package AutoSplit;

use Exporter ();
use Config qw(%Config);
use Carp qw(carp);
use File::Basename ();
use File::Path qw(mkpath);
use strict;
use vars qw(
	    $VERSION @ISA @EXPORT @EXPORT_OK
	    $Verbose $Keep $Maxlen $CheckForAutoloader $CheckModTime
	   );

$VERSION = "1.0302";
@ISA = qw(Exporter);
@EXPORT = qw(&autosplit &autosplit_lib_modules);
@EXPORT_OK = qw($Verbose $Keep $Maxlen $CheckForAutoloader $CheckModTime);

=head1 NAME

AutoSplit - split a package for autoloading

=head1 SYNOPSIS

 autosplit($file, $dir, $keep, $check, $modtime);

 autosplit_lib_modules(@modules);

=head1 DESCRIPTION

This function will split up your program into files that the AutoLoader
module can handle. It is used by both the standard perl libraries and by
the MakeMaker utility, to automatically configure libraries for autoloading.

The C<autosplit> interface splits the specified file into a hierarchy 
rooted at the directory C<$dir>. It creates directories as needed to reflect
class hierarchy, and creates the file F<autosplit.ix>. This file acts as
both forward declaration of all package routines, and as timestamp for the
last update of the hierarchy.

The remaining three arguments to C<autosplit> govern other options to
the autosplitter.

=over 2

=item $keep

If the third argument, I<$keep>, is false, then any
pre-existing C<*.al> files in the autoload directory are removed if
they are no longer part of the module (obsoleted functions).
$keep defaults to 0.

=item $check

The
fourth argument, I<$check>, instructs C<autosplit> to check the module
currently being split to ensure that it does include a C<use>
specification for the AutoLoader module, and skips the module if
AutoLoader is not detected.
$check defaults to 1.

=item $modtime

Lastly, the I<$modtime> argument specifies
that C<autosplit> is to check the modification time of the module
against that of the C<autosplit.ix> file, and only split the module if
it is newer.
$modtime defaults to 1.

=back

Typical use of AutoSplit in the perl MakeMaker utility is via the command-line
with:

 perl -e 'use AutoSplit; autosplit($ARGV[0], $ARGV[1], 0, 1, 1)'

Defined as a Make macro, it is invoked with file and directory arguments;
C<autosplit> will split the specified file into the specified directory and
delete obsolete C<.al> files, after checking first that the module does use
the AutoLoader, and ensuring that the module is not already currently split
in its current form (the modtime test).

The C<autosplit_lib_modules> form is used in the building of perl. It takes
as input a list of files (modules) that are assumed to reside in a directory
B<lib> relative to the current directory. Each file is sent to the 
autosplitter one at a time, to be split into the directory B<lib/auto>.

In both usages of the autosplitter, only subroutines defined following the
perl I<__END__> token are split out into separate files. Some
routines may be placed prior to this marker to force their immediate loading
and parsing.

=head2 Multiple packages

As of version 1.01 of the AutoSplit module it is possible to have
multiple packages within a single file. Both of the following cases
are supported:

   package NAME;
   __END__
   sub AAA { ... }
   package NAME::option1;
   sub BBB { ... }
   package NAME::option2;
   sub BBB { ... }

   package NAME;
   __END__
   sub AAA { ... }
   sub NAME::option1::BBB { ... }
   sub NAME::option2::BBB { ... }

=head1 DIAGNOSTICS

C<AutoSplit> will inform the user if it is necessary to create the
top-level directory specified in the invocation. It is preferred that
the script or installation process that invokes C<AutoSplit> have
created the full directory path ahead of time. This warning may
indicate that the module is being split into an incorrect path.

C<AutoSplit> will warn the user of all subroutines whose name causes
potential file naming conflicts on machines with drastically limited
(8 characters or less) file name length. Since the subroutine name is
used as the file name, these warnings can aid in portability to such
systems.

Warnings are issued and the file skipped if C<AutoSplit> cannot locate
either the I<__END__> marker or a "package Name;"-style specification.

C<AutoSplit> will also emit general diagnostics for inability to
create directories or files.

