/*******************************************************************************
 * Copyright (c) 2000, 2010 QNX Software Systems and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *******************************************************************************/
package com.google.eclipse.cdt.utils.spawner;

import java.util.*;

import org.eclipse.core.runtime.Platform;

/**
 * This class provides environment variables supplied as {@link Properties} class.
 */
public final class EnvironmentReader {
  private static Properties envVars = null;
  private static Properties envVarsNormalized = null;
  private static ArrayList<String> rawVars = null;

  private static synchronized void init() {
    if (envVars == null) {
      envVars = new Properties();
      // on Windows environment variable names are case-insensitive
      if (Platform.getOS().equals(Platform.OS_WIN32)) {
        envVarsNormalized = new Properties();
      } else {
        envVarsNormalized = envVars;
      }
      rawVars = new ArrayList<String>();
      Map<String, String> envMap = System.getenv();
      for (String var : envMap.keySet()) {
        String value = envMap.get(var);
        envVars.setProperty(var, value);
        if (envVarsNormalized != envVars) {
          envVarsNormalized.setProperty(var.toUpperCase(), value);
        }
        rawVars.add(var + "=" + value);
      }
      rawVars.trimToSize();
    }
  }

  public static Properties getEnvVars() {
    init();
    return (Properties) envVars.clone();
  }

  public static String getEnvVar(String key) {
    init();
    return envVarsNormalized.getProperty(key);
  }

  private EnvironmentReader() {}
}