Omitting redundant months and years in date range list - php

Question

I have got strange issue with dates of events and I have tried hard to get it fixed but unable to do it.
I am attaching a screenshot of how I want to display the dates on the page :
In the picture the first event Deine Energie in Aktion! is a combination of 5 events with each event having its start date and end date.
The first part of the event is 1 day event which starts on 4th April and ends on 4th April. Similarly the second part is on 7th April, 3rd part on 9th April and 4th part on 20th April
The last part starts on 5th May and ends on 10th May.
The dates are stored in database in this format :
I am showing the dates for last part of event.
Event Start Date : 2013-05-05 00:00:00
Event End Date : 2013-05-10 00:00:00
So I want to display dates in the format shown in the picture.
There are multiple cases:
First is if all the dates are coming within a single month then we display the month name at the end only once.
Second is if months are changed then the month name will be shown after the date when the month is changed.
I am getting events dates in a while loop, so how do I compare the current event date with the coming event date in a loop.
This is the code I have used so far to get the dates from the database..
$nid = $row->nid;
$get_product_id = "SELECT product_id from {uc_product_kits} where nid='$nid'";
$res = db_query($get_product_id);
while ($get_product_id_array_value = db_fetch_array($res)) {
$prductid = $get_product_id_array_value['product_id'];
$start_date = db_query("select event_start,event_end from {event} where nid=%d",$prductid);
$start_date_value = db_fetch_object($start_date);
$end_value = $start_date_value->event_start;
$event_end_date = $start_date_value->event_end;
$TotalStart = date("d M Y", strtotime($end_value));
$TotalEnd = date("d M Y", strtotime($event_end_date));
$onlyMonthStart = date("M", strtotime($end_value));
$onlyMonthEnd = date("M", strtotime($event_end_date));
//$groupMonth = db_query("select event_start,event_end, month from {event} where nid=%d group by ",$prductid);
if($TotalStart == $TotalEnd ){
$startDay = date("d", strtotime($end_value));
$startMonth = date("M", strtotime($end_value));
if(in_array($startMonth,$newMonth)) {
echo $onlstartdate;
}
else {
$onlstartdate = date("d", strtotime($end_value));
echo $onlstartdate;
$tempStorage[] = $startMonth
}
//$newMonth[] = $startMonth;
}
}

Answer 1

Easiest would be to first collect all data from your query into e.g. array.
Only then iterate over the array. Having all data together will allow you to compare two consecutive date ranges to decide level of details you need to print for each.
Commented example:
// collect data from SQL query into structure like this:
$events = array(
array("event_start" => "2013-4-4", "event_end" => "2013-4-4"),
array("event_start" => "2013-4-7", "event_end" => "2013-4-7"),
array("event_start" => "2013-4-9", "event_end" => "2013-4-9"),
array("event_start" => "2013-4-20", "event_end" => "2013-4-20"),
array("event_start" => "2013-5-5", "event_end" => "2013-5-10"),
array("event_start" => "2014-1-1", "event_end" => "2014-1-2"),
);
// the actual code for range list generation:
for ($i = 0; $i < count($events); $i++)
{
// parse start and end of this range
$this_event = $events[$i];
$this_start_date = strtotime($this_event["event_start"]);
$this_end_date = strtotime($this_event["event_end"]);
// extract months and years
$this_start_month = date("M", $this_start_date);
$this_end_month = date("M", $this_end_date);
$this_start_year = date("Y", $this_start_date);
$this_end_year = date("Y", $this_end_date);
$last = ($i == count($events) - 1);
// parse start and end of next range, if any
if (!$last)
{
$next_event = $events[$i + 1];
$next_start_date = strtotime($next_event["event_start"]);
$next_end_date = strtotime($next_event["event_end"]);
$next_start_month = date("M", $next_start_date);
$next_end_month = date("M", $next_end_date);
$next_start_year = date("Y", $next_start_date);
$next_end_year = date("Y", $next_end_date);
}
// ranges with different starting and ending months always go
// on their own line
if (($this_start_month != $this_end_month) ||
($this_start_year != $this_end_year))
{
echo date("j M", $this_start_date);
// print starting year only if it differs from ending year
if ($this_start_year != $this_end_year)
{
echo " ".date("Y", $this_start_date);
}
echo "-".date("j M Y", $this_end_year)." <br/>\n";
}
else
{
// this is range starting and ending in the same month
echo date("j", $this_start_date);
// different starting and ending day
if ($this_start_date != $this_end_date)
{
echo "-".date("j", $this_end_date);
}
$newline = false;
// print month for the last range;
// and for any range that starts(=ends) in different month
// than the next range ends
if ($last ||
($this_start_month != $next_end_month))
{
echo " ".date("M", $this_start_date);
$newline = true;
}
// print year for the last range;
// and for any range that starts(=ends) in different year
// than next range ends
if ($last ||
($this_start_year != $next_end_year) ||
($next_start_month != $next_end_month))
{
echo " ".date("Y", $this_start_date);
$newline = true;
}
if ($newline)
{
echo " <br/>\n";
}
else
{
// month (and year) will be printed for some future range
// on the same line
echo ", ";
}
}
}
This outputs:
4, 7, 9, 20 Apr <br/>
5-10 May 2013 <br/>
1-2 Jan 2014 <br/>

Answer 2

A possibility to check if you need to print the month for the current date item is actually to check in the next item. Let me try to explain with pseudocode:
<?php
$month = 0; // Initialize $month variable to unset
// Loop over all your events
foreach($dates as $date) {
// Convert $date to a timestamp
// If the 'month' of the current $timestamp is unequal to $month
// it means we switch months and we have to print the $month first
if(date('m', $timestamp) != $month) {
echo $month; // Of course format how you want it to be displayed
// Set $month to the new month
$month = date('m', $timestamp);
}
// Print the rest of the event, like day numbers here
}
?>

Answer 3

Well, since you need to compare value from one loop to another, you won't be able to use echo directly.
You need to use temp variables. So with the first loop for the start date, you store $tmp_day_1 and $tmp_month_1 then with the end date loop you can compare both months and check if they are diferents. Then you can use echo. I hope I make my point :)