package org.simantics.interop.update.model;

import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Deque;
import java.util.List;
import java.util.Map.Entry;

import org.simantics.Simantics;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.Session;
import org.simantics.db.Statement;
import org.simantics.db.WriteGraph;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.util.Layer0Utils;
import org.simantics.db.request.Read;
import org.simantics.interop.test.GraphChanges;
import org.simantics.interop.test.GraphComparator;
import org.simantics.utils.datastructures.BijectionMap;
import org.simantics.utils.datastructures.Pair;

public abstract class ModelUpdate {
	
	private Resource oldModel;      // old model that is going to be updated (User modified model)
	private Resource newModel;      // new model that contains the updates   (New design model)
	private Resource originalModel; // original model (optional) that is used for detecting and retaining user made changes (Old design model)
	
	private GraphChanges changes;   // changes between old /new
	private UpdateTree updateTree;
	private UpdateList updateList;
	
	private GraphChanges changes2;  // changes between original / old
	private UpdateTree updateTree2;
	private UpdateList updateList2;
	
	private GraphChanges changes3;  // changes between original / new
	private UpdateTree updateTree3;
	private UpdateList updateList3;
	
	private List<ChangeFilter> filters = new ArrayList<ChangeFilter>();
	private List<ChangeFilter> userFilters = new ArrayList<ChangeFilter>();
	
	boolean init = false;
	
	public void setInput(Resource oldModel, Resource newModel) throws DatabaseException {
		setInput(oldModel, newModel, null, false);
	}
	
	/**
	 * Initialises the ModelUpdate with given input
	 * @param oldModel the model that is going to be updated (User modified model)
	 * @param newModel the model containing updates (New design model)
	 * @param originalModel the model that is used for detecting and retaining user made changes (Old design model). Parameter can be null.
	 * @param newDistinct when originalModel is given, additions to the old and the new model (when compared to the original model) are forced to be distinct. 
	 * @throws DatabaseException
	 */
	public void setInput(Resource oldModel, Resource newModel, Resource originalModel, boolean newDistinct) throws DatabaseException{
		this.oldModel = oldModel;
		this.newModel = newModel;
		this.originalModel = originalModel;
//		addFilters(filters);
		if (originalModel != null) {
			// tree way comparison
			// compare the original and the old model
			Pair<GraphComparator,String> result2 = getChanges(originalModel, oldModel);
			GraphComparator comparator2  = result2.first;
			if (result2.second != null)
				showWarning(result2.second);
			comparator2.test(getSession());
			changes2 = comparator2.getChanges();
			changes2 = getSession().syncRequest(new FilterChangesRead(changes2, filters));
			updateTree2 = getUpdateTree(changes2);
			updateList2 = getUpdateList(changes2);
			
			// compare the original and the new model
			Pair<GraphComparator,String> result3 = getChanges(originalModel,newModel);
			GraphComparator comparator3  = result3.first;
			if (result3.second != null)
				showWarning(result3.second);
			comparator3.test(getSession());
			changes3 = comparator3.getChanges();
			changes3 = getSession().syncRequest(new FilterChangesRead(changes3, filters));
		}
		
		Pair<GraphComparator,String> result = getChanges(oldModel,newModel);
		GraphComparator comparator  = result.first;
		if (result.second != null)
			showWarning(result.second);
		if (originalModel != null) {
			// three-way comparison: use change information to configure
			// the comparison between the old and the new model.
			
