/*

 * 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.Map;

import javax.lang.model.SourceVersion;

import javax.lang.model.element.*;

import javax.lang.model.type.DeclaredType;

import javax.lang.model.util.Elements;

import javax.tools.JavaFileObject;

import static javax.lang.model.util.ElementFilter.methodsIn;

import com.sun.tools.javac.code.*;

import com.sun.tools.javac.code.Scope.WriteableScope;

import com.sun.tools.javac.code.Symbol.*;

import com.sun.tools.javac.comp.AttrContext;

import com.sun.tools.javac.comp.Enter;

import com.sun.tools.javac.comp.Env;

import com.sun.tools.javac.main.JavaCompiler;

import com.sun.tools.javac.processing.PrintingProcessor;

import com.sun.tools.javac.tree.JCTree;

import com.sun.tools.javac.tree.JCTree.*;

import com.sun.tools.javac.tree.TreeInfo;

import com.sun.tools.javac.tree.TreeScanner;

import com.sun.tools.javac.util.*;

import com.sun.tools.javac.util.DefinedBy.Api;

import com.sun.tools.javac.util.Name;

import static com.sun.tools.javac.code.Scope.LookupKind.NON_RECURSIVE;

import static com.sun.tools.javac.code.TypeTag.CLASS;

import static com.sun.tools.javac.tree.JCTree.Tag.*;

/**

 * Utility methods for operating on program elements.

 *

 * <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 JavacElements implements Elements {

    private final JavaCompiler javaCompiler;

    private final Symtab syms;

    private final Names names;

    private final Types types;

    private final Enter enter;

    public static JavacElements instance(Context context) {

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

        if (instance == null)

            instance = new JavacElements(context);

        return instance;

    }

    protected JavacElements(Context context) {

        context.put(JavacElements.class, this);

        javaCompiler = JavaCompiler.instance(context);

        syms = Symtab.instance(context);

        names = Names.instance(context);

        types = Types.instance(context);

        enter = Enter.instance(context);

    }

    @DefinedBy(Api.LANGUAGE_MODEL)

    public PackageSymbol getPackageElement(CharSequence name) {

        String strName = name.toString();

        if (strName.equals(""))

            return syms.unnamedPackage;

        return SourceVersion.isName(strName)

            ? nameToSymbol(strName, PackageSymbol.class)

            : null;

    }

    @DefinedBy(Api.LANGUAGE_MODEL)

    public ClassSymbol getTypeElement(CharSequence name) {

        String strName = name.toString();

        return SourceVersion.isName(strName)

            ? nameToSymbol(strName, ClassSymbol.class)

            : null;

    }

    /**

     * Returns a symbol given the type's or packages's canonical name,

     * or null if the name isn't found.

     */

    private <S extends Symbol> S nameToSymbol(String nameStr, Class<S> clazz) {

        Name name = names.fromString(nameStr);

        // First check cache.

        Symbol sym = (clazz == ClassSymbol.class)

                    ? syms.classes.get(name)

                    : syms.packages.get(name);

        try {

            if (sym == null)

                sym = javaCompiler.resolveIdent(nameStr);

            sym.complete();

                    sym.exists() &&

                    clazz.isInstance(sym) &&

                    name.equals(sym.getQualifiedName()))

                ? clazz.cast(sym)

                : null;

        } catch (CompletionFailure e) {

            return null;

        }

    }

    public JavacSourcePosition getSourcePosition(Element e) {

        Pair<JCTree, JCCompilationUnit> treeTop = getTreeAndTopLevel(e);

        if (treeTop == null)

            return null;

        JCTree tree = treeTop.fst;

        JCCompilationUnit toplevel = treeTop.snd;

        JavaFileObject sourcefile = toplevel.sourcefile;

        if (sourcefile == null)

            return null;

        return new JavacSourcePosition(sourcefile, tree.pos, toplevel.lineMap);

    }

    public JavacSourcePosition getSourcePosition(Element e, AnnotationMirror a) {

        Pair<JCTree, JCCompilationUnit> treeTop = getTreeAndTopLevel(e);

        if (treeTop == null)

            return null;

        JCTree tree = treeTop.fst;

        JCCompilationUnit toplevel = treeTop.snd;

