#!/usr/bin/perl 

use strict;
use warnings;
use Tk;


#
#  Create a main window.
#
my $mw = MainWindow->new;
$mw->title("Kernel (ChangeLog) Viewer");

my $g_kernel = "";


# For example purposes, we'll use one word for each letter
my @kernels = sort( glob( "Change*" ) );

#
# Create Listbox and insert the list of kernels into it.
#
my $lb = $mw->Scrolled("Listbox", -scrollbars => "osoe", 
                       )->pack(-side => "left", -fill => "y");
$lb->insert("end", @kernels);
$lb->bind( '<<ListboxSelect>>' => sub { loadKernel( $lb->curselection )  } );


#
#  Top top which has the changelog
#
my $lbtop = $mw->Scrolled("Listbox", -scrollbars => "osoe", 
                       )->pack(-side => "top", -fill => "y", -fill => "x");

$lbtop->bind('<<ListboxSelect>>' => sub { loadChangelogDetail( $lbtop->curselection ) ;} );

#
#  The text which holds the changelog entry.
#
my $textbox = $mw->Scrolled("Text")->pack( -side => "bottom", -fill => "y", -fill => "x" );

#
#  Run the mainloop
#
MainLoop;


#
#  Called when a kernel is selected.
#
#  Clear the textbox.
#
#  Load the one-line-summary of the changelog in the top listbox.
#
sub loadKernel
{
    my( $val ) = ( @_ );
    my $kernel = $lb->get($val );
    print "LOADING $kernel [index $val]\n";

    $g_kernel = $kernel;

    $lbtop->delete(0, 'end');
    $textbox->delete( "1.0", 'end' );

    open( FILE, "<", $kernel )
      or die "Failed to load file: $kernel - $!";

        my $commit;
        my $author;
        my $date;
        my $first;
    while( my $line = <FILE> )
    {
        chomp( $line );
        next if ( $line =~ /^$/ );


        if ( $line =~ /^commit (.*)/ )
        {
            $commit = $1;
        }
        elsif ( $line =~ /^Author: (.*)/ )
        {
            $author = $1;
        }
        elsif ( $line =~ /^Date: (.*)/ )
        {
            $date = $1;
        }
        else 
        {
            if ( length($author ) && length($commit) && length($date) )
            {
                if ( ! length($first ) )
                {
                    # print "Author: $author\n";
                    # print "Commit: $commit\n";
                    # print "Date: $date\n";
                    # print "\t$line\n";

                    $line =~ s/^\s+|\s+$//g;

                    $lbtop->insert("end", $line );
                    $first = $line;

                    $author = "";
                    $commit = "";
                    $date = "";
                    $first = "";
                }
            }
        }
           }
    close( FILE );
}


=begin doc

  Given a line like "KVM: foo" show all the text of that entry
 until the next commit.

=end doc

=cut

sub loadChangelogDetail
{
    my( $val ) = ( @_ );

    # the changelog entry we wish to show
    my $change = $lbtop->get( $val );

    my @lines = ();
    my $found = 0;

    open( FILE, "<", $g_kernel );
    while( my $line = <FILE> )
    {
        chomp( $line );

        my $header = $line;
        $header =~ s/^\s+|\s+$//g;

        if ( $header eq $change )
        {
            $found = 1;
        }
        if ( $found )
        {
            push( @lines, $line  . "\n");
        }
        if ( $line =~ /^$/ )
        {
            $found = 0;
        }
    }
    close( FILE );

    $textbox->delete( "1.0", "end" );

    foreach my $line ( @lines )
    {
        $textbox->insert("end", $line );
    }
}