Complex Date Issue - PHP - Codeigniter - Jquery UI Calendar - php

Question

I am creating a site that utilizes the jquery ui datepicker. I have it where items have different rental lengths. So a car might be 7 days, while a tent might be 3 days.
When the user enters a quantity of items needed, the system checks if the span of days is available and then puts together an array of dates that are already in the system. This array is passed back to the jquery ui datepicker and those dates are blocked out on the calendar.
Here's my problem. If a user picks a date range that is say, 2 days long. from the 2nd to the 4th of the month. Then a user goes back and wants to choose the 1st, obviously if the item is rented on the 2nd then a 1st to 3rd of the month rental ISNT available.
I'm stumped on how to block out days where the full rental length is not available. Here is what I have so far for the code that creates the blocked date array:
$dateArray = array();
foreach($rentals as $rental) {
//Figure out how many days are between the start and end...
$now = strtotime($rental['periodEnd']);
$your_date = strtotime($rental['periodStart']);
$datediff = $now - $your_date;
$daysBetween = floor($datediff/(60*60*24));
$i = 0;
while($i < $daysBetween) {
if($i != 0) {
$date = date('Y-m-d', strtotime($rental['periodStart']. ' + ' . $i . ' days'));
}else {
$date = date('Y-m-d', strtotime($rental['periodStart']));
}
array_push($dateArray, $date);
$i++;
}
}
//Now get rid of duplicates...
$dateArray = array_unique($dateArray);
echo json_encode($dateArray);

Answer 1

I added this exact feature to a website that offered chartered fishing trips. There were a lot more variables involved in my solution, so this may be somewhat broad/vague, but should at least push you in the right direction.
I set up a callback function for Datepicker's beforeShowDay option:
A function takes a date as a parameter and must return an array with [0] equal to true/false indicating whether or not this date is selectable, [1] equal to a CSS class name or "" for the default presentation, and [2] an optional popup tooltip for this date. It is called for each day in the datepicker before it is displayed.
In my callback, I compare the user's current choices (the trip they chose, which can vary from 1/2 to 3 days, and their chosen departure date) with a list of unavailable dates (which I generate dynamically using PHP & json_encode() like yourself).
When the user opens the Datepicker, the callback will fire for every individual day on the currently-displayed calendar. So each day will go through a logic similar to:
Is this day in the past? (Can't charter a trip in the past!)
Is this day already reserved?
How long is this reservation for? Are there any reserved days in the future that conflict with this timeframe?
Note that in my descriptions, this is all front-end / jQuery based -- current chosen values inputted by the user are pulled using $('#item').val(). The callback has no interactions with the back end. You can use ajax in your callback, but I found it to be much much slower. Your mileage may vary.
Also, you should definitely have a back-end solution that does pretty much the same thing, as well. Don't rely on JS to do your filtering.
Hope that gets you on track!