Calculate Late Fee Help.

[victorysshadow]

Guys,

I have been thinking about this problem for a while and I am sure that someone has thought/done this before...

I need to calculate a late fee, but the problem is that we only charge a late fee for the time we are open. Thus we have the following schedule:

M-Th: 8am-9pm
F: 8am-6pm
Sa: 10am-6pm

Right now I am calculating the amount of time late by subtracting a NOW timestamp from the DUE timestamp and getting the number of seconds an item is late. Now all I need is some sort of function to calculate the fee. If there isn't a programatic way of doing this perhaps I will consider revising the fee policy.

Thanks.

vs

[tekky]

I would say the easiest way would be to loop through each day from the original return date, to the actual date of return

if the return time is less than the open time for that day, return 0 and add that to the hrs late, if its > then end of the closing time, return the max hours open that day and add to the hrs late... if its anything less, subtract the hrs closed (ie, 8 if you open at 8am) from the total hrs of that day and add that to hrs late....

repeat for each day between the return date and the actual return date.....

suggested array that may help...

$dailyhrs['Mon']['open'] = '0800';
$dailyhrs['Mon']['close'] = '2100';
....
$dailyhrs['Thu']['open'] = '0800';
$dailyhrs['Thu']['close'] = '2100';
$dailyhrs['Fri']['open'] = '0800';
$dailyhrs['Fri']['close'] = '1800';
$dailyhrs['Sat']['open'] = '1000';
$dailyhrs['Sat']['close'] = '2100';

then you can just loop through and compare the 24hr times of the days with the return time....

[Cailean]

I can only assume that we are talking in hourly terms (unlike a movie rental, for example).

A simpler solution might be to take your LATE = NOW - DUE solution and then subtract the hours you were closed in between.

The easiest way to do that might be to create an array that contains the number of 'closed' hours per day. This number should be the number of closed hours following the business hours until opening the next day.
ie:

closed_hours['mon']=11; //same for tues-thurs
closed_hours['fri']=16;
closed_hours['sat']=38;  //sunday not needed since not open

You'd then need to determine how many of each day type has occured between DUE and NOW and subtract the appropriate hours from LATE. I'll have to think about that one for a bit

[Cailean]

Here's the rest, I think... not the change in the hours_closed array

<?
$due= //a timestamp value
$now= //a timestamp value

closed_hours[1]=11;  // Mon; same for tues-thurs
closed_hours[5]=16;  // Fri
closed_hours[6]=38;  //sunday (0) not needed since not open

// get the day count
for($i=$due; $i<=$now; $i+=(60*60*24)) {
	$day_count[date(w, $i)]++
	$num_days++
}

$late=$now-$due  //raw seconds late

// calculate actual seconds late
for($i=0; $i<=6; $i++){
	$late-=(closed_hours[$i]*$day_count[$i]);
}

// convert to hours
$late=round($late/60);  // could also use floor() or ceil() here
?>

[tekky]

sounds fairly much like what I suggested except your way of calculating the differences due to being closed.... your current description however seems to not account for them returning something in the middle of a day... ie, they return it at 0900 they opened at 0800 but you're gonna still substract the full time for them being closed that day.....

[Cailean]

oh, you're right....!

well, we'll just not count today when we are subtracting the closed_hours...

<?
$due=???? //a timestamp value
$now=???? //a timestamp value

closed_hours[1]=11;  // Mon
closed_hours[2]=11;  // Tues
closed_hours[3]=11;  // Wed
closed_hours[4]=11;  // Thurs
closed_hours[5]=16;  // Fri
closed_hours[6]=38;  // sunday [0] not needed since not open

// get the day count
for($i=$due; $i<=$now; $i+=(60*60*24)) {
    $day_count[date(w, $i)]++;
    $num_days++;
}

// NEW CODE so we don't subtract today's closed hours
$today=date(w, time());
$day_count[$today]--;

// raw seconds late
$late=$now-$due  

// convert to hours  NOTE THIS CODE HAS MOVED HERE FROM BELOW
$late=round($late/60/60);  // could also use floor() or ceil() here

// calculate hours late
for($i=0; $i<=6; $i++){
    $late-=(closed_hours[$i]*$day_count[$i]);
}


?> 

That should fix it. The reasons I went with the closed hours rather than open were:
1) the hours array is simpler which makes the loop simpler
2) the item can't be due or returned during closed hours so no need to deal with partial days.

