<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Appointments extends CI_Controller {
    /**
     * Default callback method of the application. 
     * 
     * This method creates the appointment book wizard. If an appointment hash
     * is provided then it means that the customer followed the appointment 
     * manage link that was send with the book success email.
     * 
     * @param string $appointment_hash The db appointment hash of an existing 
     * record.
     */
    public function index($appointment_hash = '') {
        $this->load->model('appointments_model');
        $this->load->model('providers_model');
        $this->load->model('services_model');
        $this->load->model('customers_model');
        $this->load->model('settings_model');
                
        if (strtoupper($_SERVER['REQUEST_METHOD']) !== 'POST') { 
            try {
                $available_services  = $this->services_model->get_available_services();
                $available_providers = $this->providers_model->get_available_providers();
                $company_name        = $this->settings_model->get_setting('company_name');

                // If an appointment hash is provided then it means that the customer 
                // is trying to edit a registered appointment record.
                if ($appointment_hash !== ''){ 
                    // Load the appointments data and enable the manage mode of the page.
                    $manage_mode = TRUE;

                    $results = $this->appointments_model->get_batch(array('hash' => $appointment_hash));
                    
                    if (count($results) === 0) {
                        // The requested appointment doesn't exist in the database. Display
                        // a message to the customer.
                        $view = array(
                            'message_title' => 'Appointment Not Found!',
                            'message_text'  => 'The appointment you requested does not exist in '
                                             . 'the system database anymore.',
                            'message_icon'  => $this->config->item('base_url') 
                                             . 'assets/images/error.png'
                        );
                        $this->load->view('appointments/message', $view);                        
                        return;
                    }

                    $appointment = $results[0]; 
                    $provider = $this->providers_model->get_row($appointment['id_users_provider']);
                    $customer = $this->customers_model->get_row($appointment['id_users_customer']);
                    
                } else {
                    // The customer is going to book a new appointment so there is no 
                    // need for the manage functionality to be initialized.
                    $manage_mode        = FALSE;
                    $appointment   = array();
                    $provider      = array();
                    $customer      = array();
                }

                // Load the book appointment view.
                $view = array (
                    'available_services'    => $available_services,
                    'available_providers'   => $available_providers,
                    'company_name'          => $company_name,
                    'manage_mode'           => $manage_mode,
                    'appointment_data'      => $appointment,
                    'provider_data'         => $provider,
                    'customer_data'         => $customer
                );
                
            } catch(Exception $exc) {
                $view['exceptions'][] = $exc;
            }
            
            $this->load->view('appointments/book', $view);
            
        } else { 
            // The page is a post-back. Register the appointment and send notification emails
            // to the provider and the customer that are related to the appointment. If google 
            // sync is enabled then add the appointment to the provider's account.
            
            try {
                $post_data = json_decode($_POST['post_data'], true);
                $appointment = $post_data['appointment'];
                $customer = $post_data['customer'];

                $customer_id = $this->customers_model->add($customer);
                $appointment['id_users_customer'] = $customer_id; 
                
                $appointment['id']   = $this->appointments_model->add($appointment);
                $appointment['hash'] = $this->appointments_model->get_value('hash', $appointment['id']);
                
                $provider = $this->providers_model->get_row($appointment['id_users_provider']);
                $service = $this->services_model->get_row($appointment['id_services']);
                
                $company_settings = array( 
                    'company_name'  => $this->settings_model->get_setting('company_name'),
                    'company_link'  => $this->settings_model->get_setting('company_link'),
                    'company_email' => $this->settings_model->get_setting('company_email')
                );
                
                // :: SYNCHRONIZE APPOINTMENT WITH PROVIDER'S GOOGLE CALENDAR
                // The provider must have previously granted access to his google calendar account  
                // in order to sync the appointment.
                try {
                    $google_sync = $this->providers_model->get_setting('google_sync', 
                            $appointment['id_users_provider']);

                    if ($google_sync == TRUE) {
                        $google_token = json_decode($this->providers_model
                                ->get_setting('google_token', $appointment['id_users_provider']));

                        $this->load->library('google_sync');
                        $this->google_sync->refresh_token($google_token->refresh_token);

