/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.maven.scm.provider.hg;
  
  import java.io.File;
  
  import org.apache.maven.scm.ScmException;
  import org.apache.maven.scm.ScmFileStatus;
  import org.apache.maven.scm.provider.hg.command.HgCommandConstants;
  import org.apache.maven.scm.provider.hg.command.HgConsumer;
  import org.codehaus.plexus.util.cli.Commandline;
  
  /**
   * Check hg installation.
   *
   * @author <a href="mailto:thurner.rupert@ymono.net">thurner rupert</a>
   * @author <a href="mailto:ryan@darksleep.com">ryan daum</a>
   *
   */
  public class HgConfig {
      // Minimum version for the Hg SCM
      private static final String HG_REQ = "0.9.2";
  
      // The string which indicates the beginning of the Mercurial line
      private static final String HG_VERSION_TAG = "Mercurial Distributed SCM (version ";
  
      // URL to download mercurial from
      private static final String HG_INSTALL_URL = "'http://www.selenic.com/mercurial/wiki/index.cgi/Download'";
  
      // Configuration to check with default values (not installed)
      private HgVersionConsumer hgVersion = new HgVersionConsumer(null);
  
      HgConfig(File workingDir) {
          try {
              hgVersion = getHgVersion(workingDir);
          } catch (ScmException e) {
              // Ignore -  is not installed.
              // This is already recorded thus we do not generate more info.
          }
      }
  
      /**
       * @return True if one can run basic hg commands
       */
      private boolean isInstalled() {
          return hgVersion.isVersionOk(HG_REQ);
      }
  
      /**
       * @return True if all modules for hg are installed.
       */
      private boolean isComplete() {
          return isInstalled();
      }
  
      // Consumer to find the Mercurial version
      public static HgVersionConsumer getHgVersion(File workingDir) throws ScmException {
          String[] versionCmd = new String[] {HgCommandConstants.VERSION};
          HgVersionConsumer consumer = new HgVersionConsumer(HG_VERSION_TAG);
          Commandline cmd = HgUtils.buildCmd(workingDir, versionCmd);
  
          // Execute command
          HgUtils.executeCmd(consumer, cmd);
  
          // Return result
          return consumer;
      }
  
      /**
       * Iterate through two dot-notation version strings, normalize them to the same length, then
       * do alphabetic comparison
       *
       * @param version1
       * @param version2
       * @return true if version2 is greater than version1
       */
      private static boolean compareVersion(String version1, String version2) {
          int l1, l2;
          String v1, v2;
  
          v1 = version1;
          v2 = version2;
          l1 = version1.length();
         l2 = version2.length();
 
         if (l1 > l2) {
             for (int x = l2; x >= l1; x--) {
                 v2 += ' ';
             }
         }
         if (l2 > l1) {
             for (int x = l1; x <= l2; x++) {
                 v1 += ' ';
             }
         }
 
         return v2.compareTo(v1) >= 0;
     }
 
     /**
      * Get version of the executable.
      * Version is resolved by splitting the line starting with the version tag and finding
      * the second last word.
      */
     private static class HgVersionConsumer extends HgConsumer {
 
         private String versionStr = "NA";
 
         private String versionTag;
 
         HgVersionConsumer(String versionTag) {
             this.versionTag = versionTag;
         }
 
         public void doConsume(ScmFileStatus status, String line) {
             if (line.startsWith(versionTag)) {
                 String[] elements = line.split(" ");
                 versionStr = elements[elements.length - 1].split("\\)")[0];
             }
         }
 
         String getVersion() {
             return versionStr;
         }
 
         boolean isVersionOk(String version) {
             // build one number out of the whole version #
 
             return compareVersion(version, versionStr);
         }
     }
 
     private String getInstalledStr() {
         if (isComplete()) {
             return "valid and complete.";
         }
         return (isInstalled() ? "incomplete. " : "invalid. ") + "Consult " + HG_INSTALL_URL;
     }
 
     public String toString(File workingDir) {
         boolean hgOk = hgVersion.isVersionOk(HG_REQ);
         return "\n  Your Hg installation seems to be " + getInstalledStr() + "\n    Hg version: "
                 + hgVersion.getVersion() + (hgOk ? " (OK)" : " (May be INVALID)") + "\n";
     }
 }