package org.gcube.datatransfer.resolver.services;

import java.io.IOException;
import java.io.InputStream;
import java.util.Objects;

import javax.servlet.http.HttpServletRequest;
import javax.ws.rs.GET;
import javax.ws.rs.HEAD;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.QueryParam;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.ResponseBuilder;
import javax.ws.rs.core.StreamingOutput;

import org.apache.commons.io.IOUtils;
import org.apache.http.HttpStatus;
import org.gcube.contentmanagement.blobstorage.resource.MyFile;
import org.gcube.contentmanagement.blobstorage.service.IClient;
import org.gcube.contentmanager.storageclient.wrapper.AccessType;
import org.gcube.contentmanager.storageclient.wrapper.BackendType;
import org.gcube.contentmanager.storageclient.wrapper.MemoryType;
import org.gcube.contentmanager.storageclient.wrapper.StorageClient;
import org.gcube.datatransfer.resolver.ConstantsResolver;
import org.gcube.datatransfer.resolver.ConstantsResolver.CONTENT_DISPOSITION_VALUE;
import org.gcube.datatransfer.resolver.services.error.ExceptionManager;
import org.gcube.datatransfer.resolver.storage.StorageClientInstance;
import org.gcube.datatransfer.resolver.storage.StorageMetadataFile;
import org.gcube.datatransfer.resolver.util.SingleFileStreamingOutput;
import org.gcube.datatransfer.resolver.util.ValidateContentDisposition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;



/**
 * The Class StorageIDResolver.
 *
 * @author Francesco Mangiacrapa at ISTI-CNR (francesco.mangiacrapa@isti.cnr.it)
 * Dec 14, 2018
 */
@Path("storage")
public class StorageIDResolver {

	/**
	 *
	 */
	protected static final String STORAGEID_RESOLVER = "storageid-resolver";
	private static final String STORAGE_ID = "storage-id";
	private static final AccessType STORAGE_ACCESS_TYPE=AccessType.PUBLIC;
	private static final BackendType STORAGE_BACKEND_TYPE=BackendType.MongoDB;
	private static final Logger LOG = LoggerFactory.getLogger(StorageIDResolver.class);
	
	private static String help = "https://wiki.gcube-system.org/gcube/URI_Resolver#STORAGE-ID_Resolver";

	protected static IClient storageManagerClient;
	private static MemoryType memory;

	/**
	 * Gets the storage id.
	 *
	 * @param req the req
	 * @param storageId the storage id
	 * @param fileName the file name
	 * @param contentType the content type
	 * @param validation the validation
	 * @return the storage id
	 * @throws WebApplicationException the web application exception
	 */
	@GET
	@Path("/{storage-id}")
	public Response getStorageId(@Context HttpServletRequest req,
		@PathParam(STORAGE_ID) String storageId,
		@QueryParam(ConstantsResolver.QUERY_PARAM_FILE_NAME) String fileName,
		@QueryParam(ConstantsResolver.QUERY_PARAM_CONTENT_TYPE) String contentType,
		@QueryParam(ConstantsResolver.QUERY_PARAM_CONTENTDISPOSITION) String contentDisposition,
		@QueryParam(ConstantsResolver.QUERY_PARAM_VALIDATION) boolean validation) throws WebApplicationException {

		LOG.info(this.getClass().getSimpleName()+" GET starts...");
		
		//Checking the optional parameter "Content-Disposition"
		CONTENT_DISPOSITION_VALUE dispositionValue = CONTENT_DISPOSITION_VALUE.attachment;
		//Validating the Content-Disposition value
		dispositionValue = ValidateContentDisposition.validValue(req, this.getClass(), help, contentDisposition);

		try{
			if(storageId==null || storageId.isEmpty()){
				LOG.error(STORAGE_ID+" not found");
				throw ExceptionManager.badRequestException(req,  "Missing mandatory path parameter "+STORAGE_ID, StorageIDResolver.class, help);
			}
			return resolveStorageId(req, storageId, fileName, contentType, dispositionValue, validation);
		}catch (Exception e) {

			if(!(e instanceof WebApplicationException)){
				//UNEXPECTED EXCEPTION managing it as WebApplicationException
				String error = "Error occurred on resolving the Storage ID: "+storageId+". Please, contact the support!";
				if(e.getCause()!=null)
					error+="\n\nCaused: "+e.getCause().getMessage();
				throw ExceptionManager.internalErrorException(req, error, this.getClass(), help);
			}
			//ALREADY MANAGED AS WebApplicationException
			LOG.error("Exception:", e);
			throw (WebApplicationException) e;
		}
	}


