Files
linguist/samples/Prolog/admin.pl
2014-09-04 13:49:30 -05:00

1052 lines
27 KiB
Prolog
Executable File

/* Part of ClioPatria SeRQL and SPARQL server
Author: Jan Wielemaker
E-mail: J.Wielemaker@cs.vu.nl
WWW: http://www.swi-prolog.org
Copyright (C): 2004-2010, University of Amsterdam,
VU University Amsterdam
This program is free software; you can redistribute it and/o<r
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.
This program 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 this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
As a special exception, if you link this library with other files,
compiled with a Free Software compiler, to produce an executable, this
library does not by itself cause the resulting executable to be covered
by the GNU General Public License. This exception does not however
invalidate any other reasons why the executable file might be covered by
the GNU General Public License.
*/
:- module(cpa_admin,
[ change_password_form//1
]).
:- use_module(user(user_db)).
:- use_module(library(http/http_parameters)).
:- use_module(library(http/http_session)).
:- use_module(library(http/html_write)).
:- use_module(library(http/html_head)).
:- use_module(library(http/mimetype)).
:- use_module(library(http/http_dispatch)).
:- use_module(library(url)).
:- use_module(library(debug)).
:- use_module(library(lists)).
:- use_module(library(option)).
:- use_module(library(http_settings)).
/** <module> ClioPatria administrative interface
This module provides HTTP services to perform administrative actions.
@tbd Ideally, this module should be split into an api-part, a
component-part and the actual pages. This also implies that
the current `action'-operations must (optionally) return
machine-friendly results.
*/
:- http_handler(cliopatria('admin/listUsers'), list_users, []).
:- http_handler(cliopatria('admin/form/createAdmin'), create_admin, []).
:- http_handler(cliopatria('admin/form/addUser'), add_user_form, []).
:- http_handler(cliopatria('admin/form/addOpenIDServer'), add_openid_server_form, []).
:- http_handler(cliopatria('admin/addUser'), add_user, []).
:- http_handler(cliopatria('admin/selfRegister'), self_register, []).
:- http_handler(cliopatria('admin/addOpenIDServer'), add_openid_server, []).
:- http_handler(cliopatria('admin/form/editUser'), edit_user_form, []).
:- http_handler(cliopatria('admin/editUser'), edit_user, []).
:- http_handler(cliopatria('admin/delUser'), del_user, []).
:- http_handler(cliopatria('admin/form/editOpenIDServer'), edit_openid_server_form, []).
:- http_handler(cliopatria('admin/editOpenIDServer'), edit_openid_server, []).
:- http_handler(cliopatria('admin/delOpenIDServer'), del_openid_server, []).
:- http_handler(cliopatria('admin/form/changePassword'), change_password_form, []).
:- http_handler(cliopatria('admin/changePassword'), change_password, []).
:- http_handler(cliopatria('user/form/login'), login_form, []).
:- http_handler(cliopatria('user/login'), user_login, []).
:- http_handler(cliopatria('user/logout'), user_logout, []).
:- http_handler(cliopatria('admin/settings'), settings, []).
:- http_handler(cliopatria('admin/save_settings'), save_settings, []).
%% list_users(+Request)
%
% HTTP Handler listing registered users.
list_users(_Request) :-
authorized(admin(list_users)),
if_allowed(admin(user(edit)), [edit(true)], UserOptions),
if_allowed(admin(openid(edit)), [edit(true)], OpenIDOptions),
reply_html_page(cliopatria(default),
title('Users'),
[ h1('Users'),
\user_table(UserOptions),
p(\action(location_by_id(add_user_form), 'Add user')),
h1('OpenID servers'),
\openid_server_table(OpenIDOptions),
p(\action(location_by_id(add_openid_server_form), 'Add OpenID server'))
]).
if_allowed(Token, Options, Options) :-
logged_on(User, anonymous),
catch(check_permission(User, Token), _, fail), !.
if_allowed(_, _, []).
