package org.gcube.dataharvest.harvester;

import static org.gcube.resources.discovery.icclient.ICFactory.clientFor;
import static org.gcube.resources.discovery.icclient.ICFactory.queryFor;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.time.Instant;
import java.time.LocalDate;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.List;

import org.gcube.accounting.accounting.summary.access.model.ScopeDescriptor;
import org.gcube.accounting.accounting.summary.access.model.update.AccountingRecord;
import org.gcube.common.encryption.encrypter.StringEncrypter;
import org.gcube.common.resources.gcore.ServiceEndpoint;
import org.gcube.common.resources.gcore.ServiceEndpoint.AccessPoint;
import org.gcube.common.resources.gcore.ServiceEndpoint.Property;
import org.gcube.common.resources.gcore.utils.Group;
import org.gcube.common.scope.api.ScopeProvider;
import org.gcube.common.scope.impl.ScopeBean;
import org.gcube.dataharvest.AccountingDashboardHarvesterPlugin;
import org.gcube.dataharvest.datamodel.AnalyticsReportCredentials;
import org.gcube.dataharvest.datamodel.HarvestedDataKey;
import org.gcube.dataharvest.datamodel.VREAccessesReportRow;
import org.gcube.resources.discovery.client.api.DiscoveryClient;
import org.gcube.resources.discovery.client.queries.api.SimpleQuery;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.auth.oauth2.GoogleCredential.Builder;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.googleapis.util.Utils;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.client.util.PemReader;
import com.google.api.client.util.PemReader.Section;
import com.google.api.client.util.SecurityUtils;
import com.google.api.services.analyticsreporting.v4.AnalyticsReporting;
import com.google.api.services.analyticsreporting.v4.AnalyticsReportingScopes;
import com.google.api.services.analyticsreporting.v4.model.DateRange;
import com.google.api.services.analyticsreporting.v4.model.DateRangeValues;
import com.google.api.services.analyticsreporting.v4.model.GetReportsRequest;
import com.google.api.services.analyticsreporting.v4.model.GetReportsResponse;
import com.google.api.services.analyticsreporting.v4.model.Metric;
import com.google.api.services.analyticsreporting.v4.model.Report;
import com.google.api.services.analyticsreporting.v4.model.ReportRequest;
import com.google.api.services.analyticsreporting.v4.model.ReportRow;

/**
 * 
 * @author Giancarlo Panichi (ISTI CNR)
 *
 */
public class JupyterAccessesHarvester extends BasicHarvester {

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

	private static final JsonFactory JSON_FACTORY = GsonFactory.getDefaultInstance();

	private static final String SERVICE_ENDPOINT_CATEGORY = "OnlineService";
	private static final String SERVICE_ENDPOINT_NAME = "BigGAnalyticsReportService";
	private static final String AP_VIEWS_PROPERTY = "views";
	private static final String AP_CLIENT_PROPERTY = "clientId";
	private static final String AP_PRIVATEKEY_PROPERTY = "privateKeyId";
	private static final String APPLICATION_NAME = "Analytics Reporting";

	private List<VREAccessesReportRow> vreAccesses;

	public JupyterAccessesHarvester(Date start, Date end) throws Exception {
		super(start, end);
		logger.debug("JupyerAccessHArvester: {}, {}", start, end);
		vreAccesses = getAllAccesses(start, end);
	}

	@Override
	public List<AccountingRecord> getAccountingRecords() throws Exception {
		try {
			String context = org.gcube.dataharvest.utils.Utils.getCurrentContext();

			ArrayList<AccountingRecord> accountingRecords = new ArrayList<AccountingRecord>();

			int measure = 0;

			ScopeBean scopeBean = new ScopeBean(context);
			String lowerCasedContext = scopeBean.name().toLowerCase();
			logger.debug("JupyerAccessHArvester lowerCasedContext: {}", lowerCasedContext);
			for (VREAccessesReportRow row : vreAccesses) {
				String pagePath = row.getPagePath().toLowerCase();
				if (pagePath != null && !pagePath.isEmpty()) {
					if (pagePath.contains(lowerCasedContext)) {
						if (!pagePath.contains("catalogue")) {
							if (pagePath.contains("jupyter") || pagePath.contains("jupiter")) {
								logger.trace("Matched jupyter or jupiter ({}) : {}", lowerCasedContext, pagePath);
								measure += row.getVisitNumber();
							}
						}
					}
				}
			}