                        if ($post_data['manage_mode'] === FALSE) {
                            // Add appointment to Google Calendar.
                            $google_event = $this->google_sync->add_appointment($appointment, $provider, 
                                    $service, $customer, $company_settings);
                            $appointment['id_google_calendar'] = $google_event->id;
                            $this->appointments_model->add($appointment); 
                        } else {
                            // Update appointment to Google Calendar.
                            $appointment['id_google_calendar'] = $this->appointments_model
                                    ->get_value('id_google_calendar', $appointment['id']);

                            $this->google_sync->update_appointment($appointment, $provider,
                                    $service, $customer, $company_settings);
                        }
                    }  
                } catch(Exception $exc) {
                    $view['exceptions'][] = $exc;
                }
                
                // :: SEND NOTIFICATION EMAILS TO BOTH CUSTOMER AND PROVIDER
                try {
                    $this->load->library('Notifications');

                    if (!$post_data['manage_mode']) {
                        $customer_title = 'Your appointment has been successfully booked!';
                        $customer_message = 'Thank you for arranging an appointment with us. '   
                                . 'Below you can see the appointment details. Make changes '  
                                . 'by clicking the appointment link.';
                        $customer_link = $this->config->item('base_url') . 'appointments/index/' 
                                . $appointment['hash'];

                        $provider_title = 'A new appointment has been added to your plan.';
                        $provider_message = 'You can make changes by clicking the appointment '  
                                . 'link below';
                        $provider_link = $this->config->item('base_url') . 'backend/' 
                                . $appointment['hash'];
                    } else {
                        $customer_title = 'Appointment changes have been successfully saved!';
                        $customer_message = '';
                        $customer_link = $this->config->item('base_url') . 'appointments/index/' 
                                . $appointment['hash'];

                        $provider_title = 'Appointment details have changed.';
                        $provider_message = '';
                        $provider_link = $this->config->item('base_url') . 'backend/' 
                                . $appointment['hash'];
                    }

                    $this->notifications->send_appointment_details($appointment, $provider, 
                            $service, $customer,$company_settings, $customer_title, 
                            $customer_message, $customer_link, $customer['email']);

                    $this->notifications->send_appointment_details($appointment, $provider, 
                            $service, $customer, $company_settings, $provider_title, 
                            $provider_message, $provider_link, $provider['email']);
                } catch(Exception $exc) {
                    $view['exceptions'][] = $exc;
                }
                
                // :: LOAD THE BOOK SUCCESS VIEW
                $view = array(
                    'appointment_data'  => $appointment,
                    'provider_data'     => $provider,
                    'service_data'      => $service,
                    'company_name'      => $company_settings['company_name']
                );

            } catch(Exception $exc) {
                $view['exceptions'][] = $exc;
            }
            
            $this->load->view('appointments/book_success', $view);
        }   
    }
    
    /**
     * Cancel an existing appointment. 
     * 
     * This method removes an appointment from the company's schedule.
     * In order for the appointment to be deleted, the hash string must
     * be provided. The customer can only cancel the appointment if the
     * edit time period is not over yet.
     * 
     * @param string $appointment_hash This is used to distinguish the 
     * appointment record.
     * @param string $_POST['cancel_reason'] The text that describes why
     * the customer cancelled the appointment.
     */
    public function cancel($appointment_hash) {
        try {
            $this->load->model('appointments_model');
            $this->load->model('providers_model');
            $this->load->model('customers_model');
            $this->load->model('services_model');
            $this->load->model('settings_model');
            
            // Check whether the appointment hash exists in the database.
            $records = $this->appointments_model->get_batch(array('hash' => $appointment_hash));
            if (count($records) == 0) {
                throw new Exception('No record matches the provided hash.');
            }
            
            $appointment = $records[0];
            $provider = $this->providers_model->get_row($appointment['id_users_provider']);
            $customer = $this->customers_model->get_row($appointment['id_users_customer']);
            $service = $this->services_model->get_row($appointment['id_services']);
            
            $company_settings = array(
                'company_name' => $this->settings_model->get_setting('company_name'),
                'company_email' => $this->settings_model->get_setting('company_email'),
                'company_link' => $this->settings_model->get_setting('company_link')
            );
            
            // :: DELETE APPOINTMENT RECORD FROM THE DATABASE.
            if (!$this->appointments_model->delete($appointment['id'])) {
                throw new Exception('Appointment could not be deleted from the database.');
            }
            
