/** \file commandline.h
 *  Implementation of a platform-independent command line with history.
 *
 *  The class CCommandLine has two roles:
 *  1) It has an outside interface, ReadLine(), that yields to the
 *     system until the user is finished entering an expression at
 *     the command line. The result can be found in iLine.
 *  2) It defines a mini-API needed to implement the command line.
 *     For each platform Yacas is meant to run on there should be a
 *     CCommandLine-derived class if this functionality is to be used.
 *
 */

#ifndef __commandline_h__
#define __commandline_h__

#include "lispstring.h"
#include "yacasbase.h"

enum ESpecialChars
{
    eDelete     = 0x1000,
    eBackSpace,
    eLeft,
    eRight,
    eUp,
    eDown,
    eHome,
    eEnd,
    eEnter,
    eTab,
    eEscape
};

/**
 *  Implementation of a platform-independent command line with history.
 *
 *  The class CCommandLine has two roles:
 *  1) It has an outside interface, ReadLine(), that yields to the
 *     system until the user is finished entering an expression at
 *     the command line. The result can be found in iLine.
 *  2) It defines a mini-API needed to implement the command line.
 *     For each platform Yacas is meant to run on there should be a
 *     CCommandLine-derived class if this functionality is to be used.
 *
 *  The derived class is responsible for filling the history list,
 *  and for externalizing the history list to disk when the system
 *  shuts down.
 */

/// \class CConsoleHistory, implement history list the user can browse through.
class CConsoleHistory
{
public:
  CConsoleHistory() : iHistory(),history(0) {}
  void ResetHistoryPosition();
  void AddLine(LispString& aString);
  void Append(LispString * aString);
  LispInt ArrowUp(LispString& aString,LispInt &aCursorPos);
  LispInt ArrowDown(LispString& aString,LispInt &aCursorPos);
  LispInt Complete(LispString& aString,LispInt &aCursorPos);
  LispInt NrLines();
  LispString * GetLine(LispInt aLine);
protected:
  CDeletingArrayGrower<LispString *, ArrOpsDeletingPtr<LispString> > iHistory;
  LispInt history;
};

class CCommandLine : public YacasBase
{
public:
  CCommandLine() : iFullLineDirty(LispFalse),iHistoryUnchanged(0),iLine(),iSubLine(),iHistoryList() {};
  virtual ~CCommandLine();
  /// Call this function if the user needs to enter an expression.
  virtual void ReadLine(LispChar * prompt);
public: //platform stuff
  /** return a key press, which is either an ascii value, or one
   * of the values specified in ESpecialChars
   */
  virtual LispInt GetKey() = 0;
  /// Go to the next line on the console (carriage return/line feed).
  virtual void NewLine()   = 0;
  /** Show the current line (in iSubLine), with the required prompt,
   *  and the cursor position at cursor (starting from the prompt).
   */
  virtual void ShowLine(LispChar * prompt,
                        LispInt promptlen,LispInt cursor) = 0;
  /// Pause for a short while. Used when matching brackets.
  virtual void Pause() = 0;

  /// Maximum number of history lines to be saved (-1 is all)
  virtual void MaxHistoryLinesSaved(LispInt aNrLines);

protected:
  virtual void ReadLineSub(LispChar * prompt);
private:
  void GetHistory(LispInt aLine);
  void ShowOpen(LispChar * prompt,LispInt promptlen,
                LispChar aOpen, LispChar aClose, LispInt aCurPos);
protected:
  LispInt iFullLineDirty;
  LispInt iHistoryUnchanged;

public:
  LispString iLine;
  LispString iSubLine;

  CConsoleHistory iHistoryList;
};

#endif