/*  Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        J.Wielemaker@vu.nl
    WWW:           http://www.swi-prolog.org
    Copyright (c)  2001-2014, 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(qp_foreign,
          [ load_foreign_files/0,               %
            load_foreign_files/2,               % +Files, +Libs
            load_foreign_files/3,               % +Object, +Files, +Libs
            make_shared_object/3,               % +Object, +Files, +Libs
            make_foreign_wrapper_file/1,        % +OutBase
            make_foreign_wrapper_file/2,        % +OFiles, +OutBase
                                                % SICStus stuff
            make_foreign_resource_wrapper/3,    % +Resource, +ResBase, +FileBase
            load_foreign_resource/2             % +Resource, +Dir
          ]).

:- use_module(library(shlib)).
:- use_module(library(gensym)).
:- use_module(library(lists)).
:- use_module(library(apply)).
:- use_module(library(error)).

/** <module> Quintus compatible foreign loader

This module defines a  Quintus   compatible  foreign  language interface
based on the foreign_file/2 and foreign/3 declarations.

Predicates:

        * load_foreign_files
        Load all foreign files defined with foreign_file/2 statement
        in the current module.

        * load_foreign_files(+Files, +Libs)
        Load specified foreign files, linking them with the given
        libraries

        * load_foreign_files(+SharedObject, +Files, +Libs)
        As load_foreign_files/2, but first tries to load `SharedObject'.
        If the SharedObject exists it is loaded using load_foreign_library/1.
        Otherwise it is first created with make_shared_object/3.

        * make_shared_object(+SharedObject, +Files, +Libs)
        Generate a wrapper and link it using plld to the given SharedObject.

        * make_foreign_wrapper_file(+Files, +OutBase)
        Generate wrapper for the named object files in OutBase.c.

        * make_foreign_wrapper_file(+Files)
        Generate wrapper for all declared object files in OutBase.c.

Example:

        ==
        foreign_file('-lm', [sin/2]).
        foreign(sin, c, sin(+float, [-float])).
        :- load_foreign_files,
           abolish(foreign_file, 2),
           abolish(foreign, 3).
        ==

Supported types:

        | *Spec*        | *Prolog*      | *C*                           |
        | integer       | integer       | long                          |
        | float         | float,integer | double                        |
        | single        | float,integer | single                        |
        | string        | atom,string   | char *                        |
        | atom          | atom          | atom identifier (type atomic) |

*NOTE*  This modules requires a correctly functioning swipl-ld and
        load_foreign_library/1 on your system.  If this isn't the
        case use make_foreign_wrapper_file/[1,2] to generate a
        wrapper and use static embedding.

@bug    Only supports C-interface
@bug    Insufficient checking for misusage.
@bug    Documentation is too short and very outdated
*/

:- module_transparent
    load_foreign_files/0.

:- meta_predicate
    load_foreign_files(:, +),
    load_foreign_files(+, :, +),
    make_shared_object(+, :, +),
    make_foreign_wrapper_file(:),
    make_foreign_wrapper_file(:, +),
                                    % SICStus
    make_foreign_resource_wrapper(:, +, +),
    load_foreign_resource(:, +).

setting(linker, 'swipl-ld').

hook(M:Goal) :-
    M:Goal.

%!  make_wrappers(+PrologHeads, +Module, +OutStream)

make_wrappers([], _, _).
make_wrappers([H|T], M, Out) :-
    make_wrapper(Out, M:H),
    make_wrappers(T, M, Out).

%!  make_wrapper(+Stream, :PrologHead)
%
%   Generates a C-wrapper function for the given foreign defined
%   Prolog predicate.  The wrapper is called _plw_<predname><arity>.

make_wrapper(Out, Spec) :-
    get_foreign_head(Spec, Func, Head),
    !,
    (   check_head(Head)
    ->  wrapper_name(Head, WrapName, ArgN),
        make_C_header(Out, WrapName, ArgN),
        make_C_decls(Out, Head),
        make_C_prototype(Out, Head),
        make_C_input_conversions(Out, Head),
        make_C_wrapper_setup(Out),
        make_C_call(Out, Head, Func),
        make_C_wrapper_check(Out),
        make_C_output_conversions(Out, Head),
        make_C_footer(Out)
    ;   fail
    ).
make_wrapper(_, Spec) :-
    existence_error(foreign_declaration, Spec).

