<?php

/**
 * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * or in the "license" file accompanying this file. This file 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 Amazon\ProductAdvertisingAPI\v1;

use \Exception;

/**
 * ApiException Class Doc Comment
 *
 * @category Class
 * @package  Amazon\ProductAdvertisingAPI\v1
 * @author   Product Advertising API team
 */
class HeaderSelector
{

    /**
     * @param string[] $accept
     * @param string[] $contentTypes
     * @return array
     */
    public function selectHeaders($accept, $contentTypes)
    {
        $headers = [];

        $accept = $this->selectAcceptHeader($accept);
        if ($accept !== null) {
            $headers['Accept'] = $accept;
        }

        $headers['Content-Type'] = $this->selectContentTypeHeader($contentTypes);
        return $headers;
    }

    /**
     * @param string[] $accept
     * @return array
     */
    public function selectHeadersForMultipart($accept)
    {
        $headers = $this->selectHeaders($accept, []);

        unset($headers['Content-Type']);
        return $headers;
    }

    /**
     * Return the header 'Accept' based on an array of Accept provided
     *
     * @param string[] $accept Array of header
     *
     * @return string Accept (e.g. application/json)
     */
    private function selectAcceptHeader($accept)
    {
        if (count($accept) === 0 || (count($accept) === 1 && $accept[0] === '')) {
            return null;
        } elseif (preg_grep("/application\/json/i", $accept)) {
            return 'application/json';
        } else {
            return implode(',', $accept);
        }
    }

    /**
     * Return the content type based on an array of content-type provided
     *
     * @param string[] $contentType Array fo content-type
     *
     * @return string Content-Type (e.g. application/json)
     */
    private function selectContentTypeHeader($contentType)
    {
        if (count($contentType) === 0 || (count($contentType) === 1 && $contentType[0] === '')) {
            return 'application/json';
        } elseif (preg_grep("/application\/json/i", $contentType)) {
            return 'application/json';
        } else {
            return implode(',', $contentType);
        }
    }
}