%% user_table(+Options)//
%
% HTML component generating a table of registered users.
user_table(Options) -->
{ setof(U, current_user(U), Users)
},
html([ table([ class(block)
],
[ tr([ th('UserID'),
th('RealName'),
th('On since'),
th('Idle')
])
| \list_users(Users, Options)
])
]).
list_users([], _) -->
[].
list_users([User|T], Options) -->
{ user_property(User, realname(Name)),
findall(Idle-Login,
user_property(User, connection(Login, Idle)),
Pairs0),
keysort(Pairs0, Pairs),
( Pairs == []
-> OnLine = (-)
; length(Pairs, N),
Pairs = [Idle-Login|_],
OnLine = online(Login, Idle, N)
)
},
html(tr([ td(User),
td(Name),
td(\on_since(OnLine)),
td(\idle(OnLine)),
\edit_user_button(User, Options)
])),
list_users(T, Options).
edit_user_button(User, Options) -->
{ option(edit(true), Options) }, !,
html(td(a(href(location_by_id(edit_user_form)+'?user='+encode(User)), 'Edit'))).
edit_user_button(_, _) -->
[].
on_since(online(Login, _Idle, _Connections)) --> !,
{ format_time(string(Date), '%+', Login)
},
html(Date).
on_since(_) -->
html(-).
idle(online(_Login, Idle, _Connections)) -->
{ mmss_duration(Idle, String)
},
html(String).
idle(_) -->
html(-).
mmss_duration(Time, String) :- % Time in seconds
Secs is round(Time),
Hour is Secs // 3600,
Min is (Secs // 60) mod 60,
Sec is Secs mod 60,
format(string(String), '~`0t~d~2|:~`0t~d~5|:~`0t~d~8|', [Hour, Min, Sec]).
/*******************************
* ADD USERS *
*******************************/
%% create_admin(+Request)
%
% Create the administrator login.
create_admin(_Request) :-
( current_user(_)
-> throw(error(permission_error(create, user, admin),
context(_, 'Already initialized')))
; true
),
reply_html_page(cliopatria(default),
title('Create administrator'),
[ h1(align(center), 'Create administrator'),
p('No accounts are available on this server. \c
This form allows for creation of an administrative \c
account that can subsequently be used to create \c
new users.'),
\new_user_form([ user(admin),
real_name('Administrator')
])
]).
%% add_user_form(+Request)
%
% Form to register a user.
add_user_form(_Request) :-
authorized(admin(add_user)),
reply_html_page(cliopatria(default),
title('Add new user'),
[ \new_user_form([])
]).
new_user_form(Options) -->
{ ( option(user(User), Options)
-> UserOptions = [value(User)],
PermUser = User
; UserOptions = [],
PermUser = (-)
)
},
html([ h1('Add new user'),
form([ action(location_by_id(add_user)),
method('POST')
],
table([ class((form))
],
[ \realname(Options),
\input(user, 'Login',
UserOptions),
\input(pwd1, 'Password',
[type(password)]),
\input(pwd2, 'Retype',
[type(password)]),
\permissions(PermUser),
tr(class(buttons),
td([ colspan(2),
align(right)
],
input([ type(submit),
value('Create')
])))
]))
]).
input(Name, Label, Options) -->
html(tr([ th(align(right), Label),
td(input([name(Name),size(40)|Options]))
])).
% Only provide a realname field if this is not already given. This
% is because firefox determines the login user from the text field
% immediately above the password entry. Other browsers may do it
% different, so only having one text-field is probably the savest
% solution.
realname(Options) -->
{ option(real_name(RealName), Options) }, !,
hidden(realname, RealName).
realname(_Options) -->
input(realname, 'Realname', []).
%% add_user(+Request)
%
% API to register a new user. The current user must have
% administrative rights or the user-database must be empty.
add_user(Request) :-
( \+ current_user(_)
-> FirstUser = true
; authorized(admin(add_user))
),
http_parameters(Request,
[ user(User),
realname(RealName),
pwd1(Password),
pwd2(Retype),
read(Read),
write(Write),
admin(Admin)
],
[ attribute_declarations(attribute_decl)
]),
( current_user(User)
-> throw(error(permission_error(create, user, User),
context(_, 'Already present')))
; true
),
( Password == Retype
-> true
; throw(password_mismatch)
),
password_hash(Password, Hash),
phrase(allow(Read, Write, Admin), Allow),
user_add(User,
[ realname(RealName),
password(Hash),
allow(Allow)
]),
( FirstUser == true
-> user_add(anonymous,
[ realname('Define rights for not-logged in users'),
allow([read(_,_)])
]),
reply_login([user(User), password(Password)])
; list_users(Request)
).
