Daniel@0: /* Part of DML (Digital Music Laboratory)
Daniel@0: 	Copyright 2014-2015 Samer Abdallah, University of London
Daniel@0: 	 
Daniel@0: 	This program is free software; you can redistribute it and/or
Daniel@0: 	modify it under the terms of the GNU General Public License
Daniel@0: 	as published by the Free Software Foundation; either version 2
Daniel@0: 	of the License, or (at your option) any later version.
Daniel@0: 
Daniel@0: 	This program is distributed in the hope that it will be useful,
Daniel@0: 	but WITHOUT ANY WARRANTY; without even the implied warranty of
Daniel@0: 	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
Daniel@0: 	GNU General Public License for more details.
Daniel@0: 
Daniel@0: 	You should have received a copy of the GNU General Public
Daniel@0: 	License along with this library; if not, write to the Free Software
Daniel@0: 	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
Daniel@0: */
Daniel@0: 
Daniel@0: :- module(webby, 
Daniel@0:    [ webcall/3
Daniel@0:    , restcall/4
Daniel@0:    , parts_path/2
Daniel@0:    , http_status/2
Daniel@0:    ]).
Daniel@0: /** <module> Web API tools
Daniel@0: 
Daniel@0: ---+++ Types
Daniel@0: ==
Daniel@0: web_reader ---> json(-D:dict)
Daniel@0:               ; nil.
Daniel@0: 
Daniel@0: web_method ---> get(+Params:list(param))
Daniel@0:               ; post(+D:post_data)
Daniel@0:               ; put(+D:post_data)
Daniel@0:               ; delete(+D:post_data)
Daniel@0:               .
Daniel@0: 
Daniel@0: post_data  ---> form(list(param))
Daniel@0:               ; json(dict)
Daniel@0:               .
Daniel@0: 
Daniel@0: param ---> atom=_.
Daniel@0: ==
Daniel@0: */
Daniel@0: 
Daniel@0: :- multifile read_reply/2.
Daniel@0: 
Daniel@0: :- use_module(library(http/http_open)).
Daniel@0: :- use_module(library(http/http_header)).
Daniel@0: :- use_module(library(http/json)).
Daniel@0: 
Daniel@0: parts_path(Parts,Path) :-
Daniel@0:    atomics_to_string([''|Parts],"/",Path).
Daniel@0: 
Daniel@0: %% webcall(+URL:url_spec, +Opt:options, +R:web_reader) is det.
Daniel@0: webcall(URL,Opts,Reader) :-
Daniel@0:    debug(webby,"HTTP connecting to ~w, ~w",[URL,Opts]),
Daniel@0:    setup_call_cleanup(
Daniel@0:       http_open(URL,In,[status_code(SC)|Opts]),
Daniel@0:       (  set_stream(In,encoding(utf8)), % ! 
Daniel@0:          (  between(200,299,SC) -> read_reply(Reader,In)
Daniel@0:          ;  read_stream_to_codes(In,ErrorDoc),
Daniel@0:             throw(http_bad_status(SC,codes(ErrorDoc))))),
Daniel@0:       close(In)).
Daniel@0: 
Daniel@0: read_reply(json(Dict),In) :- json_read_dict(In,Dict).
Daniel@0: read_reply(nil,_).
Daniel@0: 
Daniel@0: %% post_data(+D:post_data,-D2:post_data) is det.
Daniel@0: post_data(json(Dict),codes('application/json',Codes)) :- !, atom_json_dict(Codes,Dict,[as(codes)]).
Daniel@0: post_data(Data,Data).
Daniel@0: 
Daniel@0: %% restcall(+M:web_method, +R:web_reader, +URL:url_spec, +Opts:options) is det.
Daniel@0: restcall(get(Params), Rdr, URL, Opts) :- webcall([search(Params)|URL], Opts, Rdr).
Daniel@0: restcall(post(D),     Rdr, URL, Opts) :- post_data(D,Data), webcall(URL, [method(post),post(Data)|Opts], Rdr).
Daniel@0: restcall(delete(D),   Rdr, URL, Opts) :- post_data(D,Data), webcall(URL, [method(delete),post(Data)|Opts], Rdr).
Daniel@0: restcall(put(D),      Rdr, URL, Opts) :- post_data(D,Data), webcall(URL, [method(put),post(Data)|Opts], Rdr).
Daniel@0: 
Daniel@0: status_meaning(200,"OK").
Daniel@0: status_meaning(201,"Created").
Daniel@0: status_meaning(204,"No content").
Daniel@0: status_meaning(304,"Not modified").
Daniel@0: status_meaning(400,"Bad request").
Daniel@0: status_meaning(401,"Unauthorised").
Daniel@0: status_meaning(403,"Forbidden").
Daniel@0: status_meaning(404,"Not found").
Daniel@0: status_meaning(405,"Method not allowed").
Daniel@0: status_meaning(429,"Too many requests").
Daniel@0: status_meaning(500,"Internal server error").
Daniel@0: status_meaning(502,"Bad gateway").
Daniel@0: status_meaning(503,"Service unavailable").
Daniel@0: 
Daniel@0: http_status(Code,Meaning) :- status_meaning(Code,Meaning), !.
Daniel@0: http_status(_,"<Unrecognised status>").
Daniel@0: 
Daniel@0: prolog:message(http_bad_status(SC,codes(Doc))) --> 
Daniel@0:    {http_status(SC,Meaning)},
Daniel@0:    ["HTTP call returned status ~w (~w)."-[SC,Meaning]],
Daniel@0:    ["Reply document was |~s|"-[Doc]].