package eu.openaire.urls_controller.util;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.http.HttpServletRequest;
import java.text.SimpleDateFormat;
import java.util.Date;

public class GenericUtils {

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


    public static final String endOfLine = "\n";

    private static final SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS z");


    public static String getReadableCurrentTimeAndZone() {
        return (simpleDateFormat.format(new Date(System.currentTimeMillis())));
    }


    public static int getRandomNumber(int min, int max) {
        return (int)(Math.random() * (max - min +1) + min);
    }



    public static String getSelectedStackTraceForCausedException(Throwable thr, String firstMessage, String additionalMessage, int numOfLines)
    {
        // The stacktrace of the "ExecutionException" is the one of the current code and not the code which ran inside the background-task. Try to get the cause.
        Throwable causedThrowable = thr.getCause();
        if ( causedThrowable == null ) {
            logger.warn("No cause was retrieved for the \"ExecutionException\"!");
            causedThrowable = thr;
        }
        String initialMessage = firstMessage + causedThrowable.getMessage() + ((additionalMessage != null) ? additionalMessage : "");
        return getSelectiveStackTrace(causedThrowable, initialMessage, numOfLines);
    }


    public static String getSelectiveStackTrace(Throwable thr, String initialMessage, int numOfLines)
    {
        StackTraceElement[] stels = thr.getStackTrace();
        StringBuilder sb = new StringBuilder(numOfLines *100);
        if ( initialMessage != null )
            sb.append(initialMessage).append(GenericUtils.endOfLine).append("Stacktrace:").append(GenericUtils.endOfLine);	// This StringBuilder is thread-safe as a local-variable.
        for ( int i = 0; (i < stels.length) && (i <= numOfLines); ++i ) {
            sb.append(stels[i]);
            if (i < numOfLines) sb.append(GenericUtils.endOfLine);
        }
        return sb.toString();
    }


    public static String getRequestorAddress(HttpServletRequest request)
    {
        String remoteAddr = request.getHeader("X-FORWARDED-FOR");   // This retrieves the original IP address, if the request passes through a proxy server.
        if ( remoteAddr == null )
            remoteAddr = request.getRemoteAddr();
        return remoteAddr;
    }

}