#!/usr/bin/perl

# Simple command-line todo list manager.
# 
# Copyright 2010 Alessandro Ghedini <al3xbio@gmail.com>
# --------------------------------------------------------------
# "THE BEER-WARE LICENSE" (Revision 42):
# Alessandro Ghedini wrote this file. As long as you retain this 
# notice you can do whatever you want with this stuff. If we 
# meet some day, and you think this stuff is worth it, you can 
# buy me a beer in return.
# --------------------------------------------------------------

use strict;

die "For info type 'perldoc $0'\n" unless $#ARGV >= 0;

my ($default_todo, $default_done);

if ($^O eq 'MSWin32') {
	$default_todo = $ENV{USERPROFILE}."\\todo.txt";
	$default_done = $ENV{USERPROFILE}."\\done.txt";
} else {
	$default_todo = $ENV{HOME}."/.todo";
	$default_done = $ENV{HOME}."/.done";
}

my $todo_file = $ENV{TODO_FILE} ne "" ? $ENV{TODO_FILE} : $default_todo;
my $done_file = $ENV{DONE_FILE} ne "" ? $ENV{DONE_FILE} : $default_done;

if (!(-e $todo_file)) {
	open(TODO_FILE, ">$todo_file") or
		die("Cannot create '$todo_file'. Check TODO_FILE and DONE_FILE env variables.");
	close TODO_FILE;
}

if (!(-e $done_file)) {
	open(DONE_FILE, ">$done_file") or
		die("Cannot create '$done_file'. Check TODO_FILE and DONE_FILE env variables.");
	close DONE_FILE;
}

my $action = $ARGV[0];

if ($action eq 'add') {
	splice @ARGV, 0, 1;
	my $msg = join ' ', @ARGV;

	my $txt = $msg." {".time()."}";

	append_file($todo_file, $txt);

	print "Added new task.\n";
	
} elsif ($action eq 'rm') {
	my $id = $ARGV[1];

	my @data = read_file($todo_file);

	splice(@data, $id-1, 1);

	write_file($todo_file, \@data);

	print "Removed task number ".$id.".\n";
	
} elsif ($action eq 'ls') {
	my $grep = $ARGV[1] ne "" ? $ARGV[1] : "(.*?)";

	my @data = read_file($todo_file);

	print_tasks($grep, @data);
	
} elsif ($action eq 'do') {
	my $id = $ARGV[1];

	my @data = read_file($todo_file);

	my $done = $data[$id-1];
	splice(@data, $id-1, 1);

	write_file($todo_file, \@data);

	chomp $done;
	append_file($done_file, $done);

	print "Task number $id marked as done and moved to $done_file.\n";
	
} elsif ($action eq 'ed') {
	my $id = $ARGV[1];

	splice @ARGV, 0, 2;
	my $msg = join ' ', @ARGV;

	my @data = read_file($todo_file);

	$data[$id-1] = $msg." {".time()."}\n";

	write_file($todo_file, \@data);

	print "Task number $id successfully replaced.\n";
} elsif ($action eq 'mv') {
	my $id = $ARGV[1];
	my $new_pos = $ARGV[2];
	
	my @data = read_file($todo_file);

	my $tmp = $data[$new_pos-1];
	$data[$new_pos-1] = $data[$id-1];
	$data[$id-1] = $tmp;

	write_file($todo_file, \@data);

} elsif ($action eq 'done') {
	my $grep = $ARGV[1] ne "" ? $ARGV[1] : "(.*?)";

	my @data = read_file($done_file);

	print_tasks($grep, @data);
	
} else {
	print "ERROR: Invalid action '$action'.\n";
	print "Type 'perldoc $0' for manual\n";
}

sub print_tasks {
	my $grep  = shift;
	my @tasks = @_;
	
	my $i = 0;
	foreach my $task(@tasks) {
		$i++;
		next unless $task =~ m/$grep/;
		$task =~ m/{(.*?)}/;
		my $rel_time = relative_time($1);
		$task =~ s/\{$1\}/\ ($rel_time\)/g;
		print $i."  ".$task;
	}
}

sub read_file {
	my $file = shift;

	open(FILE, "<$file") or die("Cannot open $file in read mode.\n");
	my @data = <FILE>;
	close(FILE);

	return @data;
}

sub write_file {
	my $file = shift;
	my $data_ref = shift;

	open(FILE, ">$file") or die("Cannot open $file in write mode.\n");
	print FILE @$data_ref;
	close(FILE);
}

sub append_file {
	my $file = shift;
	my $data = shift;

	open(FILE, ">>$file") or die("Cannot open $file in append mode.\n");
	print FILE $data."\n";
	close(FILE);
}

sub relative_time {
	my $time_value = shift;

	my $now = time();
	my $delta = $now - $time_value;
	
	if($delta < 60) {
		return 'less than a minute ago';
	} elsif($delta < 120) {
		return 'about a minute ago';
	} elsif($delta < (45*60)) {
		return int($delta / 60) . ' minutes ago';
	} elsif($delta < (90*60)) {
		return 'about an hour ago';
	} elsif($delta < (24*60*60)) {
		return 'about ' . int($delta / 3600) . ' hours ago';
	} elsif($delta < (48*60*60)) {
		return '1 day ago';
	} else {
		return int($delta / 86400) . ' days ago';
	}
}

__END__

=head1 NAME

ToDo - A simple command-line todo list manager.

=head1 USAGE

B<ToDo> I<ACTION> I<ARGS>

=head1 ACTIONS

=over

=item B<add SOME TEXT @LIST>

Add a task to your todo list. List notation optional.

=item B<rm NUMBER>

Remove task on line NUMBER from your todo list.

=item B<ls TERM>

Show tasks that contain TERM. If no TERM specified, the entire list is
showed.

=item B<done TERM>

As ls but for already done tasks.

=item B<do NUMBER>

Mark the task on line NUMBER as done. It moves the task from todo file
to done file.

=item B<ed NUMBER "Some text">

Replace the task on line NUMBER with the text given.

=item B<mv NUMBER POSITION>

Move the task on line NUMBER to line POSITION and the task on POSITION
to NUMBER.

=back

=head1 CONFIGURATION

Set TODO_FILE and DONE_FILE environment variables, to your todo and done
files locations. Defaults ~/.todo and ~/.done.

=cut