/*  Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        J.Wielemaker@vu.nl
    WWW:           http://www.swi-prolog.org
    Copyright (c)  2006-2012, University of Amsterdam
                              VU University Amsterdam
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:

    1. Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.

    2. Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in
       the documentation and/or other materials provided with the
       distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.
*/

:- module(test_wizard,
          [ make_tests/3,               % +Module, +File, +Out
            make_test/3                 % +Callable, -Module, -Test
          ]).
:- use_module(library(time)).
:- use_module(library(lists)).
:- use_module(library(listing)).
:- use_module(library(readutil)).

/** <module> Test Generation Wizard

Tasks

        * Accumulate user queries
        * Suggest tests from user queries
*/

setting(max_time(5)).


                 /*******************************
                 *       UNIT GENERATION        *
                 *******************************/

%!  make_tests(+Module, +File, +Out) is det.
%
%   Create tests from queries stored in File and write the tests for
%   Module to the stream Out.

make_tests(Module, File, Out) :-
    read_file_to_terms(File, Queries, []),
    findall(Test, (   member(Q, Queries),
                      make_test(Q, Module, Test)), Tests),
    (   Tests == []
    ->  true
    ;   format(Out, ':- begin_tests(~q).~n~n', [Module]),
        maplist(portray_clause(Out), Tests),
        format(Out, '~n:- end_tests(~q).~n', [Module])
    ).


                 /*******************************
                 *       TEST GENERATION        *
                 *******************************/

%!  make_test(+Query:callable, -Module, -Test:term) is det.
%
%   Generate a test from a query. Test   is  returned as a clause of
%   test/1  or  test/2  to  be   inserted  between  begin_tests  and
%   end_tests.

make_test(Query0, Module, (test(Name, Options) :- Query)) :-
    find_test_module(Query0, Module, Query),
    pred_name(Query, Name),
    setting(max_time(Max)),
    test_result(Module:Query, Max, Options).

%!  find_test_module(+QuerySpec, ?Module, -Query).
%
%   Find module to test from a query. Note that it is very common
%   for toplevel usage to rely on SWI-Prolog's DWIM.
%
%   @tbd    What if multiple modules match?  We can select the
%           local one or ask the user.

find_test_module(Var, _, _) :-
    var(Var), !, fail.
find_test_module(M:Query, M0, Query) :-
    !,
    M0 = M.
find_test_module(Query, M, Query) :-
    current_predicate(_, M:Query),
    \+ predicate_property(M:Query, imported_from(_M2)).

%!  pred_name(+Callable, -Name) is det.
%
%   Suggest a name for the test. In   the  plunit framework the name
%   needs not be unique, so we simply take the predicate name.

pred_name(Callable, Name) :-
    strip_module(Callable, _, Term),
    functor(Term, Name, _Arity).

%!  test_result(+Callable, +Maxtime, -Result) is det.
%
%   Try running goal and get meaningful results.  Results are:
%
%           * true(Templ == Var)
%           * fail
%           * all(Templ == Bindings)
%           * throws(Error)
%           * timeout

test_result(Callable, Maxtime, Result) :-
    term_variables(Callable, Vars),
    make_template(Vars, Templ),
    catch(call_with_time_limit(Maxtime,
                               findall(Templ-Det,
                                       call_test(Callable, Det),
                                       Bindings)),
          E, true),
    (   var(E)
    ->  success(Bindings, Templ, Result)
    ;   error(E, Result)
    ).

%!  success(+Bindings, +Templ, -Result) is det.
%
%   Create test-results from non-error cases.

success([], _, [fail]) :- !.
success([[]-true],  _, []) :- !.
success([S1-true],  Templ, [ true(Templ == S1) ]) :- !.
success([[]-false], _, [ nondet ]) :- !.
success([S1-false], Templ, [ true(Templ == S1), nondet ]) :- !.
success(ListDet, Templ, [all(Templ == List)]) :-
    strip_det(ListDet, List).

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

%!  error(+ErrorTerm, -Result)

error(Error0, [throws(Error)]) :-
    generalise_error(Error0, Error).


generalise_error(error(Formal, _), error(Formal, _)) :- !.
generalise_error(Term, Term).


%!  make_template(+Vars, -Template) is det.
%
%   Make a nice looking template

make_template([], []) :- !.
make_template([One], One) :- !.
make_template([One, Two], One-Two) :- !.
make_template(List, Vars) :-
    Vars =.. [v|List].

%!  call_test(:Goal, -Det) is nondet.
%
%   True if Goal succeeded.  Det is unified to =true= if Goal left
%   no choicepoints and =false= otherwise.

call_test(Goal, Det) :-
    Goal,
    deterministic(Det).


                 /*******************************
                 *           COLLECT            *
                 *******************************/

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Collect toplevel queries if the Prolog flag log_query_file points to the
name of a writeable  file.  The  file   is  opened  in  append-mode  for
exclusive write to allow for concurrent   operation from multiple Prolog
systems using the same logfile.

The file is written in  UTF-8   encoding  and  using ignore_ops(true) to
ensure it can be read.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

:- multifile
    user:message_hook/3.

user:message_hook(toplevel_goal(Goal0, Bindings), _Level, _Lines) :-
    open_query_log(Out),
    bind_vars(Bindings),
    clean_goal(Goal0, Goal),
    call_cleanup(format(Out, '~W.~n', [Goal, [ numbervars(true),
                                               quoted(true),
                                               ignore_ops(true)
                                             ]]), close(Out)),
    fail.

clean_goal(Var, _) :-
    var(Var), !, fail.
clean_goal(user:Goal, Goal) :- !.
clean_goal(Goal, Goal).

bind_vars([]).
bind_vars([Name=Var|T]) :-
    Var = '$VAR'(Name),
    bind_vars(T).

open_query_log(Out) :-
    current_prolog_flag(log_query_file, File),
    exists_file(File),
    !,
    open(File, append, Out,
         [ encoding(utf8),
           lock(write)
         ]).
open_query_log(Out) :-
    current_prolog_flag(log_query_file, File),
    access_file(File, write),
    !,
    open(File, write, Out,
         [ encoding(utf8),
           lock(write),
           bom(true)
         ]),
    format(Out,
           '/* SWI-Prolog query log.  This file contains all syntactically\n   \c
                   correct queries issued in this directory.  It is used by the\n   \c
                   test wizard to generate unit tests.\n\c
                */~n~n', []).



