package sk.stuba.fiit.perconik.environment;

import java.lang.management.ManagementFactory;

import com.google.common.base.StandardSystemProperty;

import org.osgi.framework.Version;

import sk.stuba.fiit.perconik.environment.java.JavaVerifier;

/**
 * Bridge between plug-in environment and the native platform.
 *
 * @author Pavol Zbell
 * @since 1.0
 */
public final class Environment {
  /**
   * Presence marker for the {@code DEBUG} environment variable.
   */
  public static final boolean debug = getVariableAsBoolean("DEBUG");

  private Environment() {}

  public static Version getJavaVersion() {
    return JavaVerifier.parseJavaVersion(StandardSystemProperty.JAVA_VERSION.value());
  }

  /**
   * Returns the current JVM process identifier.
   * @throws RuntimeException if accessing the process identifier fails.
   */
  public static int getProcessIdentifier() {
    String name = ManagementFactory.getRuntimeMXBean().getName();

    try {
      return Integer.parseInt(name.substring(0, name.indexOf('@')));
    } catch (RuntimeException e) {
      throw new RuntimeException("Unable to get PID from " + name, e);
    }
  }

  /**
   * Returns the value of the specified environment variable.
   * An environment variable is a system-dependent external named value.
   * @param name the name of the environment variable, not {@code null}
   * @return the string value of the variable or {@code null}
   *         if the variables is not defined in the system environment
   *         or if {@code SecurityException} is thrown
   */
  public static String getVariable(final String name) {
    try {
      return System.getenv(name);
    } catch (SecurityException e) {
      return null;
    }
  }

  public static boolean getVariableAsBoolean(final String name) {
    String value = getVariable(name);

    return value != null && Boolean.parseBoolean(value);
  }
}