/*

 * Copyright (c) 2005, 2014, Oracle and/or its affiliates. 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.tools.javac.model;

import java.util.Collections;

import java.util.EnumSet;

import java.util.LinkedHashSet;

import java.util.List;

import java.util.Set;

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 supported API.

 * 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 final Symtab syms;

    private final Types types;

    public static JavacTypes instance(Context context) {

        JavacTypes instance = context.get(JavacTypes.class);

        if (instance == null)

            instance = new JavacTypes(context);

        return instance;

    }

    protected JavacTypes(Context context) {

        context.put(JavacTypes.class, this);

        syms = Symtab.instance(context);

        types = Types.instance(context);

    }

    public Element asElement(TypeMirror t) {

        switch (t.getKind()) {

            case DECLARED:

            case INTERSECTION:

            case ERROR:

            case TYPEVAR:

                Type type = cast(Type.class, t);

                return type.asElement();

            default:

                return null;

        }

    }

    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 types.containsType((Type) t1, (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);

        return types.directSupertypes((Type) t);

    }

    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 (PrimitiveType)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,

                                  Type.noAnnotations);

    }

    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,

                                         Type.noAnnotations);

        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<>();

            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,

                                                     Type.noAnnotations);

        }

    /**

     * 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);

    }

    public Set<MethodSymbol> getOverriddenMethods(Element elem) {

        if (elem.getKind() != ElementKind.METHOD

                || elem.getModifiers().contains(Modifier.STATIC)

                || elem.getModifiers().contains(Modifier.PRIVATE))

            return Collections.emptySet();

        if (!(elem instanceof MethodSymbol))

            throw new IllegalArgumentException();

        MethodSymbol m = (MethodSymbol) elem;

        ClassSymbol origin = (ClassSymbol) m.owner;

        Set<MethodSymbol> results = new LinkedHashSet<>();

        for (Type t : types.closure(origin.type)) {

            if (t != origin.type) {

                ClassSymbol c = (ClassSymbol) t.tsym;

                for (Symbol sym : c.members().getSymbolsByName(m.name)) {

                    if (sym.kind == Kinds.MTH && m.overrides(sym, origin, types, true)) {

                        results.add((MethodSymbol) sym);

                    }

                }

            }

        }

        return results;

    }

}