A model that i implemented to manage scheduling in my app (podigniter.com)

gistfile1.php

<?php
class Scheduler extends CI_Model {

    //var $title   = '';
    //var $content = '';
    //var $date    = '';

    function __construct()
    {
        // Call the Model constructor
        parent::__construct();
        $this->load->library('ion_auth');
        $this->load->library('mailman');
        $this->load->library('twilio');
    }
    
    public function startsWith($haystack, $needle)
	{
	    return $needle === "" || strpos($haystack, $needle) === 0;
	}
    
    public function gmt_offset($time, $is_guest = NULL)
    {
    	if(strpos($time,'-') !== false)
    	{
    		$time = str_replace('-', '', $time);
    		$time = str_replace(':00', '', $time);
    		//if first char = 0 then remove.
    		if ($this->startsWith($time, '0'))
    		{
    			$time = substr($time, 1);
    		}
    		$time = (int)$time * 3600;
    		$time = (string)('-'.$time);
    		return $time;
    	}
    	elseif(strpos($time,'+') !== false)
    	{
    		$time = str_replace('+', '', $time);
    		
    		$time = str_replace(':00', '', $time);
    		//if first char = 0 then remove.
    		if ($this->startsWith($time, '0'))
    		{
    			$time = substr($time, 1);
    		}
    		$time = (int)$time * 3600;
    		$time = (string)('+'.$time);
    		return $time;
    	}
    }
    
    public function add_sub_gmt_offset($string, $offset)
    {
    	if(strpos($offset,'-') !== false)
    	{
    		$offset = str_replace('-', '', $offset);
    		$offset = (int)$offset;
			$dtime = DateTime::createFromFormat('H:i', $string);
			$timestamp = $dtime->getTimestamp();
			$new_time = $timestamp - $offset;
			$new_time = date('H:i', $new_time);
			return $new_time;
			
    	}
    	elseif(strpos($offset,'+') !== false)
    	{
    		$$offset = str_replace('-', '', $offset);
    		$offset = (int)$offset;
			$dtime = DateTime::createFromFormat('H:i', $string);
			$timestamp = $dtime->getTimestamp();
			$new_time = $timestamp + $offset;
			$new_time = date('H:i', $new_time);
			return $new_time;
    	}
    }
    
    public function _get_gmt_offset($user_id, $is_guest = NULL)
    {
    	if ($is_guest == 'guest')
    	{
    		$q = $this->db->get_where('tbl_requesters_info', array('id' => $user_id));
    		return $q->result()[0]->gmt_timezone;
    	}
    	else
    	{
    		$q = $this->db->get_where('tbl_user_info', array('FK_user_id' => $user_id));
    		return $q->result()[0]->gmt_timezone;
    	}
    	
    }
    
    public function _get_set_time($time_id)
    {
    	$q = $this->db->get_where('tbl_user_available_times', array('id' => $time_id));
    	return $q->result()[0]->time; //apply gmt offset function to this.
    }
    
    public function get_custom_timestamp()
    {
    	$user = $this->ion_auth->user()->row();
    	$gmt_offset_string = $this->_get_gmt_offset($user->id);
    	$gmt = $this->gmt_offset($gmt_offset_string);
    	return $gmt;
    }
    
    public function _get_set_date($time_id)
    {
    	$q = $this->db->get_where('tbl_user_available_times', array('id' => $time_id));
    	$d = $q->result()[0]->FK_date_id;
    	
    	$qq = $this->db->get_where('lut_dates', array('id' => $d));
    	$qqma = $qq->result()[0]->date;
    	$myDateTime = DateTime::createFromFormat('Y-m-d', $qqma);
		$newDateString = $myDateTime->format('F jS Y');
    	return $newDateString;
    }
    
    public function _get_guest_data($guest_id)
    {
    	$q = $this->db->get_where('tbl_requesters_info', array('id' => $guest_id));
    	return $q->result()[0];
    }
    
    public function _get_episode_name($ep_id)
    {
    	$q = $this->db->get_where('episodes', array('id' => $ep_id));
    	return $q->result()[0]->name;
    }
    
