/*

 * Copyright (c) 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.

 *

 * 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 combo;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

/**

 * A combo parameter represents an 'hole' in a template that can be replaced with a given string.

 * The schema of such holes is defined in {@link ComboParameter#pattern}; the main routine for

 * replacing holes in a template scheme is {@link ComboParameter#expandTemplate(String, Resolver)}.

 */

public interface ComboParameter {

    /**

     * A combo parameter can take the form:

     * <p>

     * #{MAJOR}

     * #{MAJOR.}

     * #{MAJOR.MINOR}

     * <p>

     * where MAJOR can be IDENTIFIER or IDENTIFIER[NUMERIC_INDEX]

     * and MINOR can be an identifier.

     */

    Pattern pattern = Pattern.compile("#\\{([A-Z_][A-Z0-9_]*(?:\\[\\d+\\])?)(?:\\.([A-Z0-9_]*))?\\}");

    /**

     * Entry point for the customizable replacement logic. Subclasses must implement this method to

     * specify how a given template hole should be expanded. An optional contextual argument is passed

     * in as parameter, to make expansion more flexible.

     */

    String expand(String optParameter);

    /**

     * Helper class for defining 'constant' combo parameters - i.e. parameters that always expand

     * as a given string value - regardless of the context.

     */

    class Constant<D> implements ComboParameter {

        D data;

        public Constant(D data) {

            this.data = data;

        }

        @Override

        public String expand(String _unused) {

            return String.valueOf(data);

        }

    }

    /**

     * Helper interface used to lookup parameters given a parameter name.

     */

    interface Resolver {

        ComboParameter lookup(String name);

    }

    /**

     * Main routine for replacing holes in a template string. Holes are repeatedly searches, their

     * corresponding parameters retrieved, and replaced through expansion; since an expansion can

     * lead to more holes, the process has to be applied until a fixed point is reached.

     */

    static String expandTemplate(String template, Resolver resolver) {

        CharSequence in = template;

        StringBuffer out = new StringBuffer();

        while (true) {

            boolean more = false;

            Matcher m = pattern.matcher(in);

            while (m.find()) {

                String parameterName = m.group(1);

                String minor = m.group(2);

                ComboParameter parameter = resolver.lookup(parameterName);

                if (parameter == null) {

                    throw new IllegalStateException("Unhandled parameter name " + parameterName);

                }

                String replacement = parameter.expand(minor);

                more |= pattern.matcher(replacement).find();

                m.appendReplacement(out, replacement);

            }

            m.appendTail(out);

            if (!more)

                return out.toString();

            else {

                in = out;

                out = new StringBuffer();

            }

        }

    }

}