%!  get_foreign_head(:Spec, -Func, -Head)
%
%   Get 3rd argument of relevant foreign/3   clause. Seems there are
%   two versions. In Quintus Spec was  a predicate specification and
%   in SICStus it seems to be a (C) function name.

get_foreign_head(M:Function, Function, M:Head) :-
    prolog_load_context(dialect, sicstus),
    !,
    hook(M:foreign(Function, c, Head)).
get_foreign_head(M:Spec, Func, M:Head) :-
    (   atom(Spec),
        hook(M:foreign(Spec, c, Head)),
        functor(Head, Spec, _)
    ->  true
    ;   Spec = Name/Arity
    ->  functor(Head, Name, Arity),
        hook(M:foreign(Func, c, Head))
    ;   Head = Spec,
        hook(M:foreign(Func, c, Head))
    ).


check_head(_:Head) :-
    functor(Head, _, Arity),
    (   Arity == 0
    ->  true
    ;   arg(_, Head, [-T]),
        \+ valid_type(T)
    ->  warning('Bad return type ~w in ~w', [T, Head]),
        fail
    ;   arg(N, Head, [-_T]),
        N \== Arity
    ->  warning('Return type must be last in ~w', Head),
        fail
    ;   (arg(_, Head, -T) ; arg(_, Head, +T)),
        \+ valid_type(T)
    ->  warning('Bad type ~w in ~w', [T, Head]),
        fail
    ;   true
    ).

valid_type(int).
valid_type(integer).
valid_type(size_t).
valid_type(float).
valid_type(single).
valid_type(string).
valid_type(chars).                      % actually, `codes'!
valid_type(atom).
valid_type(term).
valid_type(address).
valid_type(address(_)).

%!  cvt_name(+Type, +IO, -Suffix) is det.

cvt_name(chars,      _, codes) :- !.
cvt_name(address(_), _, address) :- !.
cvt_name(int,        o, int64) :- !.
cvt_name(integer,    o, int64) :- !.
cvt_name(size_t,     o, int64) :- !.
cvt_name(integer,    i, long) :- !.
cvt_name(Type,       _, Type).


%!  make_C_header(+Stream, +WrapperName, +Arity)
%
%   Write function-header for the wrapper.  This is easy as the
%   the return-type is always foreign_t and the arguments are
%   always of type `term_t'.  The arguments are simply named `a',
%   `b', ...

make_C_header(Out, WrapName, ArgN) :-
    format(Out, '~n~nstatic foreign_t~n~w(', [WrapName]),
    forall(between(1, ArgN, A),
           (   (A \== 1 -> format(Out, ', ', []) ; true)
           ,   arg_name(A, AName),
               format(Out, 'term_t ~w', [AName])
           )),
    format(Out, ')~n{ ', []).

%!  make_C_decls(+Stream, :PrologHead)
%
%   Writes the C variable declarations. If  the return value is used
%   a variable named `rval' is created. For each input parameter a C
%   variable named i<argname> is created;   for each output variable
%   o<argname>.

make_C_decls(Out, _:Head) :-
    compound(Head),
    arg(_, Head, [-PlType]),
    map_C_type(PlType, CType),
    format(Out, '~wrval;~n  ', [CType]),
    fail.
make_C_decls(Out, _:Head) :-
    compound(Head),
    arg(N, Head, -PlType),
    arg_name(N, AName),
    (   PlType == term
    ->  format(Out, 'term_t o_~w = PL_new_term_ref();~n  ', [AName])
    ;   map_C_type(PlType, CType),
        format(Out, '~wo_~w;~n  ', [CType, AName])
    ),
    fail.
make_C_decls(Out, _:Head) :-
    compound(Head),
    arg(N, Head, +PlType),
    PlType \== term,
    map_C_type(PlType, CType),
    CType \== term,
    arg_name(N, AName),
    format(Out, '~wi_~w;~n  ', [CType, AName]),
    fail.
make_C_decls(Out, _) :-
    format(Out, '~n', []).

