<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed'); 

class Appointments_Model extends CI_Model {
    /**
     * Class Constructor
     */
    public function __construct() {
        parent::__construct();
    }
    
    /**
     * Add an appointment record to the database.
     * 
     * This method adds a new appointment to the database. If the 
     * appointment doesn't exists it is going to be inserted, otherwise 
     * the record is going to be updated.
     * 
     * @param array $appointment Associative array with the appointment 
     * data. Each key has the same name with the database fields.
     * @return int Returns the appointments id.
     */
    public function add($appointment) {
        // Validate the appointment data before doing anything.
        if (!$this->validate($appointment)) {
            throw new Exception('Appointment data are invalid.');
        }
        
        // Perform insert() or update() operation.
        if (!isset($appointment['id'])) {
            $appointment['id'] = $this->insert($appointment);
        } else {
            $this->update($appointment);
        }

        return $appointment['id'];
    }
    
    /**
     * Check if a particular appointment record already exists.
     * 
     * This method checks wether the given appointment already exists  
     * in the database. It doesn't search with the id, but by using the 
     * following fields: "start_datetime", "end_datetime", "id_users_provider",
     * "id_users_customer", "id_services".
     * 
     * @param array $appointment Associative array with the appointment's
     * data. Each key has the same name with the database fields.
     * @return bool Returns wether the record exists or not.
     */
    public function exists($appointment) {   
        if (!isset($appointment['start_datetime'])
                || !isset($appointment['end_datetime'])
                || !isset($appointment['id_users_provider'])
                || !isset($appointment['id_users_customer'])
                || !isset($appointment['id_services'])) {
            throw new Exception('Not all appointment field values ' 
                    . 'are provided : ' . print_r($appointment, TRUE));
        }
        
        $num_rows = $this->db->get_where('ea_appointments', array(
                'start_datetime'    => $appointment['start_datetime'],
                'end_datetime'      => $appointment['end_datetime'],
                'id_users_provider' => $appointment['id_users_provider'],
                'id_users_customer' => $appointment['id_users_customer'],
                'id_services'       => $appointment['id_services'],))
                ->num_rows();
        
        return ($num_rows > 0) ? TRUE : FALSE;
    }
    
    /**
     * Insert a new appointment record to the database.
     * 
     * @param array $appointment Associative array with the appointment's
     * data. Each key has the same name with the database fields.
     * @return int Returns the id of the new record.
     */
    private function insert($appointment) {
        $appointment['book_datetime'] = date('Y-m-d H:i:s');
        $appointment['hash'] = $this->generate_hash();
        
        if (!$this->db->insert('ea_appointments', $appointment)) {
            throw new Exception('Could not insert appointment record.');
        }
        
        return intval($this->db->insert_id());
    }
    
    /**
     * Update an existing appointment record in the database.
     * 
     * The appointment data argument should already include the record
     * id in order to process the update operation.
     * 
     * @expectedException DatabaseException Raises when the update operation 
     * failes to complete successfully.
     * 
     * @param array $appointment Associative array with the appointment's
     * data. Each key has the same name with the database fields.
     */
    private function update($appointment) {
        $this->db->where('id', $appointment['id']);
        if (!$this->db->update('ea_appointments', $appointment)) {
            throw new Exception('Could not update appointment record.');
        }
    }
    
    /**
     * Find the database id of an appointment record. 
     * 
     * The appointment data should include the following fields in order  
     * to get the unique id from the database: "start_datetime", "end_datetime", 
     * "id_users_provider", "id_users_customer", "id_services".
     * 
     * <strong>IMPORTANT!</strong> The record must already exists in the 
     * database, otherwise an exception is raised.
     * 
     * @param array $appointment Array with the appointment data. The 
     * keys of the array should have the same names as the db fields.
     * @return int Returns the db id of the record that matches the apppointment
     * data.
     */
    public function find_record_id($appointment) {        
        $this->db->where(array(
            'start_datetime'    => $appointment['start_datetime'],
            'end_datetime'      => $appointment['end_datetime'],
            'id_users_provider' => $appointment['id_users_provider'],
            'id_users_customer' => $appointment['id_users_customer'],
            'id_services'       => $appointment['id_services']
        ));
        
