package org.simantics.district.selection;

import java.awt.geom.Path2D;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.simantics.Simantics;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.common.request.ResourceRead;
import org.simantics.db.common.utils.ListUtils;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.request.ActiveModels;
import org.simantics.db.layer0.request.ActiveRuns;
import org.simantics.db.layer0.request.Configuration;
import org.simantics.db.layer0.variable.RVI;
import org.simantics.db.layer0.variable.Variable;
import org.simantics.db.layer0.variable.Variables;
import org.simantics.diagram.stubs.DiagramResource;
import org.simantics.district.network.ontology.DistrictNetworkResource;
import org.simantics.district.region.ontology.DiagramRegionsResource;
import org.simantics.district.selection.ElementSelector.AggregateCondition.Type;
import org.simantics.layer0.Layer0;
import org.simantics.modeling.ModelingResources;
import org.simantics.scl.runtime.Lists;
import org.simantics.scl.runtime.function.FunctionImpl1;
import org.simantics.scl.runtime.tuple.Tuple2;
import org.simantics.structural.stubs.StructuralResource2;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ElementSelector {
	String name;
	String expression;
	Integer count;
	Resource resource;
	
	Generator generator;
	Selector selector;
	Condition condition;
	
	static Logger LOG = LoggerFactory.getLogger(ElementSelector.class);
	
	static ElementSelectionResource ES;
	static Layer0 L0;
	static StructuralResource2 STR;
	static ModelingResources MOD;
	static DiagramResource DIA;
	static DistrictNetworkResource DN;
	
	ElementSelector(ReadGraph graph, Resource resource) throws DatabaseException {
		super();
		
		L0 = Layer0.getInstance(graph);
		ES = ElementSelectionResource.getInstance(graph);
		STR = StructuralResource2.getInstance(graph);
		MOD = ModelingResources.getInstance(graph);
		DIA = DiagramResource.getInstance(graph);
		DN = DistrictNetworkResource.getInstance(graph);
		
		this.resource = resource;
		this.count = -1;
		try {
			this.name = graph.getRelatedValue(resource, L0.HasLabel);
			this.expression = buildExpression(graph, resource);
		} catch (DatabaseException e) {
			LOG.error("Error reading element selector", e);
			throw e;
		}
	}
	
	public static ElementSelector getSelector(ReadGraph graph, Resource resource) throws DatabaseException {
		return graph.syncRequest(new ElementSelectorQuery(resource));
	}

	public String getName() {
		return name;
	}

	public String getExpression() {
		return expression;
	}

	public Resource getResource() {
		return resource;
	}

	public List<Resource> selectElementsFrom(ReadGraph graph, Resource model) throws DatabaseException {
		if (selector == null) {
			buildSelection(graph);
		}
		
		Collection<Resource> result = gather(graph, model);
		return result instanceof List ? (List<Resource>) result : new ArrayList<>(result);
	}

	private static Generator buildGenerator(ReadGraph graph, Resource resource) throws DatabaseException {
		if (!graph.isInstanceOf(resource, ES.Generator))
			throw new IllegalArgumentException("Resource " + resource + " is not a valid generator");
		
		if (graph.isInstanceOf(resource, ES.Generator_Model)) {
			return new ModelGenerator();
		}
		else if (graph.isInstanceOf(resource, ES.Generator_Diagram)) {
			return new DiagramGenerator(graph.getSingleObject(resource, ES.Generator_HasDiagram));
		}
		else if (graph.isInstanceOf(resource, ES.Generator_Explicit)) {
			return new ExplicitGenerator(graph.getObjects(resource, ES.Generator_HasSelectedElement));
		}
		else {
			throw new IllegalArgumentException("Unknown generator type " + graph.getURI(graph.getSingleType(resource)));
		}
	}

	private static Selector buildSelector(ReadGraph graph, Resource resource) throws DatabaseException {
		if (!graph.isInstanceOf(resource, ES.Selector))
			throw new IllegalArgumentException("Resource " + resource + " is not a valid selector");
		
