/*

 * Copyright (c) 2005, 2013, 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.lang.annotation.Annotation;

import java.lang.annotation.Inherited;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

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.Symbol.*;

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

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.Name;

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 JavaCompiler javaCompiler;

    private Symtab syms;

    private Names names;

    private Types types;

    private Enter enter;

    public static JavacElements instance(Context context) {

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

        if (instance == null)

            instance = new JavacElements(context);

        return instance;

    }

    /**

     * Public for use only by JavacProcessingEnvironment

     */

    protected JavacElements(Context context) {

        setContext(context);

    }

    /**

     * Use a new context.  May be called from outside to update

     * internal state for a new annotation-processing round.

     */

    public void setContext(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);

    }

    /**

     * An internal-use utility that creates a runtime view of an

     * annotation. This is the implementation of

     * Element.getAnnotation(Class).

     */

    public static <A extends Annotation> A getAnnotation(Symbol annotated,

                                                         Class<A> annoType) {

        if (!annoType.isAnnotation())

            throw new IllegalArgumentException("Not an annotation type: "

                                               + annoType);

        Attribute.Compound c;

        if (annotated.kind == Kinds.TYP && annotated instanceof ClassSymbol) {

            c = getAttributeOnClass((ClassSymbol)annotated, annoType);

        } else {

            c = getAttribute(annotated, annoType);

        }

        return c == null ? null : AnnotationProxyMaker.generateAnnotation(c, annoType);

    }

    // Helper to getAnnotation[s]

    private static <A extends Annotation> Attribute.Compound getAttribute(Symbol annotated,

                                                                          Class<A> annoType) {

        String name = annoType.getName();

        for (Attribute.Compound anno : annotated.getRawAttributes())

            if (name.equals(anno.type.tsym.flatName().toString()))

                return anno;

        return null;

    }

    // Helper to getAnnotation[s]

    private static <A extends Annotation> Attribute.Compound getAttributeOnClass(ClassSymbol annotated,

                                                                Class<A> annoType) {

        boolean inherited = annoType.isAnnotationPresent(Inherited.class);

        Attribute.Compound result = null;

        while (annotated.name != annotated.name.table.names.java_lang_Object) {

            result = getAttribute(annotated, annoType);

            if (result != null || !inherited)

                break;

            Type sup = annotated.getSuperclass();

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

                break;

            annotated = (ClassSymbol) sup.tsym;

        }

        return result;

    }

    /**

     * An internal-use utility that creates a runtime view of

     * annotations. This is the implementation of

     * Element.getAnnotations(Class).

     */

    public static <A extends Annotation> A[] getAnnotations(Symbol annotated,

                                                            Class<A> annoType) {

        if (!annoType.isAnnotation())

            throw new IllegalArgumentException("Not an annotation type: "

                                               + annoType);

        // If annoType does not declare a container this is equivalent to wrapping

        // getAnnotation(...) in an array.

        Class <? extends Annotation> containerType = getContainer(annoType);

        if (containerType == null) {

            A res = getAnnotation(annotated, annoType);

            int size;

            if (res == null) {

                size = 0;

            } else {

                size = 1;

            }

            @SuppressWarnings("unchecked") // annoType is the Class for A

            A[] arr = (A[])java.lang.reflect.Array.newInstance(annoType, size);

            if (res != null)

                arr[0] = res;

            return arr;

        }

        // So we have a containing type

        String name = annoType.getName();

        String annoTypeName = annoType.getSimpleName();

        String containerTypeName = containerType.getSimpleName();

        int directIndex = -1, containerIndex = -1;

        Attribute.Compound direct = null, container = null;

        Attribute.Compound[] rawAttributes = annotated.getRawAttributes().toArray(new Attribute.Compound[0]);

        // Find directly present annotations

        for (int i = 0; i < rawAttributes.length; i++) {

            if (annoTypeName.equals(rawAttributes[i].type.tsym.flatName().toString())) {

                directIndex = i;

                direct = rawAttributes[i];

            } else if(containerTypeName != null &&

                      containerTypeName.equals(rawAttributes[i].type.tsym.flatName().toString())) {

                containerIndex = i;

                container = rawAttributes[i];

