/*

 * Copyright (c) 2003, 2019, 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.EnumSet;

import java.util.Set;

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

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

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

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

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

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

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

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

import com.sun.tools.javac.resources.CompilerProperties.Errors;

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

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

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

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

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

/** Resolves field, method and constructor header, and constructs corresponding Symbols.

 *

 *  <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 {

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

    private final Enter enter;

    private final Log log;

    private final Check chk;

    private final Attr attr;

    private final Symtab syms;

    private final Annotate annotate;

    private final Types types;

    private final DeferredLintHandler deferredLintHandler;

    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);

        enter = Enter.instance(context);

        log = Log.instance(context);

        chk = Check.instance(context);

        attr = Attr.instance(context);

        syms = Symtab.instance(context);

        annotate = Annotate.instance(context);

        types = Types.instance(context);

        deferredLintHandler = DeferredLintHandler.instance(context);

    }

    /** 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, true);

        // 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

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

    /** 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);

    }

    public void visitMethodDef(JCMethodDecl tree) {

        WriteableScope enclScope = enter.enterScope(env);

        MethodSymbol m = new MethodSymbol(0, tree.name, null, enclScope.owner);

        m.flags_field = chk.checkFlags(tree.pos(), tree.mods.flags, m, tree);

        tree.sym = m;

        //if this is a default method, add the DEFAULT flag to the enclosing interface

        if ((tree.mods.flags & DEFAULT) != 0) {

            m.owner.flags_field |= DEFAULT;

        }

        Env<AttrContext> localEnv = methodEnv(tree, env);

        DiagnosticPosition prevLintPos = deferredLintHandler.setPos(tree.pos());

        try {

            // Compute the method type

            m.type = signature(m, tree.typarams, tree.params,

                               tree.restype, tree.recvparam,

                               tree.thrown,

                               localEnv);

        } finally {

            deferredLintHandler.setPos(prevLintPos);

        }

        if (types.isSignaturePolymorphic(m)) {

            m.flags_field |= SIGNATURE_POLYMORPHIC;

        }

        // Set m.params

        ListBuffer<VarSymbol> params = new ListBuffer<>();

        JCVariableDecl lastParam = null;

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

            JCVariableDecl param = lastParam = l.head;

            params.append(Assert.checkNonNull(param.sym));

        }

        m.params = params.toList();

        // mark the method varargs, if necessary

        if (lastParam != null && (lastParam.mods.flags & Flags.VARARGS) != 0)

            m.flags_field |= Flags.VARARGS;

        localEnv.info.scope.leave();

        if (chk.checkUnique(tree.pos(), m, enclScope)) {

        enclScope.enter(m);

        }

        annotate.annotateLater(tree.mods.annotations, localEnv, m, tree.pos());

        // Visit the signature of the method. Note that

        // TypeAnnotate doesn't descend into the body.

        annotate.queueScanTreeAndTypeAnnotate(tree, localEnv, m, tree.pos());

        if (tree.defaultValue != null) {

            m.defaultValue = annotate.unfinishedDefaultValue(); // set it to temporary sentinel for now

            annotate.annotateDefaultValueLater(tree.defaultValue, localEnv, m, tree.pos());

        }

    }

    /** Create a fresh environment for method bodies.

     *  @param tree     The method definition.

     *  @param env      The environment current outside of the method definition.

     */

    Env<AttrContext> methodEnv(JCMethodDecl tree, Env<AttrContext> env) {

        Env<AttrContext> localEnv =

            env.dup(tree, env.info.dup(env.info.scope.dupUnshared(tree.sym)));

        localEnv.enclMethod = tree;

        if (tree.sym.type != null) {

            //when this is called in the enter stage, there's no type to be set

            localEnv.info.returnResult = attr.new ResultInfo(KindSelector.VAL,

                                                             tree.sym.type.getReturnType());

        }

        if ((tree.mods.flags & STATIC) != 0) localEnv.info.staticLevel++;

        localEnv.info.yieldResult = null;

        return localEnv;

