////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2021-2022 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////

#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif

#if defined (HAVE_QSCINTILLA)

#include <QGroupBox>
#include <QHBoxLayout>
#include <QLabel>
#include <QLineEdit>
#include <QPushButton>
#include <QTextEdit>
#include <QTextBlock>
#include <QVBoxLayout>

#include "command-widget.h"

#include "cmd-edit.h"
#include "event-manager.h"
#include "gui-preferences-cs.h"
#include "gui-preferences-global.h"
#include "gui-utils.h"
#include "input.h"
#include "interpreter.h"

OCTAVE_BEGIN_NAMESPACE(octave)

  command_widget::command_widget (base_qobject& oct_qobj, QWidget *p)
    : QWidget (p), m_incomplete_parse (false),
      m_prompt (QString ()),
      m_console (new console (this, oct_qobj))
  {
    QPushButton *pause_button = new QPushButton (tr("Pause"), this);
    QPushButton *stop_button = new QPushButton (tr("Stop"), this);
    QPushButton *resume_button = new QPushButton (tr("Continue"), this);

    QGroupBox *input_group_box = new QGroupBox ();
    QHBoxLayout *input_layout = new QHBoxLayout;
    input_layout->addWidget (pause_button);
    input_layout->addWidget (stop_button);
    input_layout->addWidget (resume_button);
    input_group_box->setLayout (input_layout);

    QVBoxLayout *main_layout = new QVBoxLayout ();
    main_layout->addWidget (m_console);
    main_layout->addWidget (input_group_box);

    setLayout (main_layout);

    setFocusProxy (m_console);

    connect (pause_button, &QPushButton::clicked,
             this, &command_widget::interpreter_pause);

    connect (resume_button, &QPushButton::clicked,
             this, &command_widget::interpreter_resume);

    connect (stop_button, &QPushButton::clicked,
             this, &command_widget::interpreter_stop);

    connect (this, &command_widget::new_command_line_signal,
             m_console, &console::new_command_line);

    insert_interpreter_output ("\n\n    Welcome to Octave\n\n");

  }

  void command_widget::init_command_prompt ()
  {
    emit interpreter_event
      ([=] (interpreter& interp)
       {
         // INTERPRETER THREAD

         event_manager& evmgr = interp.get_event_manager ();
         input_system& input_sys = interp.get_input_system ();
         std::string prompt = input_sys.PS1 ();
         evmgr.update_prompt (command_editor::decode_prompt_string (prompt));

         emit new_command_line_signal ();
       });
  }

  void command_widget::update_prompt (const QString& prompt)
  {
    m_prompt = prompt;
  }

  QString command_widget::prompt ()
  {
    return m_prompt;
  }

  void command_widget::insert_interpreter_output (const QString& msg)
  {
    m_console->append (msg);
  }

  void command_widget::process_input_line (const QString& input_line)
  {
    emit interpreter_event
      ([=] (interpreter& interp)
       {
         // INTERPRETER THREAD

         interp.parse_and_execute (input_line.toStdString (),
                                   m_incomplete_parse);

         event_manager& evmgr = interp.get_event_manager ();
         input_system& input_sys = interp.get_input_system ();

         std::string prompt
           = m_incomplete_parse ? input_sys.PS2 () : input_sys.PS1 ();

         evmgr.update_prompt (command_editor::decode_prompt_string (prompt));

         emit new_command_line_signal ();
       });

  }

  void command_widget::notice_settings (const gui_settings *settings)
  {
    // Set terminal font:
    QFont term_font = QFont ();
    term_font.setStyleHint (QFont::TypeWriter);
    QString default_font = settings->value (global_mono_font).toString ();
    term_font.setFamily
      (settings->value (cs_font.key, default_font).toString ());
    term_font.setPointSize
      (settings->value (cs_font_size).toInt ());

    m_console->setFont (term_font);