        JavaFileObject sourcefile = toplevel.sourcefile;

        if (sourcefile == null)

            return null;

        JCTree annoTree = matchAnnoToTree(a, e, tree);

        if (annoTree == null)

            return null;

        return new JavacSourcePosition(sourcefile, annoTree.pos,

                                       toplevel.lineMap);

    }

    public JavacSourcePosition getSourcePosition(Element e, AnnotationMirror a,

                                            AnnotationValue v) {

        // TODO: better accuracy in getSourcePosition(... AnnotationValue)

        return getSourcePosition(e, a);

    }

    /**

     * Returns the tree for an annotation given the annotated element

     * and the element's own tree.  Returns null if the tree cannot be found.

     */

    private JCTree matchAnnoToTree(AnnotationMirror findme,

                                   Element e, JCTree tree) {

        Symbol sym = cast(Symbol.class, e);

        class Vis extends JCTree.Visitor {

            List<JCAnnotation> result = null;

            public void visitPackageDef(JCPackageDecl tree) {

                result = tree.annotations;

            }

            public void visitClassDef(JCClassDecl tree) {

                result = tree.mods.annotations;

            }

            public void visitMethodDef(JCMethodDecl tree) {

                result = tree.mods.annotations;

            }

            public void visitVarDef(JCVariableDecl tree) {

                result = tree.mods.annotations;

            }

            @Override

            public void visitTypeParameter(JCTypeParameter tree) {

                result = tree.annotations;

            }

        }

        Vis vis = new Vis();

        tree.accept(vis);

        if (vis.result == null)

            return null;

        List<Attribute.Compound> annos = sym.getAnnotationMirrors();

        return matchAnnoToTree(cast(Attribute.Compound.class, findme),

                               annos,

                               vis.result);

    }

    /**

     * Returns the tree for an annotation given a list of annotations

     * in which to search (recursively) and their corresponding trees.

     * Returns null if the tree cannot be found.

     */

    private JCTree matchAnnoToTree(Attribute.Compound findme,

                                   List<Attribute.Compound> annos,

                                   List<JCAnnotation> trees) {

        for (Attribute.Compound anno : annos) {

            for (JCAnnotation tree : trees) {

                JCTree match = matchAnnoToTree(findme, anno, tree);

                if (match != null)

                    return match;

            }

        }

        return null;

    }

    /**

     * Returns the tree for an annotation given an Attribute to

     * search (recursively) and its corresponding tree.

     * Returns null if the tree cannot be found.

     */

    private JCTree matchAnnoToTree(final Attribute.Compound findme,

                                   final Attribute attr,

                                   final JCTree tree) {

        if (attr == findme)

            return (tree.type.tsym == findme.type.tsym) ? tree : null;

        class Vis implements Attribute.Visitor {

            JCTree result = null;

            public void visitConstant(Attribute.Constant value) {

            }

            public void visitClass(Attribute.Class clazz) {

            }

            public void visitCompound(Attribute.Compound anno) {

                for (Pair<MethodSymbol, Attribute> pair : anno.values) {

                    JCExpression expr = scanForAssign(pair.fst, tree);

                    if (expr != null) {

                        JCTree match = matchAnnoToTree(findme, pair.snd, expr);

                        if (match != null) {

                            result = match;

                            return;

                        }

                    }

                }

            }

            public void visitArray(Attribute.Array array) {

                if (tree.hasTag(NEWARRAY) &&

                        types.elemtype(array.type).tsym == findme.type.tsym) {

                    List<JCExpression> elems = ((JCNewArray) tree).elems;

                    for (Attribute value : array.values) {

                        if (value == findme) {

                            result = elems.head;

                            return;

                        }

                        elems = elems.tail;

                    }

                }

            }

            public void visitEnum(Attribute.Enum e) {

            }

            public void visitError(Attribute.Error e) {

            }

        }

        Vis vis = new Vis();

        attr.accept(vis);

        return vis.result;

    }

    /**

     * Scans for a JCAssign node with a LHS matching a given

     * symbol, and returns its RHS.  Does not scan nested JCAnnotations.

