/todo

#!/usr/bin/perl

use feature "state";

use strict;
use warnings;
use Getopt::Long;
use File::Basename;

# get app name
my $app_name = basename( $0 );

# option defaults
my $todo_dir = "~/.todo";
my $display_all = 0;
my $display_section = "TODO";
my $display_headers = 0;
my $mode_edit = 0;
my $mode_help = 0;
my $mode_version = 0;

# parse command line opts
Getopt::Long::Configure( 'gnu_getopt' );
if( !GetOptions(
    'a|all' => \$display_all,
    'e|edit' => \$mode_edit,
    'h|headers' => \$display_headers,
    's|section=s' => \$display_section,
    'help' => \$mode_help,
    'version' => \$mode_version,
) || @ARGV > 0 ) {
    print "Try `$app_name --help' for more information.\n";
    exit( 1 );
}

# help mode
if( $mode_help ) {
    print "todo - display your todo file\n\n".
	#01234567890123456789012345678901234567890123456789012345678901234567890123456789
    "Usage: $app_name [OPTIONS]\n\n".
    "Options:\n".
    "  -a, --all              display all sections\n".
    "  -e, --edit             edit your todo file\n".
    "  -h, --headers          show setion headers\n".
    "  -s, --section=SECTION  display sections matching the regular expression\n".
    "      --help     display this help and exit\n".
    "      --version  output version information and exit\n".
	"\n".
	"Running without any options is the same as running with --section=TODO and\n".
	"lists the default section of the todo file.\n".
	"\n".
	"The environment variables EDITOR is used.\n".
	"\n".
	"Please report bugs to Tim Marston <tim\@ed.am>.\n";
    exit( 0 );
}

# version mode
if( $mode_version ) {
    print "todo 1.0\n".
        "Copyright (C) 2011, 2012 Tim Marston.\n".
        "http://ed.am/software/todo\n";
    exit( 0 );
}

#_______________________________________________________________________________


# check we have bazaar installed
my $output = `which bzr`;
chomp $output;
$output eq "" and die "Bazaar is not installed";

# glob todo directory
$todo_dir = glob( $todo_dir );
( -f $todo_dir ) and die "$todo_dir exists and is a file";

# edit mode
if( $mode_edit )
{
    # create the todo directory, as necessary
    if( ! -d $todo_dir ) {
        mkdir $todo_dir or die "couldn't create todo directory";
        `bzr init --no-aliases -q "$todo_dir"`;
        $? == 0 or die "couldn't init bzr repo";
    }
    
    # create a default todo file, as necessary
    if( ! -f "$todo_dir/todo" ) {
        open FILE, ">$todo_dir/todo" or die "couldn't create default todo file";
        my $content = <<"EOT";
<!-- This file uses Markdown syntax. For more info about Markdown
     syntax, see http://daringfireball.net/projects/markdown/syntax.

     There should be a main H1 header called "TODO" for the main todo
     list section (one has been added for you below). You can also add
     as many more sections as you like for other lists. And feel free
     to delete this comment! -->

TODO
====

* make a list of things to do

EOT
        print FILE $content or die "couldn't write default todo file";
        close FILE;
        `bzr add --no-aliases -q "$todo_dir/todo"`;
        $? == 0 or die "couldn't add todo file to bzr repo";
    }

    # determine editor from environment, default to "emacs -nw"
	my $editor;
	$editor = $ENV{ 'EDITOR' };
	defined $editor or $editor = 'emacs -nw';
    my @exec_array = split( / +/, $editor );
    push( @exec_array, "$todo_dir/todo" );

    # detect emacs and try to use markdown-mode
    $exec_array[ 0 ] eq "emacs" and
        push( @exec_array, '--funcall=markdown-mode' );

    # edit todo file
    system( @exec_array );
    $? == 0 or
        die "can't start editor, check EDITOR envionment variable";

    # check for changes and commit it
    $output = `bzr status --no-aliases "$todo_dir/todo"`;
    $? == 0 or die "couldn't check bzr rerpo status";
    chomp $output;
    if( $output ne "" ) {
        `bzr commit --no-aliases -q -m - "$todo_dir/todo"`;
        $? == 0 or die "couldn't commit to bzr repo";
    }

    # after editing, exit
    exit
}

# function to display a line
sub display_line
{
	my ( $line, $section ) = @_;
	state $old_section = '';

	# detect section change
	if( $section ne $old_section ) {
		$old_section = $section;
		
		# display section heading
		if( $display_headers || $display_all ) {
			print "$section\n".
				( "=" x length( $section ) )."\n";
		}
	}

	# replace tabs with 4 spaces
	$line =~ s/\t/    /g;
	
	# display the line
	print $line;
}


# scan through file
my $candidate_section = '';
my $section = '';
my $last_line = '';
open FILE, "<$todo_dir/todo" or die "can't open todo file";
while( <FILE> )
{
    # detect the line after section headings, and thus sections
    if( /^[-=]{2,}/ && $candidate_section ne '' ) {
        $section = $candidate_section;
        $candidate_section = '';
		$last_line = '';
		next;
    }

    # detect section headings
    if( /^[-_\.A-Za-z0-9 ]+$/ ) {
        $candidate_section = $_;
		chomp $candidate_section;
	}
    else {
        $candidate_section = '';
	}

	# display last line
	display_line( $last_line, $section ) if( $last_line ne '' );

    # display line
	if( ( lc( $section ) eq lc( $display_section ) ) ||
		( $section && $display_all ) )
	{
		$last_line = $_;
    }
	else {
		$last_line = '';
	}
}
display_line( $last_line, $section ) if( $last_line ne '' );