#!/usr/bin/perl -w


open TEMPFH,"DB.txt" or die "Sorry Cant Open File...$!";
#reading the File For Getting the Last id To Support Auto increment.There is another way to do it later
#using Tail .
while(<TEMPFH>){
$_ =~/^(\d*).*$/;
    $ID=$1 if eof;
}
close TEMPFH;

print "Welcome To My Simple Phone Book:)\n";
print "What Do You want me To Do\n";
while(1){
print "[L]ist,[A]dd,[D]elete,[Q]uit\n";

$userInput = <STDIN>;
chomp $userInput;

 if (uc $userInput eq "L" or uc $userInput eq "LIST"){

 open READFH,"DB.txt" or die "Sorry Cant Open the DataBase...$!";
	for (<READFH>){

		print;
}
 close READFH;
}
 elsif (uc $userInput eq "A" or uc $userInput eq "ADD"){
 
 open WRITEFH,">>DB.txt" or die "Sorry Cant open The Database..$!";
	while(<WRITEFH>){
print;}
while(1){
	print "Please enter the name\n";
	print "Please Note that Only chars,numbers and underScore are aLlowed with max 30 char and min One Char \n";
	chomp($name = <STDIN>);
	if ($name !~ /^\w{1,30}$/){
	print "Sorry Invalid Name Try Again\n";
	next;
}
else{last;}
}
	while(1){
	print "Please Enter The Number\n";
	print "Please Note that Only Numbers are allowed With max 30 digit and min 1 digit\n";
	
	chomp($number=<STDIN>);
	if ($number !~ /^\d{1,30}$/){
	
	print "Sorry Invalid Number..Try Again\n";
	next;
}
else{last;}
}
	$ID++;
	print WRITEFH "$ID:$name:$number\n";
	print "Added Succefully\n";
close WRITEFH;
}
	elsif(uc $userInput eq "Q" or uc $userInput eq "QUIT"){
        print "Thank You,Keep Visiting :D\n";	
	last;
	}
	
	elsif(uc $userInput eq "D" or uc $userInput eq "DELETE"){

		print "Please Enter the Name You Wana Delete\n";
		chomp($userToDelete = <STDIN>);
		open DELETEFH,"DB.txt" or die "Sorry Couldnt Open DB...$!";
		open TEMP,">temp.txt" or die "Sorry Couldnt Open DB...$!";
		print "Successfully Deleted...\n";
	$myid=1;	
		while (<DELETEFH>){
	
	if (/^\d:$userToDelete:\d*$/)
   {
	$ID--;
	next;
   }

	else{
		$_ =~ /^\d*:(.*)$/;
		print TEMP "$myid:$1\n";
		$myid++;
   }
				}
		close DELETEFH;
		close TEMP ;
		rename "temp.txt","DB.txt" ;
$myid=1;

		}
else{
print "Sorry Invalid Option...Try Again";
}
print "\n";
}