<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

/* ----------------------------------------------------------------------------
 * Easy!Appointments - Open Source Web Scheduler
 *
 * @package     EasyAppointments
 * @author      A.Tselegidis <alextselegidis@gmail.com>
 * @copyright   Copyright (c) 2013 - 2017, Alex Tselegidis
 * @license     http://opensource.org/licenses/GPL-3.0 - GPLv3
 * @link        http://easyappointments.org
 * @since       v1.0.0
 * ---------------------------------------------------------------------------- */

/**
 * Appointments Model
 *
 * @package Models
 */
class Appointments_Model extends CI_Model {
    /**
     * 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.
        $this->validate($appointment);

        // 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 whether 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 $appointment Associative array with the appointment's
     * data. Each key has the same name with the database fields.
     * @return bool Returns whether the record exists or not.
     */
    public function exists($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 $appointment Associative array with the appointment's
     * data. Each key has the same name with the database fields.
     * @return int Returns the id of the new record.
     */
    protected function _insert($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 (int)$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
     * fails to complete successfully.
     *
     * @param array $appointment Associative array with the appointment's
     * data. Each key has the same name with the database fields.
     */
    protected function _update($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 $appointment Array with the appointment data. The
     * keys of the array should have the same names as the db fields.
     * @return int Returns the db id of the record that matches the appointment
     * data.
     */
    public function find_record_id($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');

        // If a appointment id is given, check whether 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 service id is invalid.');
            }
        }

        return TRUE;
    }

    /**
     * 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 $unavailable Contains the unavailable data.
     * @return int Returns the record id.
     */
    public function add_unavailable($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');
    }

    /**
     * Clear google sync IDs from appointment record.
     *
     * @param numeric $provider_id The appointment provider record id.
     */
    public function clear_google_sync_ids($provider_id) {
        if (!is_numeric($provider_id)) {
            throw new Exception('Invalid argument type $provider_id (value: "'
                    . $provider_id . '")');
        }

        $this->db->update('ea_appointments', array('id_google_calendar' => NULL),
                array('id_users_provider' => $provider_id));
    }

    /**
     * Get appointment count for the provided start datetime.
     *
     * @param int $service_id Selected service ID.
     * @param string $selected_date Selected date string.
     * @param string $hour Selected hour string.
     *
     * @return int Returns the appointment number at the selected start time.
     */
    public function appointment_count_for_hour($service_id, $selected_date, $hour) {
        return $this->db->get_where('ea_appointments', [
            'id_services' => $service_id,
            'start_datetime' => date('Y-m-d H:i:s', strtotime($selected_date . ' ' . $hour . ':00'))
        ])->num_rows();
    }
}