    public function _get_user_id_from_ep($ep_id)
    {
    	$q = $this->db->get_where('episodes', array('id' => $ep_id));
    	return $q->result()[0]->user_id;
    }
    
    public function _get_user_data($user_id)
    {
    	$q = $this->db->get_where('users', array('id' => $user_id));
    	return $q->result()[0];
    }
    
    public function setting_you($str_input = 0, $user_id)
    {
    	if ($str_input != 0)
    	{    		
    		$this->db->select($str_input);
    		$this->db->where('user_id', $user_id);
    		$q = $this->db->get('reminders_settings');
    		if ($q->num_rows > 0)
    		{
	    		$res = (int)$q->result()[0]->$str_input;
	    		//print_r($res);
	    		return $res;
	    	}
	    	else
	    	{
	    		return 0;
	    	}	
    	}
    }
    
    public function setting_guest($str_input = 0, $user_id)
    {
    	if ($str_input != 0)
    	{
			$this->db->select($str_input);
    		$this->db->where('user_id', $user_id);
    		$q = $this->db->get('reminders_settings');
    		if ($q->num_rows > 0)
    		{
	    		$res = (int)$q->result()[0]->$str_input;
	    		//print_r($res);
	    		return $res;
	    	}
	    	else
	    	{
	    		return 0;
	    	}	
    	}
    }
    
    public function get_curr_accurate_time($timestring)
    {
    	$user = $this->ion_auth->user()->row();
    	$gmt_offset_string = $this->_get_gmt_offset($user->id);
    	$gmt = $this->gmt_offset($gmt_offset_string);
    	$curr_accurate_time = $this->add_sub_gmt_offset($timestring, $gmt);
    	return $curr_accurate_time;
    }
    
    public function you_reminder_email($req_id, $time_left)
    {
    	$query = $this->db->get_where('tbl_requested_meetings', array('FK_requested_time_id' => $req_id, 'approved' => 1));
    	
    	$r = $query->result()[0];
	    	//Send emails - format to user/interviewees times + gmt.										
		$guest = $this->_get_guest_data($r->FK_requester_info_id);
		$user_data = $this->_get_user_data($this->_get_user_id_from_ep($r->FK_episode_id));
		$episode = $this->_get_episode_name($r->FK_episode_id);
		$gmt_offset = $this->_get_gmt_offset($user_data->id);
		$set_time = $this->_get_set_time($r->FK_requested_time_id);
		$temp_gmt = $this->gmt_offset($gmt_offset);
		$set_time = $this->add_sub_gmt_offset($set_time, $temp_gmt);
		$set_date = $this->_get_set_date($r->FK_requested_time_id);
		$r = $this->mailman->setTransport(Mailman::MAILMAN_TRANSPORT_MANDRILL)->sendmail(array(
				'from' => 'reminders@podigniter.com',
			    'to' => $user_data->email,
			    'subject' => 'This is a reminder for your interview with '.$guest->name.', in '.$time_left,
			    'template_html' => 'emails/you_reminder',
			    'template_alt' => 'emails/you_reminder',
			    'template_data' => array(
		            'guest_name' => $guest->name,
		            'time_left' => $time_left,
		            'user_name' => $user_data->first_name,
		            'episode' => $episode,
		            'set_time' => $set_time,
		            'gmt' => $gmt_offset,
		            'date' => $set_date		
		            )
		        )
        
			);
		print_r($r);	
    }
    
    public function you_reminder_text($req_id)
    {
    	//for sms check if the user has credits, if they do, and the user has unchecked send sms reminder then send them the reminder, 
    	//then minus 1 from their credits. else if interviewee has checked send sms reminder, send it and minus 2. else dont send.
		//Disable ability to check it on interviewees end if user runs out of credits. just don't show it as an option.
		
		$query = $this->db->get_where('tbl_requested_meetings', array('FK_requested_time_id' => $req_id, 'approved' => 1));
    	
    	$r = $query->result()[0];
	    	//Send emails - format to user/interviewees times + gmt.										
		$guest = $this->_get_guest_data($r->FK_requester_info_id);
		$user_data = $this->_get_user_data();
		
		//check credits. if no, send email. with upgrade link.