	/**
	 * Resolve storage id.
	 *
	 * @param httpRequest the http request
	 * @param storageId the storage id
	 * @param fileName the file name
	 * @param contentType the content type
	 * @param validation the validation
	 * @return the response
	 * @throws Exception the exception
	 */
	protected static Response resolveStorageId(HttpServletRequest httpRequest, String storageId, String fileName, String contentType, CONTENT_DISPOSITION_VALUE contentDisposition, boolean validation) throws Exception{

		LOG.info("storage-id: "+storageId+", fileName: "+fileName+", contentType: "+contentType+", validation: "+validation);

		//Checking mandatory parameter storageId
		if (storageId == null || storageId.isEmpty()) {
			LOG.error("storageId not found");
			throw ExceptionManager.badRequestException(httpRequest,  "Missing mandatory path parameter "+STORAGE_ID, StorageIDResolver.class, help);
		}
		storageId = identifyIdAndMemory(storageId);
		IClient iClient = getStorageClientInstance(memory);
		String toSEID = null;
		LOG.info("I'm using the storageId {}",storageId);
		try{
			toSEID = iClient.getId(storageId); //to Storage Encrypted ID
			LOG.info("Decoded ID"+" = "+ toSEID);
		}catch(Exception e){
			LOG.error("Storage Client Exception when getting file from storage: ", e);
			throw ExceptionManager.notFoundException(httpRequest, "Storage Client Exception when getting file from storage with id: "+storageId, StorageIDResolver.class, help);
		}
		if(toSEID==null || toSEID.isEmpty()){
			LOG.error("Decrypted id for storageId: "+storageId +" is null or empty!");
			throw ExceptionManager.notFoundException(httpRequest, "Error on decrypting the "+STORAGE_ID+ " '"+storageId+"'. Is it a valid id?", StorageIDResolver.class, help);
		}

		//long size = iClient.getSize().RFileById(toSEID);
		long size = 0;
		
		//READING THE METADATA OF FILE FROM STORAGE
		StorageMetadataFile metaFile = getStorageMetadataFile(iClient,toSEID);
		LOG.debug("MetaFile retrieved from storage? "+ (metaFile!=null));
		
		if(metaFile!=null) {
			//Reading the fileName from Storage Metadata only if the passed fileName is null
			if(fileName==null || fileName.isEmpty()) {
				fileName= metaFile.getName();
				LOG.debug("Read filename {} from {}", fileName, StorageMetadataFile.class.getSimpleName());
			}
	
			//Reading the contentType from Storage Metadata only if the passed contentType is null
			if(contentType==null || contentType.isEmpty()) {
				contentType = metaFile.getMimeType();
				LOG.debug("Read contentType {} from {}", contentType, StorageMetadataFile.class.getSimpleName());
			}
			
			//Reading the content size
			size = metaFile.getSize();
			LOG.debug("Read size {} from {}", size, StorageMetadataFile.class.getSimpleName());
		}

		//CHECKING TO DEFAULT METADATA
		fileName = fileName==null || fileName.isEmpty()?ConstantsResolver.DEFAULT_FILENAME_FROM_STORAGE_MANAGER:fileName;
		LOG.info("filename retrieved is {}",fileName);

		contentType = contentType==null || contentType.isEmpty()?ConstantsResolver.DEFAULT_CONTENTTYPE_UNKNOWN_UNKNOWN:contentType;
		LOG.info("contentType used is {}",contentType);

		//Building the response
		InputStream streamToWrite=iClient.get().RFileAsInputStream(toSEID); //input stream
		StreamingOutput so = new SingleFileStreamingOutput(streamToWrite);

		ResponseBuilder response = Response
				.ok(so)
				.header(ConstantsResolver.CONTENT_DISPOSITION, contentDisposition.name()+"; filename=\""+fileName+"\"")
				.header(ConstantsResolver.CONTENT_LENGTH, size)
				.header("Content-Type",contentType);

