#!/usr/bin/env perl

use Pod::Usage;
use Getopt::Long;
use Digest::MD5 qw(md5_hex);
use Compress::Zlib;
use LWP::UserAgent;
use Image::Term256Color;

my $ua = LWP::UserAgent->new;
my $gravatars = { empty => [] };
for( 0..19 ){
  $gravatars->{empty}->[$_] = ' 'x40;
}

sub print_usage {
  pod2usage( { -message => $_[0] , -exitval => 1 , -verbose => 0 } );
}

my $options = {};
GetOptions( "width=i" => \$options->{width},
            "dir=s"   => \$options->{dir},
            "help|?"  => \$options->{help} );

if( $options->{help} == 1 ){
  print_usage();
}

# Global gravs dir.  Only really need to load this once.
my @gravs_dir;

{ # Do all the setup / options checking
  my @config = `git config --list`;

  foreach my $i ( @config ){
    if( $i =~ /^glog\.dir=(.+)\n/ ){
      $options->{dir} = defined( $options->{dir} ) ? $options->{dir} : $1;
    }
  }

  $options->{dir} = defined( $options->{dir} ) ? $options->{dir} : $ENV{HOME} . '/.git-glog';
  if( ! -d $options->{dir} ){
    mkdir( $options->{dir} ) or die "Failed to create git-glog dir: $options->{dir}\n";
  }

  opendir(DIR, $options->{dir});
  @gravs_dir = readdir(DIR);
  closedir(DIR);

  my $cols_wide = `tput cols`;
  $options->{width} = defined( $options->{width} ) ? $options->{width} : $cols_wide - 44;

  if( -t STDOUT ){
    open( $OUT, '| less -R' );
  } else {
    $OUT = STDOUT;
  }

} # End setup / options

sub get_gravatar_hash {
  my $email = $_[0];
  $email = lc $email;
  $email =~ s/^\s+|\s+$//g;

  return md5_hex($email);
}

sub get_gravatar_url {
  return 'http://www.gravatar.com/avatar/' . $_[0] . '?s=20&d=retro';
}

sub get_term_gravatar {
  my $email = $_[0];
  my $hash = get_gravatar_hash($email);

  if( exists($gravatars->{$hash}) ){
    return @{$gravatars->{$hash}};
  }

  foreach my $grav ( @gravs_dir ){
    if( $grav eq $hash && -M $options->{dir} . "/$hash" < 3 ){
      my $input = $options->{dir} . "/$hash";
      my $z = gzopen( $input , 'rb' );
      my @gravatar;
      my $line;
      while( $z->gzreadline($line) > 0 ){
        $line =~ s/\n|\r//g;
        push( @gravatar, $line );
      }
      $z->gzclose();

      $gravatars->{$hash} = \@gravatar;
      return @gravatar;
    }
  }
  
  my $response = $ua->get(get_gravatar_url($hash));
  
  if( $response->is_success ){
    my @gravatar = Image::Term256Color::convert($response->decoded_content);
      my $output = $options->{dir} . "/$hash";
      my $z = gzopen( $output, 'wb' );
      map { $z->gzwrite( "$_\n" ) } @gravatar;
      $z->gzclose();


    $gravatars->{$hash} = \@gravatar;
    return @gravatar;
  } else {
    return @{$gravatars->{empty}};
  }
}

# A whole lot of gunk to actually spit out the log

my @buffer;
my @cur_grav;
my $auth;
my $new_auth;
my $commit_stored = 0;
my $pipes = { top      => ' ╓→' ,
              joint    => '═╣ ' , 
              straight => ' ║ ' ,
              bottom   => ' ╙→' };
my $pipe;

