/*
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */
package org.mule.runtime.core.util;

import java.util.Map;
import java.util.TreeMap;

/**
 * filters key value pairs out of a query string
 */
// TODO: this should really be done with RegEx but I was having a lot of difficulty. See the history for this file for a solution
// that almost works, maybe someone else can figure out the last piece
public class UriParamFilter {

  public String filterParamsByValue(String uri, String paramValue) {
    int i = uri.indexOf("?");
    if (i == -1) {
      return uri;
    }
    String query = uri.substring(i + 1);
    String base = uri.substring(0, i + 1);
    StringBuilder newQuery = new StringBuilder();

    TreeMap<String, String> p = getPropertiesFromQueryString(query);
    for (Map.Entry<String, String> entry : p.entrySet()) {
      if (!paramValue.equals(entry.getValue())) {
        newQuery.append(entry.getKey()).append("=").append(entry.getValue()).append("&");
      }
    }
    String result = base + newQuery.toString();
    if (result.endsWith("?") || result.endsWith("&")) {
      result = result.substring(0, result.length() - 1);
    }
    return result;
  }

  private TreeMap<String, String> getPropertiesFromQueryString(String query) {
    TreeMap<String, String> props = new TreeMap<String, String>();

    if (query == null) {
      return props;
    }

    query = new StringBuilder(query.length() + 1).append('&').append(query).toString();

    int x = 0;
    while ((x = addProperty(query, x, '&', props)) != -1);

    return props;
  }

  private int addProperty(String query, int start, char separator, TreeMap<String, String> properties) {
    int i = query.indexOf(separator, start);
    int i2 = query.indexOf(separator, i + 1);
    String pair;
    if (i > -1 && i2 > -1) {
      pair = query.substring(i + 1, i2);
    } else if (i > -1) {
      pair = query.substring(i + 1);
    } else {
      return -1;
    }
    int eq = pair.indexOf('=');

    if (eq <= 0) {
      String value = "";
      properties.put(pair, value);
    } else {
      String key = pair.substring(0, eq);
      String value = (eq == pair.length() ? "" : pair.substring(eq + 1));
      properties.put(key, value);
    }
    return i2;
  }

}