Oauth3

auth.php

<?php

/**
     * Get access token via OAuth2 three legged dance
     * @see https://sagedocs.wholelabs.com/wiki/index.php?title=Sage-api/v2/authorize
     * @throws Exception
     * @return string
     * @todo: Doc #experiment
     */
    protected function getAccessToken()
    {
        $code = null;
        $client = $this->getClient();

        $url = $this->baseUrl . '/v' . $this->apiVersion
            . '/oauth20/authorize?response_type=code&redirect_uri='
            . urlencode($this->baseUrl) . '&client_id=' . $this->apiKey;

        try {

            $client->get($url);

        } catch (ClientException $e) {

            $code = $this->extractCode($e->getMessage());

        } catch (\Exception $e) {
            throw $e;
        }

        if (empty($code)) {
            throw new Exception('Cannot initiate authentication via GET');
        }

        // Create a base64 authorization code
        $authorizationCode = 'Basic ' . base64_encode($this->apiKey . ':' . $this->apiSecret);

        $response = $client->post(
            $this->baseUrl . '/v' . $this->apiVersion . '/oauth20/token',
            array(
                'headers' => array(
                    'Authorization' => $authorizationCode,
                    'Content-Type' => 'application/x-www-form-urlencoded',
                    'response_content_type' => 'application/json',
                    'hdr_auth_code' => $authorizationCode
                ),
                'body' => array(
                    'code' => $code,
                    'grant_type' => 'authorization_code',
                    'response_type' => 'code',
                    'redirect_uri' => urlencode($this->baseUrl . '/v' . $this->apiVersion)
                )
            )
        );

        $body = $response->getBody();
        pre($body, '$body');
        pre($code);
    }
    
    /**
     * Extract the code HTTP query string parameter from the error message guzzle returns
     * @param string $message Message to extract the auth code from an exception message
     * @throws Exception
     * @return string
     */
    protected function extractCode($message)
    {
        $url = null;
        $parts = explode(" ", $message);

        // Doing it this way for BC reasons, I would have rather used array_map()
        foreach ($parts as $part) {
            if (preg_match('/^(http|https):\/\//', $part)) {
                $url = $part;
                break;
            }
        }
        if (empty($url)) {
            throw new Exception('Cannot initiate authentication');
        }
        $parts = explode("code=", $url);

        return array_pop($parts);
    }