/*  Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        J.Wielemaker@vu.nl
    WWW:           http://www.swi-prolog.org
    Copyright (c)  2002-2015, 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;
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*/

:- module(files_ex,
          [ set_time_file/3,            % +File, -OldTimes, +NewTimes
            link_file/3,                % +OldPath, +NewPath, +Type
            relative_file_name/3,       % ?AbsPath, +RelTo, ?RelPath
            directory_file_path/3,      % +Dir, +File, -Path
            copy_file/2,                % +From, +To
            make_directory_path/1,      % +Directory
            copy_directory/2,           % +Source, +Destination
            delete_directory_and_contents/1, % +Dir
            delete_directory_contents/1 % +Dir
          ]).

/** <module> Extended operations on files

This module provides additional operations on   files.  This covers both
more  obscure  and  possible  non-portable    low-level  operations  and
high-level utilities.

Using these Prolog primitives is typically   to  be preferred over using
operating system primitives through shell/1  or process_create/3 because
(1) there are no potential file  name   quoting  issues, (2) there is no
dependency  on  operating   system   commands    and   (3)   using   the
implementations from this library is usually faster.
*/


:- use_foreign_library(foreign(files), install_files).

%!  set_time_file(+File, -OldTimes, +NewTimes) is det.
%
%   Query and set POSIX time attributes of a file. Both OldTimes and
%   NewTimes are lists of  option-terms.   Times  are represented in
%   SWI-Prolog's standard floating point numbers.   New times may be
%   specified as =now= to indicate the current time. Defined options
%   are:
%
%       * access(Time)
%       Describes the time of last access   of  the file. This value
%       can be read and written.
%
%       * modified(Time)
%       Describes the time  the  contents  of   the  file  was  last
%       modified. This value can be read and written.
%
%       * changed(Time)
%       Describes the time the file-structure  itself was changed by
%       adding (link()) or removing (unlink()) names.
%
%   Below  are  some  example  queries.   The  first  retrieves  the
%   access-time, while the second sets the last-modified time to the
%   current time.
%
%       ==
%       ?- set_time_file(foo, [access(Access)], []).
%       ?- set_time_file(foo, [], [modified(now)]).
%       ==

%!  link_file(+OldPath, +NewPath, +Type) is det.
%
%   Create a link in the filesystem   from  NewPath to OldPath. Type
%   defines the type of link and is one of =hard= or =symbolic=.
%
%   With some limitations, these  functions   also  work on Windows.
%   First of all, the unerlying filesystem  must support links. This
%   requires NTFS. Second, symbolic  links   are  only  supported in
%   Vista and later.
%
%   @error  domain_error(link_type, Type) if the requested link-type
%           is unknown or not supported on the target OS.

%!  relative_file_name(+Path:atom, +RelTo:atom, -RelPath:atom) is det.
%!  relative_file_name(-Path:atom, +RelTo:atom, +RelPath:atom) is det.
%
%   True when RelPath is Path, relative to RelTo. Path and RelTo are
%   first handed to absolute_file_name/2, which   makes the absolute
%   *and* canonical. Below are two examples:
%
%   ==
%   ?- relative_file_name('/home/janw/nice',
%                         '/home/janw/deep/dir/file', Path).
%   Path = '../../nice'.
%
%   ?- relative_file_name(Path, '/home/janw/deep/dir/file', '../../nice').
%   Path = '/home/janw/nice'.
%   ==
%
%   @param  All paths must be in canonical POSIX notation, i.e.,
%           using / to separate segments in the path.  See
%           prolog_to_os_filename/2.
%   @bug    This predicate is defined as a _syntactical_ operation.

relative_file_name(Path, RelTo, RelPath) :- % +,+,-
    nonvar(Path),
    !,
    absolute_file_name(Path, AbsPath),
    absolute_file_name(RelTo, AbsRelTo),
    atomic_list_concat(PL, /, AbsPath),
    atomic_list_concat(RL, /, AbsRelTo),
    delete_common_prefix(PL, RL, PL1, PL2),
    to_dot_dot(PL2, DotDot, PL1),
    atomic_list_concat(DotDot, /, RelPath).
relative_file_name(Path, RelTo, RelPath) :-
    (   is_absolute_file_name(RelPath)
    ->  Path = RelPath
    ;   file_directory_name(RelTo, RelToDir),
        directory_file_path(RelToDir, RelPath, Path0),
        absolute_file_name(Path0, Path)
    ).

delete_common_prefix([H|T01], [H|T02], T1, T2) :-
    !,
    delete_common_prefix(T01, T02, T1, T2).
delete_common_prefix(T1, T2, T1, T2).

to_dot_dot([], Tail, Tail).
to_dot_dot([_], Tail, Tail) :- !.
to_dot_dot([_|T0], ['..'|T], Tail) :-
    to_dot_dot(T0, T, Tail).


