/*
 * JBoss, Home of Professional Open Source.
 * See the COPYRIGHT.txt file distributed with this work for information
 * regarding copyright ownership.  Some portions may be licensed
 * to Red Hat, Inc. under one or more contributor license agreements.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301 USA.
 */

package org.teiid.query.optimizer.relational.rules;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.teiid.api.exception.query.QueryPlannerException;
import org.teiid.core.TeiidComponentException;
import org.teiid.core.TeiidException;
import org.teiid.logging.LogConstants;
import org.teiid.logging.LogManager;
import org.teiid.query.analysis.AnalysisRecord;
import org.teiid.query.metadata.QueryMetadataInterface;
import org.teiid.query.optimizer.capabilities.CapabilitiesFinder;
import org.teiid.query.optimizer.relational.OptimizerRule;
import org.teiid.query.optimizer.relational.RuleStack;
import org.teiid.query.optimizer.relational.plantree.NodeConstants;
import org.teiid.query.optimizer.relational.plantree.NodeEditor;
import org.teiid.query.optimizer.relational.plantree.PlanNode;
import org.teiid.query.rewriter.QueryRewriter;
import org.teiid.query.sql.lang.CompareCriteria;
import org.teiid.query.sql.lang.Criteria;
import org.teiid.query.sql.lang.IsNullCriteria;
import org.teiid.query.sql.lang.JoinType;
import org.teiid.query.sql.symbol.Constant;
import org.teiid.query.sql.symbol.ElementSymbol;
import org.teiid.query.sql.symbol.Expression;
import org.teiid.query.sql.visitor.EvaluatableVisitor;
import org.teiid.query.sql.visitor.GroupsUsedByElementsVisitor;
import org.teiid.query.util.CommandContext;


/**
 * For each join node this rule will find the set of criteria allowed to influence the join (the join criteria, and inner
 * side criteria on non full outer joins) and builds new criteria based upon the equality relationships found.
 * 
 * Equality relationships look like element symbol = expression regardless of whether they are from select or join criteria
 * 
 * Upon successfully changing a multi group join criteria into another expression with fewer groups, the original criteria
 * will be replace with the new criteria in the on clause.
 *  
 * RulePushNonJoinCriteia and CopyCriteria will be run again after this rule if any new join criteria is created.
 * 
 * This rule is not allowed to run exhaustively by the setting of the copied property on criteria nodes.  It also will not
 * discover all possible relationships, only those that can be discovered quickly.
 */
public final class RuleCopyCriteria implements OptimizerRule {

	/**
	 * Execute the rule as described in the class comments.
	 * @param plan Incoming query plan, may be modified during method and may be returned from method
	 * @param metadata Metadata source
	 * @param rules Rules from optimizer rule stack, may be manipulated during method
	 * @return Updated query plan if rule fired, else original query plan
	 */
	public PlanNode execute(PlanNode plan, QueryMetadataInterface metadata, CapabilitiesFinder capFinder, RuleStack rules, AnalysisRecord analysisRecord, CommandContext context) 
		throws QueryPlannerException, TeiidComponentException {

	    List<PlanNode> critNodes = NodeEditor.findAllNodes(plan, NodeConstants.Types.SELECT | NodeConstants.Types.JOIN);
        boolean shouldRun = false;
        for (PlanNode critNode : critNodes) {
            if (!critNode.hasBooleanProperty(NodeConstants.Info.IS_COPIED)) {
                shouldRun = true;
                break;
            }
        }
     
        if (!shouldRun) {
            return plan;
        }
        
        if (tryToCopy(plan, new Set[2], metadata, false)) {
            //Push any newly created criteria nodes and try to copy them afterwards
            rules.push(RuleConstants.COPY_CRITERIA);
            rules.push(RuleConstants.RAISE_ACCESS);
            rules.push(new RulePushNonJoinCriteria(false));
        }
        
        //mark the old criteria nodes as copied.  this will prevent RulePushSelectCriteria from considering them again
        for (PlanNode critNode : critNodes) {
        	critNode.setProperty(NodeConstants.Info.IS_COPIED, Boolean.TRUE);
        }
        		
		return plan;	
	}

    /**
     * Given a criteria and a map of elements to values try to create a new single group criteria
     * 
     * If the new criteria does not have exactly one group or already exists in the combined criteria,
     * it will not be added.
     *  
     * @param crit
     * @param tgtMap
     * @param joinCriteria
     * @param combinedCriteria
     * @return number of remaining groups if the copy was successful
     */
    private Integer copyCriteria(Criteria crit,
                                 Map<Expression, Expression> tgtMap,
                                 List<Criteria> joinCriteria,
                                 Set<Criteria> combinedCriteria,
                                 boolean checkForGroupReduction,
                                 QueryMetadataInterface metadata,
                                 boolean underAccess) {
        int startGroups = GroupsUsedByElementsVisitor.getGroups(crit).size();
        
