#!/usr/bin/perl -w
# Script for task management. 
# Usage :
# tasklist to list tasks
# tasklist -a to add a new task
# tasklist -r task-numbers to remove tasks from list
##################################################################################
### You have to change the above path depending upon the output of `which perl` ##
### Author: Shraddha Kulkarni                                                   ##      
##################################################################################
use strict;
use Env; # this is used to import system environment variables into %ENV hash used later in this script 
Env::import();

my @tasks;
my %tasks;
my $separator="!\@#\$^&*";
my $escaped_separator = "!@#\\\$\\\^&\\\*";

unless( -f $ENV{'HOME'}."/.tasklist"){
	open NEWTASK,">".$ENV{'HOME'}."/.tasklist";
	close NEWTASK;
	print "New task-list created ..\n. Filename is ~/.tasklist\n\n To add new tasks, use command 'tasklist -a'\n\n";
}

open TASKS,$ENV{'HOME'}."/.tasklist";

while(<TASKS>){
	#s/$escaped_separator/ - /g;
	if(/^(\d+)$escaped_separator(.*)$/){
	$tasks{$1}=$2;	
	push @tasks,$2;
	}
}
close TASKS;

####  just read the task-list ####

if(@ARGV == 0){
	foreach my $k (keys %tasks){
	print "$k - ".$tasks{$k}."\n";
	}
}
else{ ## arguments are present ... go in the else part to process
### remove from the task-list ####
if($ARGV[0] eq '-r'){
	for (my $i=1;$i<@ARGV;$i++){
	delete $tasks{$ARGV[$i]};
	}
	write_list();
}

### add tasks to the list #### 
if($ARGV[0] eq '-a'){
my $task_num = unused_tasknum();
print "Task: ";
my $task=<STDIN>;
$tasks{$task_num}=$task;
write_list();
}

### help menu !! ###
if($ARGV[0] eq '-h'){
	print "USAGE\n-----\nTo add a task: tasklist -a\nTo remove tasks from list:  tasklist -r space-separated-list-of-task-numbers\nThis help menu: tasklist -h\n";
}

}
#############

sub unused_tasknum{
	my $i=1;
	while(1){
		if ($tasks{$i}){
		$i++;
		}
		else {return $i;}
	}
}
sub write_list{
	open ADD,">".$ENV{'HOME'}."/.tasklist";
	foreach my $k(keys %tasks){
	print ADD "$k$separator$tasks{$k}\n";
	}
	close ADD;
}