        $result = $this->db->get('ea_appointments');

        if ($result->num_rows() == 0) {
            throw new Exception('Could not find appointment record id.');
        }
        
        return $result->row()->id;
    }
    
    /**
     * Validate appointment data before the insert or update operations 
     * are executed.
     * 
     * @param array $appointment Contains the appointment data.
     * @return bool Returns the validation result.
     */
    public function validate($appointment) {
        $this->load->helper('data_validation');
        
        try {
            // If a appointment id is given, check wether the record exists
            // in the database.
            if (isset($appointment['id'])) {
                $num_rows = $this->db->get_where('ea_appointments', 
                        array('id' => $appointment['id']))->num_rows();
                if ($num_rows == 0) {
                    throw new Exception('Provided appointment id does not '
                            . 'exist in the database.');
                }
            }
            
            // Check if appointment dates are valid.
            if (!validate_mysql_datetime($appointment['start_datetime'])) {
                throw new Exception('Appointment start datetime is invalid.');    
            }
            
            if (!validate_mysql_datetime($appointment['end_datetime'])) {
                throw new Exception('Appointment end datetime is invalid.');
            }

            // Check if the provider's id is valid. 
            $num_rows = $this->db
                    ->select('*')
                    ->from('ea_users')
                    ->join('ea_roles', 'ea_roles.id = ea_users.id_roles', 'inner')
                    ->where('ea_users.id', $appointment['id_users_provider'])
                    ->where('ea_roles.slug', DB_SLUG_PROVIDER)
                    ->get()->num_rows();
            if ($num_rows == 0) {
                throw new Exception('Appointment provider id is invalid.');
            }
            
            if ($appointment['is_unavailable'] == FALSE) { 
                // Check if the customer's id is valid.
                $num_rows = $this->db
                        ->select('*')
                        ->from('ea_users')
                        ->join('ea_roles', 'ea_roles.id = ea_users.id_roles', 'inner')
                        ->where('ea_users.id', $appointment['id_users_customer'])
                        ->where('ea_roles.slug', DB_SLUG_CUSTOMER)
                        ->get()->num_rows();
                if ($num_rows == 0) {
                    throw new Exception('Appointment customer id is invalid.');
                }
                
                // Check if the service id is valid.
                $num_rows = $this->db->get_where('ea_services', 
                        array('id' => $appointment['id_services']))->num_rows();
                if ($num_rows == 0) {
                    throw new Exception('Appointment customer id is invalid.');
                }
            }
            
            return TRUE;
        } catch (Exception $exc) {
            return FALSE;
        }
    }
    
    /**
     * Delete an existing appointment record from the database.
     * 
     * @expectedException InvalidArgumentException Raises when the $appointment_id
     * is not an integer.
     * 
     * @param numeric $appointment_id The record id to be deleted.
     * @return bool Returns the delete operation result.
     */
    public function delete($appointment_id) {
        if (!is_numeric($appointment_id)) { 
            throw new Exception('Invalid argument type $appointment_id (value:"' . $appointment_id . '")');
        }
        
        $num_rows = $this->db->get_where('ea_appointments', array('id' => $appointment_id))->num_rows();
        
        if ($num_rows == 0) {
            return FALSE; // Record does not exist.
        }
        
        $this->db->where('id', $appointment_id);
        return $this->db->delete('ea_appointments');
    }
    
    /**
     * Get a specific row from the appointments table.
     * 
     * @param numeric $appointment_id The record's id to be returned.
     * @return array Returns an associative array with the selected
     * record's data. Each key has the same name as the database 
     * field names.
     */
    public function get_row($appointment_id) {
        if (!is_numeric($appointment_id)) {
            throw new Exception('Invalid argument given. Expected ' 
                    . 'integer for the $appointment_id : ' . $appointment_id);
        }
        return $this->db->get_where('ea_appointments', 
                array('id' => $appointment_id))->row_array();
    }
    
