/*

 * Copyright (c) 2003, 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.comp;

import java.util.Collections;

import java.util.HashSet;

import java.util.IdentityHashMap;

import java.util.Set;

import javax.tools.JavaFileObject;

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

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

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

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

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

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

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

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

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

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

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

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

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

import static com.sun.tools.javac.code.Flags.ANNOTATION;

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

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.code.TypeTag.ERROR;

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

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

import com.sun.tools.javac.util.JCDiagnostic.DiagnosticFlag;

import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;

/** This is the second phase of Enter, in which classes are completed

 *  by entering their members into the class scope using

 *  MemberEnter.complete().  See Enter for an overview.

 *

 *  <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>

 */

public class MemberEnter extends JCTree.Visitor implements Completer {

    protected static final Context.Key<MemberEnter> memberEnterKey = new Context.Key<>();

    /** A switch to determine whether we check for package/class conflicts

     */

    final static boolean checkClash = true;

    private final Names names;

    private final Enter enter;

    private final Log log;

    private final Check chk;

    private final Attr attr;

    private final Symtab syms;

    private final TreeMaker make;

    private final Todo todo;

    private final Annotate annotate;

    private final Types types;

    private final JCDiagnostic.Factory diags;

    private final Source source;

    private final Target target;

    private final DeferredLintHandler deferredLintHandler;

    private final Lint lint;

    private final TypeEnvs typeEnvs;

    public static MemberEnter instance(Context context) {

        MemberEnter instance = context.get(memberEnterKey);

        if (instance == null)

            instance = new MemberEnter(context);

        return instance;

    }

    protected MemberEnter(Context context) {

        context.put(memberEnterKey, this);

        names = Names.instance(context);

        enter = Enter.instance(context);

        log = Log.instance(context);

        chk = Check.instance(context);

        attr = Attr.instance(context);

        syms = Symtab.instance(context);

        make = TreeMaker.instance(context);

        todo = Todo.instance(context);

        annotate = Annotate.instance(context);

        types = Types.instance(context);

        diags = JCDiagnostic.Factory.instance(context);

        source = Source.instance(context);

        target = Target.instance(context);

        deferredLintHandler = DeferredLintHandler.instance(context);

        lint = Lint.instance(context);

        typeEnvs = TypeEnvs.instance(context);

        allowTypeAnnos = source.allowTypeAnnotations();

    }

    /** Switch: support type annotations.

     */

    boolean allowTypeAnnos;

    /** A queue for classes whose members still need to be entered into the

     *  symbol table.

     */

    ListBuffer<Env<AttrContext>> halfcompleted = new ListBuffer<>();

    /** Set to true only when the first of a set of classes is

     *  processed from the half completed queue.

     */

    boolean isFirst = true;

    /** A flag to disable completion from time to time during member

     *  enter, as we only need to look up types.  This avoids

     *  unnecessarily deep recursion.

     */

    boolean completionEnabled = true;

    /** The creator that will be used for any varDef's we visit.  This

     * is used to create the position for any type annotations (or

     * annotations that potentially are type annotations) that we

     * encounter.

     */

    Annotate.PositionCreator creator;

    /* ---------- Processing import clauses ----------------

     */

    /** Import all classes of a class or package on demand.

     *  @param pos           Position to be used for error reporting.

     *  @param tsym          The class or package the members of which are imported.

     *  @param env           The env in which the imported classes will be entered.

     */

    private void importAll(int pos,

                           final TypeSymbol tsym,

                           Env<AttrContext> env) {

        // Check that packages imported from exist (JLS ???).

        if (tsym.kind == PCK && tsym.members().isEmpty() && !tsym.exists()) {

            // If we can't find java.lang, exit immediately.

            if (((PackageSymbol)tsym).fullname.equals(names.java_lang)) {

                JCDiagnostic msg = diags.fragment("fatal.err.no.java.lang");

                throw new FatalError(msg);

            } else {

                log.error(DiagnosticFlag.RESOLVE_ERROR, pos, "doesnt.exist", tsym);

            }

        }

        env.toplevel.starImportScope.importAll(tsym.members(), tsym.members(), typeImportFilter, false);

    }

    /** Import all static members of a class or package on demand.

