package grafos;

import com.github.javaparser.ast.Node;
import com.github.javaparser.ast.NodeList;
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;
import java.util.Stack;

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

	private List<Node> prevNode;
	private Stack<SwitchStmt> switchStack = new Stack<>();
	private List<BreakStmt> brokenStmts = new LinkedList<>();

	//********************************************************/
	//*********************** 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) {
		graph.beginBlock(n);
		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;
		graph.endBlock();
	}

	@Override
	public void visit(WhileStmt n, CFG graph) {
		graph.beginBlock(n);
		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);
		graph.endBlock();
	}

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

	@Override
	public void visit(ForStmt n, CFG graph) {
		graph.beginBlock(n);
		// 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();
		graph.endBlock();
	}

	@Override
	public void visit(ForeachStmt n, CFG graph) {
		graph.beginBlock(n);
		ForeachStmt copy = new ForeachStmt(n.getTokenRange().orElse(null), n.getVariable(), n.getIterable(), new EmptyStmt());
		graph.addNode(copy);
		graph.connect(prevNode, copy);
		prevNode = Collections.singletonList(copy);
		n.getBody().accept(this, graph);
		graph.connect(prevNode, copy);
		prevNode = Collections.singletonList(copy);
		graph.endBlock();
	}

	@Override
	public void visit(SwitchEntryStmt n, CFG graph) {
		// Case header
		Node caseNode = new SwitchEntryStmt(n.getTokenRange().orElse(null), n.getLabel().orElse(null), new NodeList<>());
		graph.addNode(caseNode);
		graph.connect(prevNode, caseNode);
		prevNode = Collections.singletonList(caseNode);
		// Case body
		n.getStatements().accept(this, graph);
	}

	@Override
	public void visit(SwitchStmt n, CFG graph) {
		graph.beginBlock(n);
		// Link previous statement to the switch's selector
		Node selectorNode = n.getSelector();
		graph.addNode(selectorNode);
		graph.connect(prevNode, selectorNode);
		// Analyze switch's cases
		prevNode = Collections.singletonList(selectorNode);
		switchStack.push(n);
		for (SwitchEntryStmt entry : n.getEntries()) {
			entry.accept(this, graph);
			if (prevNode.isEmpty()) {
				prevNode = Collections.singletonList(selectorNode);
			} else {
				prevNode = new LinkedList<>(prevNode);
				prevNode.add(selectorNode);
			}
		}
		switchStack.pop();
		// The next statement will be linked to:
		//		1. All break statements that broke from the switch
		// 		2. If the switch doesn't have a default statement, the switch's selector
		// 		3. If the last entry doesn't break, to the last statement
		prevNode = new LinkedList<>(prevNode); // 3
		prevNode.remove(selectorNode);
		prevNode.addAll(brokenStmts); // 1
		if (n.getEntries().get(n.getEntries().size() - 1).getLabel().isPresent())
			prevNode.add(selectorNode); // 2
		graph.endBlock();
	}

	@Override
	public void visit(BreakStmt n, CFG graph) {
		if (!switchStack.isEmpty() && !n.getLabel().isPresent()) {
			graph.addNode(n);
			graph.connect(prevNode, n);
			brokenStmts.add(n);
			prevNode = Collections.emptyList();
			return;
		}
		super.visit(n, graph);
	}

	@Override
	public void visit(ExpressionStmt es, CFG graph) {
		graph.addNode(es);
		graph.connect(prevNode, es);
		prevNode = Collections.singletonList(es);

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