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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 ClassLoader classLoader;
  private final Properties properties;

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

  public MaridPlaceholderResolver(Properties properties) {
    this(Thread.currentThread().getContextClassLoader(), properties);
  }

  public ClassLoader getClassLoader() {
    return classLoader;
  }

  public Properties getProperties() {
    return 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);
    }
  }

}