package Class::Inspector;

use 5.006;
# We don't want to use strict refs anywhere in this module, since we do a
# lot of things in here that aren't strict refs friendly.
use strict qw{vars subs};
use warnings;
use File::Spec ();

# ABSTRACT: Get information about a class and its structure
our $VERSION = '1.32'; # VERSION


# If Unicode is available, enable it so that the
# pattern matches below match unicode method names.
# We can safely ignore any failure here.
BEGIN {
  local $@;
  eval "require utf8; utf8->import";
}

# Predefine some regexs
our $RE_IDENTIFIER = qr/\A[^\W\d]\w*\z/s;
our $RE_CLASS      = qr/\A[^\W\d]\w*(?:(?:\'|::)\w+)*\z/s;

# Are we on something Unix-like?
our $UNIX  = !! ( $File::Spec::ISA[0] eq 'File::Spec::Unix'  );


#####################################################################
# Basic Methods


sub _resolved_inc_handler {
  my $class    = shift;
  my $filename = $class->_inc_filename(shift) or return undef;
  
  foreach my $inc ( @INC ) {
    my $ref = ref $inc;
    if($ref eq 'CODE') {
      my @ret = $inc->($inc, $filename);
      if(@ret) {
        return 1;
      }
    }
    elsif($ref eq 'ARRAY' && ref($inc->[0]) eq 'CODE') {
      my @ret = $inc->[0]->($inc, $filename);
      if(@ret) {
        return 1;
      }
    }
    elsif($ref && eval { $inc->can('INC') }) {
      my @ret = $inc->INC($filename);
      if(@ret) {
        return 1;
      }
    }
  }
  
  '';
}

sub installed {
  my $class = shift;
  !! ($class->loaded_filename($_[0]) or $class->resolved_filename($_[0]) or $class->_resolved_inc_handler($_[0]));
}


sub loaded {
  my $class = shift;
  my $name  = $class->_class(shift) or return undef;
  $class->_loaded($name);
}

sub _loaded {
  my $class = shift;
  my $name  = shift;

  # Handle by far the two most common cases
  # This is very fast and handles 99% of cases.
  return 1 if defined ${"${name}::VERSION"};
  return 1 if @{"${name}::ISA"};

  # Are there any symbol table entries other than other namespaces
  foreach ( keys %{"${name}::"} ) {
    next if substr($_, -2, 2) eq '::';
    return 1 if defined &{"${name}::$_"};
  }

  # No functions, and it doesn't have a version, and isn't anything.
  # As an absolute last resort, check for an entry in %INC
  my $filename = $class->_inc_filename($name);
  return 1 if defined $INC{$filename};

  '';
}


sub filename {
  my $class = shift;
  my $name  = $class->_class(shift) or return undef;
  File::Spec->catfile( split /(?:\'|::)/, $name ) . '.pm';
}


sub resolved_filename {
  my $class     = shift;
  my $filename  = $class->_inc_filename(shift) or return undef;
  my @try_first = @_;

  # Look through the @INC path to find the file
  foreach ( @try_first, @INC ) {
    my $full = "$_/$filename";
    next unless -e $full;
    return $UNIX ? $full : $class->_inc_to_local($full);
  }

  # File not found
  '';
}


sub loaded_filename {
  my $class    = shift;
  my $filename = $class->_inc_filename(shift);
  $UNIX ? $INC{$filename} : $class->_inc_to_local($INC{$filename});
}





#####################################################################
# Sub Related Methods


sub functions {
  my $class = shift;
  my $name  = $class->_class(shift) or return undef;
  return undef unless $class->loaded( $name );

  # Get all the CODE symbol table entries
  my @functions = sort grep { /$RE_IDENTIFIER/o }
    grep { defined &{"${name}::$_"} }
    keys %{"${name}::"};
  \@functions;
}


sub function_refs {
  my $class = shift;
  my $name  = $class->_class(shift) or return undef;
  return undef unless $class->loaded( $name );

  # Get all the CODE symbol table entries, but return
  # the actual CODE refs this time.
  my @functions = map { \&{"${name}::$_"} }
    sort grep { /$RE_IDENTIFIER/o }
    grep { defined &{"${name}::$_"} }
    keys %{"${name}::"};
  \@functions;
}


sub function_exists {
  my $class    = shift;
  my $name     = $class->_class( shift ) or return undef;
  my $function = shift or return undef;

