/*
 * Copyright 2005-2006 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package com.sun.tools.javac.model;

import java.util.List;
import java.util.Set;
import java.util.EnumSet;
import javax.lang.model.element.*;
import javax.lang.model.type.*;
import com.sun.tools.javac.code.*;
import com.sun.tools.javac.code.Symbol.*;
import com.sun.tools.javac.util.*;

/**
 * Utility methods for operating on types.
 *
 * <p><b>This is NOT part of any API supported by Sun Microsystems.
 * If you write code that depends on this, you do so at your own
 * risk.  This code and its internal interfaces are subject to change
 * or deletion without notice.</b></p>
 */
public class JavacTypes implements javax.lang.model.util.Types {

    private Symtab syms;
    private Types types;

    private static final Context.Key<JavacTypes> KEY =
	    new Context.Key<JavacTypes>();

    public static JavacTypes instance(Context context) {
	JavacTypes instance = context.get(KEY);
	if (instance == null) {
	    instance = new JavacTypes(context);
	    context.put(KEY, instance);
	}
	return instance;
    }

    /**
     * Public for use only by JavacProcessingEnvironment
     */
    // TODO JavacTypes constructor should be protected
    public JavacTypes(Context context) {
	setContext(context);
    }

    /**
     * Use a new context.  May be called from outside to update
     * internal state for a new annotation-processing round.
     * This instance is *not* then registered with the new context.
     */
    public void setContext(Context context) {
        syms = Symtab.instance(context);
	types = Types.instance(context);
    }

    public Element asElement(TypeMirror t) {
	Type type = cast(Type.class, t);
	if (type.tag != TypeTags.CLASS && type.tag != TypeTags.TYPEVAR)
	    return null;
	return type.asElement();
    }

    public boolean isSameType(TypeMirror t1, TypeMirror t2) {
	return types.isSameType((Type) t1, (Type) t2);
    }

    public boolean isSubtype(TypeMirror t1, TypeMirror t2) {
	validateTypeNotIn(t1, EXEC_OR_PKG);
	validateTypeNotIn(t2, EXEC_OR_PKG);
	return types.isSubtype((Type) t1, (Type) t2);
    }

    public boolean isAssignable(TypeMirror t1, TypeMirror t2) {
	validateTypeNotIn(t1, EXEC_OR_PKG);
	validateTypeNotIn(t2, EXEC_OR_PKG);
	return types.isAssignable((Type) t1, (Type) t2);
    }

    public boolean contains(TypeMirror t1, TypeMirror t2) {
	validateTypeNotIn(t1, EXEC_OR_PKG);
	validateTypeNotIn(t2, EXEC_OR_PKG);
	return ((Type) t1).contains((Type) t2);
    }

    public boolean isSubsignature(ExecutableType m1, ExecutableType m2) {
	return types.isSubSignature((Type) m1, (Type) m2);
    }

    public List<Type> directSupertypes(TypeMirror t) {
	validateTypeNotIn(t, EXEC_OR_PKG);
	Type type = (Type) t;
	Type sup = types.supertype(type);
	return (sup == Type.noType || sup == type || sup == null)
	      ? types.interfaces(type)
	      : types.interfaces(type).prepend(sup);
    }

    public TypeMirror erasure(TypeMirror t) {
	if (t.getKind() == TypeKind.PACKAGE)
	    throw new IllegalArgumentException(t.toString());
	return types.erasure((Type) t);
    }

    public TypeElement boxedClass(PrimitiveType p) {
	return types.boxedClass((Type) p);
    }

    public PrimitiveType unboxedType(TypeMirror t) {
	if (t.getKind() != TypeKind.DECLARED)
	    throw new IllegalArgumentException(t.toString());
	Type unboxed = types.unboxedType((Type) t);
	if (! unboxed.isPrimitive())	// only true primitives, not void
	    throw new IllegalArgumentException(t.toString());
	return unboxed;
    }

    public TypeMirror capture(TypeMirror t) {
	validateTypeNotIn(t, EXEC_OR_PKG);
	return types.capture((Type) t);
    }

    public PrimitiveType getPrimitiveType(TypeKind kind) {
	switch (kind) {
	case BOOLEAN:	return syms.booleanType;
	case BYTE:	return syms.byteType;
	case SHORT:	return syms.shortType;
	case INT:	return syms.intType;
	case LONG:	return syms.longType;
	case CHAR:	return syms.charType;
	case FLOAT:	return syms.floatType;
	case DOUBLE:	return syms.doubleType;
	default:
	    throw new IllegalArgumentException("Not a primitive type: " + kind);
	}
    }

    public NullType getNullType() {
	return (NullType) syms.botType;
    }

    public NoType getNoType(TypeKind kind) {
	switch (kind) {
	case VOID:	return syms.voidType;
	case NONE:	return Type.noType;
	default:
	    throw new IllegalArgumentException(kind.toString());
	}
    }