		Selector s;
		if (graph.isInstanceOf(resource, ES.Selector_All)) {
			s = new All();
		}
		else if (graph.isInstanceOf(resource, ES.PropertySelector)) {
			String propertyName = graph.getRelatedValue(resource, ES.PropertySelector_HasSelectionPropertyName);
			Integer resultCount = graph.getRelatedValue(resource, ES.PropertySelector_HasResultCount);
			boolean isSmallest = graph.isInstanceOf(resource, ES.Selector_NLowest);
			s = new PropertySelector(isSmallest, propertyName, resultCount);
		}
		else {
			throw new IllegalArgumentException("Unknown selector type " + graph.getURI(graph.getSingleType(resource)));
		}
		return s;
	}

	private static Condition buildCondition(ReadGraph graph, Resource resource) throws DatabaseException {
		if (resource == null)
			return null;
		
		if (!graph.isInstanceOf(resource, ES.Condition))
			throw new IllegalArgumentException("Resource " + resource + " is not a valid condition");
		
		Condition cond;
		if (graph.isInstanceOf(resource, ES.PropertyCondition)) {
			String propertyName = graph.getRelatedValue(resource, ES.PropertyCondition_HasPropertyName);
			Double lowerLimit = graph.getPossibleRelatedValue(resource, ES.PropertyCondition_HasLowerLimit);
			Double upperLimit = graph.getPossibleRelatedValue(resource, ES.PropertyCondition_HasUpperLimit);
			cond = new PropertyCondition(propertyName, lowerLimit, upperLimit);
		}
		else if (graph.isInstanceOf(resource, ES.RegionCondition)) {
			DiagramRegionsResource DR = DiagramRegionsResource.getInstance(graph);
			double[] region = graph.getRelatedValue(graph.getSingleObject(resource, ES.RegionCondition_HasRegion), DR.Region_area);
			cond = new RegionCondition(region);
		}
		else if (graph.isInstanceOf(resource, ES.RouteCondition)) {
			Set<Resource> routePoints = new HashSet<>(ListUtils.toList(graph, graph.getSingleObject(resource, ES.RouteCondition_HasRoute)));
			cond = new RouteCondition(routePoints);
		}
		else if (graph.isInstanceOf(resource, ES.AggregateCondition)) {
			boolean isDisjunction = graph.isInstanceOf(resource, ES.Disjunction);
			Collection<Resource> conditionResources = graph.getObjects(resource, ES.HasSubcondition);
			List<Condition> conditions = new ArrayList<>(conditionResources.size());
			for (Resource c : conditionResources) {
				conditions.add(buildCondition(graph, c));
			}
			Type type;
			if (graph.isInstanceOf(resource, ES.Conjunction))
				type = AggregateCondition.Type.CONJUNCTION;
			else if (graph.isInstanceOf(resource, ES.Negation))
				type = AggregateCondition.Type.NEGATION;
			else if (graph.isInstanceOf(resource, ES.Disjunction))
				type = AggregateCondition.Type.DISJUNCTION;
			else
				throw new IllegalArgumentException("Unknown aggreate condition type " + graph.getURI(graph.getSingleType(resource)));
				
			cond = new AggregateCondition(type, conditions);
		}
		else {
			throw new IllegalArgumentException("Unknown condition type " + graph.getURI(graph.getSingleType(resource)));
		}
		
		cond.isInverse = graph.hasStatement(resource, ES.Condition_IsInverse, resource);
		return cond;
	}

	private static String buildExpression(ReadGraph graph, Resource r) throws DatabaseException {
		if (graph.isInstanceOf(r, ES.Selection)) {
			String exp = "select " + buildExpression(graph, graph.getSingleObject(r, ES.Selection_HasSelector)) + 
			             " from " + buildExpression(graph, graph.getSingleObject(r, ES.Selection_HasGenerator));
			
