/*=========================================================================

  Library:   CTK

  Copyright (c) Kitware Inc.

  Licensed 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.commontk.org/LICENSE

  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.

=========================================================================*/
/*=========================================================================

   Program: ParaView
   Module:    $RCSfile$

   Copyright (c) 2005-2008 Sandia Corporation, Kitware Inc.
   All rights reserved.

   ParaView is a free software; you can redistribute it and/or modify it
   under the terms of the ParaView license version 1.2. 

   See License_v1.2.txt for the full ParaView license.
   A copy of this license can be obtained by contacting
   Kitware Inc.
   28 Corporate Drive
   Clifton Park, NY 12065
   USA

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

=========================================================================*/

// Qt includes
#include <QAbstractItemView>
#include <QApplication>
#include <QClipboard>
#include <QCompleter>
#include <QKeyEvent>
#include <QPointer>
#include <QTextCursor>
#include <QTextEdit>
#include <QVBoxLayout>
#include <QScrollBar>

// CTK includes
#include "ctkConsoleWidget.h"

/////////////////////////////////////////////////////////////////////////
// ctkConsoleWidget::pqImplementation

class ctkConsoleWidget::pqImplementation :
  public QTextEdit
{
public:
  pqImplementation(ctkConsoleWidget& p) :
    QTextEdit(&p),
    Parent(p),
    InteractivePosition(documentEnd())
  {
    this->setTabChangesFocus(false);
    this->setAcceptDrops(false);
    this->setAcceptRichText(false);
    this->setUndoRedoEnabled(false);
    
    QFont f;
    f.setFamily("Courier");
    f.setStyleHint(QFont::TypeWriter);
    f.setFixedPitch(true);
    
    QTextCharFormat format;
    format.setFont(f);
    format.setForeground(QColor(0, 0, 0));
    this->setCurrentCharFormat(format);
    
    this->CommandHistory.append("");
    this->CommandPosition = 0;
  }

  void keyPressEvent(QKeyEvent* e)
  {

  if (this->Completer && this->Completer->popup()->isVisible())
    {
    // The following keys are forwarded by the completer to the widget
    switch (e->key())
      {
      case Qt::Key_Enter:
      case Qt::Key_Return:
      case Qt::Key_Escape:
      case Qt::Key_Tab:
      case Qt::Key_Backtab:
        e->ignore();
        return; // let the completer do default behavior
      default:
        break;
      }
    }

    QTextCursor text_cursor = this->textCursor();

    // Set to true if there's a current selection
    const bool selection = text_cursor.anchor() != text_cursor.position();
    // Set to true if the cursor overlaps the history area
    const bool history_area =
      text_cursor.anchor() < this->InteractivePosition
      || text_cursor.position() < this->InteractivePosition;

    // Allow copying anywhere in the console ...
    if(e->key() == Qt::Key_C && e->modifiers() == Qt::ControlModifier)
      {
      if(selection)
        {
        this->copy();
        }
        
      e->accept();
      return;
      }
      
    // Allow cut only if the selection is limited to the interactive area ...
    if(e->key() == Qt::Key_X && e->modifiers() == Qt::ControlModifier)
      {
      if(selection && !history_area)
        {
        this->cut();
        }
        
      e->accept();
      return;
      }
    
    // Allow paste only if the selection is in the interactive area ...
    if(e->key() == Qt::Key_V && e->modifiers() == Qt::ControlModifier)
      {
      if(!history_area)
        {
        const QMimeData* const clipboard = QApplication::clipboard()->mimeData();
        const QString text = clipboard->text();
        if(!text.isNull())
          {
          text_cursor.insertText(text);
          this->updateCommandBuffer();
          }
        }
        
      e->accept();
      return;
      }
    
    // Force the cursor back to the interactive area
    if(history_area && e->key() != Qt::Key_Control)
      {
      text_cursor.setPosition(this->documentEnd());
      this->setTextCursor(text_cursor);
      }
    
    switch(e->key())
      {
      case Qt::Key_Up:
        e->accept();
        if (this->CommandPosition > 0)
          {
          this->replaceCommandBuffer(this->CommandHistory[--this->CommandPosition]);
          }
        break;
        
      case Qt::Key_Down:
        e->accept();
        if (this->CommandPosition < this->CommandHistory.size() - 2)
          {
          this->replaceCommandBuffer(this->CommandHistory[++this->CommandPosition]);
          }
        else
          {
          this->CommandPosition = this->CommandHistory.size()-1;
          this->replaceCommandBuffer("");
          }
        break;

      case Qt::Key_Left:
        if (text_cursor.position() > this->InteractivePosition)
          {
          QTextEdit::keyPressEvent(e);
          }
        else
          {
          e->accept();
          }
        break;
        