%!  make_C_prototype(+Stream, :PrologHead)
%
%   If the function handles floats or doubles, make a prototype
%   declaration for it to avoid unwanted conversions.

make_C_prototype(Out, M:Head) :-
    (   compound(Head),
        arg(_, Head, [-Type])
    ->  map_C_type(Type, CType)
    ;   CType = 'void '
    ),
    copy_term(Head, H2),            % don't bind Head
    hook(M:foreign(CFunc, c, H2)),
    !,
    format(Out, '  extern ~w~w(', [CType, CFunc]),
    (   compound(Head),
        arg(N, Head, AType),
        AType \= [_],               % return-type
        (N > 1 -> format(Out, ', ', []) ; true),
        (   AType = +T2
        ->  map_C_type(T2, CT2),
            format(Out, '~w', [CT2])
        ;   AType == -term
        ->  format(Out, term_t, [])
        ;   AType = -T2
        ->  map_C_type(T2, CT2),
            format(Out, '~w *', [CT2])
        ),
        fail
    ;   format(Out, ');~n~n', [])
    ).
make_C_prototype(_, _).


%!  make_C_input_conversions(+Stream, :PrologHead)
%
%   Generate the input checking and conversion code.  Assumes
%   boolean functions that take a Prolog term_t as first argument
%   and a pointer to the requested C-type as a second argument.
%   Function returns 0 if the conversion fails.

make_C_input_conversions(Out, _:Head) :-
    findall(N-T, (compound(Head),arg(N, Head, +T)), IArgs0),
    exclude(term_arg, IArgs0, IArgs),
    (   IArgs == []
    ->  true
    ;   format(Out, '  if ( ', []),
        (   member(N-T, IArgs),
            T \== term,
            (IArgs \= [N-T|_] -> format(Out, ' ||~n       ', []) ; true),
            arg_name(N, AName),
            atom_concat(i_, AName, IName),
            cvt_name(T, i, CVT),
            format(Out, '!PL_cvt_i_~w(~w, &~w)', [CVT, AName, IName]),
            fail
        ;   true
        ),
        format(Out, ' )~n    return FALSE;~n~n', [])
    ).

term_arg(_-term).


%!  make_C_call(+Stream, :PrologHead, +CFunction)
%
%   Generate  the  actual  call  to   the  foreign  function.  Input
%   variables may be handed directly; output  variables as a pointer
%   to the o<var>, except for output-variables of type term.

make_C_call(Out, _:Head, CFunc) :-
    (   compound(Head),
        arg(_, Head, [-_])
    ->  format(Out, '  rval = ~w(', [CFunc])
    ;   format(Out, '  (void) ~w(', [CFunc])
    ),
    compound(Head),
    arg(N, Head, Arg),
    Arg \= [_],
    (N \== 1 -> format(Out, ', ', []) ; true),
    arg_name(N, AName),
    (   Arg = -term
    ->  format(Out, 'o_~w', [AName])
    ;   Arg = -_
    ->  format(Out, '&o_~w', [AName])
    ;   Arg = +term
    ->  format(Out, '~w', [AName])
    ;   format(Out, 'i_~w', [AName])
    ),
    fail.
make_C_call(Out, _, _) :-
    format(Out, ');~n', []).

