HttpBatchRequestHandler.hpp

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#pragma once
#ifndef KURLYK_HEADER_KURLYK_HTTP_HTTP_REQUEST_MANAGER_HTTP_BATCH_REQUEST_HANDLER_HPP_INCLUDED
#define KURLYK_HEADER_KURLYK_HTTP_HTTP_REQUEST_MANAGER_HTTP_BATCH_REQUEST_HANDLER_HPP_INCLUDED

 
namespace kurlyk {

    class HttpBatchRequestHandler {
    public:

        explicit HttpBatchRequestHandler(std::vector<std::unique_ptr<HttpRequestContext>>& context_list)
            : m_multi_handle(curl_multi_init()) {
            if (!m_multi_handle) {
                // libcurl multi handle creation failed: fail all requests immediately.
                for (auto& context : context_list) {
                    if (!context) continue;
#                   if __cplusplus >= 201402L
                    auto response = std::make_unique<HttpResponse>();
#                   else
                    auto response = std::unique_ptr<HttpResponse>(new HttpResponse());
#                   endif
                    response->error_code = utils::make_error_code(utils::ClientError::AbortedDuringDestruction);
                    response->status_code = 499; // Client closed request
                    response->ready = true;
                    context->invoke_final_callback(std::move(response));
                    context.reset();
                }
                return;
            }
            for (auto& context : context_list) {
                if (!context) continue;
#               if __cplusplus >= 201402L
                auto handler = std::make_unique<HttpRequestHandler>(std::move(context));
#               else
                auto handler = std::unique_ptr<HttpRequestHandler>(new HttpRequestHandler(std::move(context)));
#               endif
                CURL* curl = handler->get_curl();
                if (!curl) {
                    // curl_easy_init failed: deliver error immediately.
                    auto ctx = handler->get_request_context();
                    if (ctx) {
#                       if __cplusplus >= 201402L
                        auto response = std::make_unique<HttpResponse>();
#                       else
                        auto response = std::unique_ptr<HttpResponse>(new HttpResponse());
#                       endif
                        response->error_code = utils::make_error_code(utils::ClientError::AbortedDuringDestruction);
                        response->status_code = 499; // Client closed request
                        response->ready = true;
                        ctx->invoke_final_callback(std::move(response));
                    }
                    continue;
                }
 
                curl_multi_add_handle(m_multi_handle, curl);
                m_handlers.push_back(std::move(handler));
            }
            // Ensure the source vector is empty after moving contexts into handlers or failing them.
            for (auto& context : context_list) {
                context.reset();
            }
        }

        ~HttpBatchRequestHandler() {
            for (auto& handler : m_handlers) {
                CURL* curl = handler->get_curl();
                if (!curl) continue;
                curl_multi_remove_handle(m_multi_handle, curl);
            }
            if (m_multi_handle) {
                curl_multi_cleanup(m_multi_handle);
            }
        }

        bool process() {
            if (!m_multi_handle) {
                // Multi handle was never created: fail all handlers immediately.
                for (auto& handler : m_handlers) {
                    auto ctx = handler->get_request_context();
                    if (ctx) {
#                       if __cplusplus >= 201402L
                        auto response = std::make_unique<HttpResponse>();
#                       else
                        auto response = std::unique_ptr<HttpResponse>(new HttpResponse());
#                       endif
                        response->error_code = utils::make_error_code(utils::ClientError::AbortedDuringDestruction);
                        response->status_code = 499; // Client closed request
                        response->ready = true;
                        ctx->invoke_final_callback(std::move(response));
                    }
                }
                m_handlers.clear();
                return true;
            }
            int still_running = 0;
            CURLMcode res = curl_multi_perform(m_multi_handle, &still_running);
            if (res != CURLM_OK) return false;
 
            int pending_messages;
            while (CURLMsg* message = curl_multi_info_read(m_multi_handle, &pending_messages)) {
                if (message->msg != CURLMSG_DONE) continue;
                handle_completed_request(message);
            }
            if (still_running == 0) {
                m_handlers.clear();
                return true;
            }
            return false;
        }

        std::list<std::unique_ptr<HttpRequestContext>> extract_failed_requests() {
            return std::move(m_failed_requests);
        }

        bool has_group_id(uint64_t group_id) const {
            return group_request_count(group_id) != 0;
        }

        std::size_t group_request_count(uint64_t group_id) const {
            if (group_id == 0) return 0;
 
            std::size_t count = 0;
            for (const auto& handler : m_handlers) {
                if (handler && !handler->is_done() && handler->get_group_id() == group_id) {
                    ++count;
                }
            }
            return count;
        }

        void cancel_request_by_id(const std::unordered_map<uint64_t, std::list<std::function<void()>>>& to_cancel) {
            cancel_requests(to_cancel, std::unordered_map<uint64_t, std::list<std::function<void()>>>());
        }

        void cancel_requests(
                const std::unordered_map<uint64_t, std::list<std::function<void()>>>& requests_to_cancel,
                const std::unordered_map<uint64_t, std::list<std::function<void()>>>& groups_to_cancel) {
            auto it = m_handlers.begin();
            while (it != m_handlers.end()) {
                const uint64_t request_id = (*it)->get_request_id();
                const uint64_t group_id = (*it)->get_group_id();
                const bool should_cancel =
                    (request_id != 0 && requests_to_cancel.count(request_id) > 0) ||
                    (group_id != 0 && groups_to_cancel.count(group_id) > 0);
                if (!should_cancel) {
                    ++it;
                    continue;
                }
                curl_multi_remove_handle(m_multi_handle, (*it)->get_curl());
                (*it)->cancel();
                it = m_handlers.erase(it);
            }
        }
 
    private:
        CURLM* m_multi_handle = nullptr; 
        std::vector<std::unique_ptr<HttpRequestHandler>> m_handlers; 
        std::list<std::unique_ptr<HttpRequestContext>>   m_failed_requests; 

        void handle_completed_request(CURLMsg* message) {
            CURL* curl = message->easy_handle;
 
            void* ptr = nullptr;
            curl_easy_getinfo(curl, CURLINFO_PRIVATE, &ptr);
            auto* handler = static_cast<HttpRequestHandler*>(ptr);
            if (!handler) return;
 
            const bool completed = handler->handle_curl_message(message);
            curl_multi_remove_handle(m_multi_handle, curl);
 
            if (!completed) {
                handler->mark_done();
                m_failed_requests.push_back(handler->get_request_context());
            }
        }
 
    }; // HttpBatchRequestHandler
 
} // namespace kurlyk
 
#endif // KURLYK_HEADER_KURLYK_HTTP_HTTP_REQUEST_MANAGER_HTTP_BATCH_REQUEST_HANDLER_HPP_INCLUDED