			// 1. map comparable resources
			for (Entry<Resource, Resource> origToOld : changes2.getComparable().getEntries()) {
				Resource oldR = origToOld.getValue();
				Resource newR = changes3.getComparable().getRight(origToOld.getKey());
				if (newR != null) {
					comparator.addComparableResources(oldR, newR);
				}
			}
			// 2. mark removed resources as distinct, so that comparison does not pair them
			for (Statement s : changes2.getDeletions()) {
				if (changes3.getComparable().containsLeft(s.getObject()))
					comparator.addNonMatchedRight(changes3.getComparable().getRight(s.getObject()));
			}
			
			for (Statement s : changes3.getDeletions()) {
				if (changes2.getComparable().containsLeft(s.getObject()))
					comparator.addNonMatchedLeft(changes2.getComparable().getRight(s.getObject()));
			}
			if (newDistinct) {
				// 3. mark added resources as distinct, so that comparison does not pair them
				for (Statement s : changes2.getAdditions()) {
					comparator.addNonMatchedLeft(s.getObject());
				}
				
				for (Statement s : changes3.getAdditions()) {
					comparator.addNonMatchedRight(s.getObject());
				}
			}
		}
		comparator.test(getSession());
		changes = comparator.getChanges();
		changes = getSession().syncRequest(new FilterChangesRead(changes, filters));
		updateTree = getUpdateTree(changes);
		updateList = getUpdateList(changes);
		if (userFilters.size() != 0) {
			refreshUserFilters();
		}
		
		
		if (originalModel != null) {
			defaultSelections();
		}
		
		init = true;
	}
	
	public void addFilter(ChangeFilter filter) {
		if (init)
			throw new IllegalStateException("ModelUpdate has been initialized, adjusting filters is no longer possible.");
		filters.add(filter);
		
	}
	
	/**
	 * Adds an user filter. Use refreshUserFilters() to apply the changes.
	 * @param filter
	 */
	public void addUserFilter(ChangeFilter filter) {
		userFilters.add(filter);
	}
	
	/**
	 * Removes an user filter. Use refreshUserFilters() to apply the changes.
	 * @param filter
	 */
	public void removeUserFilter(ChangeFilter filter) {
		userFilters.remove(filter);
	}
	
	/**
	 * Clears user filters.  Use refreshUserFilters() to apply the changes.
	 */
	public void clearUserFilters() {
		userFilters.clear();
	}
	
	public void refreshUserFilters() throws DatabaseException{
		// use user filters to set visible flags of changes.
		// First, set all changes visible.
		Deque<UpdateNode> stack = new ArrayDeque<>();
		stack.push(updateTree.getRootNode());
		while (!stack.isEmpty()) {
			UpdateNode n = stack.pop();
			n.setVisible(true);
			stack.addAll(n.getChildren());
		}
		for (PropertyChange pc : updateList.getChanges()) {
			pc.setVisible(true);
		}
		if (userFilters.size() > 0) {
			// Create filtered changes
			List<ChangeFilter> combined = new ArrayList<>(filters);
			combined.addAll(userFilters);
			GraphChanges filteredChanges = getSession().syncRequest(new FilterChangesRead(changes, combined));
			UpdateTree updateTreeF = getUpdateTree(filteredChanges);
			UpdateList updateListF = getUpdateList(filteredChanges);
			// hide changes that are not contained within the filtered changes.
			applyVisibleFlags(updateTree.getRootNode(), updateTreeF.getRootNode());
			applyVisibleFlags(updateList.getChanges(), updateListF.getChanges());
		}
	}
	
	private void applyVisibleFlags(UpdateNode l, UpdateNode r) {
		BijectionMap<UpdateNode, UpdateNode> comparable = new BijectionMap<>();
		for (UpdateNode lc : l.getChildren()) {
			for (UpdateNode rc : r.getChildren()) {
				if (comparable.containsRight(rc))
					continue;
				if (lc.getResource() != null) {
					if (lc.getResource().equals(rc.getResource())) {
				
						comparable.map(lc, rc);
						break;
					}
				} else if (rc.getResource() == null){
					UpdateOp lop = lc.getOp();
					UpdateOp rop = rc.getOp();
					if (lop.getStatement() != null && lop.getStatement().equals(rop.getStatement())) {
						comparable.map(lc, rc);
						break;
					}
				}
			}
		}
		for (UpdateNode lc : l.getChildren()) {
			if (!comparable.containsLeft(lc))
				lc.setVisible(false);
		}
		for (Entry<UpdateNode, UpdateNode> entry : comparable.getEntries()) {
			applyVisibleFlags(entry.getKey(), entry.getValue());
		}	
	}
	