        Criteria tgtCrit = (Criteria) crit.clone();
        
        try {
            tgtCrit = FrameUtil.convertCriteria(tgtCrit, tgtMap, metadata, true);
        } catch (QueryPlannerException err) {
            LogManager.logDetail(LogConstants.CTX_QUERY_PLANNER, err, "Could not remap target criteria in RuleCopyCriteria"); //$NON-NLS-1$
            return null;
        }
        
        if (tgtCrit instanceof IsNullCriteria && ((IsNullCriteria)tgtCrit).isNegated()) {
        	return null;
        }
        
        int endGroups = GroupsUsedByElementsVisitor.getGroups(tgtCrit).size();
        
        if (checkForGroupReduction) {
            if (endGroups >= startGroups) {
                return null;
            }
        } else if (endGroups > startGroups) {
            return null;
        }
        
        boolean isNew = combinedCriteria.add(tgtCrit);
        
        if (underAccess) {
        	boolean use = false;
        	if (isNew && !checkForGroupReduction) {
        		if (endGroups == 1) {
        			use = true;
        		} else if (tgtCrit instanceof CompareCriteria) {
	        		CompareCriteria cc = (CompareCriteria)tgtCrit;
	        		int leftGroups = GroupsUsedByElementsVisitor.getGroups(cc.getLeftExpression()).size();
	        		if (leftGroups == endGroups || leftGroups == 0) {
	        			use = true;
	        		}
	        	}
        	}
        	if (!use) {
        		return null;
        	}
        }
        
        //if this is unique or it a duplicate but reduced a current join conjunct, return true
        if (isNew) {
            joinCriteria.add(tgtCrit);
            if (tgtCrit instanceof CompareCriteria) {
            	CompareCriteria cc = (CompareCriteria)tgtCrit;
            	if (!EvaluatableVisitor.willBecomeConstant(cc.getRightExpression()) &&
            			!EvaluatableVisitor.willBecomeConstant(cc.getRightExpression())) {
            		((CompareCriteria)tgtCrit).setOptional(true);
            	}
            }
            return endGroups;
        } else if (checkForGroupReduction && endGroups < 2) {
            return endGroups;
        }
        
        return null;
    }
            
    /** 
     * Recursively tries to copy criteria across join nodes.  toCopy will contain only the single group criteria
     * that has not yet been copied.  allCriteria will contain all criteria present at the join that can effect
     * copying.
     * 
     * @param node
     * @return true if criteria has been created
     */
    private boolean tryToCopy(PlanNode node, Set<Criteria>[] criteriaInfo, QueryMetadataInterface metadata, boolean underAccess) {
        boolean changedTree = false;
        
        if (node == null) {
            return false;
        }
        
        //visit join nodes in order
        if (node.getType() == NodeConstants.Types.JOIN) {
            JoinType jt = (JoinType)node.getProperty(NodeConstants.Info.JOIN_TYPE);
            
            if (jt == JoinType.JOIN_FULL_OUTER) {
                return visitChildern(node, criteriaInfo, changedTree, metadata, underAccess);
            }
            
            Set<Criteria>[] leftChildCriteria = new Set[2];
            Set<Criteria>[] rightChildCriteria = new Set[2];
            
            changedTree |= tryToCopy(node.getFirstChild(), leftChildCriteria, metadata, underAccess);
            changedTree |= tryToCopy(node.getLastChild(), rightChildCriteria, metadata, underAccess);

            List<Criteria> joinCrits = (List<Criteria>) node.getProperty(NodeConstants.Info.JOIN_CRITERIA);
            Set<Criteria> combinedCriteria = null;
            if (joinCrits != null) {
                combinedCriteria = new LinkedHashSet<Criteria>(joinCrits); 
                combinedCriteria.addAll(leftChildCriteria[1]);
                combinedCriteria.addAll(rightChildCriteria[1]);
            }

            //combine the criteria
            leftChildCriteria[0].addAll(rightChildCriteria[0]);
            leftChildCriteria[1].addAll(rightChildCriteria[1]);
            //set the applicable criteria
            criteriaInfo[0] = leftChildCriteria[0];
            //set the all criteria
            criteriaInfo[1] = leftChildCriteria[1];

            //there's no join criteria here, so just let the criteria go up
            if (jt == JoinType.JOIN_CROSS) {
                return changedTree;
            }
            