            // :: SYNC APPOINTMENT REMOVAL WITH GOOGLE CALENDAR
        	if ($appointment['id_google_calendar'] != NULL) {
                try {
                    $google_sync = $this->providers_model->get_setting('google_sync', 
                            $appointment['id_users_provider']);

                    if ($google_sync == TRUE) {
                        $google_token = json_decode($this->providers_model
                                ->get_setting('google_token', $provider['id']));
                        $this->load->library('Google_Sync');
                        $this->google_sync->refresh_token($google_token->refresh_token);
                        $this->google_sync->delete_appointment($appointment['id_google_calendar']);
                    }
                } catch(Exception $exc) {
                    $exceptions[] = $exc;
                }
            }
            
            // :: SEND NOTIFICATION EMAILS TO CUSTOMER AND PROVIDER            
            try {
                $this->load->library('Notifications');
                $this->notifications->send_delete_appointment($appointment, $provider, 
                        $service, $customer, $company_settings, $provider['email'],
                        $_POST['cancel_reason']);
                $this->notifications->send_delete_appointment($appointment, $provider,
                        $service, $customer, $company_settings, $customer['email'],
                        $_POST['cancel_reason']);
            } catch(Exception $exc) {
                $exceptions[] = $exc;
            }
        } catch(Exception $exc) {
            // Display the error message to the customer.
            $exceptions[] = $exc;
        }
        
        if (isset($exceptions)) {
            $view['exceptions'] = $exceptions;
        }
        
        $this->load->view('appointments/cancel', $view);
    }
    
    /**
     * [AJAX] Get the available appointment hours for the given date.
     * 
     * This method answers to an AJAX request. It calculates the available hours  
     * for thegiven service, provider and date.
     * 
     * @param numeric $_POST['service_id'] The selected service's record id.
     * @param numeric $_POST['provider_id'] The selected provider's record id.
     * @param string $_POST['selected_date'] The selected date of which the  
     * available hours we want to see.
     * @param numeric $_POST['service_duration'] The selected service duration in 
     * minutes.
     * @return Returns a json object with the available hours.
     */
    public function ajax_get_available_hours() {
        $this->load->model('providers_model');
        $this->load->model('appointments_model');
        $this->load->model('settings_model');
        
        try {
            // If manage mode is TRUE then the following we should not consider the selected 
            // appointment when calculating the available time periods of the provider.
            $exclude_appointments = ($_POST['manage_mode'] === 'true') 
                    ? array($_POST['appointment_id'])
                    : array();    

            $empty_periods = $this->get_provider_available_time_periods($_POST['provider_id'], 
                    $_POST['selected_date'], $exclude_appointments);

            // Calculate the available appointment hours for the given date. 
            // The empty spaces are broken down to 15 min and if the service
            // fit in each quarter then a new available hour is added to the
            // $available hours array.

            $available_hours = array();

            foreach($empty_periods as $period) {
                $start_hour = new DateTime($_POST['selected_date'] . ' ' . $period['start']);
                $end_hour   = new DateTime($_POST['selected_date'] . ' ' . $period['end']);

                $minutes = $start_hour->format('i');

                if ($minutes % 15 != 0) {
                    // Change the start hour of the current space in order to be
                    // on of the following: 00, 15, 30, 45.
                    if ($minutes < 15) {
                        $start_hour->setTime($start_hour->format('H'), 15);
                    } else if ($minutes < 30) {
                        $start_hour->setTime($start_hour->format('H'), 30);
                    } else if ($minutes < 45) {
                        $start_hour->setTime($start_hour->format('H'), 45);
                    } else {
                        $start_hour->setTime($start_hour->format('H') + 1, 00);
                    }
                }

                $curr_hour  = $start_hour;
                $diff = $curr_hour->diff($end_hour);

                while(($diff->h * 60 + $diff->i) > intval($_POST['service_duration'])) {
                    $available_hours[] = $curr_hour->format('H:i');
                    $curr_hour->add(new DateInterval("PT15M"));
                    $diff = $curr_hour->diff($end_hour);
                }
            }