	private void applyVisibleFlags(Collection<PropertyChange> l, Collection<PropertyChange> r) {
		BijectionMap<PropertyChange, PropertyChange> comparable = new BijectionMap<>();
		for (PropertyChange lc : l) {
			for (PropertyChange rc : r) {
				if (comparable.containsRight(rc))
					continue;
				if (lc.getFirst().equals(rc.getFirst())) {
					comparable.map(lc, rc);
				}
			}
		}
		for (PropertyChange lc : l) {
			if (!comparable.containsLeft(lc))
				lc.setVisible(false);
		}
		
	}
	
	protected abstract Pair<GraphComparator,String> getChanges(Resource r1, Resource r2)  throws DatabaseException;
	protected abstract UpdateTree getUpdateTree(GraphChanges changes) throws DatabaseException;
	protected UpdateList getUpdateList(GraphChanges changes) throws DatabaseException {
		return new UpdateList(changes, changes.getModifications());
	}
	
	public Resource getOldModel() {
		return oldModel;
	}
	
	public Resource getNewModel() {
		return newModel;
	}
	
	public Resource getOriginalModel() {
		return originalModel;
	}
	
	public boolean isInit() {
		return init;
	}
	
	public GraphChanges getChanges() {
		return changes;
	}
	public UpdateTree getUpdateTree() {
		return updateTree;
	}
	public UpdateList getUpdateList() {
		return updateList;
	}
	public GraphChanges getChanges2() {
		return changes2;
	}
	
	public UpdateTree getUpdateTree2() {
		return updateTree2;
	}
	public UpdateList getUpdateList2() {
		return updateList2;
	}
	
	public GraphChanges getChanges3() {
		return changes3;
	}
	
	public UpdateTree getUpdateTree3() throws DatabaseException{
		if (updateTree3 == null && changes3 != null)
			updateTree3 = getUpdateTree(changes3);
		return updateTree3;
	}
	public UpdateList getUpdateList3() throws DatabaseException {
		if (updateList3 == null && changes3 != null)
			updateList3 = getUpdateList(changes3);
		return updateList3;
	}

	
	public void applyAll(WriteGraph graph) throws DatabaseException {
		Layer0Utils.addCommentMetadata(graph, "Apply all model updates");
		graph.markUndoPoint();
		for (PropertyChange mod : updateList.getChanges()) {
			mod.apply(graph);
		}
		
		updateTree.getUpdateOps().applyAll(graph);
	}
	
	public void applySelected(WriteGraph graph) throws DatabaseException {
		Layer0Utils.addCommentMetadata(graph, "Apply selected model updates");
		graph.markUndoPoint();
		for (PropertyChange mod : updateList.getChanges()) {
			if (mod.selected())
				mod.apply(graph);
		}
		
		updateTree.getUpdateOps().applySelected(graph);
	}
	
	
	
	
	protected Session getSession() {
		return Simantics.getSession();
	}
	
	
	
	private class FilterChangesRead implements Read<GraphChanges> {
		private GraphChanges changes;
		private List<ChangeFilter> filters;
		
		public FilterChangesRead(GraphChanges changes, List<ChangeFilter> filters) {
			this.changes = changes;
			this.filters = filters;
		}
		
		@Override
		public GraphChanges perform(ReadGraph graph) throws DatabaseException {
			return filterChanges(graph, changes);
		}
		
		/**
		 * Filters changes:
		 * 1. Changes that are not essential for model update (changes that can be found when the models are axcatly the same)
		 * 2. Runs custom filters for value changes. 
		 * 
		 * @param g
		 * @param changes
		 * @return
		 * @throws DatabaseException
		 */
		protected GraphChanges filterChanges(ReadGraph g, GraphChanges changes) throws DatabaseException 
	    {
			