            Set<Criteria> toCopy = criteriaInfo[0];
            Set<Criteria> allCriteria = criteriaInfo[1];

            if (joinCrits != null && !joinCrits.isEmpty()) {
                List<Criteria> newJoinCrits = new LinkedList<Criteria>();

                //we don't want to continue discovery since that could be recursive
                Map<Expression, Expression> srcToTgt = buildElementMap(joinCrits, node.hasBooleanProperty(NodeConstants.Info.IS_COPIED)?null:newJoinCrits, combinedCriteria, metadata, underAccess);
                
                changedTree |= !newJoinCrits.isEmpty();

                if (!toCopy.isEmpty()) {
                    
                    changedTree |= createCriteria(false, toCopy, combinedCriteria, srcToTgt, newJoinCrits, metadata, underAccess);
                    
                    srcToTgt = buildElementMap(allCriteria, null, null, metadata, underAccess);
                                
                    changedTree |= createCriteria(true, joinCrits, combinedCriteria, srcToTgt, newJoinCrits, metadata, underAccess);
                }
                
                joinCrits.addAll(newJoinCrits);
            }
            
            //before returning, filter out criteria that cannot go above the join node
            if (jt == JoinType.JOIN_RIGHT_OUTER) {
                criteriaInfo[0].removeAll(leftChildCriteria[0]);
                criteriaInfo[1].removeAll(leftChildCriteria[1]);
            } else if (jt == JoinType.JOIN_LEFT_OUTER) {
                criteriaInfo[0].removeAll(rightChildCriteria[0]);
                criteriaInfo[1].removeAll(rightChildCriteria[1]);
            } else if (node.getSubqueryContainers().isEmpty()) {
            	if (!node.hasBooleanProperty(NodeConstants.Info.IS_COPIED)) {
                    toCopy.addAll(joinCrits);
                }
                allCriteria.addAll(joinCrits);
            }
            
            return changedTree;
        }
        
        changedTree = visitChildern(node, criteriaInfo, changedTree, metadata, underAccess);

        //visit select nodes on the way back up
        switch (node.getType()) {
        
            case NodeConstants.Types.SELECT:
            {
                if (criteriaInfo[0] != null) {
                    visitSelectNode(node, criteriaInfo[0], criteriaInfo[1]);
                }
                break;
            }
            //clear the criteria when hitting the following
            case NodeConstants.Types.NULL:
            case NodeConstants.Types.SOURCE: 
            case NodeConstants.Types.GROUP:
            case NodeConstants.Types.SET_OP:
            case NodeConstants.Types.PROJECT: 
            {
                if (criteriaInfo[0] == null) {
                    criteriaInfo[0] = new LinkedHashSet<Criteria>();
                    criteriaInfo[1] = new LinkedHashSet<Criteria>();
                } else {
                    criteriaInfo[0].clear();
                    criteriaInfo[1].clear();
                }
                break;
            }
                
        }
        
        return changedTree;
    }

    private boolean createCriteria(boolean copyingJoinCriteria, Collection<Criteria> toCopy,
                                                   Set<Criteria> combinedCriteria,
                                                   Map<Expression, Expression> srcToTgt,
                                                   List<Criteria> newJoinCrits,
                                                   QueryMetadataInterface metadata, boolean underAccess) {
        boolean changedTree = false;
    	if (srcToTgt.size() == 0) {
            return changedTree;
        }
        Iterator<Criteria> i = toCopy.iterator();
        while (i.hasNext()) {
            Criteria crit = i.next();
            
            Integer endGroups = copyCriteria(crit, srcToTgt, newJoinCrits, combinedCriteria, copyingJoinCriteria, metadata, underAccess);
            
            if (endGroups != null) {
            	changedTree = true;
            	if (copyingJoinCriteria && endGroups < 2) {
            		if (crit instanceof CompareCriteria) {
            			CompareCriteria cc = (CompareCriteria)crit;
            			//don't remove theta criteria, just mark it as optional
        				cc.setOptional(null);
            			continue;
            		}
            		i.remove();
            	}
            }
        }
        return changedTree;
    }

    private void visitSelectNode(PlanNode node,
                                 Set<Criteria> toCopy,
                                 Set<Criteria> allCriteria) {
        //First examine criteria in critNode for suitability
        Criteria crit = (Criteria) node.getProperty(NodeConstants.Info.SELECT_CRITERIA);
        if(node.getGroups().size() == 1) {
            List<Criteria> crits = Criteria.separateCriteriaByAnd(crit);
            if(!node.hasBooleanProperty(NodeConstants.Info.IS_HAVING) && node.getSubqueryContainers().isEmpty()) {
                if (!node.hasBooleanProperty(NodeConstants.Info.IS_COPIED)) {
                    toCopy.addAll(crits);
                }
                allCriteria.addAll(crits);
            }
        }
    }