            // If the selected date is today, remove past hours. It is important 
            // include the timeout before booking that is set in the backoffice
            // the system. Normally we might want the customer to book an appointment
            // that is at least half or one hour from now. The setting is stored in 
            // minutes.
            if (date('m/d/Y', strtotime($_POST['selected_date'])) == date('m/d/Y')) {
                if ($_POST['manage_mode'] === 'true') {
                    $book_advance_timeout = 0;
                } else {
                    $book_advance_timeout = $this->settings_model->get_setting(
                            'book_advance_timeout');
                }

                foreach($available_hours as $index=>$value) {
                    $available_hour = strtotime($value);
                    $current_hour = strtotime('+' . $book_advance_timeout . ' minutes', 
                            strtotime('now'));

                    if ($available_hour <= $current_hour) {
                        unset($available_hours[$index]);
                    }
                }
            }

            $available_hours = array_values($available_hours);
            
            echo json_encode($available_hours);
            
        } catch(Exception $exc) {
            echo json_encode(array(
                'exceptions' => array( exceptionToJavascript($exc) )
            ));
        }
    }
    
    /**
     * Check whether the provider is still available in the selected appointment date.
     * 
     * It might be times where two or more customers select the same appointment date and time.
     * This shouldn't be allowed to happen, so one of the two customers will eventually get the
     * prefered date and the other one will have to choose for another date. Use this method 
     * just before the customer confirms the appointment details. If the selected date was taken
     * in the mean time, the customer must be prompted to select another time for his appointment.
     * 
     * @param int $_POST['id_users_provider'] The selected provider's record id.
     * @param int $_POST['id_services'] The selected service's record id.
     * @param string $_POST['start_datetime'] This is a mysql formed string.
     * @return bool Returns whether the selected datetime is still available.
     */
    public function ajax_check_datetime_availability() {
        try {
            $this->load->model('services_model');
            
            $service_duration = $this->services_model->get_value('duration', $_POST['id_services']);
            
            $available_periods = $this->get_provider_available_time_periods(
                    $_POST['id_users_provider'], $_POST['start_datetime']);

            $is_still_available = FALSE;

            foreach($available_periods as $period) {
                $appt_start = new DateTime($_POST['start_datetime']);
                $appt_start = $appt_start->format('H:i');
                
                $appt_end = new DateTime($_POST['start_datetime']);
                $appt_end->add(new DateInterval('PT' . $service_duration . 'M'));
                $appt_end = $appt_end->format('H:i');
                
                $period_start = date('H:i', strtotime($period['start']));
                $period_end = date('H:i', strtotime($period['end']));

                if ($period_start <= $appt_start && $period_end >= $appt_end) { 
                    $is_still_available = TRUE;
                    break;
                }
            }

            echo json_encode($is_still_available);
            
        } catch(Exception $exc) {
            echo json_encode(array(
                'exceptions' => array(exceptionToJavascript($exc))
            ));
        }  
    }
    
    /**
     * Get an array containing the free time periods (start - end) of a selected date.
     * 
     * This method is very important because there are many cases where the system needs to 
     * know when a provider is avaible for an appointment. This method will return an array 
     * that belongs to the selected date and contains values that have the start and the end
     * time of an available time period.
     * 
     * @param numeric $provider_id The provider's record id.
     * @param string $selected_date The date to be checked (MySQL formatted string).
     * @param array $exclude_appointments This array contains the ids of the appointments that 
     * will not be taken into consideration when the available time periods are calculated.
     * @return array Returns an array with the available time periods of the provider.
     */
    private function get_provider_available_time_periods($provider_id, $selected_date, 
            $exclude_appointments = array()) {
        $this->load->model('appointments_model');
        $this->load->model('providers_model');
        
        // Get the provider's working plan and reserved appointments.        
        $working_plan = json_decode($this->providers_model->get_setting('working_plan', 
                $provider_id), true);
        
        $where_clause = array(
            'DATE(start_datetime)' => date('Y-m-d', strtotime($selected_date)),
            'id_users_provider' => $provider_id
        );     
        
        $reserved_appointments = $this->appointments_model->get_batch($where_clause);
        
        // Sometimes it might be necessary to not take into account some appointment records
        // in order to display what the providers available time periods would be without them.
        foreach($exclude_appointments as $excluded_appointment) {
            foreach($reserved_appointments as $index=>$appointment) {
                if ($appointment['id'] == $excluded_appointment['id']) {
                    unset($reserved_appointments[$index]);
                }
            }
        }
        