			List<Pair<Statement,Statement>> modifications = new ArrayList<Pair<Statement,Statement>>();
			
	    	for (Pair<Statement, Statement> mod : changes.getModifications()) {
	    		
	    		boolean accept = true;
	    		for (ChangeFilter filter : filters) {
	    			if (!filter.accept(g, mod)) {
	    				accept = false;
	    				break;
	    			}	
	    		}
	    		if (accept)
	    			modifications.add(mod);
	    	}
	    	GraphChanges newChanges =  new GraphChanges(changes.getResource1(),changes.getResource2(),changes.getDeletions(), changes.getAdditions(), modifications, changes.getComparable());
	    	return newChanges;
	    }
	}

	
	public interface ChangeFilter {
		public boolean accept(ReadGraph g, Pair<Statement, Statement> change) throws DatabaseException;
	}

	
	/**
	 * 
	 * Filters floating point value changes (default filter is set filter when the change is less than 1%)  
	 *
	 */
	protected class FPValueFilter implements ChangeFilter  {
		
		private double percentage = 0.01;
		
		public FPValueFilter() {
			
		}
		
		public FPValueFilter(double percentage) {
			if (percentage < 0.0 || percentage > 1.0)
				throw new IllegalArgumentException("Percentage must be between 0.0 and 1.0.");
			this.percentage = percentage;
		}
		
		@Override
		public boolean accept(ReadGraph g, Pair<Statement, Statement> change) throws DatabaseException {
			//filter floating point values that have less than 1% difference.
			if (!g.hasValue(change.first.getObject()) || !g.hasValue(change.second.getObject()))
				return true;
    		Object v1 = g.getValue(change.first.getObject());
    		Object v2 = g.getValue(change.second.getObject());
    		
    		if (v1 instanceof Double && v2 instanceof Double) {
    			double d1 = (Double)v1;
    			double d2 = (Double)v2;
    			if (Math.abs(d1-d2) / Math.max(Math.abs(d1), Math.abs(d2)) < percentage)
    				return false;
    		} else if (v1 instanceof Float && v2 instanceof Float) {
    			float d1 = (Float)v1;
    			float d2 = (Float)v2;
    			if (Math.abs(d1-d2) / Math.max(Math.abs(d1), Math.abs(d2)) < percentage)
    				return false;
    		}

    		return true;
		}
	}
	
	public void defaultSelections() {
		if (changes3 == null) {
			return;
		}
		// select all changes
		for (Entry<Resource, UpdateOp> op : updateTree.getUpdateOps().getResourceMap().entrySet()) {
			op.getValue().select(true);
		}
		
		
		for (PropertyChange pair : updateList.getChanges()) {
			pair.select(true);
		}
		
		// preserve user-made changes (by removing selections)
		for (Entry<Resource, UpdateOp> op : updateTree.getUpdateOps().getResourceMap().entrySet()) {
			UpdateOp op2 = updateTree2.getUpdateOps().getUpdateOp(op.getKey());
			if (op2 == null) {
				if (changes3.getComparable().containsRight(op.getKey())){
					op2 = updateTree2.getUpdateOps().getUpdateOp(changes3.getComparable().getLeft(op.getKey()));
				}
			}
			if (op2 != null && op.getValue().getClass() == op2.getClass()) {
				op.getValue().select(false);
			}
		}
		
		for (PropertyChange pair : updateList.getChanges()) {
			if (pair.getFirst() != null) {
				boolean found = false;
				for (PropertyChange pair2 : updateList2.getChanges()) {
					if (pair.getFirst().equals(pair2.getSecond())) {
						found = true;
						break;
					}
				}
				if (found) {
					pair.select(false);
				}
			}
		}
		
	}
	
	private void showWarning(String string) {
		for (WarningListener l : warningListeners)
			l.showWarning(this, string);
	}
	
	private List<WarningListener> warningListeners = new ArrayList<>();
	
	public static interface WarningListener {
		void showWarning(ModelUpdate update, String warning);
	}
	
	public void addListener(WarningListener listener) {
		warningListeners.add(listener);
	}
	
	public void removeListener(WarningListener listener) {
		warningListeners.remove(listener);
	}
}