/**
 * 
 */
package org.vamsas.objects.utils.document;

import java.util.Hashtable;

/**
 *  enumerates versions for the VamsasDocument.Version string
 *  provides version comparison methods
 *  TODO: LATER: associate schema versions with these strings
 */
public class VersionEntries {
  public static final String ALPHA_VERSION="alpha";
  public static final String BETA_VERSION="beta";
  protected static Hashtable versions;
  static {
    versions = new Hashtable();
    // integers represent version hierarchy - 0 precedes 1
    versions.put(ALPHA_VERSION, new Integer(0)); 
    versions.put(BETA_VERSION, new Integer(1));
  }
  // TODO: LATER: decide on best pattern for enumeration classes (ie - need an ordered list of versions, and validator, plus explicit enum-strings)
  public static boolean isVersion(String vstring) {
    return versions.containsKey(vstring);
  }
  /**
   * returns 0 if levels are equivalent, 
   * 1 if higher is valid and higher, 
   * 2 if lower is valid and higher
   * -1 if both levels are invalid
   * @param higher
   * @param lower
   * @return
   */
  public static int compare(String higher, String lower) {
    int v_1 = versions.containsKey(higher) ? ((Integer) versions.get(higher)).intValue() : -1;
    int v_2 = versions.containsKey(lower) ? ((Integer) versions.get(lower)).intValue() : -1;
    int comp = v_1<v_2 ? 2 : v_1 == v_2 ? 0 : 1;
    return (comp==0) ? (v_1!=-1 ? 0 : -1) : comp;
  }
  /**
   * @return the latest version that this vamsas library supports
   */
  public static String latestVersion() {
    return BETA_VERSION;
  }

}