http_server_request.h

/************************************************************************************
 *
 * D++, A Lightweight C++ library for Discord
 *
 * SPDX-License-Identifier: Apache-2.0
 * Copyright 2021 Craig Edwards and D++ contributors 
 * (https://github.com/brainboxdotcc/DPP/graphs/contributors)
 *
 * 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.
 *
 ************************************************************************************/
#pragma once
#include <dpp/export.h>
#include <string>
#include <map>
#include <list>
#include <vector>
#include <variant>
#include <dpp/sslconnection.h>
#include <dpp/version.h>
#include <dpp/stringops.h>
#include <dpp/httpsclient.h>
#include <climits>

namespace dpp {

/**
 * @brief Callback type for HTTP server request callbacks
 */
using http_server_request_event = std::function<void(class http_server_request*)>;

/*
 * @brief Implements a HTTPS socket client based on the SSL client.
 * @note plaintext HTTP without SSL is also supported via a "downgrade" setting
 */
class DPP_EXPORT http_server_request : public ssl_connection {
	/**
	 * @brief The request body, e.g. form data
	 */
	std::string request_body;

	/**
	 * @brief Headers from the client
	 */
	http_headers request_headers;

	/**
	 * @brief Time at which the request should be abandoned
	 */
	time_t timeout;

	/**
	 * @brief Headers for our response
	 */
	http_headers response_headers;

	/**
	 * @brief Handler to handle the inbound request
	 */
	http_server_request_event handler{};

	/**
	 * @brief Response body
	 */
	std::string response_body;

protected:

	/**
	 * @brief The type of the request, e.g. GET, POST
	 */
	std::string request_type;

	/**
	 * @brief Path part of URL for HTTPS connection
	 */
	std::string path;

	/**
	 * @brief Current connection state
	 */
	http_state state;

	/**
	 * @brief HTTP status code for response
	 */
	uint16_t status{0};

	/**
	 * @brief Start the connection
	 */
	virtual void connect() override;

	/**
	 * @brief Called when the output buffer is drained to empty
	 */
	void on_buffer_drained() override;

	/**
	 * @brief Maximum size of POST body
	 */
	[[nodiscard]] uint64_t get_max_post_size() const;

	/**
	 * @brief Maximum size of headers
	 */
	[[nodiscard]] uint64_t get_max_header_size() const;

	/**
	 * @brief Reply with an error message
	 * @param error_code error code
	 * @param message message
	 */
	void generate_error(uint16_t error_code, const std::string& message);

public:
	/**
	 * @brief If true the response timed out while waiting
	 */
	bool timed_out;

	/**
	 * @brief Get request state
	 * @return request state
	 */
	http_state get_state() const;

	/**
	 * @brief Get current response body
	 * @return response body
	 */
	std::string get_response_body() const;

	/**
	 * @brief Get current request body
	 * @return request body
	 */
	std::string get_request_body() const;

	/**
	 * @brief Get current status code
	 * @return status code
	 */
	uint16_t get_status() const;

	/**
	 * @brief Content length sent by client
	 */
	uint64_t content_length{ULLONG_MAX};

	/**
	 * @brief Construct a new server request object.
	 * Server request objects are instantiated for an incoming server connection, as such they already
	 * have a file descriptor.
	 * @param creator creating owner
	 * @param fd file descriptor
	 * @param port Port the connection came in on
	 * @param plaintext_downgrade true if plaintext, false if SSL
	 * @param private_key if SSL, the path to the private key PEM
	 * @param public_key if SSL, the path to the public key PEM
	 * @param handle_request request handler callback
	 */
        http_server_request(cluster* creator, socket fd, uint16_t port, bool plaintext_downgrade, const std::string& private_key, const std::string& public_key, http_server_request_event handle_request);

	/**
	 * @brief Destroy the https client object
	 */
        virtual ~http_server_request() override;

	/**
	 * @brief Processes incoming data from the SSL socket input buffer.
	 * 
	 * @param buffer The buffer contents. Can modify this value removing the head elements when processed.
	 */
        virtual bool handle_buffer(std::string &buffer) override;

	/**
	 * @brief Close HTTPS socket
	 */
        virtual void close() override;

	/**
	 * @brief Fires every second from the underlying socket I/O loop, used for timeouts
	 */
	virtual void one_second_timer() override;

	/**
	 * @brief Get a HTTP request header
	 * 
	 * @param header_name Header name to find, case insensitive
	 * @return Header content or empty string if not found.
	 * If multiple values have the same header_name, this will return one of them.
	 * @see get_header_count to determine if multiple are present
	 * @see get_header_list to retrieve all entries of the same header_name
	 */
	[[nodiscard]] const std::string get_header(const std::string& header_name) const;

	/**
	 * @brief Get the number of headers with the same header name
	 *
	 * @param header_name
	 * @return the number of headers with this count
	 */
	[[nodiscard]] size_t get_header_count(const std::string& header_name) const;

	/**
	 * @brief Get a set of HTTP request headers with a common name
	 *
	 * @param header_name
	 * @return A list of headers with the same name, or an empty list if not found
	 */
	[[nodiscard]] std::list<std::string> get_header_list(const std::string& header_name) const;

	/**
	 * @brief Get all HTTP request headers
	 * 
	 * @return headers as a map
	 */
	[[nodiscard]] std::multimap<std::string, std::string> get_headers() const;

	/**
	 * @brief Set a response header
	 * @param header header name
	 * @param value header value
	 * @return ref to self
	 */
	http_server_request& set_response_header(const std::string& header, const std::string& value);
 
	/**
	 * @brief Set the response content
	 * 
	 * @param new_content response content
	 */
	http_server_request& set_response_body(const std::string& new_content);

	/**
	 * @brief Set the response HTTP status, e.g.
	 * 200 for OK, 404 for not found, 429 for rate limited etc.
	 *
	 * @param new_status HTTP status
	 */
	http_server_request& set_status(uint16_t new_status);

	/**
	 * @brief Get whole response as a string
	 */
	[[nodiscard]] std::string get_response();
};

}