/*
 * Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0, which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.glassfish.pfl.dynamic.codegen.impl;

import java.io.PrintStream ;

import java.util.Set ;
import java.util.Map ;
import java.util.IdentityHashMap ;

import java.lang.reflect.Modifier ;

import org.glassfish.pfl.dynamic.codegen.spi.Type ;
import org.glassfish.pfl.dynamic.codegen.spi.Variable ;

public final class Util {
    private Util() {}

    
Make sure that all variables reachable from node
are marked not available, indicating that they are
no longer in scope.  Note that only defining occurrences
of variables are to be considered here, as a scope
that merely references a variable may be closed while
the containing defining scope is still open.
/** Make sure that all variables reachable from node
     * are marked not available, indicating that they are
     * no longer in scope.  Note that only defining occurrences
     * of variables are to be considered here, as a scope
     * that merely references a variable may be closed while
     * the containing defining scope is still open.
     */
    public static void close( Node node ) {
	TreeWalkerContext context = new TreeWalkerContext() ;
	Visitor visitor = new TreeWalker( context ) {

	    @Override
	    public void blockStatementBeforeBodyStatement( BlockStatement arg, 
		Statement stmt ) {
		if (stmt instanceof DefinitionStatement) {
		    DefinitionStatement ds = 
			DefinitionStatement.class.cast( stmt ) ;
		    ((VariableInternal)ds.var()).close() ;
		}
	    }
	  
	    @Override
	    public void visitMethodGenerator( MethodGenerator arg ) {
		for (Variable var : arg.arguments()) {
		    ((VariableInternal)var).close() ;
		}
	    }

	    @Override
	    public void tryStatementBeforeBlock( TryStatement arg,
		Type type, Variable var, BlockStatement block ) {

		((VariableInternal)var).close() ;
	    }
	} ;
	context.push( visitor ) ;
	node.accept( visitor ) ;
    }

    
Throw an exception if any ExpressionInternal reachable
from expr contains a Variable that is out of scope.
Note that this is only useful for Expressions.
/** Throw an exception if any ExpressionInternal reachable
     * from expr contains a Variable that is out of scope.
     * Note that this is only useful for Expressions.
     */
    public static void checkScope( ExpressionInternal expr ) {
	TreeWalkerContext context = new TreeWalkerContext() ;
	Visitor visitor = new TreeWalker( context ) {
	    @Override
	    public boolean preVariable( Variable arg ) {
		if (!((VariableInternal)arg).isAvailable())
		    throw new IllegalStateException( arg + " is no longer in scope" ) ;
		return false ;
	    }
	} ;
	context.push( visitor ) ;
	expr.accept( visitor ) ;
    }

    
Check that node is really a tree, that is, when we traverse it
with the visitor, we never encounter the same node twice.
/** Check that node is really a tree, that is, when we traverse it
     * with the visitor, we never encounter the same node twice.
     */
    public static void checkTree( final Node node, final PrintStream pw ) {
	// Set up a visitor that counts how many times each unique node
	// object is encountered, then visit node.
	TreeWalkerContext context = new TreeWalkerContext() ;
	final Map<Node,Integer> map = new IdentityHashMap<Node,Integer>() ;
	Visitor visitor = new TreeWalker( context ) {
	    @Override
	    public boolean preNode( Node arg ) {
		Integer val = map.get( arg ) ;
		if (val == null) {
		    val = 1 ;
		} else {
		    val++ ;
		}
		map.put( arg, val ) ;
		return false ;
	    }
	} ;
	context.push( visitor ) ;
	node.accept( visitor ) ;

	// Print out any Nodes that appear more than once
	// in the tree rooted at node.
	for (Map.Entry<Node,Integer> entry : map.entrySet()) {
	    if (entry.getValue() > 1) {
		pw.print( "Node " + entry.getKey() 
		    + " appeared " + entry.getValue() + " times in the AST" ) ;
	    }
	}
    }


    // Display all attributes of node.  If the value of an attribute is itself
    // a node, display its attributes as well (recursively).  At the end,
    // leave the Printer indented one level.
    private static void displayAttributes( final Node node, final CodegenPrinter pr ) {
	Set<Attribute<?>> attrs = Attribute.getAttributes( node ) ;
	for (Attribute<?> attr : attrs) {
	    String typeName = attr.type().getName() ;
	    int lastIndex = typeName.lastIndexOf( '.' ) ;
	    if (lastIndex >= 0)
		typeName = typeName.substring( lastIndex + 1 ) ;
	    Object obj = attr.get(node) ;
	    String value = attr.get( node ).toString() ;
	    pr.nl().p("|__:").p(attr.name()).p(":").p(typeName).p("=").p(value) ;

	    if (obj instanceof Node) {
		pr.in() ;
		displayAttributes( Node.class.cast(obj), pr ) ;
		pr.out() ;
	    }
	}
    }

    public static String getNodeIdString( Node obj ) {
	return "@" + obj.id() ;
    }