    	$from = '15005550006';
		$to = '+15005550006';
		$message = 'This is a test...';

		$response = $this->twilio->sms($from, $to, $message);


		if($response->IsError)
		{
			echo 'Error: ' . $response->ErrorMessage;
		}
			
		else
		{
			echo 'Sent message to ' . $to;
		}
    }
    
    public function guest_reminder_email($req_id, $time_left)
    {
    	//Send emails - format to user/interviewees times + gmt.										
		$query = $this->db->get_where('tbl_requested_meetings', array('FK_requested_time_id' => $req_id, 'approved' => 1));
    	
    	$r = $query->result()[0];
	    	//Send emails - format to user/interviewees times + gmt.										
		$guest = $this->_get_guest_data($r->FK_requester_info_id);
		$user_data = $this->_get_user_data($this->_get_user_id_from_ep($r->FK_episode_id));
		$episode = $this->_get_episode_name($r->FK_episode_id);
		$gmt_offset = $this->_get_gmt_offset($guest->id, 'guest');
		$set_time = $this->_get_set_time($r->FK_requested_time_id);
		$temp_gmt = $this->gmt_offset($gmt_offset);
		$set_time = $this->add_sub_gmt_offset($set_time, $temp_gmt);
		$set_date = $this->_get_set_date($r->FK_requested_time_id);
		$r = $this->mailman->setTransport(Mailman::MAILMAN_TRANSPORT_MANDRILL)->sendmail(array(
				'from' => 'reminders@podigniter.com',
			    'to' => $guest->email,
			    'subject' => 'This is a reminder for your interview with '.$user_data->first_name.', in '.$time_left,
			    'template_html' => 'emails/guest_reminder',
			    'template_alt' => 'emails/guest_reminder',
			    'template_data' => array(
		            'guest_name' => $guest->name,
		            'time_left' => $time_left,
		            'user_name' => $user_data->first_name,
		            'episode' => $episode,
		            'set_time' => $set_time,
		            'gmt' => $gmt_offset,
		            'date' => $set_date		
		            )
		        )
        
			);
		print_r($guest->email);
    }
    
    public function guest_reminder_text($req_id)
    {
    	//for sms check if the user has credits, if they do, and the user has unchecked send sms reminder then send them the reminder, 
    	//then minus 1 from their credits. else if interviewee has checked send sms reminder, send it and minus 2. else dont send.
		//Disable ability to check it on interviewees end if user runs out of credits. just don't show it as an option.

    	$from = '15005550006';
		$to = '+15005550006';
		$message = 'This is a test...';

		$response = $this->twilio->sms($from, $to, $message);


		if($response->IsError)
		{
			echo 'Error: ' . $response->ErrorMessage;
		}
			
		else
		{
			echo 'Sent message to ' . $to;
		}
    }
    
    public function create_reminder_settings($user_id)
    {
    	$data = array(
    		'user_id' => $user_id
    	);
    	$this->db->insert('reminders_settings', $data);
    }
    
    public function set_state($col, $state, $user_id)
    {
    	$state = (int)$state;
    	$data = array(
    		$col => $state
    	);
    	$this->db->where('user_id', $user_id); 
		$this->db->update('reminders_settings', $data);
    }
    
    public function get_setting($col, $user)
    {    
    	$col = (string)$col;	
    	$this->db->select($col);
    	$this->db->where('user_id', $user->id);
		$query = $this->db->get('reminders_settings');
    	return $query->result()[0]->$col;
    }
    
    public function get_approved_time($time_id)
    {
    	$query = $this->db->get_where('tbl_user_available_times', array('id' => $time_id));
    	return $query->result()[0]->time;
    }
    
    public function get_req_time_id($req_id)
    {
    	$query = $this->db->get_where('tbl_requested_meetings', array('id' => $req_id));
    	return $query->result()[0]->FK_requested_time_id;
    }
    
    public function is_suggested($time_id)
    {
    	$query = $this->db->get_where('tbl_user_available_times', array('id' => $time_id));
    	if ($query->result()[0]->suggested == 1)
    	{
    		return TRUE;
    	}
    	else
    	{
    		return FALSE;
    	}
    }
    
    public function new_select($req_id, $req_time_id, $req_info_id)
    {
    	$data = array(
               'approved' => 1
            );