%% self_register(Request)
%
% Self-register and login a new user if
% cliopatria:enable_self_register is set to true.
% Users are registered with full read
% and limited (annotate-only) write access.
%
% Returns a HTTP 403 forbidden error if:
% - cliopatria:enable_self_register is set to false
% - the user already exists
self_register(Request) :-
http_location_by_id(self_register, MyUrl),
( \+ setting(cliopatria:enable_self_register, true)
-> throw(http_reply(forbidden(MyUrl)))
; true
),
http_parameters(Request,
[ user(User),
realname(RealName),
password(Password)
],
[ attribute_declarations(attribute_decl)
]),
( current_user(User)
-> throw(http_reply(forbidden(MyUrl)))
; true
),
password_hash(Password, Hash),
Allow = [ read(_,_), write(_,annotate) ],
user_add(User, [realname(RealName), password(Hash), allow(Allow)]),
reply_login([user(User), password(Password)]).
%% edit_user_form(+Request)
%
% Form to edit user properties
edit_user_form(Request) :-
authorized(admin(user(edit))),
http_parameters(Request,
[ user(User)
],
[ attribute_declarations(attribute_decl)
]),
reply_html_page(cliopatria(default),
title('Edit user'),
\edit_user_form(User)).
%% edit_user_form(+User)//
%
% HTML component to edit the properties of User.
edit_user_form(User) -->
{ user_property(User, realname(RealName))
},
html([ h1(['Edit user ', User, ' (', RealName, ')']),
form([ action(location_by_id(edit_user)),
method('POST')
],
[ \hidden(user, User),
table([ class((form))
],
[ \user_property(User, realname, 'Real name', []),
\permissions(User),
tr(class(buttons),
td([ colspan(2),
align(right)
],
input([ type(submit),
value('Modify')
])))
])
]),
p(\action(location_by_id(del_user)+'?user='+encode(User),
[ 'Delete user ', b(User), ' (', i(RealName), ')' ]))
]).
user_property(User, Name, Label, Options) -->
{ Term =.. [Name, Value],
user_property(User, Term)
-> O2 = [value(Value)|Options]
; O2 = Options
},
html(tr([ th(class(p_name), Label),
td(input([name(Name),size(40)|O2]))
])).
permissions(User) -->
html(tr([ th(class(p_name), 'Permissions'),
td([ \permission_checkbox(User, read, 'Read'),
\permission_checkbox(User, write, 'Write'),
\permission_checkbox(User, admin, 'Admin')
])
])).
permission_checkbox(User, Name, Label) -->
{ ( User \== (-),
( user_property(User, allow(Actions))
-> true
; openid_server_property(User, allow(Actions))
),
pterm(Name, Action),
memberchk(Action, Actions)
-> Opts = [checked]
; def_user_permissions(User, DefPermissions),
memberchk(Name, DefPermissions)
-> Opts = [checked]
; Opts = []
)
},
html([ input([ type(checkbox),
name(Name)
| Opts
]),
Label
]).
def_user_permissions(-, [read]).
def_user_permissions(admin, [read, write, admin]).
%% edit_user(Request)
%
% Handle reply from edit user form.
edit_user(Request) :-
authorized(admin(user(edit))),
http_parameters(Request,
[ user(User),
realname(RealName,
[ optional(true),
length > 2,
description('Comment on user identifier-name')
]),
read(Read),
write(Write),
admin(Admin)
],
[ attribute_declarations(attribute_decl)
]),
modify_user(User, realname(RealName)),
modify_permissions(User, Read, Write, Admin),
list_users(Request).
modify_user(User, Property) :-
Property =.. [_Name|Value],
( ( var(Value)
; Value == ''
)
-> true
; set_user_property(User, Property)
).
modify_permissions(User, Read, Write, Admin) :-
phrase(allow(Read, Write, Admin), Allow),
set_user_property(User, allow(Allow)).
allow(Read, Write, Admin) -->
allow(read, Read),
allow(write, Write),
allow(admin, Admin).
allow(Access, on) -->
{ pterm(Access, Allow)
}, !,
[ Allow
].
allow(_Access, off) --> !,
[].
pterm(read, read(_Repositiory, _Action)).
pterm(write, write(_Repositiory, _Action)).
pterm(admin, admin(_Action)).