%!  directory_file_path(+Directory, +File, -Path) is det.
%!  directory_file_path(?Directory, ?File, +Path) is det.
%
%   True when Path is the full path-name   for  File in Dir. This is
%   comparable to atom_concat(Directory, File, Path), but it ensures
%   there is exactly one / between the two parts.  Notes:
%
%     * In mode (+,+,-), if File is given and absolute, Path
%     is unified to File.
%     * Mode (-,-,+) uses file_directory_name/2 and file_base_name/2

directory_file_path(Dir, File, Path) :-
    nonvar(Dir), nonvar(File),
    !,
    (   (   is_absolute_file_name(File)
        ;   Dir == '.'
        )
    ->  Path = File
    ;   sub_atom(Dir, _, _, 0, /)
    ->  atom_concat(Dir, File, Path)
    ;   atomic_list_concat([Dir, /, File], Path)
    ).
directory_file_path(Dir, File, Path) :-
    nonvar(Path),
    !,
    (   nonvar(Dir)
    ->  (   Dir == '.',
            \+ is_absolute_file_name(Path)
        ->  File = Path
        ;   sub_atom(Dir, _, _, 0, /)
        ->  atom_concat(Dir, File, Path)
        ;   atom_concat(Dir, /, TheDir)
        ->  atom_concat(TheDir, File, Path)
        )
    ;   nonvar(File)
    ->  atom_concat(Dir, File, Path)
    ;   file_directory_name(Path, Dir),
        file_base_name(Path, File)
    ).
directory_file_path(_, _, _) :-
    throw(error(instantiation_error(_), _)).

%!  copy_file(From, To) is det.
%
%   Copy a file into a new file or  directory. The data is copied as
%   binary data.

copy_file(From, To) :-
    destination_file(To, From, Dest),
    setup_call_cleanup(open(Dest, write, Out, [type(binary)]),
                       copy_from(From, Out),
                       close(Out)).

copy_from(File, Stream) :-
    setup_call_cleanup(
        open(File, read, In, [type(binary)]),
        copy_stream_data(In, Stream),
        close(In)).

destination_file(Dir, File, Dest) :-
    exists_directory(Dir),
    !,
    file_base_name(File, Base),
    directory_file_path(Dir, Base, Dest).
destination_file(Dest, _, Dest).


%!  make_directory_path(+Dir) is det.
%
%   Create Dir and all required  components   (like  mkdir  -p). Can
%   raise various file-specific exceptions.

make_directory_path(Dir) :-
    make_directory_path_2(Dir),
    !.
make_directory_path(Dir) :-
    permission_error(create, directory, Dir).

make_directory_path_2(Dir) :-
    exists_directory(Dir),
    !.
make_directory_path_2(Dir) :-
    atom_concat(RealDir, '/', Dir),
    RealDir \== '',
    !,
    make_directory_path_2(RealDir).
make_directory_path_2(Dir) :-
    Dir \== (/),
    !,
    file_directory_name(Dir, Parent),
    make_directory_path_2(Parent),
    make_directory(Dir).

%!  copy_directory(+From, +To) is det.
%
%   Copy the contents of the directory  From to To (recursively). If
%   To is the name of an existing  directory, the _contents_ of From
%   are copied into To. I.e., no  subdirectory using the basename of
%   From is created.

copy_directory(From, To) :-
    (   exists_directory(To)
    ->  true
    ;   make_directory(To)
    ),
    directory_files(From, Entries),
    maplist(copy_directory_content(From, To), Entries).

copy_directory_content(_From, _To, Special) :-
    special(Special),
    !.
copy_directory_content(From, To, Entry) :-
    directory_file_path(From, Entry, Source),
    directory_file_path(To, Entry, Dest),
    (   exists_directory(Source)
    ->  copy_directory(Source, Dest)
    ;   copy_file(Source, Dest)
    ).

special(.).
special(..).

%!  delete_directory_and_contents(+Dir) is det.
%
%   Recursively remove the directory Dir and its contents. If Dir is
%   a symbolic link or symbolic links   inside  Dir are encountered,
%   the links are removed rather than their content. Use with care!

delete_directory_and_contents(Dir) :-
    read_link(Dir, _, _),
    !,
    delete_file(Dir).
delete_directory_and_contents(Dir) :-
    directory_files(Dir, Files),
    maplist(delete_directory_contents(Dir), Files),
    delete_directory(Dir).

delete_directory_contents(_, Entry) :-
    special(Entry),
    !.
delete_directory_contents(Dir, Entry) :-
    directory_file_path(Dir, Entry, Delete),
    (   exists_directory(Delete)
    ->  delete_directory_and_contents(Delete)
    ;   delete_file(Delete)
    ).

%!  delete_directory_contents(+Dir) is det.
%
%   Remove all content from  directory   Dir,  without  removing Dir
%   itself. Similar to delete_directory_and_contents/2,  if symbolic
%   links are encountered in Dir, the  links are removed rather than
%   their content.

delete_directory_contents(Dir) :-
    directory_files(Dir, Files),
    maplist(delete_directory_contents(Dir), Files).

