/*

 * 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.util.DefinedBy.Api;

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

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

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.Dependencies.AttributionKind;

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 TypeAnnotations typeAnnotations;

    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;

    private final Dependencies dependencies;

    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);

        typeAnnotations = TypeAnnotations.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);

        dependencies = Dependencies.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;

    /* ---------- 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 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.

     */

    Type signature(MethodSymbol msym,

                   List<JCTypeParameter> typarams,

                   List<JCVariableDecl> params,

                   JCTree res,

                   JCVariableDecl recvparam,

                   List<JCExpression> thrown,

                   Env<AttrContext> env) {

        // Enter and attribute type parameters.

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

        attr.attribTypeVariables(typarams, env);

        // Enter and attribute value parameters.

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

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

            memberEnter(l.head, env);

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

        }

        // Attribute result type, if one is given.

        Type restype = res == null ? syms.voidType : attr.attribType(res, env);

        // Attribute receiver type, if one is given.

        Type recvtype;

        if (recvparam!=null) {

            memberEnter(recvparam, env);

            recvtype = recvparam.vartype.type;

        } else {

            recvtype = null;

        }

        // Attribute thrown exceptions.

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

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

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

            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) {

        Env<AttrContext> prevEnv = this.env;

        try {

            this.env = env;

            tree.accept(this);

        }  catch (CompletionFailure ex) {

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

        } finally {

            this.env = prevEnv;

        }

    }

    /** Enter members from a list of trees.

     */

    void memberEnter(List<? extends JCTree> trees, Env<AttrContext> env) {

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

            memberEnter(l.head, env);

    }

    /** Enter members for a class.

     */

    void finishClass(JCClassDecl tree, 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);

    }

    /** Add the implicit members for an enum type

     *  to the symbol table.

     */

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

        // 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);

        // public static T valueOf(String name) { return ???; }

        JCMethodDecl valueOf = make.

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

                      names.valueOf,

                      make.Type(tree.sym.type),

                      List.<JCTypeParameter>nil(),

                      List.of(make.VarDef(make.Modifiers(Flags.PARAMETER |

                                                         Flags.MANDATED),

                                            names.fromString("name"),

                                            make.Type(syms.stringType), null)),

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

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

                      null);

        memberEnter(valueOf, env);

    }

    public void visitTopLevel(JCCompilationUnit tree) {

        if (!tree.starImportScope.isEmpty()) {

            // we must have already processed this toplevel

            return;

        }

        DiagnosticPosition prevLintPos = deferredLintHandler.immediate();

        Lint prevLint = chk.setLint(lint);

        try {

            // Import-on-demand java.lang.

            importAll(tree.pos, syms.enterPackage(names.java_lang), env);

            // Process the package def and all import clauses.

            memberEnter(tree.defs, env);

        } finally {

            chk.setLint(prevLint);

            deferredLintHandler.setPos(prevLintPos);

        }

    }

    public void visitPackageDef(JCPackageDecl tree) {

        // check that no class exists with same fully qualified name as

        // toplevel package

        if (checkClash && tree.pid != null) {

            Symbol p = env.toplevel.packge;

            while (p.owner != syms.rootPackage) {

                p.owner.complete(); // enter all class members of p

                if (syms.classes.get(p.getQualifiedName()) != null) {

                    log.error(tree.pos,

                              "pkg.clashes.with.class.of.same.name",

                              p);

                }

                p = p.owner;

            }

        }

        // process package annotations

        annotate.annotateLater(tree.annotations, env, env.toplevel.packge, null);

    }

    // process the non-static imports and the static imports of types.

    public void visitImport(JCImport tree) {

        dependencies.push(AttributionKind.IMPORT, tree);

        JCFieldAccess imp = (JCFieldAccess)tree.qualid;

        Name name = TreeInfo.name(imp);

        // Create a local environment pointing to this tree to disable

        // effects of other imports in Resolve.findGlobalType

        Env<AttrContext> localEnv = env.dup(tree);

        TypeSymbol p = attr.attribImportQualifier(tree, localEnv).tsym;

        if (name == names.asterisk) {

            // Import on demand.

            chk.checkCanonical(imp.selected);

            if (tree.staticImport)

                importStaticAll(tree.pos, p, env);

            else

                importAll(tree.pos, p, env);

        } else {

            // Named type import.

            if (tree.staticImport) {

                importNamedStatic(tree.pos(), p, name, localEnv);

                chk.checkCanonical(imp.selected);

            } else {

                TypeSymbol c = attribImportType(imp, localEnv).tsym;

                chk.checkCanonical(imp);

                importNamed(tree.pos(), c, env);

            }

        }

        dependencies.pop();