			Resource cond = graph.getPossibleObject(r, ES.Selection_HasCondition);
			return cond != null ? exp + " where {" + buildExpression(graph, cond) + "}" : exp;
		}
		else if (graph.isInstanceOf(r, ES.Condition)) {
			if (graph.isInstanceOf(r, ES.PropertyCondition)) {
				return buildPropertyConditionExpression(graph, r);
			}
			else if (graph.isInstanceOf(r, ES.RegionCondition)) {
				Resource region = graph.getSingleObject(r, ES.RegionCondition_HasRegion);
				String name = graph.getRelatedValue(region, L0.HasLabel);
				return "in region " + name;
			}
			else if (graph.isInstanceOf(r, ES.RouteCondition)) {
				Resource route = graph.getSingleObject(r, ES.RouteCondition_HasRoute);
				String name = graph.getRelatedValue(route, L0.HasLabel);
				return "in route " + name;
			}
			else if (graph.isInstanceOf(r, ES.AggregateCondition)) {
				String op = graph.isInstanceOf(r, ES.Conjunction) ? " and " : " or ";
				List<String> exps = new ArrayList<>();
				Collection<Resource> objects = graph.getObjects(r, ES.HasSubcondition);
				for (Resource c : objects) {
					String exp = buildExpression(graph, c);
					exps.add(objects.size() > 1 ? "{" + exp + "}" : exp);
				}
				String result = String.join(op, exps);
				if (graph.isInstanceOf(r, ES.Negation))
					result = "not {" + result + "}";
				return result;
			}
			else {
				throw new DatabaseException("Unsupported condition resource type <" + graph.getURI(graph.getSingleType(r)) + ">");
			}
		}
		else if (graph.isInstanceOf(r, ES.Selector)) {
			if (graph.isInstanceOf(r, ES.Selector_All)) {
				return "all";
			}
			else if (graph.isInstanceOf(r, ES.PropertySelector)) {
				String op;
				if (graph.isInstanceOf(r, ES.Selector_NLowest))
					op = "bottom";
				else if (graph.isInstanceOf(r, ES.Selector_NHighest))
					op = "top";
				else
					throw new DatabaseException("Unsupported property selector resource type <" + graph.getURI(graph.getSingleType(r)) + ">");
				
				String name = graph.getRelatedValue(r, ES.PropertySelector_HasSelectionPropertyName);
				Integer count = graph.getRelatedValue(r, ES.PropertySelector_HasResultCount);
				return op + " " + count + " of " + name;
			}
			else {
				throw new DatabaseException("Unsupported selector resource type <" + graph.getURI(graph.getSingleType(r)) + ">");
			}
		}
		else if (graph.isInstanceOf(r, ES.Generator)) {
			if (graph.isInstanceOf(r, ES.Generator_Model)) {
				return "model";
			}
			else if (graph.isInstanceOf(r, ES.Generator_Diagram)) {
				return "diagram \"" + graph.getRelatedValue(graph.getSingleObject(r, ES.Generator_HasDiagram), L0.HasName) + "\"";
			}
			else if (graph.isInstanceOf(r, ES.Generator_Explicit)) {
				return "<list of " + graph.getObjects(r, ES.Generator_HasSelectedElement).size() + " elements>";
			}
			else {
				throw new DatabaseException("Unsupported generator resource type <" + graph.getURI(graph.getSingleType(r)) + ">");
			}
		}
		else {
			throw new DatabaseException("Unsupported resource type <" + graph.getURI(graph.getSingleType(r)) + ">");
		}
	}

	private static String buildPropertyConditionExpression(ReadGraph graph, Resource r) throws DatabaseException {
		String propertyName = graph.getRelatedValue(r, ES.PropertyCondition_HasPropertyName);
		Double lowerLimit = graph.getPossibleRelatedValue(r, ES.PropertyCondition_HasLowerLimit);
		Double upperLimit = graph.getPossibleRelatedValue(r, ES.PropertyCondition_HasUpperLimit);
		if (lowerLimit == null && upperLimit == null) {
			return "has property " + propertyName;
		}
		else {
			StringBuilder result = new StringBuilder();
			if (lowerLimit != null) {
				result.append(lowerLimit);
				result.append(" < ");
			}
			result.append(propertyName);
			if (upperLimit != null) {
				result.append(" < ");
				result.append(upperLimit);
			}
			return result.toString();
		}
	}

	private static Collection<Resource> elementsOfDiagram(ReadGraph graph, Resource diagram) throws DatabaseException {
		if (graph.isInstanceOf(diagram, STR.Composite)) {
			// Resource is a composite - get diagram
			return elementsOfDiagram(graph, graph.getSingleObject(diagram, MOD.CompositeToDiagram));
		}
		
		Collection<Resource> elements = graph.getObjects(diagram, L0.ConsistsOf);
		Collection<Resource> result = new ArrayList<>();
		for (Resource r : elements)
			if (graph.isInstanceOf(r, DIA.Element))
				result .add(r);
		return result;
	}

	private void buildSelection(ReadGraph graph) throws DatabaseException {
		Resource selector = graph.getSingleObject(resource, ES.Selection_HasSelector);
		Resource generator = graph.getSingleObject(resource, ES.Selection_HasGenerator);
		Resource condition = graph.getPossibleObject(resource, ES.Selection_HasCondition);
		
		this.selector = buildSelector(graph, selector);
		this.generator = buildGenerator(graph, generator);
		this.condition = buildCondition(graph, condition);
	}

	private Collection<Resource> filterElementsFrom(ReadGraph graph, Collection<Resource> elements) throws DatabaseException {
		if (condition == null) return elements;
		
