package org.gcube.informationsystem.resourceregistry.contexts;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;

import org.gcube.com.fasterxml.jackson.core.JsonProcessingException;
import org.gcube.common.context.ContextUtility;
import org.gcube.common.gxhttp.reference.GXConnection;
import org.gcube.common.gxhttp.request.GXHTTPStringRequest;
import org.gcube.common.http.GXHTTPUtility;
import org.gcube.informationsystem.contexts.reference.entities.Context;
import org.gcube.informationsystem.resourceregistry.api.contexts.ContextCache;
import org.gcube.informationsystem.resourceregistry.api.contexts.ContextCacheRenewal;
import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
import org.gcube.informationsystem.resourceregistry.api.exceptions.contexts.ContextAlreadyPresentException;
import org.gcube.informationsystem.resourceregistry.api.exceptions.contexts.ContextNotFoundException;
import org.gcube.informationsystem.resourceregistry.api.request.BaseRequestInfo;
import org.gcube.informationsystem.resourceregistry.api.rest.ContextPath;
import org.gcube.informationsystem.resourceregistry.api.rest.httputils.HTTPUtility;
import org.gcube.informationsystem.serialization.ElementMapper;
import org.gcube.informationsystem.utils.UUIDManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @author Luca Frosini (ISTI - CNR)
 */
public class ResourceRegistryContextClientImpl extends BaseRequestInfo implements ResourceRegistryContextClient {
	
	private static final Logger logger = LoggerFactory.getLogger(ResourceRegistryContextClientImpl.class);
	
	private static final String ACCEPT_HTTP_HEADER_KEY = "Accept";
	private static final String CONTENT_TYPE_HTTP_HEADER_KEY = "Content-Type";
	
	protected final String address;
	
	protected Map<String, String> headers;
	
	protected ContextCache contextCache;

	private void addOptionalQueryParameters(Map<String,String> queryParams) throws UnsupportedEncodingException {
		addIncludeMeta(queryParams);
	}
	
	private GXHTTPStringRequest includeAdditionalQueryParameters(GXHTTPStringRequest gxHTTPStringRequest) throws UnsupportedEncodingException{
		Map<String,String> queryParams = new HashMap<>();
		return includeAdditionalQueryParameters(gxHTTPStringRequest, queryParams);
	}
	
	private GXHTTPStringRequest includeAdditionalQueryParameters(GXHTTPStringRequest gxHTTPStringRequest, Map<String,String> queryParams) throws UnsupportedEncodingException{
		if(queryParams==null) {
			queryParams = new HashMap<>();
		}
		addOptionalQueryParameters(queryParams);
		return gxHTTPStringRequest.queryParams(queryParams);
	}
	
	private void addIncludeMeta(Map<String,String> queryParams) throws UnsupportedEncodingException{
		addIncludeMeta(queryParams, includeMeta);
	}
	
	private void addIncludeMeta(Map<String,String> queryParams, boolean includeMeta) throws UnsupportedEncodingException{
		if(includeMeta) {
			queryParams.put(ContextPath.INCLUDE_META_QUERY_PARAMETER, Boolean.toString(includeMeta));
		}
	}
	
	/*
	private void addOffset(Map<String,String> queryParams) throws UnsupportedEncodingException{
		addOffset(queryParams, offset);
	}
	*/
	
	private void addOffset(Map<String,String> queryParams, Integer offset) throws UnsupportedEncodingException{
		if(offset!=null) {
			queryParams.put(ContextPath.OFFSET_QUERY_PARAMETER, offset.toString());
		}
	}
	
	/*
	private void addLimit(Map<String,String> queryParams) throws UnsupportedEncodingException{
		addLimit(queryParams, limit);
	}
	*/
	
	private void addLimit(Map<String,String> queryParams, Integer limit) throws UnsupportedEncodingException{
		if(limit!=null) {
			queryParams.put(ContextPath.LIMIT_QUERY_PARAMETER, limit.toString());
		}
	}
	
	protected ContextCacheRenewal contextCacheRenewal = new ContextCacheRenewal() {
		
		@Override
		public List<Context> renew() throws ResourceRegistryException {
			return getAllContextFromServer(true, 0, BaseRequestInfo.UNBOUNDED_LIMIT);
		}
		
	};
	