     *  @param pos           Position to be used for error reporting.

     *  @param tsym          The class or package the members of which are imported.

     *  @param env           The env in which the imported classes will be entered.

     */

    private void importStaticAll(int pos,

                                 final TypeSymbol tsym,

                                 Env<AttrContext> env) {

        final StarImportScope toScope = env.toplevel.starImportScope;

        final PackageSymbol packge = env.toplevel.packge;

        final TypeSymbol origin = tsym;

        // enter imported types immediately

        new SymbolImporter() {

            void doImport(TypeSymbol tsym) {

                toScope.importAll(tsym.members(), origin.members(), staticImportFilter, true);

            }

        }.importFrom(tsym);

    }

    /** Import statics types of a given name.  Non-types are handled in Attr.

     *  @param pos           Position to be used for error reporting.

     *  @param tsym          The class from which the name is imported.

     *  @param name          The (simple) name being imported.

     *  @param env           The environment containing the named import

     *                  scope to add to.

     */

    private void importNamedStatic(final DiagnosticPosition pos,

                                   final TypeSymbol tsym,

                                   final Name name,

                                   final Env<AttrContext> env) {

        if (tsym.kind != TYP) {

            log.error(DiagnosticFlag.RECOVERABLE, pos, "static.imp.only.classes.and.interfaces");

            return;

        }

        final NamedImportScope toScope = env.toplevel.namedImportScope;

        final Scope originMembers = tsym.members();

        // enter imported types immediately

        new SymbolImporter() {

            void doImport(TypeSymbol tsym) {

                Set<Symbol> maskedOut = null;

                for (Symbol sym : tsym.members().getSymbolsByName(name)) {

                    if (sym.kind == TYP &&

                        staticImportFilter.accepts(originMembers, sym) &&

                        !chk.checkUniqueStaticImport(pos, env.toplevel, sym)) {

                        if (maskedOut == null)

                            maskedOut = Collections.newSetFromMap(new IdentityHashMap<Symbol, Boolean>());

                        maskedOut.add(sym);

                    }

                }

                ImportFilter importFilter = maskedOut != null ?

                        new MaskedImportFilter(staticImportFilter, maskedOut) :

                        staticImportFilter;

                toScope.importByName(tsym.members(), originMembers, name, importFilter);

            }

        }.importFrom(tsym);

    }

    //where:

        class MaskedImportFilter implements ImportFilter {

            private final ImportFilter delegate;

            private final Set<Symbol> maskedOut;

            public MaskedImportFilter(ImportFilter delegate, Set<Symbol> maskedOut) {

                this.delegate = delegate;

                this.maskedOut = maskedOut;

            }

            @Override

            public boolean accepts(Scope origin, Symbol sym) {

                return !maskedOut.contains(sym) && delegate.accepts(origin, sym);

            }

        }

        abstract class SymbolImporter {

            Set<Symbol> processed = new HashSet<>();

            void importFrom(TypeSymbol tsym) {

                if (tsym == null || !processed.add(tsym))

                    return;

                // also import inherited names

                importFrom(types.supertype(tsym.type).tsym);

                for (Type t : types.interfaces(tsym.type))

                    importFrom(t.tsym);

                doImport(tsym);

            }

            abstract void doImport(TypeSymbol tsym);

        }

    /** Import given class.

     *  @param pos           Position to be used for error reporting.

     *  @param tsym          The class to be imported.

     *  @param env           The environment containing the named import

     *                  scope to add to.

     */

    private void importNamed(DiagnosticPosition pos, final Symbol tsym, Env<AttrContext> env) {

        if (tsym.kind == TYP &&

            chk.checkUniqueImport(pos, env.toplevel, tsym))

            env.toplevel.namedImportScope.importType(tsym.owner.members(), tsym.owner.members(), tsym);

    }

    /** Construct method type from method signature.

     *  @param msym        The MethodSymbol for the method.

     *  @param typarams    The method's type parameters.