    // Colors
    int mode = settings->value (cs_color_mode).toInt ();
    QColor fgc = settings->color_value (cs_colors[0], mode);
    QColor bgc = settings->color_value (cs_colors[1], mode);

    m_console->setStyleSheet (QString ("color: %1; background-color:%2;")
                                     .arg (fgc.name ()).arg (bgc.name ()));
  }

  // The console itself using QScintilla.
  // This implementation is partly based on the basic concept of
  // "qpconsole" as proposed by user "DerManu" in the Qt-forum thread
  // https://forum.qt.io/topic/28765/command-terminal-using-qtextedit

  console::console (command_widget *p, base_qobject&)
    : QsciScintilla (p),
      m_command_position (-1),
      m_cursor_position (0),
      m_text_changed (false),
      m_command_widget (p),
      m_last_key_string (QString ())
  {
    setMargins (0);
    setWrapMode (QsciScintilla::WrapWord);

    connect (this, SIGNAL (cursorPositionChanged (int, int)),
             this, SLOT (cursor_position_changed (int, int)));

    connect (this, SIGNAL (textChanged (void)),
             this, SLOT (text_changed (void)));

    connect (this, SIGNAL (modificationAttempted (void)),
             this, SLOT (move_cursor_to_end (void)));
  }

  // Prepare a new command line with the current prompt
  void console::new_command_line (const QString& command)
  {
    if (! text (lines () -1).isEmpty ())
      append ("\n");

    append_string (m_command_widget->prompt ());

    int line, index;
    getCursorPosition (&line,&index);
    m_command_position = positionFromLineIndex (line, index);

    append_string (command);
  }

  // Accept the current command line (or block)
  void console::accept_command_line ()
  {
    QString input_line = text (lines () - 1);

    if (input_line.startsWith (m_command_widget->prompt ()))
      input_line.remove(0, m_command_widget->prompt ().length ());

    input_line = input_line.trimmed ();

    append_string ("\n");

    if (input_line.isEmpty ())
      new_command_line ();
    else
      m_command_widget->process_input_line (input_line);
  }

  // Execute a command
  void console::execute_command (const QString& command)
  {
    if (command.trimmed ().isEmpty ())
      return;

    new_command_line (command);
    accept_command_line ();
  }

  // Append a string and update the curdor püosition
  void console::append_string (const QString& string)
  {
    setReadOnly (false);
    append (string);

    int line, index;
    lineIndexFromPosition (text ().length (), &line, &index);

    setCursorPosition (line, index);
  }

  // Cursor position changed: Are we in the command line or not?
  void console::cursor_position_changed (int line, int col)
  {
    m_cursor_position = positionFromLineIndex (line, col);
    if (m_cursor_position < m_command_position)
      {
        // We are in the read only area
        if (m_text_changed && (m_cursor_position == m_command_position - 1))
          {
            setReadOnly (false);
            insert (m_command_widget->prompt ().right (1)); // And here we have tried to remove the prompt by Backspace
            setCursorPosition (line+1, col);
          }
        setReadOnly (true);
      }
    else
      setReadOnly (false);  // Writable area

    m_text_changed = false;
  }

  // User attempted to type on read only mode: move cursor at end and allow
  // editing
  void console::move_cursor_to_end (void)
  {
    if ((! m_last_key_string.isEmpty ()) && (m_last_key_string.at (0).isPrint ()))
      {
        append_string (m_last_key_string);
        setReadOnly (true); // Avoid that changing read only text is done afterwards
      }
  }

  // Text has changed: is cursor still in "writable" area?
  // This signal seems to be emitted before cursor position changed.
  void console::text_changed (void)
  {
    m_text_changed = true;
  }

  // Re-implement key event
  void console::keyPressEvent (QKeyEvent *e)
  {
    if (e->key () == Qt::Key_Return)
      // On "return", accept the current command line
      accept_command_line ();
    else
      {
        // Otherwise, store text process the expected event
        m_last_key_string = e->text ();
        QsciScintilla::keyPressEvent(e);
      }
  }

OCTAVE_END_NAMESPACE(octave)

#endif