D-Net

package eu.dnetlib.clients.index.query;

import java.io.IOException;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.stream.Collectors;

import com.google.common.collect.Iterables;

import com.google.common.collect.Lists;

import com.google.common.collect.Maps;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.z3950.zing.cql.*;

/**

 * Use this class to cleanup a CQL tree and obtain all the options

 *

 * @author marko & claudio

 */

public class Pruner {

	/**

	 * All options have to be in this namespace.

	 */

	public static final String DNET_URI = "NAMESPACE";

	private static final Log log = LogFactory.getLog(Pruner.class); // NOPMD by marko on 11/24/08 5:02 PM

	private String optionUri = DNET_URI;

	/**

	 * Helper method, parse a given CQL string.

	 *

	 * @param cqlQuery

	 * @return

	 * @throws CQLParseException

	 * @throws IOException

	 */

	CQLNode parse(final String cqlQuery) throws CQLParseException, IOException {

		return new CQLParser().parse(cqlQuery);

	}

	/**

	 * Remove all options from a given CQL AST and return all the options.

	 * <p>

	 * The CQL tree is modified.

	 *

	 * @param root cql tree

	 * @return pair containing a new root node and a list of options

	 */

	public Result prune(final CQLNode root) {

		return prune(new HashMap<String, String>(), root);

	}

	/**

	 * Actual recursive implementation, dispatches the implementation to the appropriate overloaded method.

	 *

	 * @param prefixes

	 * @param root

	 * @return

	 */

	public Result prune(final Map<String, String> prefixes, final CQLNode root) {

		if (root instanceof CQLBooleanNode)

			return prune(prefixes, (CQLBooleanNode) root);

		if (root instanceof CQLPrefixNode)

			return prune(prefixes, (CQLPrefixNode) root);

		if (root instanceof CQLSortNode)

			return prune(prefixes, (CQLSortNode) root);

		return new Result(root, new ArrayList<String>());

	}

	/**

	 * If the current node is a cql "sort" node, just return the inner subtree.

	 *

	 * @param prefixes

	 * @param node

	 * @return

	 */

	public Result prune(final Map<String, String> prefixes, final CQLSortNode node) {

		Result res = prune(prefixes, node.subtree);

		node.subtree = res.getNode();

		res.setNode(node);

		return res;

	}

	/**

	 * If the current node is a cql "prefix" node, add his namespace declaration to the current list of namespaces and

	 * return the pruned inner subtree.

	 * <p>

	 * If the prefix node contains only one single option element, we have to return null. (TODO: perhaps there is a

	 * better solution).

	 *

	 * @param prefixes

	 * @param node

	 * @return

	 */

	public Result prune(final Map<String, String> prefixes, final CQLPrefixNode node) {

		final HashMap<String, String> subPrefixes = Maps.newHashMap(prefixes);

		subPrefixes.put(node.prefix.name, node.prefix.identifier);

		if (isOption(subPrefixes, node.subtree))

			return new Result(null, Lists.newArrayList(getOption(node.subtree)));

		boolean pruneThisPrefix = node.prefix.identifier.equals(optionUri);

		if (pruneThisPrefix)

			return prune(subPrefixes, node.subtree);

		Result res = prune(subPrefixes, node.subtree);

		node.subtree = res.getNode();

		res.setNode(node);

		return res;

	}

	/**

	 * boolean prunes are handled in the prune(prefix, node, left, right).

	 *

	 * @param prefixes

	 * @param node

	 * @return

	 */

	public Result prune(final Map<String, String> prefixes, final CQLBooleanNode node) {

		return prune(prefixes, node, node.left, node.right);

	}

	/**

	 * Detects if a left or right side of a boolean node is a option term, and returns the other side (recursively

	 * pruned). It also returns the accumulated options along the way.

	 *

	 * @param prefixes

	 * @param bool

	 * @param left

	 * @param right

	 * @return

	 */

	public Result prune(final Map<String, String> prefixes, final CQLBooleanNode bool, final CQLNode left, final CQLNode right) {

		if (isOption(prefixes, left) && isOption(prefixes, right)) {

			List<Result> r = Lists.newArrayList(trimOption(prefixes, left, right), trimOption(prefixes, right, left));

			return new Result(null, r

					.stream()

					.filter(it -> it != null)

					.map(res -> res.getOptions())

					.flatMap(strings -> strings.stream())

					.collect(Collectors.toList()));

		}

		Result res = anyNotNull(trimOption(prefixes, left, right), trimOption(prefixes, right, left));

		if (res != null)

			return res;

		final Result leftResult = prune(prefixes, left);

		final Result rightResult = prune(prefixes, right);

		bool.left = leftResult.getNode();

		bool.right = rightResult.getNode();

		return new Result(clean(bool), Iterables.concat(leftResult.getOptions(), rightResult.getOptions()));

	}

	public <T> T anyNotNull(T a, T b) {

		if (a != null)

			return a;

		return b;

	}

	/**

	 * Trims an option from a boolean node if one if it's sides is an option term.

