#!/usr/bin/perl
use strict;
use warnings;
use File::Spec;
use Getopt::Long;
use POSIX qw(:errno_h);

my $verbose=0;
my $charset='UTF-8';
my $output_base='.';
my @modules=();
my @env_dirs=();

$charset=$ENV{MM_CHARSET} if($ENV{MM_CHARSET});
$charset=$ENV{HTML_CHARSET} if($ENV{HTML_CHARSET});

GetOptions (
  "charset=s"    => \$charset,
  "outdir|dir=s" => \$output_base,
  "env=s"        => \@env_dirs,
  "module=s"     => \@modules,
  "help"         => sub{ usage(); },
  "verbose"      => \$verbose,
) || usage('Unkown option',0,EINVAL());

@modules=@ARGV if(@ARGV);
unshift(@INC,@env_dirs);
usage('No Modul !',0,EINVAL()) unless(@modules);

$Pod::Simple::HTML::Content_decl = qq{<meta http-equiv="Content-Type" content="text/html; charset=$charset" >};

########################################################################

for my $module (@modules)
{
  my $path=get_filename($module);
  if($path && -f $path )
  {
    print qq|Read Pod from $module ($path)\n| if($verbose);
    my $pod=Pod::Simple::HTML::Local->new();
    my $html='';
    $pod->output_string(\$html);
    $pod->set_module_match_ref(\@modules);
    $pod->set_source( $path );
    $pod->run;

    if($html)
    {
      print "HTML created \n" if($verbose);
      my $outputname=File::Spec->join($output_base,Pod::Simple::HTML::Local::convert_module_name($module));
      print qq(Write HTML to file "$outputname" \n) if($verbose);
      create_path($outputname) or usage(qq|ERROR create "$outputname" ($!)\n|,1,EACCES());
      open(my $fh, '>', $outputname) or usage(qq|ERROR create "$outputname" ($!)\n|,1,EACCES());
      print $fh $html;
      close($fh);
    }
    else
    { print "NO HTML created\n" if($verbose); }
  }
  else
  { usage(qq(File for Module "$module" not found!),1,ENOENT()); }
}

########################################################################
# Funktionen
########################################################################
sub usage
{
  my $msg=shift || '';
  my $nohelp=shift || 0;
  my $exit=shift || 0;

  my $out=\*STDOUT;

  if($msg)
  {
    $out=\*STDERR;
    print $out "ERROR: $msg\n";
    $exit=255 unless($exit);
  }

  print $out <<EOH if(!$nohelp);
USAGE:
  $0 [-hv] [-e <path/to/modules>] [-c <charset>] [-d <output/dir>] [-m <Module::A>] [<Module::B> [<Module::C> ...] ]

Convert POD to HTML with subpackages as local files
and set links correctly.
 OPTIONS:
  -d | -o | --dir | --outputdir
    Set destination directory for HTM files.
    Default directory is the current.
  -c | --charset
    Set the character encoding in HTML document.
    UTF-8 is set as default. If available the enviroment variable
    MM_CHARSET or HTML_CHARSET will be used.
  -m | --module
    Set one or more modules whose POD should be converted
  -e | --env
    Set one or more directories where modules can be found
  -h | --help
    Show this text
  -v | --verbose
    verbose output
EOH

 exit($exit);
}

sub get_filename
{
  my $module=shift;
  my $name=undef;

  if( -f $module)
  { $name=$module; }
  else
  {
    my @dirs=split('::',$module);
    my $path=File::Spec->join(@dirs);
    $path.='.pm';
    for my $base (@INC)
    {
      my $fullpath=File::Spec->join($base,$path);
      if(-f $fullpath)
      {
        $name=$fullpath;
        last;
      }
    }
    unless($name)
    {
      my $fullpath=File::Spec->rel2abs($path);
      $name=$fullpath if(-f $fullpath);
    }
  }
  return $name;
}

sub create_path
{
  my $path=shift;
  return 0 unless($path);

  $path=File::Spec->rel2abs($path);
  return 0 unless($path);

  my ($run,$directories,undef) = File::Spec->splitpath( $path );
  for my $dir (File::Spec->splitdir( $directories ))
  {
    $run=File::Spec->join($run,$dir);
    unless(-d $run)
    {
      return 0 unless(mkdir($run));
    }
  }

  return 1;
}

########################################################################
# Pod::Simple::HTML::Local
########################################################################

package Pod::Simple::HTML::Local;
use base 'Pod::Simple::HTML';

# Links anders verarbeiten
# das mache ich mit dem Überschreiben der passenden Funktion in
# Pod::Simple::HTML

sub set_module_match_ref
{
  my $self=shift;
  my $ref=shift;
  return 0 if(ref($ref) ne 'ARRAY');
  $self->{MODULE_MATCH}=$ref;
  return 1;
}

# Modify Links
sub resolve_pod_page_link
{
  my ($self,$it)=@_;
  $self->{MODULE_MATCH}=[] unless($self->{MODULE_MATCH} && ref($self->{MODULE_MATCH}) eq "ARRAY");
  # Das Modul ist in der Liste
  if(grep{$_ eq $it}@{$self->{MODULE_MATCH}})
  {
    #print "$it\n";
    return convert_module_name($it);
  }
  # Das Modul gehört zum selben Paket
  elsif(grep{$it=~m!^\Q$_!}@{$self->{MODULE_MATCH}})
  {
    push(@{$self->{MODULE_MATCH}},$it);
    return convert_module_name($it);
  }
  # Modul verweist woanders hin:
  # den normalen Aufruf machen.
  else
  { $self->SUPER::resolve_pod_page_link($it); }
}

########################################################################

sub convert_module_name
{
  my $module=shift || '';
  $module=~s/::/_/g;
  $module.='.html';
}