     *  @param params      The method's value parameters.

     *  @param res             The method's result type,

     *                 null if it is a constructor.

     *  @param recvparam       The method's receiver parameter,

     *                 null if none given; TODO: or already set here?

     *  @param thrown      The method's thrown exceptions.

     *  @param env             The method's (local) environment.

     *  @param declAnnos   The annotations on the method declaration,

     *                     some of which may be type annotations on

     *                     the return type.

     *  @param deferPos    The deferred diagnostic position for error

     *                     reporting.

     */

    Type signature(final MethodSymbol msym,

                   final List<JCTypeParameter> typarams,

                   final List<JCVariableDecl> params,

                   final JCTree res,

                   final JCVariableDecl recvparam,

                   final List<JCExpression> thrown,

                   final Env<AttrContext> env,

                   final List<JCAnnotation> declAnnos,

                   final DiagnosticPosition deferPos) {

        int i;

        // Enter and attribute type parameters.

        List<Type> tvars = enter.classEnter(typarams, env);

        attr.attribTypeVariables(typarams, env);

        // Handle type annotations on type parameters.

        i = 0;

        for (List<JCTypeParameter> l = typarams; l.nonEmpty();

             l = l.tail, i++) {

            final JCTypeParameter param = l.head;

            annotate.annotateTypeLater(param, env, msym, deferPos,

                                       annotate.methodTypeParamCreator(i));

            // ...and bounds on type parameters.

            int j = 0;

            for (List<JCExpression> bounds = param.bounds;

                 bounds.nonEmpty(); bounds = bounds.tail, j++) {

                annotate.annotateTypeLater(bounds.head, env, msym, deferPos,

                                           annotate.methodTypeParamBoundCreator(param, i, j));

            }

        }

        // Enter and attribute value parameters.  Type annotations get

        // METHOD_FORMAL_PARAMETER positions.

        ListBuffer<Type> argbuf = new ListBuffer<>();

        i = 0;

        for (List<JCVariableDecl> l = params; l.nonEmpty(); l = l.tail, i++) {

            // The types will get annotated by visitVarDef

            memberEnter(l.head, env, annotate.paramCreator(i));

            argbuf.append(l.head.vartype.type);

        }

        // Attribute result type, if one is given.

        Type restype;

        if (res != null) {

            // If we have any declaration annotations, they might

            // be/also be type annotations on the return type.  We

            // pass them in, so they get classified and then attached

            // to the method, or the return type, or both.

            restype = attr.attribType(res, env);

            annotate.annotateTypeLater(res, declAnnos, env, msym, deferPos,

                                       annotate.returnCreator);

        } else {

            // For constructors, we don't actually have a type, so we

            // can't have a type path (except for INNER_TYPE), and we

            // don't have annotations on arrays, type arguments, and

            // the like.

            // The only type path we have is if we are in an inner type.

            List<TypePathEntry> typepath = Annotate.makeInners(msym.owner.type);

            TypeAnnotationPosition tapos =

                TypeAnnotationPosition.methodReturn(typepath, env.getLambda(), -1);

            // We don't have to walk down a type.  We just have to do

            // repeating annotation handling, then classify and attach

            // the annotations.

            annotate.annotateWithClassifyLater(declAnnos, env, msym,

                                               deferPos, tapos);

            restype = syms.voidType;

        }

        // Attribute receiver type, if one is given.

        Type recvtype;

        if (recvparam!=null) {

            // The type will get annotated by visitVarDef

            memberEnter(recvparam, env, annotate.receiverCreator);

            recvtype = recvparam.vartype.type;

        } else {

            recvtype = null;

        }

        // Attribute thrown exceptions.