  # Only works if the class is loaded
  return undef unless $class->loaded( $name );

  # Does the GLOB exist and its CODE part exist
  defined &{"${name}::$function"};
}


sub methods {
  my $class     = shift;
  my $name      = $class->_class( shift ) or return undef;
  my @arguments = map { lc $_ } @_;

  # Process the arguments to determine the options
  my %options = ();
  foreach ( @arguments ) {
    if ( $_ eq 'public' ) {
      # Only get public methods
      return undef if $options{private};
      $options{public} = 1;

    } elsif ( $_ eq 'private' ) {
      # Only get private methods
      return undef if $options{public};
      $options{private} = 1;

    } elsif ( $_ eq 'full' ) {
      # Return the full method name
      return undef if $options{expanded};
      $options{full} = 1;

    } elsif ( $_ eq 'expanded' ) {
      # Returns class, method and function ref
      return undef if $options{full};
      $options{expanded} = 1;

    } else {
      # Unknown or unsupported options
      return undef;
    }
  }

  # Only works if the class is loaded
  return undef unless $class->loaded( $name );

  # Get the super path ( not including UNIVERSAL )
  # Rather than using Class::ISA, we'll use an inlined version
  # that implements the same basic algorithm.
  my @path  = ();
  my @queue = ( $name );
  my %seen  = ( $name => 1 );
  while ( my $cl = shift @queue ) {
    push @path, $cl;
    unshift @queue, grep { ! $seen{$_}++ }
      map { s/^::/main::/; s/\'/::/g; $_ }
      ( @{"${cl}::ISA"} );
  }

  # Find and merge the function names across the entire super path.
  # Sort alphabetically and return.
  my %methods = ();
  foreach my $namespace ( @path ) {
    my @functions = grep { ! $methods{$_} }
      grep { /$RE_IDENTIFIER/o }
      grep { defined &{"${namespace}::$_"} } 
      keys %{"${namespace}::"};
    foreach ( @functions ) {
      $methods{$_} = $namespace;
    }
  }

  # Filter to public or private methods if needed
  my @methodlist = sort keys %methods;
  @methodlist = grep { ! /^\_/ } @methodlist if $options{public};
  @methodlist = grep {   /^\_/ } @methodlist if $options{private};

  # Return in the correct format
  @methodlist = map { "$methods{$_}::$_" } @methodlist if $options{full};
  @methodlist = map { 
    [ "$methods{$_}::$_", $methods{$_}, $_, \&{"$methods{$_}::$_"} ] 
    } @methodlist if $options{expanded};

  \@methodlist;
}





#####################################################################
# Search Methods


sub subclasses {
  my $class = shift;
  my $name  = $class->_class( shift ) or return undef;

  # Prepare the search queue
  my @found = ();
  my @queue = grep { $_ ne 'main' } $class->_subnames('');
  while ( @queue ) {
    my $c = shift(@queue); # c for class
    if ( $class->_loaded($c) ) {
      # At least one person has managed to misengineer
      # a situation in which ->isa could die, even if the
      # class is real. Trap these cases and just skip
      # over that (bizarre) class. That would at limit
      # problems with finding subclasses to only the
      # modules that have broken ->isa implementation.
      local $@;
      eval {
        if ( $c->isa($name) ) {
          # Add to the found list, but don't add the class itself
          push @found, $c unless $c eq $name;
        }
      };
    }

    # Add any child namespaces to the head of the queue.
    # This keeps the queue length shorted, and allows us
    # not to have to do another sort at the end.
    unshift @queue, map { "${c}::$_" } $class->_subnames($c);
  }

  @found ? \@found : '';
}

sub _subnames {
  my ($class, $name) = @_;
  return sort
    grep {
      substr($_, -2, 2, '') eq '::'
      and
      /$RE_IDENTIFIER/o
    }
    keys %{"${name}::"};
}





#####################################################################
# Children Related Methods

# These can go undocumented for now, until I decide if its best to
# just search the children in namespace only, or if I should do it via
# the file system.