%% del_user(+Request)
%
% Delete a user
del_user(Request) :- !,
authorized(admin(del_user)),
http_parameters(Request,
[ user(User)
],
[ attribute_declarations(attribute_decl)
]),
( User == admin
-> throw(error(permission_error(delete, user, User), _))
; true
),
user_del(User),
list_users(Request).
%% change_password_form(+Request)
%
% Allow user to change the password
change_password_form(_Request) :-
logged_on(User), !,
user_property(User, realname(RealName)),
reply_html_page(cliopatria(default),
title('Change password'),
[ h1(['Change password for ', User, ' (', RealName, ')']),
\change_password_form(User)
]).
change_password_form(_Request) :-
throw(error(context_error(not_logged_in), _)).
%% change_password_form(+UserID)//
%
% HTML component that shows a form for changing the password for
% UserID.
change_password_form(User) -->
html(form([ action(location_by_id(change_password)),
method('POST')
],
[ table([ id('change-password-form'),
class(form)
],
[ \user_or_old(User),
\input(pwd1, 'New Password',
[type(password)]),
\input(pwd2, 'Retype',
[type(password)]),
tr(class(buttons),
td([ align(right),
colspan(2)
],
input([ type(submit),
value('Change password')
])))
])
])).
user_or_old(admin) --> !,
input(user, 'User', []).
user_or_old(_) -->
input(pwd0, 'Old password', [type(password)]).
%% change_password(+Request)
%
% HTTP handler to change the password. The user must be logged on.
change_password(Request) :-
logged_on(Login), !,
http_parameters(Request,
[ user(User, [ optional(true),
description('User identifier-name')
]),
pwd0(Password, [ optional(true),
description('Current password')
]),
pwd1(New),
pwd2(Retype)
],
[ attribute_declarations(attribute_decl)
]),
( Login == admin
-> ( current_user(User)
-> true
; throw(error(existence_error(user, User), _))
)
; Login = User,
validate_password(User, Password)
),
( New == Retype
-> true
; throw(password_mismatch)
),
password_hash(New, Hash),
set_user_property(User, password(Hash)),
reply_html_page(cliopatria(default),
'Password changed',
[ h1(align(center), 'Password changed'),
p([ 'Your password has been changed successfully' ])
]).
change_password(_Request) :-
throw(error(context_error(not_logged_in), _)).
/*******************************
* LOGIN *
*******************************/
%% login_form(+Request)
%
% HTTP handler that presents a form to login.
login_form(_Request) :-
reply_html_page(cliopatria(default),
'Login',
[ h1(align(center), 'Login'),
form([ action(location_by_id(user_login)),
method('POST')
],
table([ tr([ th(align(right), 'User:'),
td(input([ name(user),
size(40)
]))
]),
tr([ th(align(right), 'Password:'),
td(input([ type(password),
name(password),
size(40)
]))
]),
tr([ td([ align(right), colspan(2) ],
input([ type(submit),
value('Login')
]))
])
])
)
]).
%% user_login(+Request)
%
% Handle =user= and =password=. If there is a parameter
% =return_to= or =|openid.return_to|=, reply using a redirect to
% the given URL. Otherwise display a welcome page.
user_login(Request) :- !,
http_parameters(Request,
[ user(User),
password(Password),
'openid.return_to'(ReturnTo, [optional(true)]),
'return_to'(ReturnTo, [optional(true)])
],
[ attribute_declarations(attribute_decl)
]),
( var(ReturnTo)
-> Extra = []
; Extra = [ return_to(ReturnTo) ]
),
reply_login([ user(User),
password(Password)
| Extra
]).
reply_login(Options) :-
option(user(User), Options),
option(password(Password), Options),
validate_password(User, Password), !,
login(User),
( option(return_to(ReturnTo), Options)
-> throw(http_reply(moved_temporary(ReturnTo)))
; reply_html_page(cliopatria(default),
title('Login ok'),
h1(align(center), ['Welcome ', User]))
).
reply_login(_) :-
reply_html_page(cliopatria(default),
title('Login failed'),
[ h1('Login failed'),
p(['Password incorrect'])
]).