        ListBuffer<Type> thrownbuf = new ListBuffer<>();

        i = 0;

        for (List<JCExpression> l = thrown; l.nonEmpty(); l = l.tail, i++) {

            Type exc = attr.attribType(l.head, env);

            // Annotate each exception type.

            annotate.annotateTypeLater(l.head, env, msym, deferPos,

                                       annotate.throwCreator(i));

            if (!exc.hasTag(TYPEVAR)) {

                exc = chk.checkClassType(l.head.pos(), exc);

            } else if (exc.tsym.owner == msym) {

                //mark inference variables in 'throws' clause

                exc.tsym.flags_field |= THROWS;

            }

            thrownbuf.append(exc);

        }

        MethodType mtype = new MethodType(argbuf.toList(),

                                    restype,

                                    thrownbuf.toList(),

                                    syms.methodClass);

        mtype.recvtype = recvtype;

        return tvars.isEmpty() ? mtype : new ForAll(tvars, mtype);

    }

/* ********************************************************************

 * Visitor methods for member enter

 *********************************************************************/

    ImportFilter staticImportFilter;

    ImportFilter typeImportFilter = new ImportFilter() {

        @Override

        public boolean accepts(Scope origin, Symbol t) {

            return t.kind == Kinds.TYP;

        }

    };

    protected void memberEnter(JCCompilationUnit tree, Env<AttrContext> env) {

        ImportFilter prevStaticImportFilter = staticImportFilter;

        try {

            final PackageSymbol packge = env.toplevel.packge;

            this.staticImportFilter = new ImportFilter() {

                @Override

                public boolean accepts(Scope origin, Symbol sym) {

                    return sym.isStatic() &&

                           chk.staticImportAccessible(sym, packge) &&

                           sym.isMemberOf((TypeSymbol) origin.owner, types);

                }

            };

            memberEnter((JCTree) tree, env);

        } finally {

            this.staticImportFilter = prevStaticImportFilter;

        }

    }

    /** Visitor argument: the current environment

     */

    protected Env<AttrContext> env;

    /** Enter field and method definitions and process import

     *  clauses, catching any completion failure exceptions.

     */

    protected void memberEnter(JCTree tree, Env<AttrContext> env,

                               Annotate.PositionCreator creator) {

        Env<AttrContext> prevEnv = this.env;

        Annotate.PositionCreator prevCreator = this.creator;

        try {

            this.env = env;

            this.creator = creator;

            tree.accept(this);

        }  catch (CompletionFailure ex) {

            chk.completionError(tree.pos(), ex);

        } finally {

            this.creator = prevCreator;

            this.env = prevEnv;

        }

    }

    protected void memberEnter(JCTree tree, Env<AttrContext> env) {

        memberEnter(tree, env, annotate.noCreator);

    }

    /** Enter members from a list of trees.

     */

    void memberEnter(List<? extends JCTree> trees,

                     Env<AttrContext> env,

                     Annotate.PositionCreator creator) {

        for (List<? extends JCTree> l = trees; l.nonEmpty(); l = l.tail)

            memberEnter(l.head, env, creator);

    }

    void memberEnter(List<? extends JCTree> trees,

                     Env<AttrContext> env) {

        memberEnter(trees, env, annotate.noCreator);

    }

    /** Enter members for a class.

     */

    void finishClass(final JCClassDecl tree, final Env<AttrContext> env) {

        if ((tree.mods.flags & Flags.ENUM) != 0 &&

            (types.supertype(tree.sym.type).tsym.flags() & Flags.ENUM) == 0) {

            addEnumMembers(tree, env);

        }

        memberEnter(tree.defs, env, annotate.fieldCreator);

    }

    /** Add the implicit members for an enum type

     *  to the symbol table.

     */

    private void addEnumMembers(JCClassDecl tree, Env<AttrContext> env) {

        JCExpression valuesType = make.Type(new ArrayType(tree.sym.type, syms.arrayClass,

                                                          Type.noAnnotations));

        // public static T[] values() { return ???; }

        JCMethodDecl values = make.

            MethodDef(make.Modifiers(Flags.PUBLIC|Flags.STATIC),

                      names.values,

                      valuesType,

                      List.<JCTypeParameter>nil(),

                      List.<JCVariableDecl>nil(),

                      List.<JCExpression>nil(), // thrown

                      null, //make.Block(0, Tree.emptyList.prepend(make.Return(make.Ident(names._null)))),

                      null);

        memberEnter(values, env);