			ScopeDescriptor scopeDescriptor = AccountingDashboardHarvesterPlugin.getScopeDescriptor();

			AccountingRecord ar = new AccountingRecord(scopeDescriptor, instant,
					getDimension(HarvestedDataKey.JUPYTER_ACCESSES), (long) measure);
			logger.debug("{} : {}", ar.getDimension().getId(), ar.getMeasure());
			accountingRecords.add(ar);

			return accountingRecords;

		} catch (Exception e) {
			throw e;
		}
	}

	/**
	 * 
	 * @return a list of {@link VREAccessesReportRow} objects containing the
	 *         pagePath and the visit number e.g. VREAccessesReportRow
	 *         [pagePath=/group/agroclimaticmodelling/add-new-users,
	 *         visitNumber=1] VREAccessesReportRow
	 *         [pagePath=/group/agroclimaticmodelling/administration,
	 *         visitNumber=2] VREAccessesReportRow
	 *         [pagePath=/group/agroclimaticmodelling/agroclimaticmodelling,
	 *         visitNumber=39]
	 */
	private static List<VREAccessesReportRow> getAllAccesses(Date start, Date end) throws Exception {
		DateRange dateRange = getDateRangeForAnalytics(start, end);
		logger.trace("Getting accesses in this time range {}", dateRange.toPrettyString());

		AnalyticsReportCredentials credentialsFromD4S = getAuthorisedApplicationInfoFromIs();
		AnalyticsReporting service = initializeAnalyticsReporting(credentialsFromD4S);
		HashMap<String, List<GetReportsResponse>> responses = getReportResponses(service,
				credentialsFromD4S.getViewIds(), dateRange);
		List<VREAccessesReportRow> totalAccesses = new ArrayList<>();

		for (String view : responses.keySet()) {
			List<VREAccessesReportRow> viewReport = parseResponse(view, responses.get(view));
			logger.trace("Got {} entries from view id={}", viewReport.size(), view);
			totalAccesses.addAll(viewReport);
		}
		logger.trace("Merged in {} total entries from all views", totalAccesses.size());
		return totalAccesses;
	}

	/**
	 * Initializes an Analytics Reporting API V4 service object.
	 *
	 * @return An authorized Analytics Reporting API V4 service object.
	 * @throws IOException
	 * @throws GeneralSecurityException
	 */
	private static AnalyticsReporting initializeAnalyticsReporting(AnalyticsReportCredentials cred)
			throws GeneralSecurityException, IOException {
		HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
		GoogleCredential credential = fromD4SServiceEndpoint(cred).createScoped(AnalyticsReportingScopes.all());

		// Construct the Analytics Reporting service object.
		return new AnalyticsReporting.Builder(httpTransport, JSON_FACTORY, credential)
				.setApplicationName(APPLICATION_NAME).build();
	}

	/**
	 * Queries the Analytics Reporting API V4.
	 *
	 * @param service
	 *            An authorized Analytics Reporting API V4 service object.
	 * @return GetReportResponse The Analytics Reporting API V4 response.
	 * @throws IOException
	 */
	private static HashMap<String, List<GetReportsResponse>> getReportResponses(AnalyticsReporting service,
			List<String> viewIDs, DateRange dateRange) throws IOException {

		HashMap<String, List<GetReportsResponse>> reports = new HashMap<>();

		// Create the Metrics object.
		Metric sessions = new Metric().setExpression("ga:pageviews").setAlias("pages");
		com.google.api.services.analyticsreporting.v4.model.Dimension pageTitle = new com.google.api.services.analyticsreporting.v4.model.Dimension()
				.setName("ga:pagePath");