	@Override
	public void addHeader(String name, String value) {
		headers.put(name, value);
	}
	
	protected GXHTTPStringRequest getGXHTTPStringRequest() {
		GXHTTPStringRequest gxHTTPStringRequest = GXHTTPUtility.getGXHTTPStringRequest(address);
		gxHTTPStringRequest.from(this.getClass().getSimpleName());
		for(String name : headers.keySet()) {
			gxHTTPStringRequest.header(name, headers.get(name));
		}
		return gxHTTPStringRequest;
	}
	
	public ResourceRegistryContextClientImpl(String address) {
		this(address, true);
	}
	
	public ResourceRegistryContextClientImpl(String address, boolean sharedContextCache) {
		this.address = address;
		this.headers = new HashMap<>();
		this.includeMeta = false;
		if(sharedContextCache) {
			contextCache = ContextCache.getInstance();
		}else {
			contextCache = new ContextCache();
		}
		contextCache.setContextCacheRenewal(contextCacheRenewal);
	}
	
	private void forceCacheRefresh() {
		try {
			contextCache.cleanCache();
			contextCache.refreshContextsIfNeeded();
		}catch (Exception e) {
			logger.warn("Unable to force cache refresh.", e);
		}
	}
	
	
	/**
	 * It reads all the contexts from server. 
	 * The cache used for contexts is bypassed and not updated.
	 * @return All Contexts read from server
	 * @throws ResourceRegistryException
	 */
	public List<Context> getAllContextFromServer() throws ResourceRegistryException {
		return getAllContextFromServer(includeMeta, offset, limit);
	}
	
	protected List<Context> getAllContextFromServer(boolean includeMeta, Integer offset, Integer limit) throws ResourceRegistryException {
		try {
			logger.info("Going to read all {}s", Context.NAME);
			GXHTTPStringRequest gxHTTPStringRequest = getGXHTTPStringRequest();
			gxHTTPStringRequest.header(ACCEPT_HTTP_HEADER_KEY, GXConnection.APPLICATION_JSON_CHARSET_UTF_8);
			gxHTTPStringRequest.path(ContextPath.CONTEXTS_PATH_PART);
			
			Map<String,String> parameters = new HashMap<>();
			addIncludeMeta(parameters, includeMeta);
			addOffset(parameters, offset);
			addLimit(parameters, limit);
			gxHTTPStringRequest.queryParams(parameters);
			
			HttpURLConnection httpURLConnection = gxHTTPStringRequest.get();
			String all = HTTPUtility.getResponse(String.class, httpURLConnection);
			
			logger.debug("Got contexts are {}", Context.NAME, all);
			return ElementMapper.unmarshalList(Context.class, all);
			
		} catch(ResourceRegistryException e) {
			// logger.trace("Error Creating {}", facet, e);
			throw e;
		} catch(Exception e) {
			// logger.trace("Error Creating {}", facet, e);
			throw new RuntimeException(e);
		}
	}
	
	@Override
	public List<Context> all() throws ResourceRegistryException {
		return contextCache.getContexts();
	}
	
	@Override
	public ContextCache getContextCache() {
		return contextCache;
	}
	
	protected String internalCreate(Context context) throws ContextAlreadyPresentException, ResourceRegistryException {
		try {
			UUID uuid = context.getID();
			if(uuid == null) {
				uuid = UUIDManager.getInstance().generateValidUUID();
				context.setID(uuid);
			}
			
			
			String contextString = ElementMapper.marshal(context);
			
			logger.trace("Going to create {}", contextString);
			
			GXHTTPStringRequest gxHTTPStringRequest = getGXHTTPStringRequest();
			gxHTTPStringRequest.header(ACCEPT_HTTP_HEADER_KEY, GXConnection.APPLICATION_JSON_CHARSET_UTF_8);
			gxHTTPStringRequest.header(CONTENT_TYPE_HTTP_HEADER_KEY, GXConnection.APPLICATION_JSON_CHARSET_UTF_8);
			gxHTTPStringRequest.path(ContextPath.CONTEXTS_PATH_PART);
			gxHTTPStringRequest.path(uuid.toString());
			
			includeAdditionalQueryParameters(gxHTTPStringRequest);
			
			HttpURLConnection httpURLConnection = gxHTTPStringRequest.put(contextString);
			String c = HTTPUtility.getResponse(String.class, httpURLConnection);
			
			forceCacheRefresh();
			
			logger.trace("{} successfully created", c);
			return c;
			
		} catch(ResourceRegistryException e) {
			// logger.trace("Error Creating {}", facet, e);
			throw e;
		} catch(Exception e) {
			// logger.trace("Error Creating {}", facet, e);
			throw new RuntimeException(e);
		}
	}
	