            }

        }

        // Deal with inherited annotations

        if (annotated.kind == Kinds.TYP &&

                (annotated instanceof ClassSymbol)) {

            ClassSymbol s = (ClassSymbol)annotated;

            if (direct == null && container == null) {

                direct = getAttributeOnClass(s, annoType);

                container = getAttributeOnClass(s, containerType);

                // both are inherited and found, put container last

                if (direct != null && container != null) {

                    directIndex = 0;

                    containerIndex = 1;

                } else if (direct != null) {

                    directIndex = 0;

                } else {

                    containerIndex = 0;

                }

            } else if (direct == null) {

                direct = getAttributeOnClass(s, annoType);

                if (direct != null)

                    directIndex = containerIndex + 1;

            } else if (container == null) {

                container = getAttributeOnClass(s, containerType);

                if (container != null)

                    containerIndex = directIndex + 1;

            }

        }

        // Pack them in an array

        Attribute[] contained0 = new Attribute[0];

        if (container != null)

            contained0 = unpackAttributes(container);

        ListBuffer<Attribute.Compound> compounds = ListBuffer.lb();

        for (Attribute a : contained0)

            if (a instanceof Attribute.Compound)

                compounds = compounds.append((Attribute.Compound)a);

        Attribute.Compound[] contained = compounds.toArray(new Attribute.Compound[0]);

        int size = (direct == null ? 0 : 1) + contained.length;

        @SuppressWarnings("unchecked") // annoType is the Class for A

        A[] arr = (A[])java.lang.reflect.Array.newInstance(annoType, size);

        // if direct && container, which is first?

        int insert = -1;

        int length = arr.length;

        if (directIndex >= 0 && containerIndex >= 0) {

            if (directIndex < containerIndex) {

                arr[0] = AnnotationProxyMaker.generateAnnotation(direct, annoType);

                insert = 1;

            } else {

                arr[arr.length - 1] = AnnotationProxyMaker.generateAnnotation(direct, annoType);

                insert = 0;

                length--;

            }

        } else if (directIndex >= 0) {

            arr[0] = AnnotationProxyMaker.generateAnnotation(direct, annoType);

            return arr;

        } else {

            // Only container

            insert = 0;

        }

        for (int i = 0; i + insert < length; i++)

            arr[insert + i] = AnnotationProxyMaker.generateAnnotation(contained[i], annoType);

        return arr;

    }

    // Needed to unpack the runtime view of containing annotations

    private static final Method VALUE_ELEMENT_METHOD = initValueElementMethod();

        try {

            return c;

        } catch (ClassNotFoundException e) {

            return null;

        } catch (SecurityException e) {

            return null;

        }

    }

    private static Method initValueElementMethod() {

            return null;

        Method m = null;

        try {

            if (m != null)

                m.setAccessible(true);

            return m;

        } catch (NoSuchMethodException e) {

            return null;

        }

    }

    // Helper to getAnnotations

    private static Class<? extends Annotation> getContainer(Class<? extends Annotation> annoType) {

        // reflective invocations instead of just using its type and element method.

            VALUE_ELEMENT_METHOD != null) {

                try {

                    // Get the value element, it should be a class

                    // indicating the containing annotation type

                    @SuppressWarnings("unchecked")

                    if (containerType == null)

                        return null;

                    return containerType;

                } catch (ClassCastException e) {

                    return null;

                } catch (IllegalAccessException e) {

                    return null;

                } catch (InvocationTargetException e ) {

                    return null;

                }

            }

        }

        return null;

    }

    // Helper to getAnnotations

    private static Attribute[] unpackAttributes(Attribute.Compound container) {

        // We now have an instance of the container,

        // unpack it returning an instance of the

        // contained type or null

        return ((Attribute.Array)container.member(container.type.tsym.name.table.names.value)).values;

    }

    public PackageSymbol getPackageElement(CharSequence name) {

        String strName = name.toString();

        if (strName.equals(""))

            return syms.unnamedPackage;

        return SourceVersion.isName(strName)

            ? nameToSymbol(strName, PackageSymbol.class)

            : null;

    }

    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();

            return (sym.kind != Kinds.ERR &&

                    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 visitTopLevel(JCCompilationUnit tree) {

                result = tree.packageAnnotations;

            }

            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;

            }

        }

        Vis vis = new Vis();

        tree.accept(vis);

        if (vis.result == null)

            return null;

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

        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();