/**************************************************************************
    *
    * Copyright (c) 2015-2019 Yawg project contributors.
    *
    **************************************************************************/
   
   package com.varmateo.yawg.cli;
   
   import java.io.PrintWriter;
  import java.text.MessageFormat;
  
  import io.vavr.collection.Set;
  import org.apache.commons.cli.HelpFormatter;
  import org.apache.commons.cli.Options;
  
  import com.varmateo.yawg.cli.CliParameter;
  
  
  /**
   * Provides utility methods for printing help and varied info intended
   * for end users.
   */
  /* package private */ final class CliInfoPrinter {
  
  
      private static final String DEFAULT_ARGV0 = "";
      private static final String DEFAULT_VERSION = "";
      private static final String DEFAULT_USAGE_HEADER = "";
      private static final String DEFAULT_USAGE_FOOTER = ""
          + "\n";
  
      private static final String ERROR_FMT = ""
          + "\n"
          + "{0}: {1}\n";
  
      private String _argv0 = null;
      private String _versionMessage = null;
      private String _usageMessageHeader = null;
      private String _usageMessageFooter = null;
  
  
      /**
       * Only used internally.
       *
       */
      private CliInfoPrinter(final Builder builder) {
  
          _argv0 = builder._argv0;
          _versionMessage = builder._versionMessage;
          _usageMessageHeader = builder._usageMessageHeader;
          _usageMessageFooter = builder._usageMessageFooter;
      }
  
  
      /**
       * Creates a new builder with no initializations.
       *
       * @return A newly created <code>Builder</code> instance.
       */
      public static Builder builder() {
  
          return new Builder();
      }
  
  
      /**
       *
       */
      public void printUsage(
              final PrintWriter output,
              final Set<CliParameter> options) {
  
          final String header = MessageFormat.format(_usageMessageHeader, _argv0);
          final String footer = _usageMessageFooter;
  
          output.println(header);
  
          final Options       apacheOptions = buildApacheOptions(options);
          final HelpFormatter formatter = new HelpFormatter();
  
          formatter.printOptions(
                  output,
                  HelpFormatter.DEFAULT_WIDTH,
                  apacheOptions,
                  HelpFormatter.DEFAULT_LEFT_PAD,
                  HelpFormatter.DEFAULT_DESC_PAD);
  
          output.println(footer);
      }
  
  
      /**
       *
       */
      private static Options
          buildApacheOptions(final Set<CliParameter> options) {
  
          return options
                  .map(CliParameter::apacheOption)
                 .foldLeft(
                         new Options(),
                         (xs, x) -> xs.addOption(x));
     }
 
 
     /**
      *
      */
     public void printVersion(final PrintWriter output) {
 
         output.println(_versionMessage);
     }
 
 
     /**
      *
      */
     public void printError(
             final PrintWriter  output,
             final Throwable error) {
 
         final String errorMsg = error.getMessage();
         final String msg      = MessageFormat.format(ERROR_FMT, _argv0, errorMsg);
 
         output.println(msg);
     }
 
 
     /**
      * A builder of <code>CliInfoPrinter</code> instances.
      */
     public static final class Builder {
 
 
         private String _argv0 = DEFAULT_ARGV0;
         private String _versionMessage = DEFAULT_VERSION;
         private String _usageMessageHeader = DEFAULT_USAGE_HEADER;
         private String _usageMessageFooter = DEFAULT_USAGE_FOOTER;
 
 
         /**
          *
          */
         private Builder() {
             // Nothing to do.
         }
 
 
         /**
          *
          */
         public Builder argv0(final String argv0) {
 
             _argv0 = argv0;
 
             return this;
         }
 
 
         /**
          *
          */
         public Builder versionMessage(final String versionMessage) {
 
             _versionMessage = versionMessage;
 
             return this;
         }
 
 
         /**
          *
          */
         public Builder usageMessageHeader(final String usageMessageHeader) {
 
             _usageMessageHeader = usageMessageHeader;
 
             return this;
         }
 
 
         /**
          *
          */
         public Builder usageMessageFooter(final String usageMessageFooter) {
 
             _usageMessageFooter = usageMessageFooter;
 
             return this;
         }
 
 
         /**
          *
          */
         public CliInfoPrinter build() {
 
             return new CliInfoPrinter(this);
         }
 
     }
 
 }