        // Find the empty spaces on the plan. The first split between the plan is due to 
        // a break (if exist). After that every reserved appointment is considered to be 
        // a taken space in the plan.
        $selected_date_working_plan = $working_plan[strtolower(date('l', strtotime($selected_date)))];
        $available_periods_with_breaks = array();
        
        if (isset($selected_date_working_plan['breaks'])) {
            foreach($selected_date_working_plan['breaks'] as $index=>$break) {
                // Split the working plan to available time periods that do not
                // contain the breaks in them.
                $last_break_index = $index - 1;
                
                if (count($available_periods_with_breaks) === 0) {
                    $start_hour = $selected_date_working_plan['start'];
                    $end_hour = $break['start'];
                } else {
                    $start_hour = $selected_date_working_plan['breaks'][$last_break_index]['end'];
                    $end_hour = $break['start'];
                }
                
                $available_periods_with_breaks[] = array(
                    'start' => $start_hour,
                    'end' => $end_hour
                );
            }
            
            // Add the period from the last break to the end of the day.
            $available_periods_with_breaks[] = array(
                'start' => $selected_date_working_plan['breaks'][$index]['end'],
                'end' => $selected_date_working_plan['end']
            );
        }
        
        // Break the empty periods with the reserved appointments.
        $available_periods_with_appointments = array();
        
        if (count($reserved_appointments) > 0) {
            
            foreach($available_periods_with_breaks as $period) {
                
                foreach($reserved_appointments as $index=>$appointment) {
                    $appointment_start = date('H:i', strtotime($appointment['start_datetime']));
                    $appointment_end = date('H:i', strtotime($appointment['end_datetime']));
                    $period_start = date('H:i', strtotime($period['start']));
                    $period_end = date('H:i', strtotime($period['end']));
                    
                    if ($period_start <= $appointment_start && $period_end >= $appointment_end) {
                        // We need to check whether another appointment fits in the current 
                        // time period. If this happens, then we need to consider the whole 
                        // appointment time as one, because the provider will not be available.
                        foreach ($reserved_appointments as $tmp_appointment) {
                            $appt_start = date('H:i', strtotime($tmp_appointment['start_datetime']));
                            $appt_end = date('H:i', strtotime($tmp_appointment['end_datetime']));
                            
                            if ($period_start < $appt_start && $period_end > $appt_end) {
                                if ($appointment_start > $appt_start) {
                                    $appointment_start = $appt_start;
                                }
                                
                                if ($appointment_end < $appt_end) { 
                                    $appointment_end = $appt_end;
                                }
                            }
                        }

                        // Current appointment is within the current empty space. So 
                        // we need to break the empty space into two other spaces that 
                        // don't include the appointment.
                        $new_period = array(
                            'start' => $period_start,
                            'end' => $appointment_start
                        );
                        
                        if (!in_array($new_period, $available_periods_with_appointments)) {
                            $available_periods_with_appointments[] = $new_period;
                        }
                            
                        $new_period = array(
                            'start' => $appointment_end,
                            'end' => $period_end
                        );
                        
                        if (!in_array($new_period, $available_periods_with_appointments)) {
                            $available_periods_with_appointments[] = $new_period;
                        }
                        
                    } else {
                        // Check if there are any other appointments between this 
                        // time space. If not, it is going to be added as it is.
                        $found = FALSE;
                        
                        foreach ($reserved_appointments as $tmp_appointment) {
                            $appt_start = date('H:i', strtotime($tmp_appointment['start_datetime']));
                            $appt_end  = date('H:i', strtotime($tmp_appointment['end_datetime']));
                            
                            if ($period_start < $appt_start && $period_end > $appt_end) {
                                $found = TRUE;
                            }
                        }
                        
                        // It is also necessary to check that this time period doesn't
                        // already exist in the "$empty_spaces_with_appointments" array.
                        $empty_period = array(
                            'start' => $period_start,
                            'end' => $period_end
                        );
                        
                        $already_exist = in_array($empty_period, $available_periods_with_appointments);
                        
                        if ($found === FALSE && $already_exist === FALSE) {
                            $available_periods_with_appointments[] = $empty_period;
                        }
                    }
                }
            }
        } else {
            $available_periods_with_appointments = $available_periods_with_breaks;
        }
        
        return $available_periods_with_appointments;
    }
}

/* End of file appointments.php */
/* Location: ./application/controllers/appointments.php */