<?php
/*
 * Copyright 2013 Jan Eichhorn <exeu65@googlemail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace libs\ApaiIO\Request\Rest;

use libs\ApaiIO\ApaiIO;
use libs\ApaiIO\Configuration\ConfigurationInterface;
use libs\ApaiIO\Operations\OperationInterface;
use libs\ApaiIO\Request\RequestInterface;
use libs\ApaiIO\Request\Util;

/**
 * Basic implementation of the rest request
 *
 * @see    http://docs.aws.amazon.com/AWSECommerceService/2011-08-01/DG/AnatomyOfaRESTRequest.html
 * @author Jan Eichhorn <exeu65@googlemail.com>
 */
class Request implements RequestInterface
{
    /**
     * Connection time out in seconds
     *
     * @var int
     */
    const CONNECTION_TIMEOUT = CURLOPT_CONNECTTIMEOUT;

    /**
     * Time out in seconds
     *
     * @var int
     */
    const TIMEOUT = CURLOPT_TIMEOUT;

    /**
     * Enable/Disable location following
     *
     * @var int
     */
    const FOLLOW_LOCATION = CURLOPT_FOLLOWLOCATION;

    /**
     * Useragent
     *
     * @var string
     */
    const USERAGENT = CURLOPT_USERAGENT;

    /**
     * curl options
     *
     * @var array
     */
    private $options = array();

    /**
     * The requestscheme
     *
     * @var string
     */
    protected $requestScheme = "http://webservices.amazon.%s/onca/xml?%s";

    /**
     * @var ConfigurationInterface
     */
    protected $configuration;

    /**
     * Initialize instance
     *
     * @param array $options
     */
    public function __construct(array $options = array())
    {
        $this->options = array(
            self::USERAGENT          => "ApaiIO [" . ApaiIO::VERSION . "]",
            self::CONNECTION_TIMEOUT => 10,
            self::TIMEOUT            => 10,
            self::FOLLOW_LOCATION    => 1
        );
        $this->setOptions($options);
    }

    /**
     * Sets the curl options
     *
     * @param array $options
     */
    public function setOptions(array $options = array())
    {
        foreach ($options as $currentOption => $currentOptionValue) {
            $this->options[$currentOption] = $currentOptionValue;
        }
        $this->options[CURLOPT_RETURNTRANSFER] = 1; // force the return transfer
    }

    /**
     * return the current curl options
     *
     * @return array
     */
    public function getOptions()
    {
        return $this->options;
    }

    /**
     * {@inheritdoc}
     */
    public function setConfiguration(ConfigurationInterface $configuration)
    {
        $this->configuration = $configuration;
    }

    /**
     * {@inheritdoc}
     */
    public function perform(OperationInterface $operation)
    {
        $ch = curl_init();

        if (false === $ch) {
            throw new \RuntimeException("Cannot initialize curl resource");
        }

        $preparedRequestParams = $this->prepareRequestParams($operation);
        $queryString = $this->buildQueryString($preparedRequestParams);

        $options = $this->options;
        $options[CURLOPT_URL] = sprintf($this->requestScheme, $this->configuration->getCountry(), $queryString);

        foreach ($options as $currentOption => $currentOptionValue) {
            if (false === curl_setopt($ch, $currentOption, $currentOptionValue)) {
                throw new \RuntimeException(
                    sprintf(
                        "An error occurred while setting %s with value %s",
                        $currentOption,
                        $currentOptionValue
                    )
                );
            }
        }

        $curlError = false;
        $errorNumber = null;
        $errorMessage = null;

        $result = curl_exec($ch);

        if (false === $result) {
            $curlError = true;
            $errorNumber = curl_errno($ch);
            $errorMessage = curl_error($ch);
        }

        curl_close($ch);

        if ($curlError) {
            throw new \RuntimeException(
                sprintf(
                    "An error occurred while sending request. Error number: %d; Error message: %s",
                    $errorNumber,
                    $errorMessage
                )
            );
        }

        return $result;
    }

    /**
     * Prepares the parameters for the request
     *
     * @param OperationInterface $operation
     *
     * @return array
     */
    protected function prepareRequestParams(OperationInterface $operation)
    {
        $baseRequestParams = array(
            'Service' => 'AWSECommerceService',
            'AWSAccessKeyId' => $this->configuration->getAccessKey(),
            'AssociateTag' => $this->configuration->getAssociateTag(),
            'Operation' => $operation->getName(),
            'Version' => '2011-08-01',
            'Timestamp' => Util::getTimeStamp()
        );

        $operationParams = $operation->getOperationParameter();

        foreach ($operationParams as $key => $value) {
            if (true === is_array($value)) {
                $operationParams[$key] = implode(',', $value);
            }
        }

        $fullParameterList = array_merge($baseRequestParams, $operationParams);
        ksort($fullParameterList);

        return $fullParameterList;
    }

    /**
     * Builds the final querystring including the signature
     *
     * @param array $params
     *
     * @return string
     */
    protected function buildQueryString(array $params)
    {
        $parameterList = array();
        foreach ($params as $key => $value) {
            $parameterList[] = sprintf('%s=%s', $key, rawurlencode($value));
        }

        $parameterList[] = 'Signature=' . rawurlencode($this->buildSignature($parameterList));

        return implode("&", $parameterList);
    }

    /**
     * Calculates the signature for the request
     *
     * @param array $params
     *
     * @return string
     */
    protected function buildSignature(array $params)
    {
        $template = "GET\nwebservices.amazon.%s\n/onca/xml\n%s";

        return Util::buildSignature(
            sprintf(
                $template,
                $this->configuration->getCountry(),
                implode('&', $params)
            ),
            $this->configuration->getSecretKey()
        );
    }
}