    
Display a tree for the node.
/** Display a tree for the node.
     */
    public static void display( final Node node, final PrintStream pw ) {
	TreeWalkerContext context = new TreeWalkerContext() ;
	Visitor visitor = new TreeWalker( context ) {

	    final CodegenPrinter pr = new CodegenPrinter( pw, 2, '.' ) ;

	    private boolean done( Node node ) {
		displayAttributes( node, pr ) ;
		pr.in() ;
		return true ;
	    }

	    // Use this if no more specific type has a defined display
	    // behavior in this visitor.
	    @Override
	    public boolean preNode( Node arg ) {
		pr.nl().p("Node").p(getNodeIdString(arg))
		    .p("[").p(arg.toString()).p("]") ;

		return done( arg ) ;
	    }

	    @Override
	    public void postNode( Node arg ) {
		pr.out() ;
	    }

	    @Override
	    public boolean preClassGenerator( ClassGeneratorImpl arg ) {
		pr.nl().p("ClassGenerator").p(getNodeIdString(arg))
		    .p("[").p(Modifier.toString(arg.modifiers()))
		    .p(" ").p((arg.isInterface() ? "interface" : "class"))
		    .p(" ").p(arg.name()).p("]") ;
		
		return done( arg ) ;
	    }

	    @Override
	    public boolean preMethodGenerator( MethodGenerator arg ) {
		pr.nl().p( "MethodGenerator").p(getNodeIdString(arg))
		    .p("[").p(Modifier.toString(arg.modifiers()))
		    .p(" ").p(arg.returnType().name()).p(" ").p(arg.name()).p("]") ;

		return done( arg ) ;
	    }

	    @Override
	    public boolean preThrowStatement( ThrowStatement arg ) {
		pr.nl().p("ThrowStatement").p(getNodeIdString(arg)) ;

		return done( arg ) ;
	    }

	    @Override
	    public boolean preAssignmentStatement( AssignmentStatement arg ) {
		pr.nl().p("AssignmentStatement").p(getNodeIdString(arg)) ;

		return done( arg ) ;
	    }

	    @Override
	    public boolean preBlockStatement( BlockStatement arg ) {
		pr.nl().p("BlockStatement").p(getNodeIdString(arg)) ;

		return done( arg ) ;
	    }

	    @Override
	    public boolean preCaseBranch( CaseBranch arg ) {
		pr.nl().p("CaseBranch").p(getNodeIdString(arg))
		    .p("[").p(Integer.toString(arg.label())).p("]") ;

		return done( arg ) ;
	    }

	    @Override
	    public boolean preDefinitionStatement( DefinitionStatement arg ) {
		pr.nl().p("DefinitionStatement").p(getNodeIdString(arg)) ;

		return done( arg ) ;
	    }

	    @Override
	    public boolean preIfStatement( IfStatement arg ) {
		pr.nl().p("IfStatement").p(getNodeIdString(arg)) ;

		return done( arg ) ;
	    }

	    @Override
	    public void ifStatementBeforeTruePart( IfStatement arg ) {
		pr.out().nl().p("IfStatement:true").in() ;
	    }

	    @Override
	    public boolean ifStatementBeforeFalsePart( IfStatement arg ) {
		pr.out().nl().p("IfStatement:false").in() ;
		return true ;
	    }

	    @Override
	    public boolean preBreakStatement( BreakStatement arg ) {
		pr.nl().p("BreakStatement").p(getNodeIdString(arg)) ;

		return done( arg ) ;
	    }

	    @Override
	    public boolean preReturnStatement( ReturnStatement arg ) {
		pr.nl().p("ReturnStatement").p(getNodeIdString(arg)) ;

		return done( arg ) ;
	    }

	    @Override
	    public boolean preSwitchStatement( SwitchStatement arg ) {
		pr.nl().p("SwitchStatement").p(getNodeIdString(arg)) ;

		return done( arg ) ;
	    }

	    @Override
	    public boolean preTryStatement( TryStatement arg ) {
		pr.nl().p("TryStatement").p(getNodeIdString(arg)) ;	

		return done( arg ) ;
	    }

	    @Override
	    public void tryStatementBeforeBlock( TryStatement arg,
		Type type, Variable var, BlockStatement block ) {
                VariableInternal ivar = (VariableInternal)var ;
		pr.out().nl().p("TryStatement:catch[").p("type=").p(type.name())
		    .p(",var=").p(ivar.ident()).p("]").in() ;
		ivar.accept( this ) ;
	    }

	    @Override
	    public boolean tryStatementBeforeFinalPart( TryStatement arg ) {
		pr.out().nl().p("TryStatement:finally").in() ;

		return true ;
	    }

	    @Override
	    public boolean preWhileStatement( WhileStatement arg ) {
		pr.nl().p("WhileStatement").p(getNodeIdString(arg)) ;

		return done( arg ) ;
	    }

	    @Override
	    // All Expressions define a usable toString, so they all
	    // can be handled by this method.
	    public boolean preExpression( ExpressionInternal arg ) {
		pr.nl().p(arg.toString()) ;

		return done( arg ) ;
	    }

	    @Override
	    public boolean preFieldGenerator( FieldGenerator arg ) {
		pr.nl().p(arg.toString()) ;

		return done( arg ) ;
	    }

	} ;
	context.push( visitor ) ;
	node.accept( visitor ) ;
    }
}