		ArrayList<Resource> result = new ArrayList<>();
		for (Resource r : elements) {
			if (condition.match(graph, r))
				result.add(r);
		}
		
		return result;
	}
	
	private Collection<Resource> gather(ReadGraph graph, Resource model) throws DatabaseException {
		return selector.select(graph, filterElementsFrom(graph, generator.generate(graph, model)));
	}
	
	static Variable getVariableForElement(ReadGraph graph, Resource element) throws DatabaseException {
		Resource component = graph.getPossibleObject(element, MOD.ElementToComponent);
		if (component != null) {
			Variable var = Variables.getVariable(graph, component);
			RVI realRvi = var.getRVI(graph);
			
			for (Resource activeModel : graph.syncRequest(new ActiveModels(Simantics.getProjectResource()))) {
				for (Variable run : graph.syncRequest(new ActiveRuns(activeModel))) {
					Variable v = realRvi.resolvePossible(graph, run);
					if (v != null) {
						return v;
					}
				}
				Variable configuration = Variables.getPossibleConfigurationContext(graph, activeModel);
				if (configuration != null) {
					Variable v = realRvi.resolvePossible(graph, configuration);
					if (v != null) {
						return v;
					}
				}
			}
		}
		
		return null;
	}
	
	static Double getPropertyValue(ReadGraph graph, Resource element, String propertyName) {
		try {
			Variable v = getVariableForElement(graph, element);
			if (v != null) {
				Number value = v.getPossiblePropertyValue(graph, propertyName);
				if (value != null)
					return value.doubleValue();
			}
			
			// No property found - try possible mapped element property as well
			Resource mappedElement = graph.getPossibleObject(element, DN.MappedComponent);
			if (mappedElement != null)
				return getPropertyValue(graph, mappedElement, propertyName);
		}
		catch (DatabaseException e) {
		}
		
		return null;
	}
	
	// Generators
	
	static abstract class Generator {
		abstract Collection<Resource> generate(ReadGraph graph, Resource model) throws DatabaseException;
	}
	
	static class ModelGenerator extends Generator {
		@Override
		Collection<Resource> generate(ReadGraph graph, Resource model) throws DatabaseException {
			Resource conf = graph.syncRequest(new Configuration(model));
			
			ArrayList<Resource> result = new ArrayList<>();
			
			// Iterate over diagrams
			for (Resource comp : graph.getObjects(conf, L0.ConsistsOf)) {
				if (!graph.isInstanceOf(comp, STR.Composite)) continue;
				
				Resource diagram = graph.getPossibleObject(comp, MOD.CompositeToDiagram);
				if (diagram != null) result.addAll(elementsOfDiagram(graph, diagram));
			}
			
			return result;
		}
	}
	
	static class DiagramGenerator extends Generator {
		Resource diagram;
		
		public DiagramGenerator(Resource diagram) {
			this.diagram = diagram;
		}

		@Override
		Collection<Resource> generate(ReadGraph graph, Resource model) throws DatabaseException {
			return elementsOfDiagram(graph, diagram);
		}
	}
	
	static class ExplicitGenerator extends Generator {
		public ExplicitGenerator(Collection<Resource> elements) {
			this.elements = elements;
		}

		Collection<Resource> elements;

		@Override
		Collection<Resource> generate(ReadGraph graph, Resource model) {
			return elements;
		}
	}
	
	// Selectors
	
	static abstract class Selector {
		abstract Collection<Resource> select(ReadGraph graph, Collection<Resource> elements);
	}
	
	static class All extends Selector {
		public All() {
		}

		@Override
		Collection<Resource> select(ReadGraph graph, Collection<Resource> elements) {
			return elements;
		}
	}
	
	static class PropertySelector extends Selector {
		public PropertySelector(boolean smallest, String propertyName, int resultCount) {
			this.smallest = smallest;
			this.propertyName = propertyName;
			this.resultCount = resultCount;
		}
		
		boolean smallest;
		String propertyName;
		int resultCount;
		
