#!/usr/bin/perl -w

use strict;
use Math::Random;

my %shiftSchedule = (
    "first" =>  { "start" =>  6.00, "end" => 14.00 },
    "second" => { "start" => 14.00, "end" => 22.00 },
    "third" =>  { "start" => 22.00, "end" =>  6.00 }
);
my $shift = "third";         # shift to monitor
my $inspectionRate = 1 / 2;  # every 1/2 hour
my $drift = 1.5;             # sigma drift to simulate
my $m = 25;                  # samples in control chart setup
my $target = 0.10;           # fraction nonconforming target

my $c = $target;
my $n = 48;                  # observations per sample
my $hour;
my $i;
my $minute;
my @observations;
my $observation;
my $setupM = $m;

print "timestamp sample sampleSize observation phase\r\n";

for ($i = 1; $i <= $m; $i++) {
    @observations = Math::Random::random_poisson($n, $c);
    $observation = 0;
    map { $observation += $_ } @observations;
    printf "     0:00 %6d     %6d          %2d setup\r\n", $i, $n, $observation;
}

$m = $shiftSchedule{$shift}{"end"} - $shiftSchedule{$shift}{"start"};
if ($m < 0) {
    $m += 24;
}
$m /= $inspectionRate;
for ($i = 1; $i <= $m; $i++) {
    $hour = int($i * $inspectionRate + $shiftSchedule{$shift}{"start"});
    if ($hour >= 24) {
	$hour -= 24;
    }
    $minute = ($i & 0x1) ? (60 * $inspectionRate) : 0;
    if ($i >= (0.25 * $m)) {
	if ($i < (0.75 * $m)) {
	    $c = $target + ($drift * $target / (0.5 * $m)) * ($i - (0.25 * $m));
	} else {
	    $c = $target + $drift * $target;
	}
    }
    @observations = Math::Random::random_poisson($n, $c);
    $observation = 0;
    map { $observation += $_ } @observations;
    printf "    %2d:%02d %6d     %6d          %2d monitoring\r\n", $hour, $minute, $setupM + $i, $n, $observation;
}