# Print the commit in the buffer, except for the last line.
#   We don't know if we need to print a new gravatar yet
sub print_commit {
  my $length = scalar( @buffer ) - 1;

  for( my $i=0; $i<$length; $i++ ){
    if( scalar( @cur_grav ) == 20 ){ $pipe = $pipes->{'top'}; }
    elsif( scalar( @cur_grav ) == 18 ){ $pipe = $pipes->{'joint'}; }
    else { $pipe = $pipes->{'straight'}; }

    if( @cur_grav ){
      print $OUT shift( @cur_grav ) . $pipe . shift( @buffer ) . "\n";
    } else {
      print $OUT ' 'x40 . $pipe . shift( @buffer ) . "\n";
    }
  }
}

# If the commit is fewer lines then the gravatar and the next commit
#   is by another author, finish printing the current gravatar.
sub print_grav {
  unless(@cur_grav || $commit_stored < 2){
    print $OUT ' 'x40 . $pipes->{bottom} . shift( @buffer ) . "\n";
  }
  my $length = @cur_grav;

  for( my $i=0; $i<$length; $i++ ){
    if( $i == 0 ){
      print $OUT shift( @cur_grav ) . $pipes->{'straight'} . shift( @buffer ) . "\n";
    } elsif( $i == ($length - 1) ){
      print $OUT shift( @cur_grav ) . $pipes->{'bottom'} . "\n";
    } else {
      print $OUT shift( @cur_grav ) . $pipes->{'straight'} . "\n";
    }
  }
}

# Open git log with some pretty colors and the provided args
open(GIT, 'git log --color=always --decorate ' . join(' ', @ARGV) . '|');
while(<GIT>){
  chomp;
  if( $_ =~ /^.{5}commit\s[0-9a-z]{40}/ ){
    if( $commit_stored ){
      # print out previous commit
      print_commit();
    }
    $commit_stored++;
  }
  if( $_ =~ /^Author:\s+.+<(.+)>/ ){
    $new_auth = $1;

    if( $auth ne $new_auth){
      print_grav();
      @cur_grav = get_term_gravatar($1);
      $auth = $new_auth;
    } else {
      unless(@cur_grav || $commit_stored < 2){
        print $OUT ' 'x40 . $pipes->{straight} . shift( @buffer ) . "\n";
      }
    }
  }

  if( length( $_ ) > $options->{width} ){
    my $width = $options->{width};
    push( @buffer, split( /(.{$width})/, $_ ));
  } else {
    push( @buffer, $_ );
  }
}

# Need to make sure our buffers are empty
print_commit();
print_grav();

exit 0;

__END__
 
=head1 NAME
 
git-glog - Spicey git-log with a hint of gravatars, nutmeg and cinnamon
 
=head1 SYNOPSIS
 
git glog [options] [-- git-log options]
 
 Options:
   --help|-h            brief help message
   --width|-w           set the width of the output ascii
   --dir|-d             directory to fetch/store ascii gravatars

=head1 OPTIONS

=over 8

=item --help|-h

Prints a brief help message and exits.

=item --width|-w

Controls how wide the resulting ascii is in columns.  The Default will
take up the entire width ( if necessary ).

=item --dir|-d

The directory to store and read the gzipped ascii gravatars from.
Same as glog.dir in the L</SETTINGS> section of the man page.  
This option overrides any stored settings.

=back
 
=head1 DESCRIPTION
 
git-glog is a perl wrapper around git-log that displays gravatars in your
256 color terminal. git-glog is a part of the L<Git::Glog> perl module
distribution.

=head1 SETTINGS

git-glog will attempt to read your git settings for the following:

=over 8

=item glog.dir

The directory to store and read the gzipped ascii gravatars from.
Default is F<$HOME/.git-glog/>

    git config --global --add glog.dir $HOME/.git-glog

To take a peek at the stored ascii gravatars, try:

    cat $(git config --get glog.dir)/* | gunzip | less -R

or

    cat ~/.git-glog/* | gunzip | less -R

=back

=head1 EXAMPLES

A fancy git log:

    git glog -- --stat --summary --pretty=fuller

=head1 CAVEATS

git may complain of a non-zero exit code if git-glog does not complete.
This will probably occur if the log is generated from a large repository or
is left completely open ended ( no from... to ).

Right now the output is piped to F<less -R> ( when STDOUT is a tty ). FYI.

=cut