	@Override
	public Context create(Context context) throws ContextAlreadyPresentException, ResourceRegistryException {
		try {
			String res = internalCreate(context);
			return ElementMapper.unmarshal(Context.class, res);
		} catch(ResourceRegistryException e) {
			// logger.trace("Error Creating {}", facet, e);
			throw e;
		} catch(Exception e) {
			// logger.trace("Error Creating {}", facet, e);
			throw new RuntimeException(e);
		}
	}
	
	@Override
	public String create(String context) throws ContextAlreadyPresentException, ResourceRegistryException {
		try {
			Context c = ElementMapper.unmarshal(Context.class, context);
			return internalCreate(c);
		} catch(ResourceRegistryException e) {
			// logger.trace("Error Creating {}", facet, e);
			throw e;
		} catch(Exception e) {
			// logger.trace("Error Creating {}", facet, e);
			throw new RuntimeException(e);
		}
	}
	
	public boolean existFromServer(String uuid) throws ContextNotFoundException, ResourceRegistryException {
		try {
			logger.trace("Going to read {} with UUID {}", Context.NAME, uuid);
			GXHTTPStringRequest gxHTTPStringRequest = getGXHTTPStringRequest();
			gxHTTPStringRequest.header(ACCEPT_HTTP_HEADER_KEY, GXConnection.APPLICATION_JSON_CHARSET_UTF_8);
			gxHTTPStringRequest.path(ContextPath.CONTEXTS_PATH_PART);
			gxHTTPStringRequest.path(uuid);
			
			HttpURLConnection httpURLConnection = gxHTTPStringRequest.head();
			HTTPUtility.getResponse(String.class, httpURLConnection);
			
			return true;
		} catch (NotFoundException e) {
			return false;
		} catch(ResourceRegistryException e) {
			// logger.trace("Error Creating {}", facet, e);
			throw e;
		} catch(Exception e) {
			// logger.trace("Error Creating {}", facet, e);
			throw new RuntimeException(e);
		}
	}
	
	@Override
	public boolean exist(String uuid) throws ResourceRegistryException {
		return exist(UUID.fromString(uuid));
	}
	
	@Override
	public boolean exist(UUID uuid) throws ResourceRegistryException {
		try {
			read(uuid);
			return true;
		}catch (ContextNotFoundException e) {
			return false;
		}
	}

	@Override
	public Context read(Context context) throws ContextNotFoundException, ResourceRegistryException {
		return read(context.getID());
	}
	
	@Override
	public Context read(UUID uuid) throws ContextNotFoundException, ResourceRegistryException {
		Context context = contextCache.getContextByUUID(uuid);;
		if(context == null) {
			String contextJson = readFromServer(uuid.toString());
			try {
				context = ElementMapper.unmarshal(Context.class, contextJson);
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
			forceCacheRefresh();
			Context c = contextCache.getContextByUUID(context.getID());
			if(c!=null){
				context = c;
			}else {
				logger.error("Context with UUID {} is {}. It is possibile to get it from the server but not from the cache. This is very strange and should not occur.", uuid, context);
			}
		}
		return context;
	}
	
	@Override
	public Context readCurrentContext() throws ContextNotFoundException, ResourceRegistryException {
		String contextFullName = ContextUtility.getCurrentContextFullName();
		UUID uuid = contextCache.getUUIDByFullName(contextFullName);
		return read(uuid);
	}
	
	@Override
	public String read(String uuid) throws ContextNotFoundException, ResourceRegistryException {
		try {
			return ElementMapper.marshal(read(UUID.fromString(uuid)));
		} catch (ContextNotFoundException e) {
			throw e;
		} catch (JsonProcessingException e) {
			throw new RuntimeException(e);
		} catch (ResourceRegistryException e) {
			throw e;
		}
	}
	
	public String readFromServer(String uuid) throws ContextNotFoundException, ResourceRegistryException {
		try {
			logger.trace("Going to read {} with UUID {}", Context.NAME, uuid);
			GXHTTPStringRequest gxHTTPStringRequest = getGXHTTPStringRequest();
			gxHTTPStringRequest.header(ACCEPT_HTTP_HEADER_KEY, GXConnection.APPLICATION_JSON_CHARSET_UTF_8);
			gxHTTPStringRequest.path(ContextPath.CONTEXTS_PATH_PART);
			gxHTTPStringRequest.path(uuid);
			
			includeAdditionalQueryParameters(gxHTTPStringRequest);
			