    }

    public void visitVarDef(JCVariableDecl tree) {

        Env<AttrContext> localEnv = env;

        if ((tree.mods.flags & STATIC) != 0 ||

            (env.info.scope.owner.flags() & INTERFACE) != 0) {

            localEnv = env.dup(tree, env.info.dup());

            localEnv.info.staticLevel++;

        }

        DiagnosticPosition prevLintPos = deferredLintHandler.setPos(tree.pos());

        try {

            if (TreeInfo.isEnumInit(tree)) {

                attr.attribIdentAsEnumType(localEnv, (JCIdent)tree.vartype);

            } else if (!tree.isImplicitlyTyped()) {

                attr.attribType(tree.vartype, localEnv);

                if (TreeInfo.isReceiverParam(tree))

                    checkReceiver(tree, localEnv);

            }

        } finally {

            deferredLintHandler.setPos(prevLintPos);

        }

        if ((tree.mods.flags & VARARGS) != 0) {

            //if we are entering a varargs parameter, we need to

            //replace its type (a plain array type) with the more

            //precise VarargsType --- we need to do it this way

            //because varargs is represented in the tree as a

            //modifier on the parameter declaration, and not as a

            //distinct type of array node.

            ArrayType atype = (ArrayType)tree.vartype.type;

            tree.vartype.type = atype.makeVarargs();

        }

        WriteableScope enclScope = enter.enterScope(env);

        Type vartype = tree.isImplicitlyTyped()

                ? env.info.scope.owner.kind == MTH ? Type.noType : syms.errType

                : tree.vartype.type;

        VarSymbol v = new VarSymbol(0, tree.name, vartype, enclScope.owner);

        v.flags_field = chk.checkFlags(tree.pos(), tree.mods.flags, v, tree);

        tree.sym = v;

        if (tree.init != null) {

            v.flags_field |= HASINIT;

            if ((v.flags_field & FINAL) != 0 &&

                needsLazyConstValue(tree.init)) {

                Env<AttrContext> initEnv = getInitEnv(tree, env);

                initEnv.info.enclVar = v;

                v.setLazyConstValue(initEnv(tree, initEnv), attr, tree);

            }

        }

        if (chk.checkUnique(tree.pos(), v, enclScope)) {

            chk.checkTransparentVar(tree.pos(), v, enclScope);

            enclScope.enter(v);

        } else if (v.owner.kind == MTH) {

            enclScope.enter(v);

        }

        annotate.annotateLater(tree.mods.annotations, localEnv, v, tree.pos());

        if (!tree.isImplicitlyTyped()) {

            annotate.queueScanTreeAndTypeAnnotate(tree.vartype, localEnv, v, tree.pos());

        }

        v.pos = tree.pos;

    }

    // where

    void checkType(JCTree tree, Type type, Error errorKey) {

        if (!tree.type.isErroneous() && !types.isSameType(tree.type, type)) {

            log.error(tree, errorKey);

        }

    }

    void checkReceiver(JCVariableDecl tree, Env<AttrContext> localEnv) {

        attr.attribExpr(tree.nameexpr, localEnv);

        MethodSymbol m = localEnv.enclMethod.sym;

        if (m.isConstructor()) {

            Type outertype = m.owner.owner.type;

            if (outertype.hasTag(TypeTag.METHOD)) {

                // we have a local inner class

                outertype = m.owner.owner.owner.type;

            }

            if (outertype.hasTag(TypeTag.CLASS)) {

                checkType(tree.vartype, outertype, Errors.IncorrectConstructorReceiverType(outertype, tree.vartype.type));

                checkType(tree.nameexpr, outertype, Errors.IncorrectConstructorReceiverName(outertype, tree.nameexpr.type));

            } else {

                log.error(tree, Errors.ReceiverParameterNotApplicableConstructorToplevelClass);

            }

        } else {

            checkType(tree.vartype, m.owner.type, Errors.IncorrectReceiverType(m.owner.type, tree.vartype.type));

            checkType(tree.nameexpr, m.owner.type, Errors.IncorrectReceiverName(m.owner.type, tree.nameexpr.type));

        }

    }

    public boolean needsLazyConstValue(JCTree tree) {

        InitTreeVisitor initTreeVisitor = new InitTreeVisitor();

        tree.accept(initTreeVisitor);

        return initTreeVisitor.result;

    }

    /** Visitor class for expressions which might be constant expressions,

     *  as per JLS 15.28 (Constant Expressions).