//		if (contentType!= null)
//			response.header("Content-Type",contentType);
		
		return response.build();

	}



	

	/**
	 * Http do head.
	 *
	 * @param req the http request
	 * @param storageId the storage id
	 * @param hproxycheck the hproxycheck
	 * @return the response
	 * @throws WebApplicationException the web application exception
	 */
	@HEAD
	@Path("/{storage-id}")
	public Response httpDoHead(@Context HttpServletRequest req,
		@PathParam(STORAGE_ID) String storageId,
		@QueryParam(ConstantsResolver.HPC) boolean hproxycheck) throws WebApplicationException {

		LOG.info(this.getClass().getSimpleName()+" HEAD starts...");
		LOG.info("The query string is: {}", req.getQueryString());
		LOG.info("Query parameter {} is {}", ConstantsResolver.HPC, hproxycheck);

		try{
			//THIS IS FOR HPROXY CHECK
			if(hproxycheck){
				LOG.trace("returning status 200 for Hproxy check");
				ResponseBuilder response = Response.status(HttpStatus.SC_OK);
				return response.build();
			}

			return validationPayload(req, storageId);

		}catch (Exception e) {

			if(!(e instanceof WebApplicationException)){
				//UNEXPECTED EXCEPTION managing it as WebApplicationException
				String error = "Error occurred on resolving the Storage ID: "+storageId+". Please, contact the support!";
				if(e.getCause()!=null)
					error+="\n\nCaused: "+e.getCause().getMessage();
				throw ExceptionManager.internalErrorException(req, error, this.getClass(), help);
			}
			//ALREADY MANAGED AS WebApplicationException
			LOG.error("Exception:", e);
			throw (WebApplicationException) e;
		}
	}


	/**
	 * Validation payload.
	 *
	 * @param httpRequest the http request
	 * @param storageId the storage id
	 * @return the response
	 * @throws Exception the exception
	 */
	protected Response validationPayload(HttpServletRequest httpRequest, String storageId) throws Exception{
		LOG.info("validationPayload called");

		//Checking mandatory parameter storageId
		if (storageId == null || storageId.isEmpty()) {
			LOG.warn("storageId not found");
			throw ExceptionManager.badRequestException(httpRequest, "Storage Client Exception when getting file from storage with id: "+storageId, this.getClass(), help);
		}	
		storageId = identifyIdAndMemory(storageId);
		IClient iClient = getStorageClientInstance(memory);
		String toSEID = null;
		LOG.info("I'm using the storageId {}",storageId);
		try{
			toSEID = iClient.getId(storageId); //to Storage Encrypted ID
			LOG.info("Decoded ID"+" = "+ toSEID);
		}catch(Exception e){
			LOG.error("Storage Client Exception when getting file from storage: ", e);
			throw ExceptionManager.notFoundException(httpRequest, "Storage Client Exception when getting file from storage with id: "+storageId, StorageIDResolver.class, help);
		}
		if(toSEID==null || toSEID.isEmpty()){
			LOG.error("Decrypted id for storageId: "+storageId +" is null or empty!");
			throw ExceptionManager.notFoundException(httpRequest, "Error on decrypting the "+STORAGE_ID+ " '"+storageId+"'. Is it a valid id?", StorageIDResolver.class, help);
		}
		//SETTING DEFAULT METADATA
		String fileName = ConstantsResolver.DEFAULT_FILENAME_FROM_STORAGE_MANAGER;
		String contentType = ConstantsResolver.DEFAULT_CONTENTTYPE_UNKNOWN_UNKNOWN;
		//READING THE METADATA OF FILE FROM STORAGE
		StorageMetadataFile metadataFile = getStorageMetadataFile(iClient,toSEID);
		LOG.debug("MetaFile retrieved from storage? "+ (metadataFile!=null));
		long size = 0;

		if (metadataFile != null) {

			// Reading the fileName from Storage Metadata only if it is not null
			if (metadataFile.getName() != null) {
				fileName = metadataFile.getName();
				LOG.debug("Read filename {} from {}", fileName, StorageMetadataFile.class.getSimpleName());
			}