     */

    private JCExpression scanForAssign(final MethodSymbol sym,

                                       final JCTree tree) {

        class TS extends TreeScanner {

            JCExpression result = null;

            public void scan(JCTree t) {

                if (t != null && result == null)

                    t.accept(this);

            }

            public void visitAnnotation(JCAnnotation t) {

                if (t == tree)

                    scan(t.args);

            }

            public void visitAssign(JCAssign t) {

                if (t.lhs.hasTag(IDENT)) {

                    JCIdent ident = (JCIdent) t.lhs;

                    if (ident.sym == sym)

                        result = t.rhs;

                }

            }

        }

        TS scanner = new TS();

        tree.accept(scanner);

        return scanner.result;

    }

    /**

     * Returns the tree node corresponding to this element, or null

     * if none can be found.

     */

    public JCTree getTree(Element e) {

        Pair<JCTree, ?> treeTop = getTreeAndTopLevel(e);

        return (treeTop != null) ? treeTop.fst : null;

    }

    @DefinedBy(Api.LANGUAGE_MODEL)

    public String getDocComment(Element e) {

        // Our doc comment is contained in a map in our toplevel,

        // indexed by our tree.  Find our enter environment, which gives

        // us our toplevel.  It also gives us a tree that contains our

        // tree:  walk it to find our tree.  This is painful.

        Pair<JCTree, JCCompilationUnit> treeTop = getTreeAndTopLevel(e);

        if (treeTop == null)

            return null;

        JCTree tree = treeTop.fst;

        JCCompilationUnit toplevel = treeTop.snd;

        if (toplevel.docComments == null)

            return null;

        return toplevel.docComments.getCommentText(tree);

    }

    @DefinedBy(Api.LANGUAGE_MODEL)

    public PackageElement getPackageOf(Element e) {

        return cast(Symbol.class, e).packge();

    }

    @DefinedBy(Api.LANGUAGE_MODEL)

    public boolean isDeprecated(Element e) {

        Symbol sym = cast(Symbol.class, e);

        return (sym.flags() & Flags.DEPRECATED) != 0;

    }

    @DefinedBy(Api.LANGUAGE_MODEL)

    public Name getBinaryName(TypeElement type) {

        return cast(TypeSymbol.class, type).flatName();

    }

    @DefinedBy(Api.LANGUAGE_MODEL)

    public Map<MethodSymbol, Attribute> getElementValuesWithDefaults(

                                                        AnnotationMirror a) {

        Attribute.Compound anno = cast(Attribute.Compound.class, a);

        DeclaredType annotype = a.getAnnotationType();

        Map<MethodSymbol, Attribute> valmap = anno.getElementValues();

        for (ExecutableElement ex :

                 methodsIn(annotype.asElement().getEnclosedElements())) {

            MethodSymbol meth = (MethodSymbol) ex;

            Attribute defaultValue = meth.getDefaultValue();

            if (defaultValue != null && !valmap.containsKey(meth)) {

                valmap.put(meth, defaultValue);

            }

        }

        return valmap;

    }

    /**

     * {@inheritDoc}

     */

    @DefinedBy(Api.LANGUAGE_MODEL)

    public FilteredMemberList getAllMembers(TypeElement element) {

        Symbol sym = cast(Symbol.class, element);

        WriteableScope scope = sym.members().dupUnshared();

        List<Type> closure = types.closure(sym.asType());

        for (Type t : closure)

            addMembers(scope, t);

        return new FilteredMemberList(scope);

    }

    // where

        private void addMembers(WriteableScope scope, Type type) {

            members:

            for (Symbol e : type.asElement().members().getSymbols(NON_RECURSIVE)) {

                for (Symbol overrider : scope.getSymbolsByName(e.getSimpleName())) {

                    if (overrider.kind == e.kind && (overrider.flags() & Flags.SYNTHETIC) == 0) {

                        if (overrider.getKind() == ElementKind.METHOD &&

                                overrides((ExecutableElement)overrider, (ExecutableElement)e, (TypeElement)type.asElement())) {

                            continue members;

                        }

                    }

                }

                boolean derived = e.getEnclosingElement() != scope.owner;

                ElementKind kind = e.getKind();

                boolean initializer = kind == ElementKind.CONSTRUCTOR

                    || kind == ElementKind.INSTANCE_INIT

                    || kind == ElementKind.STATIC_INIT;

                if (!derived || (!initializer && e.isInheritedIn(scope.owner, types)))

                    scope.enter(e);

            }

        }

    /**

     * Returns all annotations of an element, whether

     * inherited or directly present.

