static StartupOption parseArguments()

in hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNode.java [1650:1780]
124 lines of code
39 McCabe index (conditional complexity)

  static StartupOption parseArguments(String args[]) {
    int argsLen = (args == null) ? 0 : args.length;
    StartupOption startOpt = StartupOption.REGULAR;
    for(int i=0; i < argsLen; i++) {
      String cmd = args[i];
      if (StartupOption.FORMAT.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.FORMAT;
        for (i = i + 1; i < argsLen; i++) {
          if (args[i].equalsIgnoreCase(StartupOption.CLUSTERID.getName())) {
            i++;
            if (i >= argsLen) {
              // if no cluster id specified, return null
              LOG.error("Must specify a valid cluster ID after the "
                  + StartupOption.CLUSTERID.getName() + " flag");
              return null;
            }
            String clusterId = args[i];
            // Make sure an id is specified and not another flag
            if (clusterId.isEmpty() ||
                clusterId.equalsIgnoreCase(StartupOption.FORCE.getName()) ||
                clusterId.equalsIgnoreCase(
                    StartupOption.NONINTERACTIVE.getName())) {
              LOG.error("Must specify a valid cluster ID after the "
                  + StartupOption.CLUSTERID.getName() + " flag");
              return null;
            }
            startOpt.setClusterId(clusterId);
          }

          if (args[i].equalsIgnoreCase(StartupOption.FORCE.getName())) {
            startOpt.setForceFormat(true);
          }

          if (args[i].equalsIgnoreCase(StartupOption.NONINTERACTIVE.getName())) {
            startOpt.setInteractiveFormat(false);
          }
        }
      } else if (StartupOption.GENCLUSTERID.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.GENCLUSTERID;
      } else if (StartupOption.REGULAR.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.REGULAR;
      } else if (StartupOption.BACKUP.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.BACKUP;
      } else if (StartupOption.CHECKPOINT.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.CHECKPOINT;
      } else if (StartupOption.OBSERVER.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.OBSERVER;
      } else if (StartupOption.UPGRADE.getName().equalsIgnoreCase(cmd)
          || StartupOption.UPGRADEONLY.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.UPGRADE.getName().equalsIgnoreCase(cmd) ? 
            StartupOption.UPGRADE : StartupOption.UPGRADEONLY;
        /* Can be followed by CLUSTERID with a required parameter or
         * RENAMERESERVED with an optional parameter
         */
        while (i + 1 < argsLen) {
          String flag = args[i + 1];
          if (flag.equalsIgnoreCase(StartupOption.CLUSTERID.getName())) {
            if (i + 2 < argsLen) {
              i += 2;
              startOpt.setClusterId(args[i]);
            } else {
              LOG.error("Must specify a valid cluster ID after the "
                  + StartupOption.CLUSTERID.getName() + " flag");
              return null;
            }
          } else if (flag.equalsIgnoreCase(StartupOption.RENAMERESERVED
              .getName())) {
            if (i + 2 < argsLen) {
              FSImageFormat.setRenameReservedPairs(args[i + 2]);
              i += 2;
            } else {
              FSImageFormat.useDefaultRenameReservedPairs();
              i += 1;
            }
          } else {
            LOG.error("Unknown upgrade flag: {}", flag);
            return null;
          }
        }
      } else if (StartupOption.ROLLINGUPGRADE.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.ROLLINGUPGRADE;
        ++i;
        if (i >= argsLen) {
          LOG.error("Must specify a rolling upgrade startup option "
              + RollingUpgradeStartupOption.getAllOptionString());
          return null;
        }
        startOpt.setRollingUpgradeStartupOption(args[i]);
      } else if (StartupOption.ROLLBACK.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.ROLLBACK;
      } else if (StartupOption.IMPORT.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.IMPORT;
      } else if (StartupOption.BOOTSTRAPSTANDBY.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.BOOTSTRAPSTANDBY;
        return startOpt;
      } else if (StartupOption.INITIALIZESHAREDEDITS.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.INITIALIZESHAREDEDITS;
        for (i = i + 1 ; i < argsLen; i++) {
          if (StartupOption.NONINTERACTIVE.getName().equals(args[i])) {
            startOpt.setInteractiveFormat(false);
          } else if (StartupOption.FORCE.getName().equals(args[i])) {
            startOpt.setForceFormat(true);
          } else {
            LOG.error("Invalid argument: " + args[i]);
            return null;
          }
        }
        return startOpt;
      } else if (StartupOption.RECOVER.getName().equalsIgnoreCase(cmd)) {
        if (startOpt != StartupOption.REGULAR) {
          throw new RuntimeException("Can't combine -recover with " +
              "other startup options.");
        }
        startOpt = StartupOption.RECOVER;
        while (++i < argsLen) {
          if (args[i].equalsIgnoreCase(
                StartupOption.FORCE.getName())) {
            startOpt.setForce(MetaRecoveryContext.FORCE_FIRST_CHOICE);
          } else {
            throw new RuntimeException("Error parsing recovery options: " + 
              "can't understand option \"" + args[i] + "\"");
          }
        }
      } else if (StartupOption.METADATAVERSION.getName().equalsIgnoreCase(cmd)) {
        startOpt = StartupOption.METADATAVERSION;
      } else {
        return null;
      }
    }
    return startOpt;
  }