%!  make_C_wrapper_setup(+Stream)
%
%   Call SP_WRAP_INIT() when  running  on   SICStus.  This  supports
%   SP_fail() and SP_raise_exception().

make_C_wrapper_setup(Stream) :-
    prolog_load_context(dialect, sicstus),
    !,
    format(Stream, '  SP_WRAP_INIT();~n', []).
make_C_wrapper_setup(_).


%!  make_C_wrapper_check(+Stream)
%
%   Call  SP_WRAP_CHECK_STATE()  when  running    on  SICStus.  This
%   supports SP_fail() and SP_raise_exception().

make_C_wrapper_check(Stream) :-
    prolog_load_context(dialect, sicstus),
    !,
    format(Stream, '  SP_WRAP_CHECK_STATE();~n', []).
make_C_wrapper_check(_).


%!  make_C_output_conversions(+Stream, :PrologHead)
%
%   Generate conversions for the output arguments and unify them
%   with the Prolog term_t arguments.

make_C_output_conversions(Out, _:Head) :-
    findall(N-T, (compound(Head),arg(N, Head, -T)), OArgs0),
    (   compound(Head),
        arg(_, Head, [-RT])
    ->  OArgs = [rval-RT|OArgs0]
    ;   OArgs = OArgs0
    ),
    (   OArgs == []
    ->  true
    ;   format(Out, '~n  if ( ', []),
        (   member(N-T, OArgs),
            (   N == rval
            ->  OName = rval,
                arg(RN, Head, [-_]),
                arg_name(RN, AName)
            ;   arg_name(N, AName),
                atom_concat(o_, AName, OName)
            ),
            (OArgs = [N-T|_] -> true ; format(Out, ' ||~n       ', [])),
            (   T == term
            ->  format(Out, '!PL_unify(~w, ~w)', [OName, AName])
            ;   cvt_name(T, o, CVT),
                format(Out, '!PL_cvt_o_~w(~w, ~w)', [CVT, OName, AName])
            ),
            fail
        ;   true
        ),
        format(Out, ' )~n    return FALSE;~n', [])
    ).


make_C_footer(Out) :-
    format(Out, '~n  return TRUE;~n}~n', []).

                 /*******************************
                 *        INIT STATEMENT        *
                 *******************************/

%!  make_C_init(+Stream, +InstallFunc, +InitFunc, +Module, +PredList)
%
%   Generate an array of PL_extension structures,   that may be used
%   to create a statically  linked  image   as  well  as through the
%   PL_load_extensions() call.
%
%   Of the supported PL_FA_<FLAGS>, TRANSPARENT   may be declared by
%   looking at the transparent  (meta_predivate)   attribute  of the
%   predicate.

make_C_init(Out, InstallFunc, Init, M, Preds) :-
    format(Out, '~n~nstatic PL_extension predicates [] =~n{~n', []),
    format(Out, '/*{ "name", arity, function, PL_FA_<flags> },*/~n', []),
    (   member(Pred, Preds),
        get_foreign_head(M:Pred, _Func, Head),
        Head = M:H,
        functor(H, Name, Arity),
        wrapper_name(Head, Wrapper, Arity),
        foreign_attributes(M:H, Atts),
        format(Out, '  { "~w", ~d, ~w, ~w },~n',
               [Name, Arity, Wrapper, Atts]),
        fail
    ;   true
    ),
    format(Out, '  { NULL, 0, NULL, 0 } /* terminator */~n};~n~n', []),
    format(Out, 'install_t~n~w()~n{ PL_load_extensions(predicates);~n',
           [InstallFunc]),
    sicstus_init_function(Out, Init),
    format(Out, '}~n', []).

sicstus_init_function(_, -) :- !.
sicstus_init_function(Out, Init) :-
    format(Out, '  extern void ~w(int);~n', [Init]),
    format(Out, '  ~w(0);~n', [Init]).

foreign_attributes(Head, Atts) :-
    findall(A, foreign_attribute(Head, A), A0),
    (   A0 == []
    ->  Atts = 0
    ;   atomic_list_concat(A0, '|', Atts)
    ).

foreign_attribute(Head, 'PL_FA_TRANSPARENT') :-
    predicate_property(Head, transparent).