=cut

# for portability warn about names longer than $maxlen
$Maxlen  = 8;	# 8 for dos, 11 (14-".al") for SYSVR3
$Verbose = 1;	# 0=none, 1=minimal, 2=list .al files
$Keep    = 0;
$CheckForAutoloader = 1;
$CheckModTime = 1;

my $IndexFile = "autosplit.ix";	# file also serves as timestamp
my $maxflen = 255;
$maxflen = 14 if $Config{'d_flexfnam'} ne 'define';
if (defined (&Dos::UseLFN)) {
     $maxflen = Dos::UseLFN() ? 255 : 11;
}
my $Is_VMS = ($^O eq 'VMS');


sub autosplit{
    my($file, $autodir,  $keep, $ckal, $ckmt) = @_;
    # $file    - the perl source file to be split (after __END__)
    # $autodir - the ".../auto" dir below which to write split subs
    # Handle optional flags:
    $keep = $Keep unless defined $keep;
    $ckal = $CheckForAutoloader unless defined $ckal;
    $ckmt = $CheckModTime unless defined $ckmt;
    autosplit_file($file, $autodir, $keep, $ckal, $ckmt);
}


# This function is used during perl building/installation
# ./miniperl -e 'use AutoSplit; autosplit_lib_modules(@ARGV)' ...

sub autosplit_lib_modules{
    my(@modules) = @_; # list of Module names

    while(defined($_ = shift @modules)){
	s#::#/#g;	# incase specified as ABC::XYZ
	s|\\|/|g;		# bug in ksh OS/2
	s#^lib/##; # incase specified as lib/*.pm
	if ($Is_VMS && /[:>\]]/) { # may need to convert VMS-style filespecs
	    my ($dir,$name) = (/(.*])(.*)/);
	    $dir =~ s/.*lib[\.\]]//;
	    $dir =~ s#[\.\]]#/#g;
	    $_ = $dir . $name;
	}
	autosplit_file("lib/$_", "lib/auto",
		       $Keep, $CheckForAutoloader, $CheckModTime);
    }
    0;
}


# private functions

sub autosplit_file {
    my($filename, $autodir, $keep, $check_for_autoloader, $check_mod_time)
	= @_;
    my(@outfiles);
    local($_);
    local($/) = "\n";

    # where to write output files
    $autodir ||= "lib/auto";
    if ($Is_VMS) {
	($autodir = VMS::Filespec::unixpath($autodir)) =~ s|/$||;
	$filename = VMS::Filespec::unixify($filename); # may have dirs
    }
    unless (-d $autodir){
	mkpath($autodir,0,0755);
	# We should never need to create the auto dir
	# here. installperl (or similar) should have done
	# it. Expecting it to exist is a valuable sanity check against
	# autosplitting into some random directory by mistake.
	print "Warning: AutoSplit had to create top-level " .
	    "$autodir unexpectedly.\n";
    }

    # allow just a package name to be used
    $filename .= ".pm" unless ($filename =~ m/\.pm$/);

    open(IN, "<$filename") or die "AutoSplit: Can't open $filename: $!\n";
    my($pm_mod_time) = (stat($filename))[9];
    my($autoloader_seen) = 0;
    my($in_pod) = 0;
    my($def_package,$last_package,$this_package,$fnr);
    while (<IN>) {
	# Skip pod text.
	$fnr++;
	$in_pod = 1 if /^=/;
	$in_pod = 0 if /^=cut/;
	next if ($in_pod || /^=cut/);

	# record last package name seen
	$def_package = $1 if (m/^\s*package\s+([\w:]+)\s*;/);
	++$autoloader_seen if m/^\s*(use|require)\s+AutoLoader\b/;
	++$autoloader_seen if m/\bISA\s*=.*\bAutoLoader\b/;
	last if /^__END__/;
    }
    if ($check_for_autoloader && !$autoloader_seen){
	print "AutoSplit skipped $filename: no AutoLoader used\n"
	    if ($Verbose>=2);
	return 0;
    }
    $_ or die "Can't find __END__ in $filename\n";

    $def_package or die "Can't find 'package Name;' in $filename\n";

    my($modpname) = _modpname($def_package); 