    /**
     * Get a specific field value from the database.
     * 
     * @param string $field_name The field name of the value to be returned.
     * @param numeric $appointment_id The selected record's id.
     * @return string Returns the records value from the database.
     */
    public function get_value($field_name, $appointment_id) {
        if (!is_numeric($appointment_id)) {
            throw new Exception('Invalid argument given, expected ' 
                    . 'integer for the $appointment_id : ' . $appointment_id);
        }
        
        if (!is_string($field_name)) {
            throw new Exception('Invalid argument given, expected ' 
                    . 'string for the $field_name : ' . $field_name);
        }
        
        if ($this->db->get_where('ea_appointments', 
                array('id' => $appointment_id))->num_rows() == 0) {
            throw new Exception('The record with the provided id ' 
                    . 'does not exist in the database : ' . $appointment_id);
        }
        
        $row_data = $this->db->get_where('ea_appointments', 
                array('id' => $appointment_id))->row_array();
        
        if (!isset($row_data[$field_name])) {
            throw new Exception('The given field name does not ' 
                    . 'exist in the database : ' . $field_name);
        }
        
        return $row_data[$field_name];
    }
    
    /**
     * Get all, or specific records from appointment's table.
     * 
     * @example $this->Model->getBatch('id = ' . $recordId);
     * 
     * @param string $where_clause (OPTIONAL) The WHERE clause of  
     * the query to be executed. DO NOT INCLUDE 'WHERE' KEYWORD.
     * @return array Returns the rows from the database.
     */
    public function get_batch($where_clause = '') {
        if ($where_clause != '') {
            $this->db->where($where_clause);
        }
        
        return $this->db->get('ea_appointments')->result_array();
    }
    
    /**
     * Generate a unique hash for the given appointment data.
     * 
     * This method uses the current date-time to generate a unique 
     * hash string that is later used to identify this appointment. 
     * Hash is needed when the email is send to the user with an 
     * edit link.
     * 
     * @return string Returns the unique appointment hash.
     */
    public function generate_hash() {
        $current_date = new DateTime();
        return md5($current_date->getTimestamp());
    }
    
    /**
     * Inserts or updates an unavailable period record in the database.
     * 
     * @param array $unavailable Contains the unavaible data.
     * @return int Returns the record id.
     */
    public function add_unavailable($unavailable) {
        // Validate period
        $start = strtotime($unavailable['start_datetime']);
        $end = strtotime($unavailable['end_datetime']);
        if ($start > $end) {
            throw new Exception('Unavailable period start must be prior to end.');
        }
        
        // Validate provider record
        $where_clause = array(
            'id' => $unavailable['id_users_provider'],
            'id_roles' => $this->db->get_where('ea_roles', array('slug' => DB_SLUG_PROVIDER))->row()->id
        );
        
        if ($this->db->get_where('ea_users', $where_clause)->num_rows() == 0) {
            throw new Exception('Provider id was not found in database.');
        }
        
        // Add record to database (insert or update).
        if (!isset($unavailable['id'])) {
            $unavailable['book_datetime'] = date('Y-m-d H:i:s');
            $unavailable['is_unavailable'] = true;
            
            $this->db->insert('ea_appointments', $unavailable); 
            $unavailable['id'] = $this->db->insert_id();
        } else {
            $this->db->where(array('id' => $unavailable['id']));
            $this->db->update('ea_appointments', $unavailable);
        }
        
        return $unavailable['id'];
    }
    
    /**
     * Delete an unavailable period.
     * 
     * @param numeric $unavailable_id Record id to be deleted.
     */
    public function delete_unavailable($unavailable_id) {
        if (!is_numeric($unavailable_id)) { 
            throw new Exception('Invalid argument type $unavailable_id (value:"' . 
                    $unavailable_id . '")');
        }
        
        $num_rows = $this->db->get_where('ea_appointments', array('id' => $unavailable_id))
                ->num_rows();
        if ($num_rows == 0) {
            return FALSE; // Record does not exist.
        }
        
        $this->db->where('id', $unavailable_id);
        return $this->db->delete('ea_appointments');
    }
}

/* End of file appointments_model.php */
/* Location: ./application/models/appointments_model.php */