/*

 * Copyright (c) 2017, 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.

 *

 * 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.experimental.bytecode;

import java.util.Iterator;

/**

 * Helper to create and manipulate type descriptors, where type descriptors

 * are represented as JVM type descriptor strings and symbols are represented

 * as name strings

 */

public class BasicTypeHelper implements TypeHelper<String, String> {

    @Override

    public String elemtype(String s) {

        if (!s.startsWith("[")) {

            throw new IllegalStateException();

        }

        return s.substring(1);

    }

    @Override

    public String arrayOf(String s) {

        return "[" + s;

    }

    @Override

    public String type(String s) {

        return "L" + s + ";";

    }

    @Override

    public TypeTag tag(String s) {

        switch (s.charAt(0)) {

            case '[':

            case 'L':

                return TypeTag.A;

            case 'B':

            case 'C':

            case 'Z':

            case 'S':

            case 'I':

                return TypeTag.I;

            case 'F':

                return TypeTag.F;

            case 'J':

                return TypeTag.J;

            case 'D':

                return TypeTag.D;

            case 'V':

                return TypeTag.V;

            case 'Q':

                return TypeTag.Q;

            default:

                throw new IllegalStateException("Bad type: " + s);

        }

    }

    @Override

    public String nullType() {

        // Needed in TypedCodeBuilder; ACONST_NULL pushes a 'null' onto the stack,

        // and stack maps handle null differently

        return "<null>";

    }

    @Override

    public String commonSupertype(String t1, String t2) {

        if (t1.equals(t2)) {

            return t1;

        } else {

            try {

                Class<?> c1 = from(t1);

                Class<?> c2 = from(t2);

                if (c1.isAssignableFrom(c2)) {

                    return t1;

                } else if (c2.isAssignableFrom(c1)) {

                    return t2;

                } else {

                    return "Ljava/lang/Object;";

                }

            } catch (Exception e) {

                return null;

            }

        }

    }

    public Class<?> from(String desc) throws ReflectiveOperationException {

        if (desc.startsWith("[")) {

            return Class.forName(desc.replaceAll("/", "."));

        } else {

            return Class.forName(symbol(desc).replaceAll("/", "."));

        }

    }

    @Override

    public Iterator<String> parameterTypes(String s) {

        //TODO: gracefully non-method types

        return new Iterator<String>() {

            int ch = 1;

            @Override

            public boolean hasNext() {

                return s.charAt(ch) != ')';

            }

            @Override

            public String next() {

                char curr = s.charAt(ch);

                switch (curr) {

                    case 'C':

                    case 'B':

                    case 'S':

                    case 'I':

                    case 'J':

                    case 'F':

                    case 'D':

                    case 'Z':

                        ch++;

                        return String.valueOf(curr);

                    case '[':

                        ch++;

                        return "[" + next();

                    case 'L':

                    case 'Q':

                        StringBuilder builder = new StringBuilder();

                        while (curr != ';') {

                            builder.append(curr);

                            curr = s.charAt(++ch);

                        }

                        builder.append(';');

                        ch++;

                        return builder.toString();

                    default:

                        throw new AssertionError("cannot parse string: " + s);

                }

            }

        };

    }

    @Override

    public String symbolFrom(String s) {

        return s;

    }

    @Override

    public String fromTag(TypeTag tag) {

        return tag.name();

    }

    @Override

    public String symbol(String type) {

        return (type.startsWith("L") || type.startsWith("Q")) ? type.substring(1, type.length() - 1) : type;

    }

    @Override

    public String returnType(String s) {

        return s.substring(s.indexOf(')') + 1, s.length());

    }

}