Question

I have an array that is produced from people wanting to reserve a time block to volunteer with our organization. I want to check to see if they chose time blocks on the same day that overlap. In my example array below the first and third elements are overlapping and I need to detect that. Any recommendation would be much appreciated:

 Array
(
    [0] => Array
        (
            [id_pc_time_blocks] => 3
            [id_pc] => 2
            [pc_date] => 2012-11-21
            [pc_time_block] => 9:00 AM-1:00 PM
            [pc_time_block_max] => 25
            [pc_time_block_count] => 0
            [pc_name] => Atlanta
        )

    [1] => Array
        (
            [id_pc_time_blocks] => 4
            [id_pc] => 2
            [pc_date] => 2012-11-21
            [pc_time_block] => 1:00 PM-5:00 PM
            [pc_time_block_max] => 25
            [pc_time_block_count] => 10
            [pc_name] => Atlanta
        )

    [2] => Array
        (
            [id_pc_time_blocks] => 6
            [id_pc] => 2
            [pc_date] => 2012-11-21
            [pc_time_block] => 10:00 AM-2:00 PM
            [pc_time_block_max] => 25
            [pc_time_block_count] => 0
            [pc_name] => Atlanta
        )

       [3] => Array
        (
            [id_pc_time_blocks] => 6
            [id_pc] => 2
            [pc_date] => 2012-11-23
            [pc_time_block] => 10:00 AM-2:00 PM
            [pc_time_block_max] => 25
            [pc_time_block_count] => 0
            [pc_name] => Atlanta
        )

       [4] => Array
        (
            [id_pc_time_blocks] => 6
            [id_pc] => 2
            [pc_date] => 2012-11-23
            [pc_time_block] => 3:00 AM-6:00 PM
            [pc_time_block_max] => 25
            [pc_time_block_count] => 0
            [pc_name] => Atlanta
        )

)

Answer 1

Here is my solution for checking each date for overlapping times. The only thing is, this is for my particular scenario and does not account for overlapping years as I dont have that need for this application.

Here is my working example:

$dateIdx = 0;
    foreach($timeblocks_array as $obj) {
           $timeblocks_array[$dateIdx]["intDay"] = idate("z",strtotime($obj["pc_date"]));
           $timeblocks_array[$dateIdx]["intStart"] = intval($obj["start_time"]);
           $timeblocks_array[$dateIdx]["intEnd"] = intval($obj["end_time"]);
           $mindates[] = idate("z",strtotime($obj["pc_date"]));
           $dateIdx++;
    }
    $minDateSingle = min($mindates);
    $maxDateSingle = max($mindates);

    $currentDate = $minDateSingle;
    $dateIdx = 0;
    while ($currentDate <= $maxDateSingle) {
           $hrIndex = 0;
           while ($hrIndex < 24) {
                  $matrixArray[$dateIdx][$hrIndex]["count"] = 0;
                  $matrixArray[$dateIdx][$hrIndex]["intDay"] = $currentDate;
                  $hrIndex++;         
           }
           // calculate counts:
           $hourIdx = 0;
           foreach($matrixArray[$dateIdx] as $hour){
                  foreach($timeblocks_array as $block) {
                         if ($hour["intDay"] == $block["intDay"]) {
                               if ($hourIdx >= $block["intStart"] && $hourIdx < $block["intEnd"]) {
                                      $matrixArray[$dateIdx][$hourIdx]["count"] = $matrixArray[$dateIdx][$hourIdx]["count"] + 1;
                                      $matrixArray[$dateIdx][$hourIdx]["requests"][] = $block;
                               }
                         }
                  }
                  $hourIdx++;
           }
           $dateIdx++;
           $currentDate = $currentDate + 1; 
    }

    //loop through the matrix array and timeblocks array to see if they intersect
    foreach($matrixArray as $day) {
           $hourIdx = 0;
           foreach($day as $hour) {
                  if ($hour["count"] > 1) {
                         //echo $hour["intDay"]." - Overlap on Hour $hourIdx\n";
                         $smarty->assign('overlappingError', 1);
                         $error = 1;
                         foreach($hour["requests"] as $overlapblock) {
                               //echo " --> conflict: ". $overlapblock["pc_date"]." ".$overlapblock["pc_time_block"]." (".$overlapblock["intStart"]." to ".$overlapblock["intEnd"].")\n";
                         }
                  } else if ($hour["count"] == 1) {
                         // these are valid hours
                  }     
                  $hourIdx++;
           }     
    }