		@SuppressWarnings("unchecked")
		@Override
		Collection<Resource> select(ReadGraph graph, Collection<Resource> elements) {
			List<Resource> result = new ArrayList<>(elements);
			List<Tuple2> result2 = Lists.map(new FunctionImpl1<Resource, Tuple2>() {
				@Override
				public Tuple2 apply(Resource r) {
					return new Tuple2(r, getPropertyValue(graph, r, propertyName));
				}
			}, result);
			
			result2 = Lists.filter(new FunctionImpl1<Tuple2, Boolean>() {
				@Override
				public Boolean apply(Tuple2 t) {
					return t.c1 != null;
				}
			}, result2);
			
			result2.sort((t1, t2) -> smallest ? Double.compare((Double) t1.c1, (Double) t2.c1) : Double.compare((Double) t2.c1, (Double) t1.c1));
			
			if (resultCount < result2.size())
				result2 = result2.subList(0, resultCount);
			
			result = Lists.map(new FunctionImpl1<Tuple2, Resource>() {
				@Override
				public Resource apply(Tuple2 p0) {
					return (Resource) p0.c0;
				}
			}, result2);
			
			return result;
		}
	}
	
	// Conditions
	
	static abstract class Condition {
		boolean isInverse;
		abstract boolean match(ReadGraph graph, Resource r) throws DatabaseException;
	}
	
	static class PropertyCondition extends Condition {
		public PropertyCondition(String propertyName, Double lowerLimit, Double upperLimit) {
			super();
			this.propertyName = propertyName;
			this.lowerLimit = lowerLimit;
			this.upperLimit = upperLimit;
		}
		
		String propertyName;
		Double lowerLimit;
		Double upperLimit;
		
		@Override
		boolean match(ReadGraph graph, Resource r) {
			Double value = getPropertyValue(graph, r, propertyName);
			return value != null && (lowerLimit == null || value >= lowerLimit) && (upperLimit == null || value <= upperLimit);
		}
	}
	
	static class RegionCondition extends Condition {
		public RegionCondition(double[] region) {
			super();
			this.region = region;
			
			Path2D path = new Path2D.Double();
			double startX = region[0];
			double startY = region[1];
			path.moveTo(startX, startY);
			for (int i = 2; i < region.length; i+=2)
				path.lineTo(region[i], region[i+1]);
			path.closePath();

			this.path = path;
		}

		double[] region;
		Path2D path;

		@Override
		boolean match(ReadGraph graph, Resource r) throws DatabaseException {
			double[] transform = graph.getRelatedValue(r, DIA.HasTransform);
			double x = transform[4];
			double y = transform[5];
			return path.contains(x, y);
		} 
	}
	
	static class RouteCondition extends Condition {
		public RouteCondition(Set<Resource> routePoints) {
			super();
			this.routePoints = routePoints;
		}

		Set<Resource> routePoints;

		@Override
		boolean match(ReadGraph graph, Resource r) throws DatabaseException {
			return routePoints.contains(r);
		}
	}
	
	static class DiagramCondition extends Condition {
		public DiagramCondition(Resource diagram) {
			super();
			this.diagram = diagram;
		}

		Resource diagram;

		@Override
		boolean match(ReadGraph graph, Resource r) throws DatabaseException {
			return graph.getSingleObject(r, L0.PartOf).equals(diagram);
		}
	}
	
	static class AggregateCondition extends Condition {
		static enum Type { DISJUNCTION, CONJUNCTION, NEGATION };
		
		public AggregateCondition(Type type, List<Condition> conditions) {
			super();
			this.type = type;
			this.conditions = conditions;
		}
		
		Type type;
		List<Condition> conditions;
		
		@Override
		boolean match(ReadGraph graph, Resource r) throws DatabaseException {
			switch (type) {
			case DISJUNCTION:
				for (Condition c : conditions)
					if (c.match(graph, r)) return true;
				return false;
			case CONJUNCTION:
				for (Condition c : conditions)
					if (!c.match(graph, r)) return false;
				return true;
			case NEGATION:
				for (Condition c : conditions)
					if (c.match(graph, r)) return false;
				return true;
			default:
				// Should not happen
				throw new IllegalArgumentException("Unknown aggregate condition type " + type);
			}
		}
	}
	
	public static class ElementSelectorQuery extends ResourceRead<ElementSelector> {
		public ElementSelectorQuery(Resource resource) {
			super(resource);
		}
		
		@Override
		public ElementSelector perform(ReadGraph graph) throws DatabaseException {
			return new ElementSelector(graph, resource);
		}
	}
}