/**
 *
 */
package org.gcube.portlets.user.uriresolvermanager;

import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Timer;
import java.util.TimerTask;

import org.gcube.common.scope.api.ScopeProvider;
import org.gcube.portlets.user.uriresolvermanager.entity.Resolver;
import org.gcube.portlets.user.uriresolvermanager.entity.ServiceAccessPoint;
import org.gcube.portlets.user.uriresolvermanager.entity.ServiceParameter;
import org.gcube.portlets.user.uriresolvermanager.exception.IllegalArgumentException;
import org.gcube.portlets.user.uriresolvermanager.exception.NotImplementedException;
import org.gcube.portlets.user.uriresolvermanager.exception.UriResolverMapException;
import org.gcube.portlets.user.uriresolvermanager.readers.RuntimeResourceReader;
import org.gcube.portlets.user.uriresolvermanager.readers.UriResolverMapReader;
import org.gcube.portlets.user.uriresolvermanager.util.UrlEncoderUtil;
import org.gcube.portlets.user.uriresolvermanager.util.UrlEncoderUtil.URI_PART;
import org.gcube.portlets.user.urlshortener.UrlShortener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * The Class UriResolverManager.
 *
 * @author Francesco Mangiacrapa francesco.mangiacrapa@isti.cnr.it Sep 6, 2016
 */
public class UriResolverManager {

	private UriResolverMapReader uriResolverMapReader;
	private Map<String, Resolver> applicationTypes;
	private String applicationType;
	private RuntimeResourceReader reader;

	/**
	 * A lock to prevent reader = null;
	 */
	private int usingReader = 0;

	private ServiceAccessPoint serviceAccessPoint;

	private Timer timer;

	/**
	 * Lock reader.
	 */
	public synchronized void lockReader() {
		usingReader++;
	}

	/**
	 * Release reader.
	 */
	public synchronized void releaseReader() {
		usingReader--;
	}

	/**
	 * Count readers.
	 *
	 * @return the int
	 */
	public synchronized int countReaders() {
		return usingReader;
	}

	public static final Logger LOG = LoggerFactory.getLogger(UriResolverManager.class);

	/**
	 * Instantiates a new uri resolver manager. Precondition: set the scope into
	 * ScopeProvider {@link ScopeProvider#get()} The scope is used to look up the
	 * generic resource with name:
	 * {@link UriResolverMapReader#URI_RESOLVER_MAP_RESOURCE_NAME}, secondary type:
	 * {@link UriResolverMapReader#URIRESOLVERMAP_SECONDARY_TYPE} from IS to map
	 * ApplicationType with its Resolver
	 *
	 * @throws UriResolverMapException  the uri resolver map exception
	 * @throws IllegalArgumentException the illegal argument exception
	 */
	public UriResolverManager() throws UriResolverMapException, IllegalArgumentException {
		try {

			String scope = ScopeProvider.instance.get();
			LOG.info("UriResolverManager is using scope: " + scope + ", read from ScopeProvider");

			if (scope == null)
				throw new UriResolverMapException("Scope is null, set scope into ScopeProvider!");

			this.uriResolverMapReader = new UriResolverMapReader();
			this.applicationTypes = uriResolverMapReader.getApplicationTypes();
			// this.setTimerUriResolverReader(RESET_DELAY, RESET_TIME);
		} catch (UriResolverMapException e) {
			LOG.error("UriResolverMapException: ", e);
			throw e;
		} catch (Exception e) {
			LOG.error("UriResolverManager: ", e);
			throw new UriResolverMapException("Map Application Type - Resources not found in IS");
		}
	}

	/**
	 * Sets the application type.
	 *
	 * @param applicationType the applicationType to set
	 * @throws IllegalArgumentException the illegal argument exception
	 */
	public void setApplicationType(String applicationType) throws IllegalArgumentException {
		if (!this.applicationTypes.containsKey(applicationType)) {
			throw new IllegalArgumentException("Application type '" + applicationType
					+ "' not found in Application Types: " + getApplicationTypes());

		}
		this.applicationType = applicationType;
	}

	/**
	 * Instance a UriResolverManager Precondition: set the scope provider
	 * {@link ScopeProvider.instance.get()} The scope is used to look up the generic
	 * resource {@link UriResolverMapReader#URI_RESOLVER_MAP} available in the
	 * infrastructure to map ApplicationType with its Resolver
	 *
	 * @param applicationType a (valid) key Application Type
	 *                        {@link UriResolverManager#getApplicationTypes()}
	 * @throws UriResolverMapException  the uri resolver map exception
	 * @throws IllegalArgumentException the illegal argument exception
	 */
	public UriResolverManager(String applicationType) throws UriResolverMapException, IllegalArgumentException {
		this();
		setApplicationType(applicationType);
	}