     *

     * @param e  the element being examined

     * @return all annotations of the element

     */

    @Override @DefinedBy(Api.LANGUAGE_MODEL)

    public List<Attribute.Compound> getAllAnnotationMirrors(Element e) {

        Symbol sym = cast(Symbol.class, e);

        List<Attribute.Compound> annos = sym.getAnnotationMirrors();

        while (sym.getKind() == ElementKind.CLASS) {

            Type sup = ((ClassSymbol) sym).getSuperclass();

            if (!sup.hasTag(CLASS) || sup.isErroneous() ||

                    sup.tsym == syms.objectType.tsym) {

                break;

            }

            sym = sup.tsym;

            List<Attribute.Compound> oldAnnos = annos;

            List<Attribute.Compound> newAnnos = sym.getAnnotationMirrors();

            for (Attribute.Compound anno : newAnnos) {

                if (isInherited(anno.type) &&

                        !containsAnnoOfType(oldAnnos, anno.type)) {

                    annos = annos.prepend(anno);

                }

            }

        }

        return annos;

    }

    /**

     * Tests whether an annotation type is @Inherited.

     */

    private boolean isInherited(Type annotype) {

        return annotype.tsym.attribute(syms.inheritedType.tsym) != null;

    }

    /**

     * Tests whether a list of annotations contains an annotation

     * of a given type.

     */

    private static boolean containsAnnoOfType(List<Attribute.Compound> annos,

                                              Type type) {

        for (Attribute.Compound anno : annos) {

            if (anno.type.tsym == type.tsym)

                return true;

        }

        return false;

    }

    @DefinedBy(Api.LANGUAGE_MODEL)

    public boolean hides(Element hiderEl, Element hideeEl) {

        Symbol hider = cast(Symbol.class, hiderEl);

        Symbol hidee = cast(Symbol.class, hideeEl);

        // Fields only hide fields; methods only methods; types only types.

        // Names must match.  Nothing hides itself (just try it).

        if (hider == hidee ||

                hider.kind != hidee.kind ||

                hider.name != hidee.name) {

            return false;

        }

        // Only static methods can hide other methods.

        // Methods only hide methods with matching signatures.

            if (!hider.isStatic() ||

                        !types.isSubSignature(hider.type, hidee.type)) {

                return false;

            }

        }

        // Hider must be in a subclass of hidee's class.

        // Note that if M1 hides M2, and M2 hides M3, and M3 is accessible

        // in M1's class, then M1 and M2 both hide M3.

        ClassSymbol hiderClass = hider.owner.enclClass();

        ClassSymbol hideeClass = hidee.owner.enclClass();

        if (hiderClass == null || hideeClass == null ||

                !hiderClass.isSubClass(hideeClass, types)) {

            return false;

        }

        // Hidee must be accessible in hider's class.

        // The method isInheritedIn is poorly named:  it checks only access.

        return hidee.isInheritedIn(hiderClass, types);

    }

    @DefinedBy(Api.LANGUAGE_MODEL)

    public boolean overrides(ExecutableElement riderEl,

                             ExecutableElement rideeEl, TypeElement typeEl) {

        MethodSymbol rider = cast(MethodSymbol.class, riderEl);

        MethodSymbol ridee = cast(MethodSymbol.class, rideeEl);

        ClassSymbol origin = cast(ClassSymbol.class, typeEl);

        return rider.name == ridee.name &&

               // not reflexive as per JLS

               rider != ridee &&

               // we don't care if ridee is static, though that wouldn't

               // compile

               !rider.isStatic() &&

               // Symbol.overrides assumes the following

               ridee.isMemberOf(origin, types) &&

               // check access and signatures; don't check return types

               rider.overrides(ridee, origin, types, false);

    }

    @DefinedBy(Api.LANGUAGE_MODEL)

    public String getConstantExpression(Object value) {

        return Constants.format(value);

    }

    /**

     * Print a representation of the elements to the given writer in

     * the specified order.  The main purpose of this method is for

     * diagnostics.  The exact format of the output is <em>not</em>

     * specified and is subject to change.