/*
 * This file is part of the Flowee project
 * Copyright (C) 2025 Tom Zander <tom@flowee.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef SIMPLEHTTPCLIENT_H
#define SIMPLEHTTPCLIENT_H

#include <QObject>
#include <QDateTime>

#include <boost/asio/io_context.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <streaming/ConstBuffer.h>

#include <boost/beast/core.hpp>
#include <boost/beast/http.hpp>
#include <boost/beast/ssl.hpp>
#include <boost/beast/http/field.hpp>

class SimpleHttpClient : public QObject, public std::enable_shared_from_this<SimpleHttpClient>
{
    Q_OBJECT
public:
    /**
     * Example:
     * @code
     * // for a HEAD
     *
     *  boost::beast::http::request<boost::beast::http::vector_body<char>> request;
     *  request.version(11); // http 1.1
     *  request.method(boost::beast::http::verb::head);
     *  request.target("/index.html");
     *  request.set(boost::beast::http::field::host, "flowee.org");
     *
     * // or for a POST;
     *
     *  boost::beast::http::request<boost::beast::http::vector_body<char>> request;
     *  request.version(11);
     *  request.method(boost::beast::http::verb::post);
     *  request.target("/upload");
     *  request.set(boost::beast::http::field::host, "flowee.org");
     *  request.set(boost::beast::http::field::content_type, "application/octet-stream");
     *  request.body() = std::vector<char>(data.begin(), data.end());
     *
     * // or for a GET
     *
     *  boost::beast::http::request<boost::beast::http::vector_body<char>> request;
     *  request.version(11);
     *  request.method(boost::beast::http::verb::get);
     *  request.target("/image.png");
     *  request.set(boost::beast::http::field::host, "flowee.org");
     * @endcode
     */
    static std::shared_ptr<SimpleHttpClient> create(boost::asio::io_context &context,
            boost::asio::ssl::context &sslContext,
            const boost::beast::http::request<boost::beast::http::vector_body<char>> &request);

    /**
     * Create a client that does not wait for the entire download to finish before emitting a signal.
     * This is very similar in usage to the basic create() method, but the client will emit
     * "dataAvailable()" signals that HAVE to be handled because they hold the data payload.
     * The responseBody will always return an empty field in this version.
     */
    static std::shared_ptr<SimpleHttpClient> createIncremental(boost::asio::io_context &context,
            boost::asio::ssl::context &sslContext,
            const boost::beast::http::request<boost::beast::http::vector_body<char>> &request);

    enum ErrorType {
        NoError,
        DnsIssues,
        SslIssues,
        SendIssues,
        ReceiveIssues,
        PeerIssues, // remote server gave error
    };

    Streaming::ConstBuffer responseBody() const;
    ErrorType error() const;
    int httpErrorCode() const;

    /// Response headers access.
    std::string_view headerValue(const char *name) const;
    /// Response headers access.
    std::string_view headerValue(boost::beast::http::field field) const;

    QDateTime headerDate(boost::beast::http::field field) const;

    boost::beast::http::request<boost::beast::http::vector_body<char>> request() const;

signals:
    void finished();
    void errored(ErrorType type);
    void dataAvailable(const Streaming::ConstBuffer &data);

private:
    SimpleHttpClient(boost::asio::io_context &context, boost::asio::ssl::context &sslContext);

    void resolve();
    void connect(boost::beast::error_code ec, boost::asio::ip::tcp::resolver::results_type results);
    void sslHandshake(boost::beast::error_code ec);
    void sendRequest(boost::beast::error_code ec);
    void requestSent(boost::beast::error_code ec, std::size_t bytesTransferred);
    void readHeaderReply(boost::beast::error_code ec, std::size_t bytesTransferred);
    void readReply(boost::beast::error_code ec, std::size_t bytesTransferred);
    void readPartialReply(boost::beast::error_code ec, std::size_t bytesTransferred);
    void connectionShutdown(boost::beast::error_code ec);

    void setError(ErrorType newError);

    boost::asio::ip::tcp::resolver m_resolver;
    boost::beast::ssl_stream<boost::beast::tcp_stream> m_stream;
    boost::beast::http::request<boost::beast::http::vector_body<char>> m_request;
    boost::beast::flat_buffer m_readBuffer; // for the response
    std::unique_ptr<boost::beast::http::response<boost::beast::http::dynamic_body>> m_response;
    // for HEAD requests
    boost::beast::http::response<boost::beast::http::empty_body> m_headResponse;
    std::unique_ptr<boost::beast::http::response_parser<boost::beast::http::empty_body>> m_parser;
    // for partial requests
    std::unique_ptr<boost::beast::http::response_parser<boost::beast::http::dynamic_body>> m_partialParser;

    Streaming::ConstBuffer m_responseBody;


    ErrorType m_error = NoError;
    bool m_incremental = false;
};

#endif