    private boolean visitChildern(PlanNode node,
                                  Set<Criteria>[] criteriaInfo,
                                  boolean changedTree,
                                  QueryMetadataInterface metadata, boolean underAccess) {
        if (node.getChildCount() > 0) {
        	underAccess |= node.getType() == NodeConstants.Types.ACCESS;
            List<PlanNode> children = node.getChildren();
            for (int i = 0; i < children.size(); i++) {
                PlanNode childNode = children.get(i);
                changedTree |= tryToCopy(childNode, i==0?criteriaInfo:new Set[2], metadata, underAccess);
            }
        }
        return changedTree;
    }
        
    /**
     * Construct a mapping of element symbol to value map based upon equality CompareCriteria in crits
     *  
     * @param crits
     * @param newJoinCrits 
     * @param metadata 
     * @return
     */
    Map<Expression, Expression> buildElementMap(Collection<Criteria> crits, List<Criteria> newJoinCrits, Set<Criteria> allCriteria, QueryMetadataInterface metadata, boolean underAccess) {
        Map<Expression, Expression> srcToTgt = null;
        for (Iterator<Criteria> iter = crits.iterator(); iter.hasNext();) {
        	Criteria theCrit = iter.next();
            if (theCrit instanceof IsNullCriteria) {
            	IsNullCriteria isNull = (IsNullCriteria)theCrit;
            	if (!isNull.isNegated() && isNull.getExpression() instanceof ElementSymbol) {
            		if (srcToTgt == null) {
            			srcToTgt = new HashMap<Expression, Expression>();
            		}
            		srcToTgt.put(isNull.getExpression(), new Constant(null, isNull.getExpression().getType()));
            	}
            	continue;
            }
            if(!(theCrit instanceof CompareCriteria)) {
                continue;
            }
            CompareCriteria crit = (CompareCriteria) theCrit;
            if (crit.getOperator() == CompareCriteria.EQ) {
                if (srcToTgt == null) {
                    srcToTgt = new HashMap<Expression, Expression>();
            	}
                Expression oldValue = srcToTgt.put(crit.getLeftExpression(), crit.getRightExpression());
                boolean removed = false;
                if (checkWithinJoin(crit, newJoinCrits, allCriteria, oldValue, crit.getRightExpression(), metadata, underAccess)) {
                	iter.remove();
                	removed = true;
                }
                oldValue = srcToTgt.put(crit.getRightExpression(), crit.getLeftExpression());
                if (checkWithinJoin(crit, newJoinCrits, allCriteria, oldValue, crit.getLeftExpression(), metadata, underAccess) && !removed) {
                	iter.remove();
                }
            }
        }
        if (srcToTgt == null) {
            return Collections.emptyMap();
        }
        return srcToTgt;
    }

    /**
     * @return true if the original crit can be removed
     */
	private boolean checkWithinJoin(CompareCriteria crit, List<Criteria> newJoinCrits, Set<Criteria> allCriteria,
			Expression oldValue, Expression left, QueryMetadataInterface metadata, boolean underAccess) {
		if (newJoinCrits == null || oldValue == null) {
			return false;
		}
		if (oldValue.equals(left)) {
			return true;
		}
		Criteria newCrit = new CompareCriteria((Expression)left.clone(), CompareCriteria.EQ, (Expression)oldValue.clone());
		try {
			newCrit = QueryRewriter.rewriteCriteria(newCrit, null, metadata);
		} catch (TeiidException e) {
			LogManager.logDetail(LogConstants.CTX_QUERY_PLANNER, e, "Could not remap target criteria in RuleCopyCriteria"); //$NON-NLS-1$
			return false;
		}
		if (allCriteria.add(newCrit)) {
			if (underAccess && GroupsUsedByElementsVisitor.getGroups(newCrit).size() > 1) {
				return false;
			}
			if (newCrit instanceof CompareCriteria) {
				((CompareCriteria)newCrit).setOptional(true);
			}
			newJoinCrits.add(newCrit);
		}
		if (!GroupsUsedByElementsVisitor.getGroups(crit.getLeftExpression()).isEmpty() && !GroupsUsedByElementsVisitor.getGroups(crit.getRightExpression()).isEmpty()
				&& (GroupsUsedByElementsVisitor.getGroups(left).isEmpty() || GroupsUsedByElementsVisitor.getGroups(oldValue).isEmpty())) {
			crit.setOptional(null); //the original has been simplified
		}
		return false;
	}
    

	public String toString() {
		return "CopyCriteria"; //$NON-NLS-1$
	}
		
}