		$this->db->where('id', $req_id);
		$this->db->update('tbl_requested_meetings', $data);
		
		if ($this->db->affected_rows() > 0)
		{
		  $data1 = array(
               'reserved' => 1
            );

		  $this->db->where('id', $req_time_id);
		  $this->db->update('tbl_user_available_times', $data1);
		  $user_id = $this->ion_auth->user()->row()->id;
		  $q = $this->db->get_where('tbl_user_available_times', array('reserved' => 1, 'FK_user_id' => $user_id));
		  foreach ($q->result() as $r)
		  {
		  	if ($r->id != $req_time_id)
		  	{
		  		$data0 = array(
               'reserved' => 0
	            );
	
			  $this->db->where('id', $r->id);
			  $this->db->update('tbl_user_available_times', $data0);
		  	}
		  }	
		  $query = $this->db->get_where('tbl_requested_meetings', array('FK_requester_info_id' => $req_info_id));
		  foreach ($query->result() as $row)
		  {
		  	if ($row->id != $req_id)
		  	{
		  		$data_2 = array(
               		'approved' => 0
            	);
		  		$this->db->where('id', $row->id);
				$this->db->update('tbl_requested_meetings', $data_2);
		  	} 
		  }
		  return TRUE;
		}
		else
		{
		  return FALSE;
		}
    }
    
    public function get_completed_time($time, $episode_id)
    {
    	
		$query = $this->db->get_where('episodes', array('id' => $episode_id));
		  
		$duration = (int)$query->result()[0]->meeting_duration;
		
		$duration = $duration * 60;
		
		$time = strtotime($time);
		
		$nw_time = date("H:i", ($time += ($duration)));
		
		return $nw_time;
    }
    
    public function get_requester_info($requester_info_id)
    {
    	
		$query = $this->db->get_where('tbl_requesters_info', array('id' => $requester_info_id));
		  
		return $query->result()[0];
    }
    
    public function get_upcoming()
    {
    	$user = $this->ion_auth->user()->row();
    	$this->db->select('*');
		$this->db->from('tbl_requested_meetings');
		$this->db->join('tbl_user_available_times', 'tbl_user_available_times.id= tbl_requested_meetings.FK_requested_time_id');
		$this->db->where('tbl_user_available_times.FK_user_id', $user->id);
		$this->db->where('tbl_requested_meetings.approved', 1);
		$this->db->order_by("tbl_requested_meetings.id", "desc"); 
		$q = $this->db->get();
		
		return $q;
    }
    
    public function get_pending()
    {
    	$user = $this->ion_auth->user()->row();
    	$this->db->select('*');
		$this->db->from('tbl_requested_meetings');
		$this->db->join('tbl_user_available_times', 'tbl_user_available_times.id= tbl_requested_meetings.FK_requested_time_id');
		$this->db->where('tbl_user_available_times.FK_user_id', $user->id);
		$this->db->where('tbl_requested_meetings.approved', 0);
		$this->db->order_by("tbl_requested_meetings.id", "desc");
		$q = $this->db->get();
		
		return $q;
    }
    
    public function get_completed()
    {
    	$user = $this->ion_auth->user()->row();
    	$this->db->select('*');
		$this->db->from('tbl_requested_meetings');
		$this->db->join('tbl_user_available_times', 'tbl_user_available_times.id= tbl_requested_meetings.FK_requested_time_id');
		$this->db->where('tbl_user_available_times.FK_user_id', $user->id);
		$this->db->where('tbl_requested_meetings.approved', 2);
		$this->db->order_by("tbl_requested_meetings.id", "desc");
		$q = $this->db->get();
		
		return $q;
    }
    
    public function get_all_approved_times()
    {
    	$query = $this->db->get_where('tbl_requested_meetings', array('approved' => 1));
    	return $query;
    }

}