%% user_logout(+Request)
%
% Logout the current user
user_logout(_Request) :-
logged_on(User), !,
logout(User),
reply_html_page(cliopatria(default),
title('Logout'),
h1(align(center), ['Logged out ', User])).
user_logout(_Request) :-
reply_html_page(cliopatria(default),
title('Logout'),
[ h1(align(center), ['Not logged on']),
p(['Possibly you are logged out because the session ',
'has timed out.'])
]).
%% attribute_decl(+Param, -DeclObtions) is semidet.
%
% Provide reusable parameter declarations for calls to
% http_parameters/3.
attribute_decl(user,
[ description('User identifier-name'),
length > 1
]).
attribute_decl(realname,
[ description('Comment on user identifier-name')
]).
attribute_decl(description,
[ optional(true),
description('Descriptive text')
]).
attribute_decl(password,
[ description('Password')
]).
attribute_decl(pwd1,
[ length > 5,
description('Password')
]).
attribute_decl(pwd2,
[ length > 5,
description('Re-typed password')
]).
attribute_decl(openid_server,
[ description('URL of an OpenID server')
]).
attribute_decl(read,
[ description('Provide read-only access to the RDF store')
| Options]) :- bool(off, Options).
attribute_decl(write,
[ description('Provide write access to the RDF store')
| Options]) :- bool(off, Options).
attribute_decl(admin,
[ description('Provide administrative rights')
| Options]) :- bool(off, Options).
bool(Def,
[ default(Def),
oneof([on, off])
]).
/*******************************
* OPENID ADMIN *
*******************************/
%% add_openid_server_form(+Request)
%
% Return an HTML page to add a new OpenID server.
add_openid_server_form(_Request) :-
authorized(admin(add_openid_server)),
reply_html_page(cliopatria(default),
title('Add OpenID server'),
[ \new_openid_form
]).
%% new_openid_form// is det.
%
% Present form to add a new OpenID provider.
new_openid_form -->
html([ h1('Add new OpenID server'),
form([ action(location_by_id(add_openid_server)),
method('GET')
],
table([ id('add-openid-server'),
class(form)
],
[ \input(openid_server, 'Server homepage', []),
\input(openid_description, 'Server description',
[]),
\permissions(-),
tr(class(buttons),
td([ colspan(2),
align(right)
],
input([ type(submit),
value('Create')
])))
])),
p([ 'Use this form to define access rights for users of an ',
a(href('http://www.openid.net'), 'OpenID'), ' server. ',
'The special server ', code(*), ' specifies access for all OpenID servers. ',
'Here are some examples of servers:'
]),
ul([ li(code('http://myopenid.com'))
])
]).
%% add_openid_server(+Request)
%
% Allow access from an OpenID server
add_openid_server(Request) :-
authorized(admin(add_openid_server)),
http_parameters(Request,
[ openid_server(Server0,
[ description('URL of the server to allow')]),
openid_description(Description,
[ optional(true),
description('Description of the server')
]),
read(Read),
write(Write)
],
[ attribute_declarations(attribute_decl)
]),
phrase(allow(Read, Write, off), Allow),
canonical_url(Server0, Server),
Options = [ description(Description),
allow(Allow)
],
remove_optional(Options, Properties),
openid_add_server(Server, Properties),
list_users(Request).
remove_optional([], []).
remove_optional([H|T0], [H|T]) :-
arg(1, H, A),
nonvar(A), !,
remove_optional(T0, T).
remove_optional([_|T0], T) :-
remove_optional(T0, T).
canonical_url(Var, Var) :-
var(Var), !.
canonical_url(*, *) :- !.
canonical_url(URL0, URL) :-
parse_url(URL0, Parts),
parse_url(URL, Parts).