     */

    static class InitTreeVisitor extends JCTree.Visitor {

        private static final Set<Tag> ALLOWED_OPERATORS =

                EnumSet.of(Tag.POS, Tag.NEG, Tag.NOT, Tag.COMPL, Tag.PLUS, Tag.MINUS,

                           Tag.MUL, Tag.DIV, Tag.MOD, Tag.SL, Tag.SR, Tag.USR,

                           Tag.LT, Tag.LE, Tag.GT, Tag.GE, Tag.EQ, Tag.NE,

                           Tag.BITAND, Tag.BITXOR, Tag.BITOR, Tag.AND, Tag.OR);

        boolean result = true;

        @Override

        public void visitTree(JCTree tree) {

            result = false;

        }

        @Override

        public void visitLiteral(JCLiteral that) {}

        @Override

        public void visitTypeCast(JCTypeCast tree) {

            tree.expr.accept(this);

        }

        @Override

        public void visitUnary(JCUnary that) {

            if (!ALLOWED_OPERATORS.contains(that.getTag())) {

                result = false;

                return ;

            }

            that.arg.accept(this);

        }

        @Override

        public void visitBinary(JCBinary that) {

            if (!ALLOWED_OPERATORS.contains(that.getTag())) {

                result = false;

                return ;

            }

            that.lhs.accept(this);

            that.rhs.accept(this);

        }

        @Override

        public void visitConditional(JCConditional tree) {

            tree.cond.accept(this);

            tree.truepart.accept(this);

            tree.falsepart.accept(this);

        }

        @Override

        public void visitParens(JCParens tree) {

            tree.expr.accept(this);

        }

        @Override

        public void visitIdent(JCIdent that) {}

        @Override

        public void visitSelect(JCFieldAccess tree) {

            tree.selected.accept(this);

        }

    }

    /** Create a fresh environment for a variable's initializer.

     *  If the variable is a field, the owner of the environment's scope

     *  is be the variable itself, otherwise the owner is the method

     *  enclosing the variable definition.

     *

     *  @param tree     The variable definition.

     *  @param env      The environment current outside of the variable definition.

     */

    Env<AttrContext> initEnv(JCVariableDecl tree, Env<AttrContext> env) {

        Env<AttrContext> localEnv = env.dupto(new AttrContextEnv(tree, env.info.dup()));

        if (tree.sym.owner.kind == TYP) {

            localEnv.info.scope = env.info.scope.dupUnshared(tree.sym);

        }

        if ((tree.mods.flags & STATIC) != 0 ||

                ((env.enclClass.sym.flags() & INTERFACE) != 0 && env.enclMethod == null))

            localEnv.info.staticLevel++;

        return localEnv;

    }

    /** Default member enter visitor method: do nothing

     */

    public void visitTree(JCTree tree) {

    }

    public void visitErroneous(JCErroneous tree) {

        if (tree.errs != null)

            memberEnter(tree.errs, env);

    }

    public Env<AttrContext> getMethodEnv(JCMethodDecl tree, Env<AttrContext> env) {

        Env<AttrContext> mEnv = methodEnv(tree, env);

        mEnv.info.lint = mEnv.info.lint.augment(tree.sym);

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

            mEnv.info.scope.enterIfAbsent(l.head.type.tsym);

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

            mEnv.info.scope.enterIfAbsent(l.head.sym);

        return mEnv;

    }

    public Env<AttrContext> getInitEnv(JCVariableDecl tree, Env<AttrContext> env) {

        Env<AttrContext> iEnv = initEnv(tree, env);

        return iEnv;

    }

}