package org.gcube.data.transfer.service.transfers.engine.impl;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Map.Entry;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.gcube.data.transfer.model.PluginInvocation;
import org.gcube.data.transfer.model.TransferTicket;
import org.gcube.data.transfer.model.TransferTicket.Status;
import org.gcube.data.transfer.model.options.TransferOptions.TransferMethod;
import org.gcube.data.transfer.model.settings.FileUploadSettings;
import org.gcube.data.transfer.model.settings.HttpDownloadSettings;
import org.gcube.data.transfer.service.transfers.engine.PersistenceProvider;
import org.gcube.data.transfer.service.transfers.engine.PluginManager;
import org.gcube.data.transfer.service.transfers.engine.faults.ManagedException;
import org.gcube.data.transfer.service.transfers.engine.faults.NotSupportedMethodException;

import lombok.extern.slf4j.Slf4j;

@Slf4j
public abstract class AbstractTicketHandler {

	private TransferTicket ticket;

	PersistenceProvider persistenceProvider;
	PluginManager pluginManager;


	public AbstractTicketHandler(PersistenceProvider persProv,PluginManager plugMan, TransferTicket ticket) {		
		this.persistenceProvider=persProv;
		this.pluginManager=plugMan;
		this.ticket=ticket;
	}

	protected void onStep(String msg,double progress,Status status,long transferredBytes){
		ticket.setStatus(status);
		ticket.setMessage(msg);
		ticket.setPercent(progress);
		ticket.setTransferredBytes(transferredBytes);
		try{
			long elapsedTime=System.currentTimeMillis()-ticket.getSubmissionTime().getValue().getTimeInMillis();
			long average=(transferredBytes/((elapsedTime==0?1:elapsedTime)))*1000;
			ticket.setAverageTransferSpeed(average);
		}catch(Exception e){
			log.warn("Unable to evaluate average ",e);
		}
	}
	protected void onError(String message){
		onStep(message,ticket.getPercent(),Status.ERROR);
	}

	protected void onStep(String msg,double progress,Status status){
		onStep(msg,progress,status,ticket.getTransferredBytes());
	}

	public TransferTicket getTicket(){
		return ticket;
	}
	
	
	
	public void handle(){
		
		InputStream is=null;
		BufferedOutputStream out=null;
		Boolean completedTransfer=false;
		File destination=null;
	
		try{
			if(ticket.getSettings().getOptions().getMethod().equals(TransferMethod.DirectTransfer))
				throw new NotSupportedMethodException("Unable to manage request [ID "+ticket.getId()+"]. Method not supported : "+ticket.getSettings().getOptions().getMethod());


			log.trace("Request handling started. Ticket is "+ticket);

			onStep("Checking destination",0d,Status.TRANSFERRING,0l);
			destination =persistenceProvider.prepareDestination(ticket.getDestinationSettings());
			ticket.setDestinationFileName(destination.getAbsolutePath());
			onStep("Opening input stream",0d,Status.TRANSFERRING,0l);

			
			is=getInputStream();
		

			try{
				out=new BufferedOutputStream(new FileOutputStream(destination));
			} catch (IOException e) {
				log.warn("Unable to create destination file.",e);
				throw new ManagedException("Cannot save file in host");
			}
			
			transferStream(is, out);
			completedTransfer=true;
			// IF TRANSFER FAILS, EXCEPTIONS AR THROWN



			//Plugin execution
			if(ticket.getPluginInvocations()!=null){				
				for(PluginInvocation invocation:ticket.getPluginInvocations()){
					log.debug("Execution {}",invocation);
					if(invocation.getParameters().containsValue(PluginInvocation.DESTINATION_FILE_PATH)){
						log.debug("Checking for param value : "+PluginInvocation.DESTINATION_FILE_PATH);
						for(Entry<String,String> param:invocation.getParameters().entrySet())
							if(param.getValue().equals(PluginInvocation.DESTINATION_FILE_PATH)){
								log.debug("Setting {} = {} ",param.getKey(),ticket.getDestinationFileName());
								param.setValue(ticket.getDestinationFileName());
							}

					}
					onStep("Executing invocation "+invocation.getPluginId(),1d,Status.PLUGIN_EXECUTION);
					pluginManager.execute(invocation);
				}
			}


			onStep("Completed transfer",1d,Status.SUCCESS);			
		}catch(NotSupportedMethodException e){
			onError(e.getMessage());
		}catch(ManagedException e){
			onError(e.getMessage());
		}catch(Throwable t){
			onError("Unexpected error while downloading : "+t.getMessage());
			log.error("Unexpected error occurred",t);
		}finally{
			log.debug("Finalizing transfer, ticket ID {} ",ticket.getId());
			if(out!=null)IOUtils.closeQuietly(out);
			if(is!=null)IOUtils.closeQuietly(is);
			
			if((!completedTransfer)&& (destination!=null) && (destination.exists())) {
				log.debug("Removing incomplete transfer..");
				try{
					FileUtils.forceDelete(destination);
				}catch(Exception e){
					log.warn("Unable to clean {} ",destination);
				}
			}

		}
	}


	private void transferStream(InputStream in, OutputStream out) throws ManagedException{

		long receivedTotal=0l;

		try{
			byte[] internalBuf=new byte[1024];
			int received=0;
			while ((received=in.read(internalBuf))!=-1){
				out.write(internalBuf,0,received);
				receivedTotal+=received;
				onStep("Transferring",0d,Status.TRANSFERRING,receivedTotal);					            
			}
			out.flush();
		}catch(IOException e){
			log.debug("Unable to read from source",e);
			throw new ManagedException("Unable to read from source.");
		}
		log.debug("Completed transfer phase for ticket ID {}. Transferred {} bytes. ",ticket.getId(),receivedTotal);
	}
	
	private InputStream getInputStream() throws ManagedException{
		switch(ticket.getSettings().getOptions().getMethod()){
		case HTTPDownload:{  
			try{
				HttpDownloadSettings options=(HttpDownloadSettings) (ticket.getSettings());
				return new BufferedInputStream(options.getSource().openStream());
			}catch(Exception e){
				log.debug("Unable to open connection ",e);
				throw new ManagedException("Cannot open connection to source");
			}
		}
		case FileUpload :{
			try{
				FileUploadSettings options=(FileUploadSettings) (ticket.getSettings());
				return new BufferedInputStream(options.getPassedStream());
			}catch(Exception e){
				log.debug("Unable to open connection ",e);
				throw new ManagedException("Cannot open connection to source");
			}
		}
		default:
			throw new ManagedException(ticket.getSettings().getOptions().getMethod()+" cannot be managed");
		}
	}
}