[tekky]

you need one more revision 😉 (I think...)

this will count sundays because your for loop up top will count sundays and since they are technically close 0 hrs... it should end up counting as a full day of business....

I have no way of testing it so this is all in my head of course, but I Would make this change...

you should add an if check in the first loop

for($i=$due; $i<=$now; $i+=(60*60*24)) { 
    $day_count[date(w, $i)]++; 
    $num_days++; 
} 

to:

for($i=$due; $i<=$now; $i+=(60*60*24)) {
    $dow = date(w,$i); //day of week numerically
    if ($dow != 0)  //if its Sunday, ignore it
        $day_count[$dow]++; 
    $num_days++; 
} 

This could also be fixed by adding Sunday ito the closed array as a 24, that way if that ever changes.... its a quick fix

one more thing... by subtracting the day and not using open and close hours, how do you prepose to count the actual seconds late since opening time? 😉 Your closed array doesn't take into account when those hours of closure are... so there is no way of determining that, which was why I initially stated an array that tracked both 😉

[Cailean]

the first for loop does count the Sundays, but since the closed value for Sundays is zero, nothing happens during the second for loop. The Saturday hours (34) cover all of Sunday. The 'rule' is that you assign each day the number hours until the next opening. So if you decided to open on Sunday, say from noon to 5, you would change Saturday's value to 15 and Sunday's to 15.

The time between opening and $now is included in the initial $late=$due-$now and it is never subtracted. Also included are the hours between when it was due and closing that day.

Works like this: (results, not actual code)

$due=monday at noon
$now=wednesday at 3pm

$day_count[1] = 1
$day_count[2] = 1
$day_count[3] = 0  (today was removed)

$late=183600  seconds
$late=51 hours

$late=51-11-11

$late=29 hours late  (which I think is correct)

Imagine that, I found an error - I was subtracting hours from seconds!! I've changed it above. I would never suggest that my code the best or easiest or most effecient way to do something -- it's merely a representation of how my weird little brain works... the results are, therefore, unpredictable!

[tekky]

Originally posted by Cailean
The Saturday hours (34) cover all of Sunday. The 'rule' is that you assign each day the number hours until the next opening.

doh, I didnt catch that huge increase in hours, nevermind that method will work then 😉

[victorysshadow]

I just want to thank you all. Great helps you've been!! I appreciate the time you spent to think about this. Works GREAT!

[victorysshadow]

when you say timestamp, what do you mean? I am getting that items are late 98 hours instead of 1 hour when I test it.

thanks.

vs

[tekky]

timestamp = unix timestamp which is the number of seconds since jan 1 1970 if I recall (if you look on php.net under time() it will tell ya

[Cailean]

UNIX timestamps are handy for finding elapsed time... a timestamp is the seconds elapsed since the epoch, Jan 1, 1970.
time() gives you the current timestamp, mktime() finds the timestamp for any date past, present or future.

To set the $due & $now (or $returned is probably better) in your situation:
let's say it was due March 5th, 2005 @ 3pm and returned March 5th @ 4pm.

I would insert the $due variable to the DB when the item is checked out...
$due=mktime(15,0,0,3,5,2005);

When the item is returned, use can just use time() OR, better, use the mktime() function again. This will allow you the option of manually adjusting the return time. in this case, it would look like:
$returned=mktime(16,0,0,3,5,2005);

You could also use strtotime(), but your input form probably has the date/time components separated anyway.

[victorysshadow]

I figured it out. It was the round($late/60)... it needed to be divided by 60 twice.

Thanks.

vs

[Cailean]

Imagine if there were only 60 seconds in an hour? 🙂 Glad you found the error... I've fixed it above.