/*
 * Copyright (c) 2011, 2015, 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.sjavac.comp;

import static javax.lang.model.element.Modifier.PRIVATE;

import java.util.List;
import java.util.stream.Collectors;

import javax.lang.model.element.Element;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.TypeElement;
import javax.lang.model.element.TypeParameterElement;
import javax.lang.model.element.VariableElement;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.util.ElementScanner9;

import com.sun.tools.javac.code.Symbol.ClassSymbol;
import com.sun.tools.javac.util.DefinedBy;
import com.sun.tools.javac.util.DefinedBy.Api;
import com.sun.tools.sjavac.pubapi.PubApi;
import com.sun.tools.sjavac.pubapi.PubApiTypeParam;
import com.sun.tools.sjavac.pubapi.PubMethod;
import com.sun.tools.sjavac.pubapi.PubType;
import com.sun.tools.sjavac.pubapi.PubVar;
import com.sun.tools.sjavac.pubapi.TypeDesc;

/** Utility class that constructs a textual representation
 * of the public api of a class.
 *
 *  <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 PubapiVisitor extends ElementScanner9<Void, Void> {

    private PubApi collectedApi = new PubApi();

    private boolean isNonPrivate(Element e) {
        return !e.getModifiers().contains(PRIVATE);
    }

    @Override @DefinedBy(Api.LANGUAGE_MODEL)
    public Void visitType(TypeElement e, Void p) {
        if (isNonPrivate(e)) {
            PubApi prevApi = collectedApi;
            collectedApi = new PubApi();
            super.visitType(e, p);
            if (!isAnonymous(e)) {
                String name = ((ClassSymbol) e).flatname.toString();
                PubType t = new PubType(e.getModifiers(),
                                        name,
                                        //e.getQualifiedName().toString(),
                                        collectedApi);
                prevApi.types.put(t.fqName, t);
            }
            collectedApi = prevApi;
        }
        return null;
    }

    private boolean isAnonymous(TypeElement e) {
        return e.getQualifiedName().length() == 0;
    }

    private static String encodeChar(int c) {
        return String.format("\\u%04x", c);
    }

    @Override @DefinedBy(Api.LANGUAGE_MODEL)
    public Void visitVariable(VariableElement e, Void p) {
        if (isNonPrivate(e)) {
            Object constVal = e.getConstantValue();
            String constValStr = null;
            // TODO: This doesn't seem to be entirely accurate. What if I change
            // from, say, 0 to 0L? (And the field is public final static so that
            // it could get inlined.)
            if (constVal != null) {
                if (e.asType().toString().equals("char")) {
                    // What type is 'value'? Is it already a char?
                    char c = constVal.toString().charAt(0);
                    constValStr = "'" + encodeChar(c) + "'";
                } else {
                    constValStr = constVal.toString()
                                          .chars()
                                          .mapToObj(PubapiVisitor::encodeChar)
                                          .collect(Collectors.joining("", "\"", "\""));
                }
            }

            PubVar v = new PubVar(e.getModifiers(),
                                  TypeDesc.fromType(e.asType()),
                                  e.toString(),
                                  constValStr);
            collectedApi.variables.put(v.identifier, v);
        }

        // Safe to not recurse here, because the only thing
        // to visit here is the constructor of a variable declaration.
        // If it happens to contain an anonymous inner class (which it might)
        // then this class is never visible outside of the package anyway, so
        // we are allowed to ignore it here.
        return null;
    }

    @Override @DefinedBy(Api.LANGUAGE_MODEL)
    public Void visitExecutable(ExecutableElement e, Void p) {
        if (isNonPrivate(e)) {
            PubMethod m = new PubMethod(e.getModifiers(),
                                        getTypeParameters(e.getTypeParameters()),
                                        TypeDesc.fromType(e.getReturnType()),
                                        e.getSimpleName().toString(),
                                        getTypeDescs(getParamTypes(e)),
                                        getTypeDescs(e.getThrownTypes()));
            collectedApi.methods.put(m.asSignatureString(), m);
        }
        return null;
    }

    private List<PubApiTypeParam> getTypeParameters(List<? extends TypeParameterElement> elements) {
        return elements.stream()
                       .map(e -> new PubApiTypeParam(e.getSimpleName().toString(), getTypeDescs(e.getBounds())))
                       .collect(Collectors.toList());
    }

    private List<TypeMirror> getParamTypes(ExecutableElement e) {
        return e.getParameters()
                .stream()
                .map(VariableElement::asType)
                .collect(Collectors.toList());
    }

    private List<TypeDesc> getTypeDescs(List<? extends TypeMirror> list) {
        return list.stream()
                   .map(TypeDesc::fromType)
                   .collect(Collectors.toList());
    }

    public PubApi getCollectedPubApi() {
        return collectedApi;
    }
}
