Extract time frames from time period - php

Question

I am creating an application that charges a client based on time usage of a service. The problem is that the services can have double charge for a pre-specified time period of the day.
So let's say we have a service for printing documents and the charge for using the printer is 5€ per hour and 10€ between 23:00 and 02:00 in the morning. Also a client can rent the printer for as much time as he likes. This can be from 1 minute to months or even years.
Now the specific problem:
Let's say a client comes in my office to rent the printer for 55 hours. Also the rent starts at 20:00 at night.
So the charge must be for 43 hours in single charge and for 12 hours in double charge. Here are two example images:
Now, let me give you some extra info about the hours. In programming, each hour has a timestamp that it is time passed from January 1, 1970 00:00:00 to the time in seconds.
So the date July 05 2012 11:15:40 has the timestamp 1373022940 and the date July 05 2012 11:15:50 has the timestamp 1373022950
In the above example lets say that the first example placed in the date May 1, 2013, so the timestamp for 23:00 will be 1367449200 and the time stamp for three days later at the 02:00 the morning is 1367546400
Now the question:
Is there a way to extract the time duration of the double charged hours from a time frame? If so, what is the process?

Answer 1

Of course there is. You just need to count the interval between dates.
Let's say someone started using service since 8:00 and ended in 16:00.
Price from 8:00 - 16:00 = 2$
Price from 16:00 - 8:00 = 1$
So you need to convert the start of usage time and end of usage time to timestamp
date_default_timezone_set('UTC');
$day_start = '2011-06-22';
$day_end = '2011-06-22';
$start_usage = strtotime($day_start.' 8:00');
$end_usage = strtotime($day_end.' 17:00');
$price_low_rate = 1; //price for using service 16-8
$price_high_rate = 2; // price for using service since 8-16
$fee_for_eight_sixteen = 0; // total price for using service since 8-16
$fee_for_sixteen_eight = 0; // total price for using service 16-8
if($end_usage >strtotime($day_start.' 16:01'))
{
$fee_for_sixteen_eight = ($end_usage - strtotime($day_end.' 16:00'))/3600 * $price_low_rate;
}
if($start_usage >= strtotime($day_start.' 8:00'))
{
$fee_for_eight_sixteen = (strtotime($day_end.' 16:00') - $start_usage)/3600 * $price_high_rate;
}
echo $fee_for_eight_sixteen.' - '.$fee_for_sixteen_eight;
I've tested it and it works. Hope it helps.

Answer 2

Haven't tested this, but I hope it gets you on the right track:
<?php
$price = 0;
$start_timestamp = 1367449200;
$end_timestamp = 1367546400;
$start_time_of_day = 1367449200 % (24*60*60); // Number of seconds from start of the day
$end_time_of_day = 1367546400 % (24*60*60); // Number of seconds from start of the day
// How much time the time period spends in the first day (in seconds)
$first_day_time = (24*60*60) - $start_time_of_day;
// How much time the time period spends in the last day (in seconds)
$last_day_time = (24*60*60) - $end_time_of_day;
$full_days_time = $end_timestamp + $last_day_time - ($start_timestamp + $first_day_time);
$full_days = round($full_days_time/(24*60*60));
// You can calculate by hand how much one full 24-hour day from 00:00 to 00:00 costs
$price += $full_days * (2*10 + 21*5 + 1*10);
// so now the difficulty is the pieces of time on the first day and the last day.
$expensive_time = 0; // Expensive time spent on the first and last day
$cheap_time = 0;
if ($start_time_of_day<2*60*60)
{
// Renting starts before 02:00
$expensive_time += 2*60*60 - $start_time_of_day;
$cheap_time += 21*60*60; // Full 21 hours of cheap time
$expensive_time += 1*60*60; // 1 hour of expensive time from 23:00 to midnight
}
elseif ($start_time_of_day<23*60*60)
{
// Renting starts after 02:00 and before 23:00
$cheap_time += 23*60*60 - $start_time_of_day;
$expensive_time += 1*60*60; // 1 hour of expensive time from 23:00 to midnight
}
else
{
// Renting starts after 23:00
$expensive_time += 24*60*60 - $start_time_of_day;
}
// !! Use a similar strategy for the $end_time_of_day here
$price += ceil($expensive_time/60/60) * 10;
$price += ceil($cheap_time/60/60) * 5;
echo $price." euro";
?>