# Find all the loaded classes below us
sub children {
  my $class = shift;
  my $name  = $class->_class(shift) or return ();

  # Find all the Foo:: elements in our symbol table
  no strict 'refs';
  map { "${name}::$_" } sort grep { s/::$// } keys %{"${name}::"};
}

# As above, but recursively
sub recursive_children {
  my $class    = shift;
  my $name     = $class->_class(shift) or return ();
  my @children = ( $name );

  # Do the search using a nicer, more memory efficient 
  # variant of actual recursion.
  my $i = 0;
  no strict 'refs';
  while ( my $namespace = $children[$i++] ) {
    push @children, map { "${namespace}::$_" }
      grep { ! /^::/ } # Ignore things like ::ISA::CACHE::
      grep { s/::$// }
      keys %{"${namespace}::"};
  }

  sort @children;
}





#####################################################################
# Private Methods

# Checks and expands ( if needed ) a class name
sub _class {
  my $class = shift;
  my $name  = shift or return '';

  # Handle main shorthand
  return 'main' if $name eq '::';
  $name =~ s/\A::/main::/;

  # Check the class name is valid
  $name =~ /$RE_CLASS/o ? $name : '';
}

# Create a INC-specific filename, which always uses '/'
# regardless of platform.
sub _inc_filename {
  my $class = shift;
  my $name  = $class->_class(shift) or return undef;
  join( '/', split /(?:\'|::)/, $name ) . '.pm';
}

# Convert INC-specific file name to local file name
sub _inc_to_local {
  # Shortcut in the Unix case
  return $_[1] if $UNIX;

  # On other places, we have to deal with an unusual path that might look
  # like C:/foo/bar.pm which doesn't fit ANY normal pattern.
  # Putting it through splitpath/dir and back again seems to normalise
  # it to a reasonable amount.
  my $class              = shift;
  my $inc_name           = shift or return undef;
  my ($vol, $dir, $file) = File::Spec->splitpath( $inc_name );
  $dir = File::Spec->catdir( File::Spec->splitdir( $dir || "" ) );
  File::Spec->catpath( $vol, $dir, $file || "" );
}

1;

__END__

=pod

=encoding UTF-8

=head1 NAME

Class::Inspector - Get information about a class and its structure

=head1 VERSION

version 1.32

=head1 SYNOPSIS

  use Class::Inspector;
  
  # Is a class installed and/or loaded
  Class::Inspector->installed( 'Foo::Class' );
  Class::Inspector->loaded( 'Foo::Class' );
  
  # Filename related information
  Class::Inspector->filename( 'Foo::Class' );
  Class::Inspector->resolved_filename( 'Foo::Class' );
  
  # Get subroutine related information
  Class::Inspector->functions( 'Foo::Class' );
  Class::Inspector->function_refs( 'Foo::Class' );
  Class::Inspector->function_exists( 'Foo::Class', 'bar' );
  Class::Inspector->methods( 'Foo::Class', 'full', 'public' );
  
  # Find all loaded subclasses or something
  Class::Inspector->subclasses( 'Foo::Class' );

=head1 DESCRIPTION

Class::Inspector allows you to get information about a loaded class. Most or
all of this information can be found in other ways, but they aren't always
very friendly, and usually involve a relatively high level of Perl wizardry,
or strange and unusual looking code. Class::Inspector attempts to provide 
an easier, more friendly interface to this information.

=head1 METHODS

=head2 installed

 my $bool = Class::Inspector->installed($class);

The C<installed> static method tries to determine if a class is installed
on the machine, or at least available to Perl. It does this by wrapping
around C<resolved_filename>.

Returns true if installed/available, false if the class is not installed,
or C<undef> if the class name is invalid.

=head2 loaded

 my $bool = Class::Inspector->loaded($class);

The C<loaded> static method tries to determine if a class is loaded by
looking for symbol table entries.

This method it uses to determine this will work even if the class does not
have its own file, but is contained inside a single file with multiple
classes in it. Even in the case of some sort of run-time loading class
being used, these typically leave some trace in the symbol table, so an
L<Autoload> or L<Class::Autouse>-based class should correctly appear
loaded.

Returns true if the class is loaded, false if not, or C<undef> if the
class name is invalid.

=head2 filename

 my $filename = Class::Inspector->filename($class);

For a given class, returns the base filename for the class. This will NOT
be a fully resolved filename, just the part of the filename BELOW the
C<@INC> entry.

  print Class->filename( 'Foo::Bar' );
  > Foo/Bar.pm

This filename will be returned with the right separator for the local
platform, and should work on all platforms.

Returns the filename on success or C<undef> if the class name is invalid.

=head2 resolved_filename

 my $filename = Class::Inspector->resolved_filename($class);
 my $filename = Class::Inspector->resolved_filename($class, @try_first);

For a given class, the C<resolved_filename> static method returns the fully
resolved filename for a class. That is, the file that the class would be
loaded from.

This is not necessarily the file that the class WAS loaded from, as the
value returned is determined each time it runs, and the C<@INC> include
path may change.