		for (String view : viewIDs) {
			List<GetReportsResponse> gReportResponses = new ArrayList<>();
			logger.info("Getting data from Google Analytics for viewid: " + view);
			boolean iterateMorePages = true;
			String nextPageToken = null;
			while (iterateMorePages) {
				// Create the ReportRequest object.
				ReportRequest request = new ReportRequest().setViewId(view.trim())
						.setDateRanges(Arrays.asList(dateRange)).setMetrics(Arrays.asList(sessions))
						.setDimensions(Arrays.asList(pageTitle));
				request.setPageSize(1000);
				request.setPageToken(nextPageToken);
				ArrayList<ReportRequest> requests = new ArrayList<ReportRequest>();
				requests.add(request);
				// Create the GetReportsRequest object.
				GetReportsRequest getReport = new GetReportsRequest().setReportRequests(requests);
				// Call the batchGet method.
				GetReportsResponse response = service.reports().batchGet(getReport).execute();
				nextPageToken = response.getReports().get(0).getNextPageToken();
				iterateMorePages = (nextPageToken != null);
				logger.debug("got nextPageToken: " + nextPageToken);
				gReportResponses.add(response);
			}
			reports.put(view, gReportResponses);
		}
		// Return the response.
		return reports;
	}

	/**
	 * Parses and prints the Analytics Reporting API V4 response.
	 *
	 * @param response
	 *            An Analytics Reporting API V4 response.
	 */
	/**
	 * Parses and prints the Analytics Reporting API V4 response.
	 *
	 * @param response
	 *            An Analytics Reporting API V4 response.
	 */
	private static List<VREAccessesReportRow> parseResponse(String viewId, List<GetReportsResponse> responses) {
		logger.debug("parsing Response for " + viewId);

		List<VREAccessesReportRow> toReturn = new ArrayList<>();
		for (GetReportsResponse response : responses) {
			for (Report report : response.getReports()) {
				List<ReportRow> rows = report.getData().getRows();
				if (rows == null) {
					logger.warn("No data found for " + viewId);
				} else {
					for (ReportRow row : rows) {
						String dimension = row.getDimensions().get(0);
						DateRangeValues metric = row.getMetrics().get(0);
						VREAccessesReportRow var = new VREAccessesReportRow();
						boolean validEntry = false;
						String pagePath = dimension;
						if (pagePath.startsWith("/group") || pagePath.startsWith("/web")) {
							var.setPagePath(dimension);
							validEntry = true;
						}
						if (validEntry) {
							var.setVisitNumber(Integer.parseInt(metric.getValues().get(0)));
							toReturn.add(var);
						}
					}
				}
			}
		}
		return toReturn;
	}

	private static GoogleCredential fromD4SServiceEndpoint(AnalyticsReportCredentials cred) throws IOException {

		String clientId = cred.getClientId();
		String clientEmail = cred.getClientEmail();
		String privateKeyPem = cred.getPrivateKeyPem();
		String privateKeyId = cred.getPrivateKeyId();
		String tokenUri = cred.getTokenUri();
		String projectId = cred.getProjectId();

		if (clientId == null || clientEmail == null || privateKeyPem == null || privateKeyId == null) {
			throw new IOException("Error reading service account credential from stream, "
					+ "expecting  'client_id', 'client_email', 'private_key' and 'private_key_id'.");
		}

		PrivateKey privateKey = privateKeyFromPkcs8(privateKeyPem);

		Collection<String> emptyScopes = Collections.emptyList();

		Builder credentialBuilder = new GoogleCredential.Builder().setTransport(Utils.getDefaultTransport())
				.setJsonFactory(Utils.getDefaultJsonFactory()).setServiceAccountId(clientEmail)
				.setServiceAccountScopes(emptyScopes).setServiceAccountPrivateKey(privateKey)
				.setServiceAccountPrivateKeyId(privateKeyId);

		if (tokenUri != null) {
			credentialBuilder.setTokenServerEncodedUrl(tokenUri);
		}

		if (projectId != null) {
			credentialBuilder.setServiceAccountProjectId(projectId);
		}