%!  make_C_deinit(+Stream, +UninstallFunc, +DeInitFunc) is det.
%
%   Write the uninstall function

make_C_deinit(_, _, -) :- !.
make_C_deinit(Out, Func, DeInit) :-
    format(Out, '~ninstall_t~n', []),
    format(Out, '~w()~n', [Func]),
    format(Out, '{ extern void ~w(int);~n', [DeInit]),
    format(Out, '  ~w(0);~n', [DeInit]),
    format(Out, '}~n', []).


%!  make_C_file_header(+Stream)
%
%   Output the generic header declarations needed and some comments

make_C_file_header(Out) :-
    current_prolog_flag(version_data, swi(Major, Minor, Patch, _)),
    get_time(Time),
    format_time(string(When), '%F %H:%M', Time),
    format(Out, '/*  SWI-Prolog link wrapper~n', []),
    format(Out, '    Generated by SWI-Prolog version ~w.~w.~w~n',
           [Major, Minor, Patch]),
    format(Out, '    At ~s~n', [When]),
    (   source_location(File, Line)
    ->  format(Out, '    Source context ~w:~d~n', [File, Line])
    ;   true
    ),
    format(Out, '*/~n~n', []),
    format(Out, '#include <SWI-Prolog.h>~n', []),
    make_C_compat_file_header(Out),
    format(Out, '#ifndef NULL~n', []),
    format(Out, '#define NULL ((void *)0)~n', []),
    format(Out, '#endif~n~n', []).


make_C_compat_file_header(Out) :-
    prolog_load_context(dialect, sicstus),
    !,
    format(Out, '#define SP_WRAPPER 1~n', []),
    format(Out, '#include <sicstus/sicstus.h>~n', []).
make_C_compat_file_header(_).


                 /*******************************
                 *           TOPLEVEL           *
                 *******************************/

%!  load_foreign_files is det.
%!  load_foreign_files(:Files, +Libs) is det.
%!  load_foreign_files(+SharedObject, :Files, +Libs) is det.
%
%   Calls make_foreign_wrapper_file(+File), compiles the wrapper
%   and loads the predicates.

load_foreign_files :-
    context_module(M),
    findall(File, hook(M:foreign_file(File, _)), OFiles),
    load_foreign_files(M:OFiles, []).
load_foreign_files(OFiles, Libs) :-
    gensym(link, LinkBase),
    load_foreign_files(LinkBase, OFiles, Libs).

load_foreign_files(LinkBase, M:_, _) :-
    catch(load_foreign_library(M:LinkBase), _, fail),
    !.
load_foreign_files(LinkBase, OFiles, Libs) :-
    make_shared_object(LinkBase, OFiles, Libs),
    OFiles = M:_List,
    load_foreign_library(M:LinkBase).

%!  make_shared_object(+Object, :Files, +Libs) is det.
%
%   Generate  a  wrapper  and  link  it  using  plld  to  the  given
%   SharedObject.

make_shared_object(LinkBase, M:OFiles, Libs) :-
    make_foreign_wrapper_file(M:OFiles, LinkBase),
    file_name_extension(LinkBase, c, CFile),
    build_shared_object(LinkBase, [CFile|OFiles], Libs).

%!  make_foreign_wrapper_file(:OutFile) is det.
%!  make_foreign_wrapper_file(:Files, +OutFile) is det.
%
%   Just output the wrapper file to the named .c file.  May be used
%   to prepare for static linking or the preparation of the native
%   SWI-Prolog foreign-file.

make_foreign_wrapper_file(M:CFile) :-
    findall(File, hook(M:foreign_file(File, _)), OFiles),
    make_foreign_wrapper_file(M:OFiles, CFile).
make_foreign_wrapper_file(M:OFiles, Base) :-
    file_name_extension(Base, c, CFile),
    file_base_name(Base, FuncBase),
    atom_concat(install_, FuncBase, InstallFunc),
    collect_foreign_predicates(OFiles, M, Preds),
    open(CFile, write, Out),
    make_C_file_header(Out),
    make_wrappers(Preds, M, Out),
    make_C_init(Out, InstallFunc, -, M, Preds),
    close(Out).


