awsmug/alexa-sdk

<?php

namespace Alexa;
use Alexa\Input\Input_Stream;
use Alexa\Output\Output_Stream;

/**
 * Class Skill
 *
 * @since 1.0.0
 *
 * @package Alexa
 */
abstract class Skill {
    /**
     * Logging functionality
     *
     * @since 1.0.0
     */
    use Logger;

    /**
     * Application ID
     *
     * @var string
     */
    private $application_id;

    /**
     * Raw input data from Alexa as JSON String
     *
     * @since 1.0.0
     *
     * @var Input\Input_Stream
     */
    private $input;

    /**
     * Output data for Alexa
     *
     * @since 1.0.0
     *
     * @var Output\Output_Stream
     */
    private $output;

    /**
     * Skill constructor.
     *
     * @since 1.0.0
     *
     * @param string $application_id Skill Application ID
     */
    public function __construct( $application_id ) {
        $this->application_id = $application_id;
    }

    /**
     * Getting Data from Alexa
     *
     * @since 1.0.0
     *
     * @param \stdClass $input
     *
     * @return Input_Stream
     *
     * @throws Exception
     */
    public function input( $input = null ) {
        if( ! empty( $input ) ){
            $this->input = new Input_Stream( $input );
        }

        if( empty( $this->input ) ) {
            $this->input = new Input_Stream( $this->receive() );
        }

        if( ! $this->input->session()->application()->id_equals( $this->application_id ) ) {
            throw new Exception( 'Wrong Application ID' );
        }

        return $this->input;
    }

    /**
     * Outputting data to Alexa
     *
     * @since 1.0.0
     *
     * @return Output_Stream $output
     */
    public function output() {
        if( empty( $this->output ) ) {
            $this->output = new Output_Stream();
        }

        return $this->output;
    }

    /**
     * Getting input from Alexa
     *
     * @since 1.0.0
     *
     * @return \StdClass
     *
     * @throws Exception
     */
    private function receive() {
        $input = file_get_contents( 'php://input' );

        if( empty( $input ) ) {
            throw new Exception( 'No input from Alexa' );
        }

        $this->input = json_decode( $input );

        $this->log( $this->input );

        return $this->input;
    }

    /**
     * Preparing data for output to Alexa
     *
     * @since 1.0.0
     *
     * @param \stdClass $response
     */
    public function send( $response ) {
        $response = json_encode( $response );
        $size = strlen ( $response );

        header( 'Content-Type: application/json' );
        header( 'Content-length: ' . $size );

        echo $response;
    }
}