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/*-
 * #%L
 * marid-runtime
 * %%
 * Copyright (C) 2012 - 2017 MARID software development group
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see .
 * #L%
 */

package org.marid.runtime.context;

import org.marid.runtime.exception.MaridCircularPlaceholderException;

import java.util.LinkedHashSet;
import java.util.Properties;

/**
 * @author Dmitry Ovchinnikov
 */
public class MaridPlaceholderResolver {

    private final Properties properties;

    public MaridPlaceholderResolver(Properties properties) {
        this.properties = properties;
    }

    public String resolvePlaceholders(String value) {
        if (value == null || value.isEmpty() || value.indexOf('$') < 0) {
            return value;
        } else {
            return resolvePlaceholders(new LinkedHashSet<>(), value);
        }
    }

    private String resolvePlaceholders(LinkedHashSet passed, String value) {
        if (value == null || value.isEmpty() || value.indexOf('$') < 0) {
            return value;
        } else {
            final StringBuilder builder = new StringBuilder(value);
            for (int i = 0; i < builder.length(); ) {
                if (builder.charAt(i) == '$') {
                    if (i < builder.length() - 1) {
                        if (builder.charAt(i + 1) == '{') {
                            final int closeIndex = builder.indexOf("}", i + 1);
                            if (closeIndex < 0) {
                                return builder.toString();
                            } else {
                                final String placeholder = builder.substring(i + 2, closeIndex);
                                final int defIndex = placeholder.lastIndexOf(':');
                                final String name;
                                final String defValue;
                                if (defIndex < 0) {
                                    name = placeholder;
                                    defValue = "";
                                } else {
                                    name = placeholder.substring(0, defIndex);
                                    defValue = placeholder.substring(defIndex + 1);
                                }
                                final String toReplace = String.valueOf(resolvePlaceholder(passed, name, defValue));
                                builder.replace(i, closeIndex + 1, toReplace);
                                i += toReplace.length();
                            }
                        } else {
                            i++;
                        }
                    } else {
                        i++;
                    }
                } else {
                    i++;
                }
            }
            return builder.toString();
        }
    }

    private String resolvePlaceholder(LinkedHashSet passed, String name, String defValue) {
        if (passed.add(name)) {
            final String result = resolvePlaceholders(passed, properties.getProperty(name, defValue));
            passed.remove(name);
            return result;
        } else {
            throw new MaridCircularPlaceholderException(passed, name);
        }
    }

}