    # this _has_ to match so we have a reasonable timestamp file
    die "Package $def_package ($modpname.pm) does not ".
	"match filename $filename"
	    unless ($filename =~ m/\Q$modpname.pm\E$/ or
		    ($^O eq 'dos') or ($^O eq 'MSWin32') or
	            $Is_VMS && $filename =~ m/$modpname.pm/i);

    my($al_idx_file) = "$autodir/$modpname/$IndexFile";

    if ($check_mod_time){
	my($al_ts_time) = (stat("$al_idx_file"))[9] || 1;
	if ($al_ts_time >= $pm_mod_time){
	    print "AutoSplit skipped ($al_idx_file newer than $filename)\n"
		if ($Verbose >= 2);
	    return undef;	# one undef, not a list
	}
    }

    print "AutoSplitting $filename ($autodir/$modpname)\n"
	if $Verbose;

    unless (-d "$autodir/$modpname"){
	mkpath("$autodir/$modpname",0,0777);
    }

    # We must try to deal with some SVR3 systems with a limit of 14
    # characters for file names. Sadly we *cannot* simply truncate all
    # file names to 14 characters on these systems because we *must*
    # create filenames which exactly match the names used by AutoLoader.pm.
    # This is a problem because some systems silently truncate the file
    # names while others treat long file names as an error.

    my $Is83 = $maxflen==11;  # plain, case INSENSITIVE dos filenames

    my(@subnames, $subname, %proto, %package);
    my @cache = ();
    my $caching = 1;
    $last_package = '';
    while (<IN>) {
	$fnr++;
	$in_pod = 1 if /^=/;
	$in_pod = 0 if /^=cut/;
	next if ($in_pod || /^=cut/);
	# the following (tempting) old coding gives big troubles if a
	# cut is forgotten at EOF:
	# next if /^=\w/ .. /^=cut/;
	if (/^package\s+([\w:]+)\s*;/) {
	    $this_package = $def_package = $1;
	}
	if (/^sub\s+([\w:]+)(\s*\(.*?\))?/) {
	    print OUT "# end of $last_package\::$subname\n1;\n"
		if $last_package;
	    $subname = $1;
	    my $proto = $2 || '';
	    if ($subname =~ s/(.*):://){
		$this_package = $1;
	    } else {
		$this_package = $def_package;
	    }
	    my $fq_subname = "$this_package\::$subname";
	    $package{$fq_subname} = $this_package;
	    $proto{$fq_subname} = $proto;
	    push(@subnames, $fq_subname);
	    my($lname, $sname) = ($subname, substr($subname,0,$maxflen-3));
	    $modpname = _modpname($this_package);
	    mkpath("$autodir/$modpname",0,0777);
	    my($lpath) = "$autodir/$modpname/$lname.al";
	    my($spath) = "$autodir/$modpname/$sname.al";
	    my $path;
	    if (!$Is83 and open(OUT, ">$lpath")){
	        $path=$lpath;
		print "  writing $lpath\n" if ($Verbose>=2);
	    } else {
		open(OUT, ">$spath") or die "Can't create $spath: $!\n";
		$path=$spath;
		print "  writing $spath (with truncated name)\n"
			if ($Verbose>=1);
	    }
	    push(@outfiles, $path);
	    print OUT <<EOT;
# NOTE: Derived from $filename.
# Changes made here will be lost when autosplit again.
# See AutoSplit.pm.
package $this_package;

#line $fnr "$filename (autosplit into $path)"
EOT
	    print OUT @cache;
	    @cache = ();
	    $caching = 0;
	}
	if($caching) {
	    push(@cache, $_) if @cache || /\S/;
	} else {
	    print OUT $_;
	}
	if(/^\}/) {
	    if($caching) {
		print OUT @cache;
		@cache = ();
	    }
	    print OUT "\n";
	    $caching = 1;
	}
	$last_package = $this_package if defined $this_package;
    }
    print OUT @cache,"1;\n# end of $last_package\::$subname\n";
    close(OUT);
    close(IN);
    
