, R) :- !.
same_resource(R1, R2) :- 
	resource_base_name(R1, B),
	resource_base_name(R2, B),
	absolute_http_location(R1, Path),
	absolute_http_location(R2, Path).

:- dynamic
	base_cache/2.
:- volatile
	base_cache/2.

resource_base_name(Spec, Base) :-
	(   base_cache(Spec, Base0)
	->  Base = Base0
	;   uncached_resource_base_name(Spec, Base0),
	    assert(base_cache(Spec, Base0)),
	    Base = Base0
	).

uncached_resource_base_name(Atom, Base) :-
	atomic(Atom), !,
	file_base_name(Atom, Base).
uncached_resource_base_name(Compound, Base) :-
	arg(1, Compound, Base0),
	file_base_name(Base0, Base).

%%	html_include(+PathOrList)// is det.
%
%	Include to HTML resources  that  must   be  in  the  HTML <head>
%	element. Currently onlu supports  =|.js|=   and  =|.css|= files.
%	Extend this to support more  header   material.  Do not use this
%	predicate directly. html_requires//1 is the  public interface to
%	include HTML resources.
%	
%	@param	HTTP location or list of these.

html_include([]) --> !.
html_include([H|T]) --> !,
	html_include(H),
	html_include(T).
html_include(Path) -->
	{ file_mime_type(Path, Mime) }, !,
	html_include(Mime, Path).

html_include(text/css, Path) --> !,
	html(link([ rel(stylesheet),
		    type('text/css'),
		    href(Path)
		  ], [])).
html_include(text/javascript, Path) --> !,
	html(script([ type('text/javascript'),
		      src(Path)
		    ], [])).
html_include(Mime, Path) -->
	{ print_message(warning, html_include(dont_know, Mime, Path))
	}.



		 /*******************************
		 *	      PATHS		*
		 *******************************/

:- multifile
	http:location_path/2.
:- dynamic
	http:location_path/2.

%%	http_location_path(+Alias, -Expansion) is det.
%
%	Expansion is the expanded HTTP location for Alias. As we have no
%	condition search, we demand a single  expansion for an alias. An
%	ambiguous alias results in a printed   warning.  A lacking alias
%	results in an exception.
%	
%	@error	existence_error(http_alias, Alias)

http_location_path(Alias, Path) :-
	findall(Path, http:location_path(Alias, Path), Paths0),
	sort(Paths0, Paths),
	(   Paths = [One]
	->  Path = One
	;   Paths = [Path|_]
	->  print_message(warning, ambiguous_http_location(Alias, Paths))
	;   Alias \== prefix
	->  existence_error(http_alias, Alias)
	).
http_location_path(prefix, Path) :-
	(   setting(http:prefix, Prefix),
	    Prefix \== ''
	->  (	sub_atom(Prefix, 0, _, _, /)
	    ->  Path = Prefix
	    ;	atom_concat(/, Prefix, Path)
	    )
	;   Path = /
	).

%%	absolute_http_location(+Spec, -Path) is det.
%%	absolute_http_location(+Spec, +Base, -Path) is det.
%
%	True if Path is the full HTTP   location  for Spec. This behaves
%	very much like absolute_file_name/2. Path-alias   are defined by
%	the dynamic multifile predicate  http:location_path/2, using the
%	same syntax as user:file_search_path/2.

:- dynamic
	location_cache/3.
:- volatile
	location_cache/3.

absolute_http_location(Spec, Path) :-
	absolute_http_location(Spec, /, Path).

absolute_http_location(Spec, Base, Path) :-
	location_cache(Spec, Base, Path), !.
absolute_http_location(Spec, Base, Path) :-
	uncached_absolute_http_location(Spec, Base, Path),
	assert(location_cache(Spec, Base, Path)).

uncached_absolute_http_location(Spec, Base, Path) :-
	(   atomic(Spec)
	->  relative_to(Base, Spec, Path)
	;   Spec =.. [Alias, Sub],
	    http_location_path(Alias, Parent),
	    absolute_http_location(Parent, /, ParentLocation),
	    phrase(sub_list(Sub), List),
	    concat_atom(List, /, SubAtom),
	    (	ParentLocation == ''
	    ->	Path = SubAtom
	    ;	sub_atom(ParentLocation, _, _, 0, /)
	    ->	atom_concat(ParentLocation, SubAtom, Path)
	    ;	concat_atom([ParentLocation, SubAtom], /, Path)
	    )
	).

%%	relative_to(+Base, +Path, -AbsPath) is det.
%
%	AbsPath is an absolute URL location created from Base and Path.
%	The result is cleaned

relative_to(/, Path, Path) :- !.
relative_to(_Base, Path, Path) :-
	sub_atom(Path, 0, _, _, /), !.
relative_to(Base, Local, Path) :-
	path_segments(Base, BaseSegments),
	append(BaseDir, [_], BaseSegments) ->
	path_segments(Local, LocalSegments),
	append(BaseDir, LocalSegments, Segments0),
	clean_segments(Segments0, Segments),
	path_segments(Path, Segments).
	
path_segments(Path, Segments) :-
	concat_atom(Segments, /, Path).

%%	clean_segments(+SegmentsIn, -SegmentsOut) is det.
%
%	Clean a path represented  as  a   segment  list,  removing empty
%	segments and resolving .. based on syntax.

clean_segments([''|T0], [''|T]) :- !,
	exclude(empty_segment, T0, T1),
	clean_parent_segments(T1, T).
clean_segments(T0, T) :-
	exclude(empty_segment, T0, T1),
	clean_parent_segments(T1, T).

clean_parent_segments([], []).
clean_parent_segments([..|T0], T) :- !,
	clean_parent_segments(T0, T).
clean_parent_segments([_,..|T0], T) :- !,
	clean_parent_segments(T0, T).
clean_parent_segments([H|T0], [H|T]) :-
	clean_parent_segments(T0, T).

empty_segment('').
empty_segment('.').


%%	sub_list(+Spec, -List) is det.

sub_list(Var) -->
	{ var(Var), !,
	  instantiation_error(Var)
	}.
sub_list(A/B) --> !,
	sub_list(A),
	sub_list(B).
sub_list(A) -->
	[A].


		 /*******************************
		 *	  CACHE CLEANUP		*
		 *******************************/

clean_location_cache :-
	retractall(location_cache(_,_,_)).

:- listen(settings(changed(http:prefix, _, _)),
	  clean_location_cache).

:- multifile
	user:message_hook/3.
:- dynamic
	user:message_hook/3.

user:message_hook(make(done(Reload)), _Level, _Lines) :-
	Reload \== [],
	clean_location_cache,
	clean_same_about_cache,
	clean_aggregate_cache,
	fail.


		 /*******************************
		 *	       EDIT		*
		 *******************************/

% Allow edit(Location) to edit the :- html_resource declaration.
:- multifile
	prolog_edit:locate/3.

prolog_edit:locate(Path, html_resource(Spec), [file(File), line(Line)]) :-
	atom(Path),
	html_resource(Spec, File:Line, _Properties),
	sub_term(Path, Spec).