/*
 * Copyright 2016-2018 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://aws.amazon.com/apache2.0/
 *
 * 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.
 */

#ifndef ALEXA_CLIENT_SDK_AVSCOMMON_UTILS_INCLUDE_AVSCOMMON_UTILS_LIBCURLUTILS_HTTPPOST_H_
#define ALEXA_CLIENT_SDK_AVSCOMMON_UTILS_INCLUDE_AVSCOMMON_UTILS_LIBCURLUTILS_HTTPPOST_H_

#include <chrono>
#include <curl/curl.h>
#include <iostream>
#include <memory>
#include <mutex>
#include <string>

#include "AVSCommon/Utils/LibcurlUtils/CurlEasyHandleWrapper.h"
#include "AVSCommon/Utils/LibcurlUtils/HttpPostInterface.h"

namespace alexaClientSDK {
namespace avsCommon {
namespace utils {
namespace libcurlUtils {

/// LIBCURL based implementation of HttpPostInterface.
class HttpPost : public HttpPostInterface {
public:
    /**
     * Create a new HttpPost instance, passing ownership of the new instance on to the caller.
     *
     * @return Returns an std::unique_ptr to the new HttpPost instance, or @c nullptr of the operation failed.
     */
    static std::unique_ptr<HttpPost> create();

    /**
     * HttpPost destructor
     */
    ~HttpPost() = default;

    /**
     * Deleted copy constructor.
     *
     * @param rhs The 'right hand side' to not copy.
     */
    HttpPost(const HttpPost& rhs) = delete;

    /**
     * Deleted assignment operator.
     *
     * @param rhs The 'right hand side' to not copy.
     * @return The object assigned to.
     */
    HttpPost& operator=(const HttpPost& rhs) = delete;

    long doPost(const std::string& url, const std::string& data, std::chrono::seconds timeout, std::string& body)
        override;

    HTTPResponse doPost(
        const std::string& url,
        const std::vector<std::string> headerLines,
        const std::vector<std::pair<std::string, std::string>>& data,
        std::chrono::seconds timeout) override;

    HTTPResponse doPost(
        const std::string& url,
        const std::vector<std::string> headerLines,
        const std::string& data,
        std::chrono::seconds timeout) override;

private:
    /**
     * Default HttpPost constructor.
     */
    HttpPost() = default;

    /**
     * Build POST data from a vector of key value pairs.
     *
     * @param data Vector of key, value pairs from which to build the POST data.
     * @return
     */
    std::string buildPostData(const std::vector<std::pair<std::string, std::string>>& data) const;

    /**
     * Callback function used to accumulate the body of the HTTP Post response
     * This is called when doPost() is holding @c m_mutex.
     *
     * @param ptr Pointer to the first/next block of received bytes.
     * @param size count of 'nmemb' sized chunks of pointed to by 'ptr'.
     * @param nmemb count of bytes in each chunk received.
     * @param userdata Our 'this' pointer passed through by libcurl.
     * @return The number of bytes processed (size*nmemb upon success).
     */
    static size_t staticWriteCallbackLocked(char* ptr, size_t size, size_t nmemb, void* userdata);

    /// Mutex to serialize access to @c m_curl and @c m_response.
    std::mutex m_mutex;

    /// CURL handle with which to make requests
    CurlEasyHandleWrapper m_curl;

    /// String used to accumulate the response body.
    std::string m_bodyAccumulator;
};

}  // namespace libcurlUtils
}  // namespace utils
}  // namespace avsCommon
}  // namespace alexaClientSDK

#endif  // ALEXA_CLIENT_SDK_AVSCOMMON_UTILS_INCLUDE_AVSCOMMON_UTILS_LIBCURLUTILS_HTTPPOST_H_