/*
* ReadCmd.java --
*
* Copyright (c) 1997 Sun Microsystems, Inc.
*
* See the file "license.terms" for information on usage and
* redistribution of this file, and for a DISCLAIMER OF ALL
* WARRANTIES.
* 
* Included in SQLite3 port to C# for use in testharness only;  2008 Noah B Hart
*
* RCS @(#) $Id: ReadCmd.java,v 1.8 2003/03/08 03:42:44 mdejong Exp $
*
*/
using System.Text;
using System.IO;
namespace tcl.lang
{

  /// <summary> This class implements the built-in "read" command in Tcl.</summary>

  class ReadCmd : Command
  {

    /// <summary> This procedure is invoked to process the "read" Tcl command.
    /// See the user documentation for details on what it does.
    /// 
    /// </summary>
    /// <param name="interp">the current interpreter.
    /// </param>
    /// <param name="argv">command arguments.
    /// </param>

    public TCL.CompletionCode cmdProc( Interp interp, TclObject[] argv )
    {

      Channel chan; // The channel being operated on this 
      // method 
      int i = 1; // Index to the next arg in argv
      int toRead = 0; // Number of bytes or chars to read from channel
      int charactersRead; // Number of bytes or chars read from channel
      bool readAll = true; // If true read-all else toRead
      bool noNewline = false; // If true, strip the newline if there
      TclObject result;


      if ( ( argv.Length != 2 ) && ( argv.Length != 3 ) )
      {

        errorWrongNumArgs( interp, argv[0].ToString() );
      }


      if ( argv[i].ToString().Equals( "-nonewline" ) )
      {
        noNewline = true;
        i++;
      }

      if ( i == argv.Length )
      {

        errorWrongNumArgs( interp, argv[0].ToString() );
      }


      chan = TclIO.getChannel( interp, argv[i].ToString() );
      if ( chan == null )
      {

        throw new TclException( interp, "can not find channel named \"" + argv[i].ToString() + "\"" );
      }

      // Consumed channel name. 

      i++;

      // Compute how many bytes or chars to read, and see whether the final
      // noNewline should be dropped.

      if ( i < argv.Length )
      {

        string arg = argv[i].ToString();

        if ( System.Char.IsDigit( arg[0] ) )
        {
          toRead = TclInteger.get( interp, argv[i] );
          readAll = false;
        }
        else if ( arg.Equals( "nonewline" ) )
        {
          noNewline = true;
        }
        else
        {
          throw new TclException( interp, "bad argument \"" + arg + "\": should be \"nonewline\"" );
        }
      }

      try
      {
        if ( (System.Object)chan.Encoding == null )
        {
          result = TclByteArray.newInstance();
        }
        else
        {
          result = TclString.newInstance( new StringBuilder( 64 ) );
        }
        if ( readAll )
        {
          charactersRead = chan.read( interp, result, TclIO.READ_ALL, 0 );

          // If -nonewline was specified, and we have not hit EOF
          // and the last char is a "\n", then remove it and return.

          if ( noNewline )
          {

            string inStr = result.ToString();
            if ( ( charactersRead > 0 ) && ( inStr[charactersRead - 1] == '\n' ) )
            {
              interp.setResult( inStr.Substring( 0, ( ( charactersRead - 1 ) ) - ( 0 ) ) );
              return TCL.CompletionCode.RETURN;
            }
          }
        }
        else
        {
          // FIXME: Bug here, the -nonewline flag must be respected
          // when reading a set number of bytes
          charactersRead = chan.read( interp, result, TclIO.READ_N_BYTES, toRead );
        }

        /*
        // FIXME: Port this -nonewline logic from the C code.
        if (charactersRead < 0) {
        Tcl_ResetResult(interp);
        Tcl_AppendResult(interp, "error reading \"", name, "\": ",
        Tcl_PosixError(interp), (char *) NULL);
        Tcl_DecrRefCount(resultPtr);
        return TCL_ERROR;
        }
				
        // If requested, remove the last newline in the channel if at EOF.
				
        if ((charactersRead > 0) && (newline != 0)) {
        char *result;
        int length;
				
        result = Tcl_GetStringFromObj(resultPtr, length);
        if (result[length - 1] == '\n') {
        Tcl_SetObjLength(resultPtr, length - 1);
        }
        }
				
        */

        interp.setResult( result );
      }
      catch ( IOException e )
      {
        throw new TclRuntimeError( "ReadCmd.cmdProc() Error: IOException when reading " + chan.ChanName );
      }
      return TCL.CompletionCode.RETURN;
    }

    /// <summary> A unique error msg is printed for read, therefore dont call this 
    /// instead of the standard TclNumArgsException().
    /// 
    /// </summary>
    /// <param name="interp">the current interpreter.
    /// </param>
    /// <param name="cmd">the name of the command (extracted form argv[0] of cmdProc)
    /// </param>

    private void errorWrongNumArgs( Interp interp, string cmd )
    {
      throw new TclException( interp, "wrong # args: should be \"" + "read channelId ?numChars?\" " + "or \"read ?-nonewline? channelId\"" );
    }
  }
}