	/**
	 * Gets the link.
	 *
	 * @param applicationType the application type
	 * @param parameters      the map of the parameters sent as HTTP query string
	 * @param shortLink       if true the link is shorted otherwise none
	 * @return the link
	 * @throws IllegalArgumentException the illegal argument exception
	 * @throws UriResolverMapException  the uri resolver map exception
	 */
	public String getLink(String applicationType, Map<String, String> parameters, boolean shortLink)
			throws IllegalArgumentException, UriResolverMapException {
		this.applicationType = applicationType;
		return getLink(parameters, shortLink);
	}

	/**
	 * Gets the link.
	 *
	 * @param parameters            the map of the parameters sent as HTTP query
	 *                              string
	 * @param queryStringParameters the query string parameters
	 * @param shortLink             if true the link is shortened otherwise none
	 * @return the link
	 * @throws IllegalArgumentException the illegal argument exception
	 * @throws UriResolverMapException  the uri resolver map exception
	 */
	public String getLink(Map<String, String> parameters, boolean shortLink)
			throws IllegalArgumentException, UriResolverMapException {

		if (applicationType == null)
			throw new IllegalArgumentException("Application type is null");

		Resolver resolver = this.applicationTypes.get(applicationType);
		LOG.debug("The resolver found is of kind: "+ resolver.getClass().getSimpleName());
		String link = null;

		if (parameters == null)
			throw new IllegalArgumentException("Input Map parameters is null");

		try {

			// lockReader();

			if (reader == null) {
				LOG.info("Runtime Resource Reader is null, istancing...");
				reader = new RuntimeResourceReader(resolver.getResourceName());
			}

			if (resolver.getEntryName() == null || resolver.getEntryName().isEmpty()) {
				LOG.warn("The entryname to " + resolver.getResourceName()
						+ " is null or empty, reading first Access Point!!");
				serviceAccessPoint = reader.getServiceAccessPoints().get(0);
			} else {
				LOG.warn("Reading Access Point for Entry Name: " + resolver.getEntryName());
				serviceAccessPoint = reader.getServiceAccessPointForEntryName(resolver.getEntryName());
				if (serviceAccessPoint == null)
					throw new UriResolverMapException("Entry Name " + resolver.getEntryName()
							+ " not found in Resource name: " + resolver.getResourceName());
			}

			List<ServiceParameter> resourceParameters = serviceAccessPoint.getServiceParameters();
			LOG.debug("Service parameters are: " + resourceParameters);
			// CHECK PARAMETERS
			for (ServiceParameter serviceParameter : resourceParameters) {
				if (serviceParameter.isMandatory()) {
					if (!parameters.containsKey(serviceParameter.getKey())) {
						throw new IllegalArgumentException("Mandatory service key (parameter) '"
								+ serviceParameter.getKey() + "' not found into input map");
					}
				}
			}

			String baseURI = serviceAccessPoint.getServiceUrl();

			// SPECIALIZED IMPLEMENTATION OF RESOLVER
			try {
				link = resolver.getLink(baseURI, parameters);
				LOG.debug("Read specialized getLink: " + link);
				if (shortLink) {
					link = resolver.shortLink(link, parameters);
				}

				return link;
			} catch (NotImplementedException e) {
				LOG.info("Specialized getLink not implemented, going to default implementation");
			}

			// GENERIC IMPLEMENTATION OF RESOLVER. DEFAULT IMPLEMENTATION APPLYING...
			if (link == null) {
				// not shortening so returning the link with the query string with only the
				// parameters encoded
				LOG.info("Specialized getLink is null, applying DEFAULT implementation via GET request on base URI and encoded query-string");
				String queryString = UrlEncoderUtil.encodeQuery(parameters);
				link = String.format("%s?%s", baseURI, queryString);
				// LOG.info("returning base URI with encoded parameters in the query string: " +
				// linkEncoded);
				// return toReturn;
			} else {
				LOG.info("Specialized getLink is not null");
			}

			String linkNotShort = link;
			LOG.info("Created HTTP link: " + link);
			// Short link required
			if (shortLink) {
				try {
					LOG.info("Short link requested, so encoding query string is required...");

					URI_PART uriParts = UrlEncoderUtil.getURIParts(link);
					if (uriParts.getQueryString() != null && !uriParts.getQueryString().isEmpty()) {
						LOG.info("QueryString part " + uriParts.getQueryString() + " is not null, encoding it");
						String queryStringEncoded = UrlEncoderUtil.encodeString(uriParts.getQueryString());
						link = String.format("%s?%s", uriParts.getBaseURI(), queryStringEncoded);
					}
					LOG.info("Encoded link is: " + link);
					LOG.info("Shortner starts..");
					String shortenedLink = shortTheLink(link);
					if (shortenedLink != null && shortenedLink.equals(link)) {
						// here the short link and the input link are identical
						// so the shortening did not work
						// I'm returning the decoded link because it is directly consumable via browser
						LOG.info("Short link is equal to long link, returning long link: " + linkNotShort);
						link = linkNotShort;
					} else {
						// here the link is really shortened
						LOG.debug("The link is really short, returning it");
						link = shortenedLink;
					}