  
      case Qt::Key_Delete:
        e->accept();
        QTextEdit::keyPressEvent(e);
        this->updateCommandBuffer();
        break;
        
      case Qt::Key_Backspace:
        e->accept();
        if(text_cursor.position() > this->InteractivePosition)
          {
          QTextEdit::keyPressEvent(e);
          this->updateCommandBuffer();
          this->updateCompleterIfVisible();
          }
        break;

      case Qt::Key_Tab:
        e->accept();
        this->updateCompleter();
        this->selectCompletion();
        break;
        

      case Qt::Key_Home:
        e->accept();
        text_cursor.setPosition(this->InteractivePosition);
        this->setTextCursor(text_cursor);
        break;
        
      case Qt::Key_Return:
      case Qt::Key_Enter:
        e->accept();
        
        text_cursor.setPosition(this->documentEnd());
        this->setTextCursor(text_cursor);
        
        this->internalExecuteCommand();
        break;
        
      default:
        e->accept();
        QTextEdit::keyPressEvent(e);
        this->updateCommandBuffer();
        this->updateCompleterIfVisible();
        break;
      }
  }
  
  /// Returns the end of the document
  /*const*/ int documentEnd()
  {
    QTextCursor c(this->document());
    c.movePosition(QTextCursor::End);
    return c.position();
  }

  void focusOutEvent(QFocusEvent *e)
  {
    QTextEdit::focusOutEvent(e);

    // For some reason the QCompleter tries to set the focus policy to
    // NoFocus, set let's make sure we set it back to the default WheelFocus.
    this->setFocusPolicy(Qt::WheelFocus);
  }

  void updateCompleterIfVisible()
  {
    if (this->Completer && this->Completer->popup()->isVisible())
      {
      this->updateCompleter();
      }
  }

  /// If there is exactly 1 completion, insert it and hide the completer,
  /// else do nothing.
  void selectCompletion()
  {
  if (this->Completer && this->Completer->completionCount() == 1)
    {
    this->Parent.insertCompletion(this->Completer->currentCompletion());
    this->Completer->popup()->hide();
    }
  }

  void updateCompleter()
  {
    if (this->Completer)
      {
      // Get the text between the current cursor position
      // and the start of the line
      QTextCursor text_cursor = this->textCursor();
      text_cursor.setPosition(this->InteractivePosition, QTextCursor::KeepAnchor);
      QString commandText = text_cursor.selectedText();

      // Call the completer to update the completion model
      this->Completer->updateCompletionModel(commandText);

      // Place and show the completer if there are available completions
      if (this->Completer->completionCount())
        {
        // Get a QRect for the cursor at the start of the
        // current word and then translate it down 8 pixels.
        text_cursor = this->textCursor();
        text_cursor.movePosition(QTextCursor::StartOfWord);
        QRect cr = this->cursorRect(text_cursor);
        cr.translate(0,8);
        cr.setWidth(this->Completer->popup()->sizeHintForColumn(0)
          + this->Completer->popup()->verticalScrollBar()->sizeHint().width());
        this->Completer->complete(cr);
        }
      else
        {
        this->Completer->popup()->hide();
        }
      }
  }
  
  /// Update the contents of the command buffer from the contents of the widget
  void updateCommandBuffer()
  {
    this->commandBuffer() = this->toPlainText().mid(this->InteractivePosition);
  }
  
  /// Replace the contents of the command buffer, updating the display
  void replaceCommandBuffer(const QString& Text)
  {
    this->commandBuffer() = Text;
  
    QTextCursor c(this->document());
    c.setPosition(this->InteractivePosition);
    c.movePosition(QTextCursor::End, QTextCursor::KeepAnchor);
    c.removeSelectedText();
    c.insertText(Text);
  }
  
  /// References the buffer where the current un-executed command is stored
  QString& commandBuffer()
  {
    return this->CommandHistory.back();
  }
  
  /// Implements command-execution
  void internalExecuteCommand()
    {
    // First update the history cache. It's essential to update the
    // this->CommandPosition before calling internalExecuteCommand() since that
    // can result in a clearing of the current command (BUG #8765).
    QString command = this->commandBuffer();
    if (!command.isEmpty()) // Don't store empty commands in the history
      {
      this->CommandHistory.push_back("");
      this->CommandPosition = this->CommandHistory.size() - 1;
      }
    QTextCursor c(this->document());
    c.movePosition(QTextCursor::End);
    c.insertText("\n");

    this->InteractivePosition = this->documentEnd();
    this->Parent.internalExecuteCommand(command);
    }

  void setCompleter(ctkConsoleWidgetCompleter* completer)
    {
    if (this->Completer)
      {
      this->Completer->setWidget(0);
      QObject::disconnect(this->Completer, SIGNAL(activated(const QString&)),
                        &this->Parent, SLOT(insertCompletion(const QString&)));