%% edit_openid_server_form(+Request)
%
% Form to edit user properties
edit_openid_server_form(Request) :-
authorized(admin(openid(edit))),
http_parameters(Request,
[ openid_server(Server)
],
[ attribute_declarations(attribute_decl)
]),
reply_html_page(cliopatria(default),
title('Edit OpenID server'),
\edit_openid_server_form(Server)).
edit_openid_server_form(Server) -->
html([ h1(['Edit OpenID server ', Server]),
form([ action(location_by_id(edit_openid_server)),
method('GET')
],
[ \hidden(openid_server, Server),
table([ class(form)
],
[ \openid_property(Server, description, 'Description', []),
\permissions(Server),
tr(class(buttons),
td([ colspan(2),
align(right)
],
input([ type(submit),
value('Modify')
])))
])
]),
p(\action(location_by_id(del_openid_server) +
'?openid_server=' + encode(Server),
[ 'Delete ', b(Server) ]))
]).
openid_property(Server, Name, Label, Options) -->
{ Term =.. [Name, Value],
openid_server_property(Server, Term)
-> O2 = [value(Value)|Options]
; O2 = Options
},
html(tr([ th(align(right), Label),
td(input([name(Name),size(40)|O2]))
])).
%% openid_server_table(+Options)//
%
% List registered openid servers
openid_server_table(Options) -->
{ setof(S, openid_current_server(S), Servers), !
},
html([ table([ class(block)
],
[ tr([ th('Server'),
th('Description')
])
| \openid_list_servers(Servers, Options)
])
]).
openid_server_table(_) -->
[].
openid_list_servers([], _) -->
[].
openid_list_servers([H|T], Options) -->
openid_list_server(H, Options),
openid_list_servers(T, Options).
openid_list_server(Server, Options) -->
html(tr([td(\openid_server(Server)),
td(\openid_field(Server, description)),
\edit_openid_button(Server, Options)
])).
edit_openid_button(Server, Options) -->
{ option(edit(true), Options) }, !,
html(td(a(href(location_by_id(edit_openid_server_form) +
'?openid_server='+encode(Server)
), 'Edit'))).
edit_openid_button(_, _) --> [].
openid_server(*) --> !,
html(*).
openid_server(Server) -->
html(a(href(Server), Server)).
openid_field(Server, Field) -->
{ Term =.. [Field, Value],
openid_server_property(Server, Term)
}, !,
html(Value).
openid_field(_, _) -->
[].
%% edit_openid_server(Request)
%
% Handle reply from OpenID server form.
edit_openid_server(Request) :-
authorized(admin(openid(edit))),
http_parameters(Request,
[ openid_server(Server),
description(Description),
read(Read),
write(Write),
admin(Admin)
],
[ attribute_declarations(attribute_decl)
]),
modify_openid(Server, description(Description)),
openid_modify_permissions(Server, Read, Write, Admin),
list_users(Request).
modify_openid(User, Property) :-
Property =.. [_Name|Value],
( ( var(Value)
; Value == ''
)
-> true
; openid_set_property(User, Property)
).
openid_modify_permissions(Server, Read, Write, Admin) :-
phrase(allow(Read, Write, Admin), Allow),
openid_set_property(Server, allow(Allow)).
%% del_openid_server(+Request)
%
% Delete an OpenID Server
del_openid_server(Request) :- !,
authorized(admin(openid(delete))),
http_parameters(Request,
[ openid_server(Server)
],
[ attribute_declarations(attribute_decl)
]),
openid_del_server(Server),
list_users(Request).
/*******************************
* SETTINGS *
*******************************/
%% settings(+Request)
%
% Show current settings. If user has administrative rights, allow
% editing the settings.
settings(_Request) :-
( catch(authorized(admin(edit_settings)), _, fail)
-> Edit = true
; authorized(read(admin, settings)),
Edit = false
),
reply_html_page(cliopatria(default),
title('Settings'),
[ h1('Application settings'),
\http_show_settings([ edit(Edit),
hide_module(false),
action('save_settings')
]),
\warn_no_edit(Edit)
]).
warn_no_edit(true) --> !.
warn_no_edit(_) -->
html(p(id(settings_no_edit),
[ a(href(location_by_id(login_form)), 'Login'),
' as ', code(admin), ' to edit the settings.' ])).
%% save_settings(+Request)
%
% Save modified settings.
save_settings(Request) :-
authorized(admin(edit_settings)),
reply_html_page(cliopatria(default),
title('Save settings'),
\http_apply_settings(Request, [save(true)])).
/*******************************
* EMIT *
*******************************/
%% hidden(+Name, +Value)
%
% Create a hidden input field with given name and value
hidden(Name, Value) -->
html(input([ type(hidden),
name(Name),
value(Value)
])).
action(URL, Label) -->
html([a([href(URL)], Label), br([])]).