package grafos;

import com.github.javaparser.ast.Node;
import com.github.javaparser.ast.body.MethodDeclaration;
import com.github.javaparser.ast.expr.Expression;
import com.github.javaparser.ast.stmt.*;
import com.github.javaparser.ast.visitor.VoidVisitorAdapter;

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

public class Visitador extends VoidVisitorAdapter<CFG> {
	//********************************************************/
	//********************** Atributos ***********************/
	//********************************************************/

	private List<Node> prevNode;

	//********************************************************/
	//*********************** Metodos ************************/
	//********************************************************/

	// Visitador de métodos
	// Este visitador añade el nodo final al CFG	
	@Override
	public void visit(MethodDeclaration methodDeclaration, CFG graph) {
		prevNode = Collections.singletonList(graph.beginNode());

		// Visitamos el método
		super.visit(methodDeclaration, graph);

		// Añadimos el nodo final al CFG
		Node end = graph.endNode();
		for (Node n : prevNode)
			if (n != end)
				graph.connect(n, end);
	}

	@Override
	public void visit(ReturnStmt n, CFG arg) {
		arg.addNode(n);
		arg.connect(prevNode, n);
		super.visit(n, arg);
		arg.connect(n, arg.endNode());
		prevNode = Collections.emptyList();
	}

	@Override
	public void visit(IfStmt n, CFG graph) {
		Node ifStart = n.getCondition();
		graph.addNode(ifStart);
		graph.connect(prevNode, ifStart);

		// TODO: shortcut conditions (||, &&)

		prevNode = Collections.singletonList(ifStart);
		List<Node> prevNodeBegin = prevNode;
		n.getThenStmt().accept(this, graph);
		List<Node> newPrev = new LinkedList<>();
		if (prevNode == prevNodeBegin)
			newPrev.add(ifStart);
		else newPrev.addAll(prevNode);
		prevNode = Collections.singletonList(ifStart);
		if (n.getElseStmt().isPresent()) {
			n.getElseStmt().get().accept(this, graph);
			if (prevNode == prevNodeBegin)
				newPrev.add(ifStart);
			else newPrev.addAll(prevNode);
		} else {
			newPrev.add(ifStart);
		}
		prevNode = newPrev;
	}

	@Override
	public void visit(WhileStmt n, CFG graph) {
		Node whileStart = n.getCondition();
		graph.addNode(whileStart);
		graph.connect(prevNode, whileStart);

		// TODO: shortcut conditions (||, &&)

		prevNode = Collections.singletonList(whileStart);
		n.getBody().accept(this, graph);
		graph.connect(prevNode, whileStart);
		prevNode = Collections.singletonList(whileStart);
	}

	@Override
	public void visit(DoStmt n, CFG graph) {
		prevNode = new LinkedList<>(prevNode);
		prevNode.add(n.getCondition());
		n.getBody().accept(this, graph);
		graph.addNode(n.getCondition());
		graph.connect(prevNode, n.getCondition());
		prevNode = Collections.singletonList(n.getCondition());
	}

	@Override
	public void visit(ForStmt n, CFG graph) {
		// Initialization expressions
		if (n.getInitialization() != null) {
			for (Expression e : n.getInitialization()) {
				graph.addNode(e);
				graph.connect(prevNode, e);
				prevNode = Collections.singletonList(e);
			}
		}
		// Comparison expression
		// TODO: shortcut conditions (||, &&)
		if (n.getCompare().isPresent()) {
			graph.addNode(n.getCompare().get());
			graph.connect(prevNode, n.getCompare().get());
			prevNode = Collections.singletonList(n.getCompare().get());
		}
		// Loop body
		n.getBody().accept(this, graph);
		// Update expressions
		if (n.getUpdate() != null) {
			for (Expression e : n.getUpdate()) {
				graph.addNode(e);
				graph.connect(prevNode, e);
				prevNode = Collections.singletonList(e);
			}
		}
		// Connect to comparison expression
		if (n.getCompare().isPresent())
			graph.connect(prevNode, n.getCompare().get());
		else {
			// TODO: connect last update / end of loop with first element of loop body
		}
		// Set comparison as last possible statement
		if (n.getCompare().isPresent())
			prevNode = Collections.singletonList(n.getCompare().get());
		else // There is no comparison, can't exit the loop TODO implement break and continue as way to exit
			prevNode = Collections.emptyList();
	}

	// Visitador de expresiones
	// Cada expresión encontrada genera un nodo en el CFG	
	@Override
	public void visit(ExpressionStmt es, CFG graph) {
		graph.addNode(es);
		graph.connect(prevNode, es);
		prevNode = Collections.singletonList((Node) es);

		// Seguimos visitando...
		super.visit(es, graph);
	}
}