package org.gcube.data.publishing.ckan2zenodo.commons;

import java.io.File;
import java.io.InputStream;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;
import java.security.DigestInputStream;
import java.security.MessageDigest;

import org.gcube.data.publishing.ckan2zenodo.model.CkanResource;
import org.gcube.data.publishing.ckan2zenodo.model.DownloadedFile;

import lombok.extern.slf4j.Slf4j;

@Slf4j
public class Net {

	public static DownloadedFile download(CkanResource toDownload) throws Exception {
		String urlString=toDownload.getUrl();
		log.debug("Downloading "+urlString);
		//Download locally into temp
		URL url=new URL(urlString);
		File temp=File.createTempFile("zenodo_", ".tmp");
		MessageDigest md = MessageDigest.getInstance("MD5");
		
		// Multiple tries
		InputStream is=null;
		int attempt=0;
		Exception lastException=null;
		while(is==null&&attempt<5) {
			try {
				attempt++;
				is=url.openStream();
			}catch(Exception e) {
				lastException=e;
				try{
					Thread.sleep(500*attempt);
				}catch(InterruptedException e1) {}
			}
		}
		if(is==null) throw new Exception("Unable to download "+urlString,lastException);
		
		DigestInputStream dis = new DigestInputStream(is, md);
		
		
		// Download
		long size=Files.copy(is, temp.toPath(),StandardCopyOption.REPLACE_EXISTING);
		
		return new DownloadedFile(toDownload,temp,dis.getMessageDigest().toString());
		
		
	}
	
	
}