		// Don't do a refresh at this point, as it will always fail before the
		// scopes are added.
		return credentialBuilder.build();
	}

	private static PrivateKey privateKeyFromPkcs8(String privateKeyPem) throws IOException {
		Reader reader = new StringReader(privateKeyPem);
		Section section = PemReader.readFirstSectionAndClose(reader, "PRIVATE KEY");
		if (section == null) {
			throw new IOException("Invalid PKCS8 data.");
		}
		byte[] bytes = section.getBase64DecodedBytes();
		PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(bytes);
		Exception unexpectedException = null;
		try {
			KeyFactory keyFactory = SecurityUtils.getRsaKeyFactory();
			PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
			return privateKey;
		} catch (NoSuchAlgorithmException exception) {
			unexpectedException = exception;
		} catch (InvalidKeySpecException exception) {
			unexpectedException = exception;
		}
		throw new IOException("Unexpected exception reading PKCS data", unexpectedException);
	}

	private static List<ServiceEndpoint> getAnalyticsReportingConfigurationFromIS(String infrastructureScope)
			throws Exception {
		String scope = infrastructureScope;
		String currScope = ScopeProvider.instance.get();
		ScopeProvider.instance.set(scope);
		SimpleQuery query = queryFor(ServiceEndpoint.class);
		query.addCondition("$resource/Profile/Category/text() eq '" + SERVICE_ENDPOINT_CATEGORY + "'");
		query.addCondition("$resource/Profile/Name/text() eq '" + SERVICE_ENDPOINT_NAME + "'");
		DiscoveryClient<ServiceEndpoint> client = clientFor(ServiceEndpoint.class);
		List<ServiceEndpoint> toReturn = client.submit(query);
		ScopeProvider.instance.set(currScope);
		return toReturn;
	}

	/**
	 * l
	 * 
	 * @throws Exception
	 */
	private static AnalyticsReportCredentials getAuthorisedApplicationInfoFromIs() throws Exception {
		AnalyticsReportCredentials reportCredentials = new AnalyticsReportCredentials();

		String context = org.gcube.dataharvest.utils.Utils.getCurrentContext();
		try {
			List<ServiceEndpoint> list = getAnalyticsReportingConfigurationFromIS(context);
			if (list.size() > 1) {
				logger.error("Too many Service Endpoints having name " + SERVICE_ENDPOINT_NAME
						+ " in this scope having Category " + SERVICE_ENDPOINT_CATEGORY);
			} else if (list.size() == 0) {
				logger.warn("There is no Service Endpoint having name " + SERVICE_ENDPOINT_NAME + " and Category "
						+ SERVICE_ENDPOINT_CATEGORY + " in this context: " + context);
			} else {

				for (ServiceEndpoint res : list) {
					reportCredentials.setTokenUri(res.profile().runtime().hostedOn());
					Group<AccessPoint> apGroup = res.profile().accessPoints();
					AccessPoint[] accessPoints = (AccessPoint[]) apGroup.toArray(new AccessPoint[apGroup.size()]);
					AccessPoint found = accessPoints[0];
					reportCredentials.setClientEmail(found.address());
					reportCredentials.setProjectId(found.username());
					reportCredentials.setPrivateKeyPem(StringEncrypter.getEncrypter().decrypt(found.password()));
					for (Property prop : found.properties()) {
						if (prop.name().compareTo(AP_VIEWS_PROPERTY) == 0) {
							String decryptedValue = StringEncrypter.getEncrypter().decrypt(prop.value());
							String[] views = decryptedValue.split(";");
							reportCredentials.setViewIds(Arrays.asList(views));
						}
						if (prop.name().compareTo(AP_CLIENT_PROPERTY) == 0) {
							String decryptedValue = StringEncrypter.getEncrypter().decrypt(prop.value());
							reportCredentials.setClientId(decryptedValue);
						}
						if (prop.name().compareTo(AP_PRIVATEKEY_PROPERTY) == 0) {
							String decryptedValue = StringEncrypter.getEncrypter().decrypt(prop.value());
							reportCredentials.setPrivateKeyId(decryptedValue);
						}
					}
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
		return reportCredentials;
	}

	private static LocalDate asLocalDate(Date date) {
		return Instant.ofEpochMilli(date.getTime()).atZone(ZoneId.systemDefault()).toLocalDate();
	}

	private static DateRange getDateRangeForAnalytics(Date start, Date end) {
		DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd"); // required
																					// by
																					// Analytics
		String startDate = asLocalDate(start).format(formatter);
		String endDate = asLocalDate(end).format(formatter);
		DateRange dateRange = new DateRange();// date format `yyyy-MM-dd`
		dateRange.setStartDate(startDate);
		dateRange.setEndDate(endDate);
		return dateRange;
	}

}