			HttpURLConnection httpURLConnection = gxHTTPStringRequest.get();
			String c = HTTPUtility.getResponse(String.class, httpURLConnection);
			
			logger.debug("Got {} is {}", Context.NAME, c);
			return c;
		} catch(ResourceRegistryException e) {
			// logger.trace("Error Creating {}", facet, e);
			throw e;
		} catch(Exception e) {
			// logger.trace("Error Creating {}", facet, e);
			throw new RuntimeException(e);
		}
	}
	
	public String internalUpdate(Context context) throws ContextNotFoundException, ResourceRegistryException {
		try {
			String contextString = ElementMapper.marshal(context);
			logger.trace("Going to update {}", contextString);
			
			UUID uuid = context.getID();
			
			GXHTTPStringRequest gxHTTPStringRequest = getGXHTTPStringRequest();
			gxHTTPStringRequest.header(ACCEPT_HTTP_HEADER_KEY, GXConnection.APPLICATION_JSON_CHARSET_UTF_8);
			gxHTTPStringRequest.header(CONTENT_TYPE_HTTP_HEADER_KEY, GXConnection.APPLICATION_JSON_CHARSET_UTF_8);
			gxHTTPStringRequest.path(ContextPath.CONTEXTS_PATH_PART);
			gxHTTPStringRequest.path(uuid.toString());
			
			includeAdditionalQueryParameters(gxHTTPStringRequest);
			
			HttpURLConnection httpURLConnection = gxHTTPStringRequest.put(contextString);
			String c = HTTPUtility.getResponse(String.class, httpURLConnection);
			
			forceCacheRefresh();
			
			logger.trace("{} successfully updated", c);
			return c;
			
		} catch(ResourceRegistryException e) {
			// logger.trace("Error Creating {}", facet, e);
			throw e;
		} catch(Exception e) {
			// logger.trace("Error Creating {}", facet, e);
			throw new RuntimeException(e);
		}
	}
	
	@Override
	public Context update(Context context) throws ContextNotFoundException, ResourceRegistryException {
		try {
			String res = internalUpdate(context);
			return ElementMapper.unmarshal(Context.class, res);
		} catch(ResourceRegistryException e) {
			// logger.trace("Error Updating {}", facet, e);
			throw e;
		} catch(Exception e) {
			// logger.trace("Error Updating {}", facet, e);
			throw new RuntimeException(e);
		}
	}
	
	@Override
	public String update(String context) throws ContextNotFoundException, ResourceRegistryException {
		try {
			Context c = ElementMapper.unmarshal(Context.class, context);
			return internalUpdate(c);
		} catch(ResourceRegistryException e) {
			// logger.trace("Error Updating {}", facet, e);
			throw e;
		} catch(Exception e) {
			// logger.trace("Error Updating {}", facet, e);
			throw new RuntimeException(e);
		}
	}
	
	@Override
	public boolean delete(Context context) throws ContextNotFoundException, ResourceRegistryException {
		return delete(context.getID());
	}
	
	@Override
	public boolean delete(UUID uuid) throws ContextNotFoundException, ResourceRegistryException {
		return delete(uuid.toString());
	}
	
	@Override
	public boolean delete(String uuid) throws ContextNotFoundException, ResourceRegistryException {
		try {
			logger.trace("Going to delete {} with UUID {}", Context.NAME, uuid);
			GXHTTPStringRequest gxHTTPStringRequest = getGXHTTPStringRequest();
			gxHTTPStringRequest.header(ACCEPT_HTTP_HEADER_KEY, GXConnection.APPLICATION_JSON_CHARSET_UTF_8);
			gxHTTPStringRequest.path(ContextPath.CONTEXTS_PATH_PART);
			gxHTTPStringRequest.path(uuid);
			
			HttpURLConnection httpURLConnection = gxHTTPStringRequest.delete();
			HTTPUtility.getResponse(String.class, httpURLConnection);
			
			boolean deleted = true;
			
			logger.info("{} with UUID {} {}", Context.NAME, uuid,
					deleted ? " successfully deleted" : "was NOT deleted");
			return deleted;
		} catch(ResourceRegistryException e) {
			// logger.trace("Error Creating {}", facet, e);
			throw e;
		} catch(Exception e) {
			// logger.trace("Error Creating {}", facet, e);
			throw new RuntimeException(e);
		}finally {
			try {
				forceCacheRefresh();
			}catch (Exception e) {
				
			}
		}
	}
	
}