    if (!$keep){  # don't keep any obsolete *.al files in the directory
	my(%outfiles);
	# @outfiles{@outfiles} = @outfiles;
	# perl downcases all filenames on VMS (which upcases all filenames) so
	# we'd better downcase the sub name list too, or subs with upper case
	# letters in them will get their .al files deleted right after they're
	# created. (The mixed case sub name won't match the all-lowercase
	# filename, and so be cleaned up as a scrap file)
	if ($Is_VMS or $Is83) {
	    %outfiles = map {lc($_) => lc($_) } @outfiles;
	} else {
	    @outfiles{@outfiles} = @outfiles;
	}  
	my(%outdirs,@outdirs);
	for (@outfiles) {
	    $outdirs{File::Basename::dirname($_)}||=1;
	}
	for my $dir (keys %outdirs) {
	    opendir(OUTDIR,$dir);
	    foreach (sort readdir(OUTDIR)){
		next unless /\.al$/;
		my($file) = "$dir/$_";
		$file = lc $file if $Is83 or $Is_VMS;
		next if $outfiles{$file};
		print "  deleting $file\n" if ($Verbose>=2);
		my($deleted,$thistime);  # catch all versions on VMS
		do { $deleted += ($thistime = unlink $file) } while ($thistime);
		carp "Unable to delete $file: $!" unless $deleted;
	    }
	    closedir(OUTDIR);
	}
    }

    open(TS,">$al_idx_file") or
	carp "AutoSplit: unable to create timestamp file ($al_idx_file): $!";
    print TS "# Index created by AutoSplit for $filename\n";
    print TS "#    (file acts as timestamp)\n";
    $last_package = '';
    for my $fqs (@subnames) {
	my($subname) = $fqs;
	$subname =~ s/.*:://;
	print TS "package $package{$fqs};\n"
	    unless $last_package eq $package{$fqs};
	print TS "sub $subname $proto{$fqs};\n";
	$last_package = $package{$fqs};
    }
    print TS "1;\n";
    close(TS);

    _check_unique($filename, $Maxlen, 1, @outfiles);

    @outfiles;
}

sub _modpname ($) {
    my($package) = @_;
    my $modpname = $package;
    if ($^O eq 'MSWin32') {
	$modpname =~ s#::#\\#g; 
    } else {
	$modpname =~ s#::#/#g;
    }
    $modpname;
}

sub _check_unique {
    my($filename, $maxlen, $warn, @outfiles) = @_;
    my(%notuniq) = ();
    my(%shorts)  = ();
    my(@toolong) = grep(
			length(File::Basename::basename($_))
			> $maxlen,
			@outfiles
		       );

    foreach (@toolong){
	my($dir) = File::Basename::dirname($_);
	my($file) = File::Basename::basename($_);
	my($trunc) = substr($file,0,$maxlen);
	$notuniq{$dir}{$trunc} = 1 if $shorts{$dir}{$trunc};
	$shorts{$dir}{$trunc} = $shorts{$dir}{$trunc} ?
	    "$shorts{$dir}{$trunc}, $file" : $file;
    }
    if (%notuniq && $warn){
	print "$filename: some names are not unique when " .
	    "truncated to $maxlen characters:\n";
	foreach my $dir (sort keys %notuniq){
	    print " directory $dir:\n";
	    foreach my $trunc (sort keys %{$notuniq{$dir}}) {
		print "  $shorts{$dir}{$trunc} truncate to $trunc\n";
	    }
	}
    }
}

1;
__END__

# test functions so AutoSplit.pm can be applied to itself:
sub test1 ($)   { "test 1\n"; }
sub test2 ($$)  { "test 2\n"; }
sub test3 ($$$) { "test 3\n"; }
sub testtesttesttest4_1  { "test 4\n"; }
sub testtesttesttest4_2  { "duplicate test 4\n"; }
sub Just::Another::test5 { "another test 5\n"; }
sub test6       { return join ":", __FILE__,__LINE__; }
package Yet::Another::AutoSplit;
sub testtesttesttest4_1 ($)  { "another test 4\n"; }
sub testtesttesttest4_2 ($$) { "another duplicate test 4\n"; }