			// Reading the contentType from Storage Metadata only if it is not null
			if (metadataFile.getMimeType() != null) {
				contentType = metadataFile.getMimeType();
				LOG.debug("Read contentType {} from {}", contentType, StorageMetadataFile.class.getSimpleName());
			}

			size = metadataFile.getSize();
			LOG.debug("Read size {} from {}", size, StorageMetadataFile.class.getSimpleName());
		}

		//Building the response
		InputStream streamToWrite=iClient.get().RFileAsInputStream(toSEID); //input stream

		byte[] bytes = new byte[1]; //1B
		int c;
		ResponseBuilder response = null;
		try {
			c = streamToWrite.read(bytes);
			LOG.info(c+" byte read from InputStream");
			if(c>0){
				LOG.info("at least 1 byte read, returning status 200");
				IOUtils.closeQuietly(streamToWrite);
				response = Response.status(HttpStatus.SC_OK);
			}else
				throw ExceptionManager.notFoundException(httpRequest, "The file with id: "+storageId+" is missing in the storage", StorageIDResolver.class, help);
		}
		catch (IOException e2) {
			LOG.error("Error on validating the file: ",e2);
			throw ExceptionManager.internalErrorException(httpRequest, "Error on validating the file with id: "+storageId, StorageIDResolver.class, help);
		}

		if(response==null)
			throw ExceptionManager.internalErrorException(httpRequest, "Error on validating the file with id: "+storageId, StorageIDResolver.class, help);
		
		response = response
				.header("Content-Type", contentType)
				.header(ConstantsResolver.CONTENT_LENGTH, size)
				.header(ConstantsResolver.CONTENT_DISPOSITION,"attachment; filename=\""+fileName+"\"");
		iClient.forceClose();
		return response.build();

	}
	
	/**
	 * Get a storage-manager client instance. A new storage instance will be instantied only if the memory type is not the same of the previous one.
	 * In this case the old connection will be closed.
	 *
	 * @param memoryType indicates the memory type (Persistent, Volatile or whatever)
	 * @return the storage client instance
	 */
	protected static IClient getStorageClientInstance(MemoryType memory) {
		if ((!Objects.isNull(storageManagerClient)) && (storageManagerClient.getGcubeMemoryType().equals(memory)))
			return storageManagerClient;
		else {
			if(!Objects.isNull(storageManagerClient)) {
				LOG.debug("going to close an old storage-client instance");
				storageManagerClient.forceClose();
			}
			LOG.debug("initializing a new storage-client instance");
			storageManagerClient=new StorageClient(StorageIDResolver.class.getName(), StorageIDResolver.class.getSimpleName(), STORAGEID_RESOLVER, STORAGE_ACCESS_TYPE, memory, STORAGE_BACKEND_TYPE).getClient();
			return storageManagerClient;
		}
	}
	
	/**
	 * Set the right memory type extrapolated from the storageid
	 * @param storageId storageid with backend type specification (if present)
	 * @return storageId without backend type specification
	 */
	private static String identifyIdAndMemory(String storageId) {
		if(storageId.endsWith(org.gcube.contentmanagement.blobstorage.transport.backend.util.Costants.VOLATILE_URL_IDENTIFICATOR)){
			LOG.info("identificated a VOLATILE url");
			memory=MemoryType.VOLATILE;
			storageId=storageId.replace(org.gcube.contentmanagement.blobstorage.transport.backend.util.Costants.VOLATILE_URL_IDENTIFICATOR, "");
		}else {
			memory=MemoryType.PERSISTENT;
		}
		return storageId;
	}
	
	/**
	 * Gets the storage metadata file.
	 *
	 * @param iClient the i client
	 * @param toSEID the to SEID
	 * @return the storage metadata file
	 */
	public static StorageMetadataFile getStorageMetadataFile(IClient iClient, String toSEID) {

		try{
			if(iClient==null)
				throw new Exception("The "+IClient.class.getName()+" is not instancied correclty. It is null!");
			
			if(toSEID==null || toSEID.isEmpty())
				throw new Exception("Invalid input identifier. The input Storage Encrypted ID is null or empty!");
			
			long size = iClient.getSize().RFileById(toSEID);
			MyFile myFile = iClient.getMetaFile().RFile(toSEID);
			
			return new StorageMetadataFile(myFile, size);

		}catch (Exception e) {
			LOG.warn("Error on getting file metadata from storage, printing this warning and trying to continue..", e);
			return null;
		}

	}

}