To get the actual file for a loaded class, see the C<loaded_filename>
method.

Returns the filename for the class, or C<undef> if the class name is
invalid.

=head2 loaded_filename

 my $filename = Class::Inspector->loaded_filename($class);

For a given loaded class, the C<loaded_filename> static method determines
(via the C<%INC> hash) the name of the file that it was originally loaded
from.

Returns a resolved file path, or false if the class did not have it's own
file.

=head2 functions

 my $arrayref = Class::Inspector->functions($class);

For a loaded class, the C<functions> static method returns a list of the
names of all the functions in the classes immediate namespace.

Note that this is not the METHODS of the class, just the functions.

Returns a reference to an array of the function names on success, or C<undef>
if the class name is invalid or the class is not loaded.

=head2 function_refs

 my $arrayref = Class::Inspector->function_refs($class);

For a loaded class, the C<function_refs> static method returns references to
all the functions in the classes immediate namespace.

Note that this is not the METHODS of the class, just the functions.

Returns a reference to an array of C<CODE> refs of the functions on
success, or C<undef> if the class is not loaded.

=head2 function_exists

 my $bool = Class::Inspector->function_exists($class, $functon);

Given a class and function name the C<function_exists> static method will
check to see if the function exists in the class.

Note that this is as a function, not as a method. To see if a method
exists for a class, use the C<can> method for any class or object.

Returns true if the function exists, false if not, or C<undef> if the
class or function name are invalid, or the class is not loaded.

=head2 methods

 my $arrayref = Class::Inspector->methods($class, @options);

For a given class name, the C<methods> static method will returns ALL
the methods available to that class. This includes all methods available
from every class up the class' C<@ISA> tree.

Returns a reference to an array of the names of all the available methods
on success, or C<undef> if the class name is invalid or the class is not
loaded.

A number of options are available to the C<methods> method that will alter
the results returned. These should be listed after the class name, in any
order.

  # Only get public methods
  my $method = Class::Inspector->methods( 'My::Class', 'public' );

=over 4

=item public

The C<public> option will return only 'public' methods, as defined by the Perl
convention of prepending an underscore to any 'private' methods. The C<public> 
option will effectively remove any methods that start with an underscore.

=item private

The C<private> options will return only 'private' methods, as defined by the
Perl convention of prepending an underscore to an private methods. The
C<private> option will effectively remove an method that do not start with an
underscore.

B<Note: The C<public> and C<private> options are mutually exclusive>

=item full

C<methods> normally returns just the method name. Supplying the C<full> option
will cause the methods to be returned as the full names. That is, instead of
returning C<[ 'method1', 'method2', 'method3' ]>, you would instead get
C<[ 'Class::method1', 'AnotherClass::method2', 'Class::method3' ]>.

=item expanded

The C<expanded> option will cause a lot more information about method to be 
returned. Instead of just the method name, you will instead get an array
reference containing the method name as a single combined name, a la C<full>,
the separate class and method, and a CODE ref to the actual function ( if
available ). Please note that the function reference is not guaranteed to 
be available. C<Class::Inspector> is intended at some later time, to work 
with modules that have some kind of common run-time loader in place ( e.g
C<Autoloader> or C<Class::Autouse> for example.

The response from C<methods( 'Class', 'expanded' )> would look something like
the following.

  [
    [ 'Class::method1',   'Class',   'method1', \&Class::method1   ],
    [ 'Another::method2', 'Another', 'method2', \&Another::method2 ],
    [ 'Foo::bar',         'Foo',     'bar',     \&Foo::bar         ],
  ]

=back

=head2 subclasses

 my $arrayref = Class::Inspector->subclasses($class);

The C<subclasses> static method will search then entire namespace (and thus
B<all> currently loaded classes) to find all classes that are subclasses
of the class provided as a the parameter.

The actual test will be done by calling C<isa> on the class as a static
method. (i.e. C<My::Class-E<gt>isa($class)>.

Returns a reference to a list of the loaded classes that match the class
provided, or false is none match, or C<undef> if the class name provided
is invalid.

=head1 SEE ALSO

L<http://ali.as/>, L<Class::Handle>, L<Class::Inspector::Functions>

=head1 AUTHOR

Original author: Adam Kennedy E<lt>adamk@cpan.orgE<gt>

Current maintainer: Graham Ollis E<lt>plicease@cpan.orgE<gt>

Contributors:

Tom Wyant

Steffen Müller

Kivanc Yazan (KYZN)

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2016 by Adam Kennedy.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=cut