/*

 * Copyright (c) 2014, 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 jdk.jshell;

import com.sun.source.tree.ClassTree;

import com.sun.source.tree.CompilationUnitTree;

import com.sun.source.tree.ExpressionTree;

import com.sun.source.tree.MethodTree;

import com.sun.source.tree.ReturnTree;

import com.sun.source.tree.StatementTree;

import com.sun.source.tree.Tree;

import com.sun.source.tree.VariableTree;

import com.sun.source.util.SourcePositions;

import com.sun.source.util.TreePath;

import com.sun.source.util.Trees;

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

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

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

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

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

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

import static jdk.jshell.Util.isDoIt;

import jdk.jshell.Wrap.Range;

import java.util.List;

import java.util.Locale;

import java.util.function.BinaryOperator;

import javax.lang.model.type.TypeMirror;

/**

 * Utilities for analyzing compiler API parse trees.

 * @author Robert Field

 */

class TreeDissector {

    private static final String OBJECT_TYPE = "Object";

    static class ExpressionInfo {

        boolean isNonVoid;

        String typeName;

        ExpressionTree tree;

        String signature;

    }

    private final TaskFactory.BaseTask bt;

    private ClassTree firstClass;

    private SourcePositions theSourcePositions = null;

    TreeDissector(TaskFactory.BaseTask bt) {

        this.bt = bt;

    }

    ClassTree firstClass() {

        if (firstClass == null) {

            firstClass = computeFirstClass();

        }

        return firstClass;

    }

    CompilationUnitTree cuTree() {

        return bt.cuTree();

    }

    Types types() {

        return bt.types();

    }

    Trees trees() {

        return bt.trees();

    }

    SourcePositions getSourcePositions() {

        if (theSourcePositions == null) {

            theSourcePositions = trees().getSourcePositions();

        }

        return theSourcePositions;

    }

    int getStartPosition(Tree tree) {

        return (int) getSourcePositions().getStartPosition(cuTree(), tree);

    }

    int getEndPosition(Tree tree) {

        return (int) getSourcePositions().getEndPosition(cuTree(), tree);

    }

    Range treeToRange(Tree tree) {

        return new Range(getStartPosition(tree), getEndPosition(tree));

    }

    Range treeListToRange(List<? extends Tree> treeList) {

        int start = Integer.MAX_VALUE;

        int end = -1;

        for (Tree t : treeList) {

            int tstart = getStartPosition(t);

            int tend = getEndPosition(t);

            if (tstart < start) {

                start = tstart;

            }

            if (tend > end) {

                end = tend;

            }

        }

        if (start == Integer.MAX_VALUE) {

            return null;

        }

        return new Range(start, end);

    }

    Tree firstClassMember() {

        if (firstClass() != null) {

            //TODO: missing classes

            for (Tree mem : firstClass().getMembers()) {

                if (mem.getKind() == Tree.Kind.VARIABLE) {

                    return mem;

                }

                if (mem.getKind() == Tree.Kind.METHOD) {

                    MethodTree mt = (MethodTree) mem;

                    if (!isDoIt(mt.getName()) && !mt.getName().toString().equals("<init>")) {

                        return mt;

                    }

                }

            }

        }

        return null;

    }

    StatementTree firstStatement() {

        if (firstClass() != null) {

            for (Tree mem : firstClass().getMembers()) {

                if (mem.getKind() == Tree.Kind.METHOD) {

                    MethodTree mt = (MethodTree) mem;

                    if (isDoIt(mt.getName())) {

                        List<? extends StatementTree> stmts = mt.getBody().getStatements();

                        if (!stmts.isEmpty()) {

                            return stmts.get(0);

                        }

                    }

                }

            }

        }

        return null;

    }

    VariableTree firstVariable() {

        if (firstClass() != null) {

            for (Tree mem : firstClass().getMembers()) {

                if (mem.getKind() == Tree.Kind.VARIABLE) {

                    VariableTree vt = (VariableTree) mem;

                    return vt;

                }

            }

        }

        return null;

    }

    private ClassTree computeFirstClass() {

        if (cuTree() == null) {

            return null;

        }

        for (Tree decl : cuTree().getTypeDecls()) {

            if (decl.getKind() == Tree.Kind.CLASS || decl.getKind() == Tree.Kind.INTERFACE) {

                return (ClassTree) decl;

            }

        }

        return null;

    }

    ExpressionInfo typeOfReturnStatement(JavacMessages messages, BinaryOperator<String> fullClassNameAndPackageToClass) {

        ExpressionInfo ei = new ExpressionInfo();

        Tree unitTree = firstStatement();

        if (unitTree instanceof ReturnTree) {

            ei.tree = ((ReturnTree) unitTree).getExpression();

            if (ei.tree != null) {

                TreePath viPath = trees().getPath(cuTree(), ei.tree);

                if (viPath != null) {

                    TypeMirror tm = trees().getTypeMirror(viPath);

                    if (tm != null) {

                        Type type = (Type)tm;

                        TypePrinter tp = new TypePrinter(messages, fullClassNameAndPackageToClass, type);

                        ei.typeName = tp.visit(type, Locale.getDefault());

                        switch (tm.getKind()) {

                            case VOID:

                            case NONE:

                            case ERROR:

                            case OTHER:

                                break;

                            case NULL:

                                ei.isNonVoid = true;

                                ei.typeName = OBJECT_TYPE;

                                break;

                            default: {

                                ei.isNonVoid = true;

                                break;

                            }

                        }

                    }

                }

            }

        }

        return ei;

    }

    String typeOfMethod() {

        Tree unitTree = firstClassMember();

        if (unitTree instanceof JCMethodDecl) {

            JCMethodDecl mtree = (JCMethodDecl) unitTree;

            Type mt = types().erasure(mtree.type);

            if (mt instanceof MethodType) {

                return signature(types(), (MethodType) mt);

            }

        }

        return null;

    }

    static String signature(Types types, MethodType mt) {

        TDSignatureGenerator sg = new TDSignatureGenerator(types);

        sg.assembleSig(mt);

        return sg.toString();

    }

    /**

     * Signature Generation

     */

    private static class TDSignatureGenerator extends Types.SignatureGenerator {

        /**

         * An output buffer for type signatures.

         */

        StringBuilder sb = new StringBuilder();

        TDSignatureGenerator(Types types) {

            super(types);

        }

        @Override

        protected void append(char ch) {

            sb.append(ch);

        }

        @Override

        protected void append(byte[] ba) {

            sb.append(new String(ba));

        }

        @Override

        protected void append(Name name) {

            sb.append(name);

        }

        @Override

        public String toString() {

            return sb.toString();

        }

    }

}