/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.jena.arq.querybuilder.handlers;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.apache.jena.graph.Node;
import org.apache.jena.query.Query;
import org.apache.jena.query.QueryBuildException;
import org.apache.jena.sparql.core.Var;
import org.apache.jena.sparql.engine.binding.BindingHashMap;
import org.apache.jena.sparql.syntax.ElementData;

public class ValuesHandler implements Handler {

	private Map<Var, List<Node>> valuesTable;

	/*
	 * the map used during build to substitute vars modified by the setVars()
	 * method
	 */
	private Map<Var, Node> valueMap;

	// the query to modify
	private final Query query;

	/**
	 * Constructor.
	 */
	public ValuesHandler() {
		this( null );
	}
	
	public ValuesHandler( Query query ) {
		this.query = query;
		this.valuesTable = new LinkedHashMap<Var, List<Node>>();
		this.valueMap = Collections.emptyMap();
	}
	
	public ElementData asElement() {
		ElementData ed = new ElementData();
		// remove all the vars that have been set
		List<Var> vars = new ArrayList<Var>(valuesTable.keySet());
		vars.removeAll(valueMap.keySet());
		if (vars.isEmpty()) {
			return ed;
		}
		vars.forEach( var -> ed.add(var));
	
		//List<Binding> bindings = new ArrayList<Binding>();
		int count = valuesTable.get(vars.get(0)).size();
		for (int i = 0; i < count; i++) {
			BindingHashMap b = new BindingHashMap();
			for (Var var : vars) {
				List<Node> lst = valuesTable.get(var);
				// must be square
				if (lst.size() != count) {
					throw new QueryBuildException(
							String.format("The number of data items for %s (%s) is not the same as for %s (%s)", var,
									lst.size(), vars.get(0), count));
				}
				Node n = lst.get(i);
				if (n != null) {
					if (valueMap.containsKey(n)) {
						n = valueMap.get(n);
					}
					b.add(var, n);
				}
			}
	
			if (!b.isEmpty()) {
				ed.add(b);
			}
		}
		return ed;
	}

	public boolean isEmpty()
	{
		return valuesTable.isEmpty();
	}
	
	@Override
	public void setVars(Map<Var, Node> values) {
		valueMap = values;
	}

	@Override
	public void build() {
		if (query != null)
		{
		ElementData ed = asElement();
		if (!ed.getRows().isEmpty()) {
			query.setValuesDataBlock(ed.getVars(), ed.getRows());
		}
		}
	}

	private List<Node> getNodesList(Var var) {
		List<Node> values = valuesTable.get(var);
		if (values == null) {
			values = new ArrayList<Node>();
			valuesTable.put(var, values);
		}
		return values;
	}

	/**
	 * Add a variable to the value statement.
	 * 
	 * A variable may only be added once. Attempting to add the same variable
	 * multiple times will be silently ignored.
	 * 
	 * @param var
	 *            The variable to add.
	 */
	public void addValueVar(Var var, Collection<Node> nodes) {
		List<Node> values = getNodesList(var);
		if (nodes != null) {
			values.addAll(nodes);
		}
	}

	/**
	 * Add the values for the variables. There must be one value for each value
	 * var.
	 * 
	 * @param values
	 *            the collection of values to add.
	 */
	public void addValueRow(Collection<Node> values) {
		if (values.size() != valuesTable.size()) {
			throw new IllegalArgumentException(String.format("Number of values (%s) must match number of columns %s",
					values.size(), valuesTable.size()));
		}
		Iterator<Node> iter = values.iterator();
		for (Var v : valuesTable.keySet()) {
			List<Node> lst = getNodesList(v);
			lst.add(iter.next());
		}
	}

	/**
	 * Add the ValuesHandler values to this values Handler.
	 * 
	 * @param handler
	 *            the handler that has the values to add.
	 */
	public void addAll(ValuesHandler handler) {
		if (handler.valuesTable.size() == 0) {
			return;
		}
		// assume our table is square.
		int count = 0;
		if (valuesTable.size() > 0) {
			count = valuesTable.values().iterator().next().size();
		}

		for (Var var : handler.valuesTable.keySet()) {
			List<Node> lst = valuesTable.get(var);
			if (lst == null) {
				lst = new ArrayList<Node>();
				lst.addAll(Arrays.asList(new Node[count]));
				valuesTable.put(var, lst);
			}
			lst.addAll(handler.valuesTable.get(var));
		}

		// keep table square by adding nulls to the vars that are not in the
		// other table.
		List<Var> lst = new ArrayList<Var>(valuesTable.keySet());
		lst.removeAll(handler.valuesTable.keySet());
		if (!lst.isEmpty()) {
			count = handler.valuesTable.values().iterator().next().size();
			for (Var var : lst) {
				List<Node> lst2 = valuesTable.get(var);
				lst2.addAll(Arrays.asList(new Node[count]));
			}
		}

	}

	public void clear()
	{
		valuesTable.clear();
	}
	
	public List<Var> getValuesVars()
	{
		return Collections.unmodifiableList(new ArrayList<Var>(valuesTable.keySet()));
	}
	
	public Map<Var,List<Node>> getValuesMap() {
		Map<Var,List<Node>> m = new LinkedHashMap<Var, List<Node>>();
		for (Var key : valuesTable.keySet())
		{
			m.put(key, Collections.unmodifiableList( valuesTable.get(key)));
		}
		return Collections.unmodifiableMap(m);
	}
}