collect_foreign_predicates([], _, []).
collect_foreign_predicates([File|Files], M, Preds) :-
    hook(M:foreign_file(File, P0)),
    collect_foreign_predicates(Files, M, P1),
    append(P0, P1, Preds).

build_shared_object(Object, Files, Libs) :-
    current_prolog_flag(shared_object_extension, Ext),
    file_name_extension(Object, Ext, SharedObject),
    append(Files, Libs, Input),
    atomic_list_concat(Input, ' ', InputAtom),
    setting(linker, Linker),
    format(string(Command),
           '~w -shared -o ~w ~w', [Linker, SharedObject, InputAtom]),
    shell(Command).


                 /*******************************
                 *            SICSTUS           *
                 *******************************/

%!  make_foreign_resource_wrapper(:Resource, +ResBase, +FileBase)
%
%   Create a wrapper-file for the given foreign resource

make_foreign_resource_wrapper(M:Resource, ResBase, FileBase) :-
    hook(M:foreign_resource(Resource, Functions)),
    take(init(Init), Functions, Functions1, -),
    take(deinit(DeInit), Functions1, Preds, -),
    file_name_extension(FileBase, c, CFile),
    file_base_name(ResBase, FuncBase),
    atom_concat(install_, FuncBase, InstallFunc),
    atom_concat(uninstall_, FuncBase, UninstallFunc),
    open(CFile, write, Out),
    make_C_file_header(Out),
    make_wrappers(Preds, M, Out),
    make_C_init(Out, InstallFunc, Init, M, Preds),
    make_C_deinit(Out, UninstallFunc, DeInit),
    close(Out).

take(Term, List, Rest, Default) :-
    (   select(Term, List, Rest)
    ->  true
    ;   arg(1, Term, Default),
        Rest = List
    ).


%!  load_foreign_resource(:Resource, +Dir)
%
%   Load a foreign module. First try to  load from the same direcory
%   as the Prolog file. Otherwise   load  using SWI-Prolog's default
%   search path.

load_foreign_resource(M:Resource, Source) :-
    absolute_file_name(Resource, Object,
                       [ file_type(executable),
                         relative_to(Source),
                         file_errors(fail)
                       ]),
    !,
    load_foreign_library(M:Object).
load_foreign_resource(M:Resource, _) :-
    load_foreign_library(M:foreign(Resource)).


                 /*******************************
                 *             UTIL             *
                 *******************************/

arg_name(N, Name) :-
    C is N + 0'a - 1,
    atom_codes(Name, [C]).

wrapper_name(_:Head, Wrapper, Arity) :-
    functor(Head, Name, Arity),
    atomic_list_concat(['_plw_', Name, Arity], Wrapper).

%!  map_C_type(+Prolog, -C)
%
%   Map Prolog interface type declarations into C types.

map_C_type(X, Y) :-
    map_C_type_(X, Y),
    !.
map_C_type(X, X).

map_C_type_(int, 'int ').
map_C_type_(integer, 'long ').
map_C_type_(size_t, 'size_t ').
map_C_type_(float,   'double ').
map_C_type_(string,  'char *').
map_C_type_(chars,   'char *').
map_C_type_(address, 'void *').
map_C_type_(address(Of), Type) :-
    atom_concat(Of, ' *', Type).
map_C_type_(term,    'term_t ').

warning(Fmt, Args) :-
    print_message(warning, format(Fmt, Args)).


                 /*******************************
                 *            XREF              *
                 *******************************/

:- multifile
    prolog:hook/1.

prolog:hook(foreign(_,_,_)).
prolog:hook(foreign_resource(_,_)).