	 * <p>

	 * Intended to be used once for each sides and then swap.

	 *

	 * @param prefixes

	 * @param a

	 * @param b

	 * @return

	 */

	public Result trimOption(final Map<String, String> prefixes, final CQLNode a, final CQLNode b) {

		log.debug("trim option?" + prefixes + " a " + a.toCQL());

		if (isOption(prefixes, a)) {

			log.debug("IS OPTION...");

			return trimOption(prefixes, prefixFromOption(a), getOption(a), b);

		}

		log.debug("IS NOT OPTION");

		return null;

	}

	/**

	 * prune(prefixes, bool, left, right) uses this helper method to do the dirty job:

	 * <p>

	 * we have to detect if a term node is a term option node. by checking the namespace uri associated with the term

	 * prefix according the the current namespace prefix scope (held in prefixes, which is passed down recursively by

	 * copy).

	 *

	 * @param prefixes

	 * @param ns

	 * @param o

	 * @param subtree

	 * @return

	 */

	public Result trimOption(final Map<String, String> prefixes, final String ns, final String o, final CQLNode subtree) {

		log.debug("trimming " + prefixes + " ns " + ns + " o " + o);

		final String namespaceUri = prefixes.get(ns);

		if (!optionUri.equals(namespaceUri)) {

			return null;

		}

		final Result res = prune(prefixes, subtree);

		return new Result(res.getNode(), Iterables.concat(Lists.newArrayList(o), res.getOptions()));

	}

	/**

	 * Drop a boolean node (and, or etc) if one of the sides has been dropped.

	 *

	 * @param bool

	 * @return

	 */

	private CQLNode clean(final CQLBooleanNode bool) {

		if (bool.left == null)

			return bool.right;

		if (bool.right == null)

			return bool.left;

		return bool;

	}

	public String getOption(final CQLNode node) {

		return indexFromOption(node) + "=" + termFromOption(node);

	}

	////////////////// helpers

	private String indexFromOption(final CQLNode node) {

		return ((CQLTermNode) node).getIndex().replaceAll("[a-z]*\\.(.+)", "$1");

	}

	private String termFromOption(final CQLNode node) {

		return ((CQLTermNode) node).getTerm();

	}

	public String prefixFromOption(final String option) {

		return option.replaceAll("([a-z]*)\\..+", "$1");

	}

	public String prefixFromOption(final CQLNode node) {

		if (node instanceof CQLTermNode)

			return prefixFromOption(((CQLTermNode) node).getIndex());

		return null;

	}

	public boolean isOption(final Map<String, String> prefixes, final String option) {

		return prefixes.containsKey(prefixFromOption(option)) && prefixes.get(prefixFromOption(option)).equals(getOptionUri());

	}

	public boolean isOption(final Map<String, String> prefixes, final CQLNode node) {

		if (node instanceof CQLTermNode)

			return isOption(prefixes, ((CQLTermNode) node).getIndex());

		return false;

	}

	public String getOptionUri() {

		return optionUri;

	}

	public void setOptionUri(String optionUri) {

		this.optionUri = optionUri;

	}

	class Result {

		private CQLNode node;

		private List<String> options;

		public Result(final CQLNode node, final List<String> options) {

			super();

			this.node = node;

			this.options = options;

		}

		public Result(final CQLNode node, final Iterable<String> concat) {

			this.node = node;

			this.options = Lists.newArrayList(concat);

		}

		public CQLNode getNode() {

			return node;

		}

		public void setNode(final CQLNode node) {

			this.node = node;

		}

		public List<String> getOptions() {

			return options;

		}

		public void setOptions(final List<String> options) {

			this.options = options;

		}

		public Map<String, List<String>> getOptionMap() {

			Map<String, List<String>> res = new HashMap<String, List<String>>();

			for (String opt : options) {

				String[] k = opt.split("=");

				List<String> l = res.get(k[0]);

				if (l == null)

					l = new ArrayList<String>();

				l.add(k[1]);

				res.put(k[0], l);

			}

			return res;

		}

	}

}