				} catch (Exception e) {
					LOG.warn("An error occurred during link shortening: ", e);
					// here I'm returning the decoded link in case of error on shortening it
					link = linkNotShort;
				}
			}
		} catch (IllegalArgumentException e) {
			LOG.error("Uri Resolver IllegalArgumentException: ", e);
			throw e;
		} catch (Exception e) {
			LOG.error("Uri Resolver Exception: ", e);
			throw new UriResolverMapException("Uri Resolver error: " + e.getMessage());
		}

		LOG.info("Returning HTTP(s) link: " + link);
		return link;
	}

	private String shortTheLink(String sourceLink) {

		String toReturnLink = sourceLink;
		try {
			UrlShortener shortener = new UrlShortener();
			String shortLink = shortener.shorten(sourceLink);
			LOG.info("Short link is: " + shortLink);
			toReturnLink = shortLink;
		} catch (Exception e) {
			LOG.warn("Returning source link, an error occurred during link shortening: ", e);
		}
		return toReturnLink;
	}

	/**
	 * Gets the application types.
	 *
	 * @return the Application Types available
	 */
	public Set<String> getApplicationTypes() {
		return this.applicationTypes.keySet();
	}

	/**
	 * Discovery service parameters.
	 *
	 * @param resolver the resolver
	 * @return the list
	 * @throws IllegalArgumentException the illegal argument exception
	 * @throws Exception                the exception
	 */
	public List<ServiceParameter> discoveryServiceParameters(Resolver resolver)
			throws IllegalArgumentException, Exception {
		try {

			String scope = ScopeProvider.instance.get();
			LOG.info("DiscoveryServiceParameters is using scope: " + scope + ", read from ScopeProvider");

			if (scope == null)
				throw new UriResolverMapException("Scope is null, set scope into ScopeProvider!");

			if (resolver == null)
				throw new IllegalArgumentException("Resolver is null, set Resolver");

			RuntimeResourceReader reader = new RuntimeResourceReader(resolver.getResourceName());

			ServiceAccessPoint serviceAccessPoint = null;
			if (resolver.getEntryName() == null || resolver.getEntryName().isEmpty()) {
				LOG.warn("The entryname to " + resolver.getResourceName()
						+ " is null or empty, reading first Access Point!!");
				serviceAccessPoint = reader.getServiceAccessPoints().get(0);
			} else {
				LOG.info("Reading Access Point for entryname: " + resolver.getEntryName());
				serviceAccessPoint = reader.getServiceAccessPointForEntryName(resolver.getEntryName());
				if (serviceAccessPoint == null)
					throw new UriResolverMapException("Entry Name " + resolver.getEntryName()
							+ " not found in Resource name: " + resolver.getResourceName());
			}

			return serviceAccessPoint.getServiceParameters();
		} catch (Exception e) {
			LOG.error("Uri Resolver error: ", e);
			throw new UriResolverMapException("Uri Resolver error: " + e.getMessage());
		}
	}

	/**
	 * Gets the resolver.
	 *
	 * @param applicationType the application type
	 * @return the resolver
	 */
	public Resolver getResolver(String applicationType) {
		return this.applicationTypes.get(applicationType);
	}

	/**
	 * Gets the capabilities.
	 *
	 * @return a map Application Type - Resolver
	 */
	public Map<String, Resolver> getCapabilities() {
		return this.applicationTypes;
	}

	/**
	 * Sets the timer uri resolver reader.
	 *
	 * @param delay  the delay
	 * @param period the period
	 */
	public void setTimerUriResolverReader(long delay, long period) {

		cancelTimerUriResolverReader();

		timer = new Timer(true);

		timer.schedule(new TimerTask() {
			@Override
			public void run() {
				LOG.info("Timer Reset Runtime Resource running..");
				int counters = countReaders();
				if (counters == 0) {
					LOG.info("Reader not locked, resetting");
					reader = null;
				} else
					LOG.info("Reader locked, counters is/are:" + counters + ", skipping");

			}
		}, delay, period);
	}

	/**
	 * Cancel timer uri resolver reader.
	 */
	public void cancelTimerUriResolverReader() {
		if (timer != null)
			timer.cancel();
	}

	/**
	 * Invalid uri resolver reader.
	 */
	public void invalidUriResolverReader() {
		reader = null;
	}

}