      }
    this->Completer = completer;
    if (this->Completer)
      {
      this->Completer->setWidget(this);
      QObject::connect(this->Completer, SIGNAL(activated(const QString&)),
                      &this->Parent, SLOT(insertCompletion(const QString&)));
      }
    }
  
  /// Stores a back-reference to our owner
  ctkConsoleWidget& Parent;

  /// A custom completer
  QPointer<ctkConsoleWidgetCompleter> Completer;

  /** Stores the beginning of the area of interactive input, outside which
  changes can't be made to the text edit contents */
  int InteractivePosition;
  /// Stores command-history, plus the current command buffer
  QStringList CommandHistory;
  /// Stores the current position in the command-history
  int CommandPosition;
};

/////////////////////////////////////////////////////////////////////////
// ctkConsoleWidget

ctkConsoleWidget::ctkConsoleWidget(QWidget* Parent) :
  QWidget(Parent),
  Implementation(new pqImplementation(*this))
{
  QVBoxLayout* const l = new QVBoxLayout(this);
  l->setMargin(0);
  l->addWidget(this->Implementation);
}

//-----------------------------------------------------------------------------
ctkConsoleWidget::~ctkConsoleWidget()
{
  delete this->Implementation;
}

//-----------------------------------------------------------------------------
QTextCharFormat ctkConsoleWidget::getFormat()
{
  return this->Implementation->currentCharFormat();
}

//-----------------------------------------------------------------------------
void ctkConsoleWidget::setFormat(const QTextCharFormat& Format)
{
  this->Implementation->setCurrentCharFormat(Format);
}

//-----------------------------------------------------------------------------
void ctkConsoleWidget::setCompleter(ctkConsoleWidgetCompleter* completer)
{
  this->Implementation->setCompleter(completer);
}

//-----------------------------------------------------------------------------
void ctkConsoleWidget::insertCompletion(const QString& completion)
{
  QTextCursor tc = this->Implementation->textCursor();
  tc.movePosition(QTextCursor::Left, QTextCursor::KeepAnchor);
  if (tc.selectedText()==".")
    {
    tc.insertText(QString(".") + completion);
    }
  else
    {
    tc = this->Implementation->textCursor();
    tc.movePosition(QTextCursor::StartOfWord, QTextCursor::MoveAnchor);
    tc.movePosition(QTextCursor::EndOfWord, QTextCursor::KeepAnchor);
    tc.insertText(completion);
    this->Implementation->setTextCursor(tc);
    }
  this->Implementation->updateCommandBuffer();
}

//-----------------------------------------------------------------------------
void ctkConsoleWidget::printString(const QString& Text)
{
  this->Implementation->textCursor().movePosition(QTextCursor::End);
  this->Implementation->textCursor().insertText(Text);
  this->Implementation->InteractivePosition = this->Implementation->documentEnd();
  this->Implementation->ensureCursorVisible();
}

//-----------------------------------------------------------------------------
void ctkConsoleWidget::printCommand(const QString& cmd)
{
  this->Implementation->textCursor().insertText(cmd);
  this->Implementation->updateCommandBuffer();
}

//-----------------------------------------------------------------------------
void ctkConsoleWidget::prompt(const QString& text)
{
  QTextCursor text_cursor = this->Implementation->textCursor();

  // if the cursor is currently on a clean line, do nothing, otherwise we move
  // the cursor to a new line before showing the prompt.
  text_cursor.movePosition(QTextCursor::StartOfLine);
  int startpos = text_cursor.position();
  text_cursor.movePosition(QTextCursor::EndOfLine);
  int endpos = text_cursor.position();
  if (endpos != startpos)
    {
    this->Implementation->textCursor().insertText("\n");
    }

  this->Implementation->textCursor().insertText(text);
  this->Implementation->InteractivePosition = this->Implementation->documentEnd();
  this->Implementation->ensureCursorVisible();
}

//-----------------------------------------------------------------------------
void ctkConsoleWidget::clear()
{
  this->Implementation->clear();

  // For some reason the QCompleter tries to set the focus policy to
  // NoFocus, set let's make sure we set it back to the default WheelFocus.
  this->Implementation->setFocusPolicy(Qt::WheelFocus);
}

//-----------------------------------------------------------------------------
void ctkConsoleWidget::internalExecuteCommand(const QString& Command)
{
  emit this->executeCommand(Command);
}