calendar.php

<?php
require_once("classes/connection.php");
require_once("classes/sql.php");
require_once("classes/utils.php");
require("classes/components.php");

/// This must come first when we need access to the current session
session_start();;

Components::pageHeaderAlt("Book Appointment", ["style"], ["mobile-nav"]);

/**
 * Function to build a calendar for a given month and year, displaying available appointment slots.
 */
function build_calendar($month, $year){


    $bookings = array();
    

    /**
     * Set up information about the days of the week and the first day of the month.
     */
    $daysOfWeek = array('Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat','Sun');
    $firstDayOfMonth = mktime(0,0,0,$month,1,$year);
    $numberDays = date('t',$firstDayOfMonth);
    $dateComponents = getdate($firstDayOfMonth);
    $monthName = $dateComponents['month'];
    $dayOfWeek = $dateComponents['wday'];

    if($dayOfWeek==0){
        $dayOfWeek = 6;
    }else{
        $dayOfWeek = $dayOfWeek-1;
    }
    
    /**
     * Generates a calendar for booking appointments centered around the current date.
     */
    $dateToday = date('Y-m-d');
    $calendar = "<center>Book Appointment</center>";
    $prev_month = date('m', mktime(0,0,0,$month-1,1,$year));
    $prev_year = date('Y', mktime(0,0,0,$month-1,1,$year));
    $next_month = date('m', mktime(0,0,0,$month+1,1,$year));
    $next_year = date('y', mktime(0,0,0,$month+1,1,$year));

    /**
     * Generate a calendar HTML string for the specified month and year.
     */
    $calendar .= "<center><h2>$monthName $year</h2>";
    $calendar .= "<a class='btn btn-primary btn-xs' href='?month=".$prev_month."&year=".$prev_year."'>Prev Month</a>";
    $calendar .= "<a class='btn btn-primary btn-xs' href='?month=".date('m')."&year=".date('Y')."'>Current Month</a>";
    $calendar .= "<a class='btn btn-primary btn-xs' href='?month=".$next_month."&year=".$next_year."'>Next Month</a>";
    $calendar .= "<br><table class='table table-bordered'>";
    $calendar .= "<tr>";

    /**
     * Generate table header cells for each day of the week.
     */
    foreach($daysOfWeek as $day){
        $calendar .= "<th class='day-names'>$day</th>";
    }

    /**
     * Generates a calendar table row with empty cells for days before the first day of the month.
     */
    $calendar .= "</tr><tr>";
    $currentDay = 1;
    if($dayOfWeek > 0){
        for($k = 0; $k < $dayOfWeek; $k++){
            $calendar .= "<td class='empty'></td>";
        }
    }

    /**
     * Pads a string to a certain length with another string on the left.
     */
    $month = str_pad($month, 2, "0", STR_PAD_LEFT);
    while($currentDay <= $numberDays){
        if($dayOfWeek == 7){
            $dayOfWeek = 0;
            $calendar .= "</tr><tr>";
        }
    
        $currentDayRel = str_pad($currentDay,2,"0", STR_PAD_LEFT);
        $date = "$year-$month-$currentDayRel";
        $dayName = strtolower(date('l',strtotime($date))); /// Get the day name in lowercase
    
        /// Check if the current day is Sunday
        if($dayName == 'sunday'){
            $calendar .= "<td class='day-row closed'><h4>$currentDay</h4><a class='btn btn-danger btn-xs'>Closed</a></td>";
        } else {
            /// Otherwise, normal cell
            if($date < date('Y-m-d')){
                $calendar .= "<td class='day-row booked'><h4>$currentDay</h4><a class='btn btn-danger btn-xs'>N/A</a></td>";
            } else {
                $totalbookings = checkSlots($date);
                if($totalbookings == 18){
                    $calendar .= "<td class='day-row booked'><h4>$currentDay</h4><a class='btn btn-danger btn-xs'>All Booked</a></td>";
                } else{
                    $availableSlots = 18 - $totalbookings;

                    $calendar .= "<td class='day-row'><h4>$currentDay</h4><a href='book.php?date=$date' class='btn btn-success btn-xs'>Book</a>
                    <small><i>$availableSlots slots left</i></small>";
                }
            }
        }
    
        $currentDay++;
        $dayOfWeek++;
    }

    /**
     * Generate empty table cells for the remaining days in the week after a given day.
     */
    if($dayOfWeek < 7){
        $remainingDays =  7 - $dayOfWeek;
        for($i=0; $i < $remainingDays; $i++){
            $calendar.="<td class='empty'></td>";
        }
    }

    $calendar .= "</tr></table>";
    $calendar .= "</center>";

    return $calendar;
}

/**
 * Check the total number of bookings for a given date.
 *
 * @param string $date The date for which bookings need to be checked.
 * @return int The total number of bookings for the given date.
 */
function checkSlots($date){

    $conn = Connection::connect();


    $stmt = $conn->prepare(SQL::$getBookingsByDate);
    $stmt->bindParam(1, $date, PDO::PARAM_STR);
    
    $totalbookings = 0;

    if ($stmt->execute()) {
        $result = $stmt->fetchAll(PDO::FETCH_ASSOC);
        $totalbookings = count($result);
    }
    
    return $totalbookings;
}

?>
<main class="content-wrapper calendar-content">
    <div class="container">
        <div class="row">
            <div class="col-md-12">
            <?php
            $dateComponents = getdate();
            if(isset($_GET['month'])&&($_GET['year'])){
                $month = $_GET['month'];
                $year = $_GET['year'];
            } else {
                $month = $dateComponents['mon'];
                $year = $dateComponents['year'];
            }

            echo build_calendar($month, $year);
            ?>
            </div>
        </div>
    </div>
</main>
<?php

Components::pageFooter();

?>