package eu.openaire.urls_controller.services;

import eu.openaire.urls_controller.controllers.UrlsController;
import eu.openaire.urls_controller.models.WorkerInfo;
import eu.openaire.urls_controller.util.UriBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Service;
import org.springframework.web.client.HttpServerErrorException;
import org.springframework.web.client.RestTemplate;

import java.net.ConnectException;
import java.util.regex.Pattern;


@Service
public class ShutdownServiceImpl implements ShutdownService {


    private static final Logger logger = LoggerFactory.getLogger(ShutdownServiceImpl.class);

    // Private Addresses, according to RFC 1918: https://www.rfc-editor.org/rfc/rfc1918
    private static final Pattern PRIVATE_IP_ADDRESSES_RFC_1918 = Pattern.compile("(?:10.|172.(?:1[6-9]|2[0-9]|3[0-1])|192.168.)[0-9.]+");


    @Value("${services.pdfaggregation.worker.port}")
    private String workerPort;


    public ResponseEntity<?> passSecurityChecks(String remoteAddr, String initMsg)
    {
        //  In case the Controller is running inside a docker container, and we want to send the "shutdownServiceRequest" from the terminal (with curl), without entering inside the container,
        //  then the request will appear coming from a local (private) IP, instead of localhost.
        if ( ! (remoteAddr.equals("127.0.0.1") || remoteAddr.equals(UriBuilder.ip) || PRIVATE_IP_ADDRESSES_RFC_1918.matcher(remoteAddr).matches()) ) {
            logger.error(initMsg + "The request came from another IP: " + remoteAddr + " | while the Controller has the IP: " + UriBuilder.ip);
            return ResponseEntity.status(HttpStatus.FORBIDDEN).build();
        }
        return null;    // The checks are passing.
    }


    public void postShutdownOrCancelRequestsToAllWorkers(boolean shouldCancel)
    {
        // Send "shutdownWorker" requests to all active Workers.
        for ( String workerId : UrlsController.workersInfoMap.keySet() ) {
            WorkerInfo workerInfo = UrlsController.workersInfoMap.get(workerId);
            if ( ! workerInfo.getHasShutdown() )    // A worker may have shutdown on its own (by sending it a shutDown request manually), so it will have told the Controller when it shut down. In case of a Worker-crash, the Controller will not know about it.
                postShutdownOrCancelRequestToWorker(workerId, workerInfo.getWorkerIP(), shouldCancel);
            else
                logger.warn("Will not post " + (shouldCancel ? "Cancel-" : "") + "ShutdownRequest to Worker \"" + workerId + "\", since is it has already shutdown.");
        }
    }


    private static final RestTemplate restTemplate = new RestTemplate();

    public boolean postShutdownOrCancelRequestToWorker(String workerId, String workerIp, boolean shouldCancel)
    {
        String url = "http://" + workerIp + ":" + workerPort + "/api/" + (shouldCancel ? "cancelShutdownWorker" : "shutdownWorker");
        try {
            ResponseEntity<?> responseEntity = restTemplate.postForEntity(url, null, String.class);
            int responseCode = responseEntity.getStatusCodeValue();
            if ( responseCode != HttpStatus.OK.value() ) {
                logger.error("HTTP-Connection problem with the submission of the \"postShutdownOrCancelRequestToWorker\" of worker \"" + workerId + "\"! Error-code was: " + responseCode);
                return false;
            } else
                return true;
        } catch (HttpServerErrorException hsee) {
            logger.error("The Worker \"" + workerId + "\" failed to handle the \"postShutdownOrCancelRequestToWorker\": " + hsee.getMessage());
            return false;
        } catch (Exception e) {
            // The Spring RestTemplate may return a "ResourceAccessException", but the actual cause will has to be identified, in order to set the worker as shutdown.
            Throwable cause = e.getCause(); // No need to check explicitly for null.
            if ( cause instanceof ConnectException ) {   // This includes the "ConnectException".
                logger.error("Got a \"ConnectException\" when doing a \"postShutdownOrCancelRequestToWorker\", to the Worker: \"" + workerId + "\". | Will register this worker as \"shutdown\".\n" + cause.getMessage());
                UrlsController.workersInfoMap.get(workerId).setHasShutdown(true);
            } else {
                logger.error("Error for \"postShutdownOrCancelRequestToWorker\", to the Worker: " + workerId, e);
                // TODO - What should we do? If there was some error from the Controller, side, it does not mean that the worker has shutdown..
                // For now, let's handle that case manually, by check with that specific worker and sending it a shutdownRequest from inside its VM.
                // Then the Worker will automatically send a "shutdownReport" to the Controller, causing it to shutdown (when all other workers have shutdown as well).
            }
            return false;
        }
    }

}