    public ArrayType getArrayType(TypeMirror componentType) {
	switch (componentType.getKind()) {
	case VOID:
	case EXECUTABLE:
	case WILDCARD:	// heh!
	case PACKAGE:
	    throw new IllegalArgumentException(componentType.toString());
	}
	return new Type.ArrayType((Type) componentType, syms.arrayClass);
    }

    public WildcardType getWildcardType(TypeMirror extendsBound,
					TypeMirror superBound) {
	BoundKind bkind;
	Type bound;
	if (extendsBound == null && superBound == null) {
	    bkind = BoundKind.UNBOUND;
	    bound = syms.objectType;
	} else if (superBound == null) {
	    bkind = BoundKind.EXTENDS;
	    bound = (Type) extendsBound;
	} else if (extendsBound == null) {
	    bkind = BoundKind.SUPER;
	    bound = (Type) superBound;
	} else {
	    throw new IllegalArgumentException(
		    "Extends and super bounds cannot both be provided");
	}
	switch (bound.getKind()) {
	case ARRAY:
	case DECLARED:
	case ERROR:
	case TYPEVAR:
	    return new Type.WildcardType(bound, bkind, syms.boundClass);
	default:
	    throw new IllegalArgumentException(bound.toString());
	}
    }

    public DeclaredType getDeclaredType(TypeElement typeElem,
					TypeMirror... typeArgs) {
	ClassSymbol sym = (ClassSymbol) typeElem;

	if (typeArgs.length == 0)
	    return (DeclaredType) sym.erasure(types);
	if (sym.type.getEnclosingType().isParameterized())
	    throw new IllegalArgumentException(sym.toString());

	return getDeclaredType0(sym.type.getEnclosingType(), sym, typeArgs);
    }

    public DeclaredType getDeclaredType(DeclaredType enclosing,
					TypeElement typeElem,
					TypeMirror... typeArgs) {
	if (enclosing == null)
	    return getDeclaredType(typeElem, typeArgs);

	ClassSymbol sym = (ClassSymbol) typeElem;
	Type outer = (Type) enclosing;

	if (outer.tsym != sym.owner.enclClass())
	    throw new IllegalArgumentException(enclosing.toString());
	if (!outer.isParameterized())
	    return getDeclaredType(typeElem, typeArgs);

	return getDeclaredType0(outer, sym, typeArgs);
    }
    // where
        private DeclaredType getDeclaredType0(Type outer,
					      ClassSymbol sym,
					      TypeMirror... typeArgs) {
	    if (typeArgs.length != sym.type.getTypeArguments().length())
		throw new IllegalArgumentException(
		"Incorrect number of type arguments");
	    
	    ListBuffer<Type> targs = new ListBuffer<Type>();
	    for (TypeMirror t : typeArgs) {
		if (!(t instanceof ReferenceType || t instanceof WildcardType))
		    throw new IllegalArgumentException(t.toString());
		targs.append((Type) t);
	    }
	    // TODO: Would like a way to check that type args match formals.
	    
	    return (DeclaredType) new Type.ClassType(outer, targs.toList(), sym);
	}

    /**
     * Returns the type of an element when that element is viewed as
     * a member of, or otherwise directly contained by, a given type.
     * For example,
     * when viewed as a member of the parameterized type {@code Set<String>},
     * the {@code Set.add} method is an {@code ExecutableType}
     * whose parameter is of type {@code String}.
     *
     * @param containing  the containing type
     * @param element     the element
     * @return the type of the element as viewed from the containing type
     * @throws IllegalArgumentException if the element is not a valid one
     *		for the given type
     */
    public TypeMirror asMemberOf(DeclaredType containing, Element element) {
        Type site = (Type)containing;
	Symbol sym = (Symbol)element;
	if (types.asSuper(site, sym.getEnclosingElement()) == null)
	    throw new IllegalArgumentException(sym + "@" + site);
	return types.memberType(site, sym);
    }


    private static final Set<TypeKind> EXEC_OR_PKG =
	    EnumSet.of(TypeKind.EXECUTABLE, TypeKind.PACKAGE);

    /**
     * Throws an IllegalArgumentException if a type's kind is one of a set.
     */
    private void validateTypeNotIn(TypeMirror t, Set<TypeKind> invalidKinds) {
	if (invalidKinds.contains(t.getKind()))
	    throw new IllegalArgumentException(t.toString());
    }

    /**
     * Returns an object cast to the specified type.
     * @throws NullPointerException if the object is {@code null}
     * @throws IllegalArgumentException if the object is of the wrong type
     */
    private static <T> T cast(Class<T> clazz, Object o) {
	if (! clazz.isInstance(o))
	    throw new IllegalArgumentException(o.toString());
	return clazz.cast(o);
    }
}