package edu.princeton.toy;

import java.awt.*;
import java.awt.event.*;

import edu.princeton.swing.*;
import edu.princeton.swing.text.*;
import edu.princeton.toy.lang.*;

/**
 * TCommentingAutoCompleter is an subclass of TUncommentingAutoCompleter which will also
 * automatically update or add an autocomment when the user completes or modifies a command.
 *
 * @version 7.1
 * @author btsang
 */

public class TCommentingAutoCompleter extends TUncommentingAutoCompleter
{
    public TCommentingAutoCompleter()
    {

    }

    /**
     * The PHighlightedTextArea will pass all key events to its auto-completer before processing
     * the event for itself.
     *
     * @param comp The component which recieved the KeyEvent.
     * @param e The event which occurred.
     * @return True if the component should ignore the KeyEvent (because this method already
     * performed a special action associated with it).  In either case, KeyListeners of the
     * component will still be informed of the event.
     */
    public boolean interceptKeyEvent(PHighlightedTextArea comp, KeyEvent e)
    {
        // Allow the indenter+uncommenter to try to intercept the KeyEvent
        if (super.interceptKeyEvent(comp, e))
            return true;
        
        
        // do not intercept if the user has pressed an action key
        // right and left arrows are an exception (they may have a meaning)
        if (e.isActionKey() && 
            e.getKeyCode() != KeyEvent.VK_RIGHT  &&
            e.getKeyCode() != KeyEvent.VK_LEFT) 
            return false;
        
        
        // do not intercept if the user is trying to do any keyboard shortcut
        // excluding the paste command. 
        int mask;
        if (System.getProperty("os.name").startsWith("Mac"))
            mask = InputEvent.META_DOWN_MASK;
        else
            mask = InputEvent.CTRL_DOWN_MASK;
        if ((e.getModifiersEx() & mask) == mask) {
            if (e.getKeyChar() == 'c' || e.getKeyChar() == 'z' ||
                e.getKeyChar() == 'o' || e.getKeyChar() == 'n' ||
                e.getKeyChar() == 'q' || e.getKeyChar() == 's' ||
                e.getKeyChar() == 'a' || e.getKeyChar() == 'e' ||
                e.getKeyChar() == 'f' || e.getKeyChar() == 'y') {
                return false;
            }
        }
        
        
        // get the caret position
        int selectionDot = comp.getSelectionDot();
        HighlightedDocument document = comp.getDocument();
        Point coordinate = document.offsetToCoordinate(selectionDot);
        
        // get the current line
        int lineStartDot = selectionDot - coordinate.x;
        int lineEndDot = document.coordinateToOffset(Integer.MAX_VALUE, 
                                                     coordinate.y);
        String line = document.getText(lineStartDot, lineEndDot);
        int length = line.length();
        
        // Check if the line already has an instruction + pseudocode or not
        boolean hasInstruction = false;
        if (length >= 8)
            hasInstruction = TWord.isCommand(line.substring(0, 8));
        
        // Check if some text is selected (highlited)
        Point selStart = document.offsetToCoordinate(comp.getSelectionStart());
        Point selEnd = document.offsetToCoordinate(comp.getSelectionEnd());
        boolean hasSelection = (selStart.x != selEnd.x && selStart.y == selEnd.y) || 
                               (selStart.y != selEnd.y);
        
        boolean startIn = selStart.x >= 8 && selStart.x <= TProgramDocument.COMMENT_COLUMN;
        boolean startAfter = selStart.x > TProgramDocument.COMMENT_COLUMN;
        
        
        // skip over the pseudocode if the user hits left while being at the beginning of
        // the user comments column or hits right while being at the end of the instruction
        // column

        mask = InputEvent.SHIFT_DOWN_MASK;

        int mark;
        if (selectionDot == comp.getSelectionStart())
            mark = comp.getSelectionEnd();
        else
            mark = comp.getSelectionStart();
        
        if (hasInstruction && coordinate.x == 8 && 
            e.getKeyCode() == KeyEvent.VK_RIGHT && 
            e.getID() == KeyEvent.KEY_PRESSED) {
            
            int newPos = selectionDot + TProgramDocument.COMMENT_COLUMN - 8;
            
            if ((e.getModifiersEx() & mask) == mask)
                comp.select(newPos, mark, newPos);
            else
                comp.select(newPos, newPos, newPos);
            
            return true;
        } else if (hasInstruction && 
                   coordinate.x == TProgramDocument.COMMENT_COLUMN && 
                   e.getKeyCode() == KeyEvent.VK_LEFT && 
                   e.getID() == KeyEvent.KEY_PRESSED) {
            
            int newPos = selectionDot - TProgramDocument.COMMENT_COLUMN + 8;
             
            if ((e.getModifiersEx() & mask) == mask)
                comp.select(newPos, mark, newPos);
            else
                comp.select(newPos, newPos, newPos);
            
            return true;
        } else if (e.getKeyCode() == KeyEvent.VK_RIGHT || e.getKeyCode() == KeyEvent.VK_LEFT)
            return false;
        
        
        // Do nothing if the user is modifying the user-comments column.
        if ((startAfter) || (selStart.x == TProgramDocument.COMMENT_COLUMN && hasSelection) ||
            (coordinate.x == TProgramDocument.COMMENT_COLUMN && 
             e.getKeyCode() != KeyEvent.VK_BACK_SPACE && 
             selStart.x >= coordinate.x)) {
                return false;
        }
        
        
        // Prevent the user from typing in the auto-comment column IF the line
        // begins with a valid instruction
        if (hasInstruction && startIn) {
            // Exclude the case when the user is trying to remove the last character
            // of an instruction.
            if (coordinate.x == 8 && (e.getKeyCode() == KeyEvent.VK_BACK_SPACE)) {
                return false;
            }
            else {
                if (canBeep(e))
                    java.awt.Toolkit.getDefaultToolkit().beep();
                return true;
            }
        }
        
        
        // Prevent the user from typing in the instructions column if there is a
        // valid instruction. The user can only delete or replace the instruction,
        // but not add.
        if (hasInstruction && !hasSelection && coordinate.x < 8) {
            if (e.getKeyCode() != KeyEvent.VK_BACK_SPACE && e.getKeyChar() != '\n') {
                if (canBeep(e))
                    java.awt.Toolkit.getDefaultToolkit().beep();
                return true;
            }
        }

        return false;
    }
    
    private boolean canBeep(KeyEvent e) {
        return e.getID() == KeyEvent.KEY_PRESSED && 
               e.getKeyCode() != KeyEvent.VK_SHIFT &&
               e.getKeyCode() != KeyEvent.VK_CONTROL &&
               e.getKeyCode() != KeyEvent.VK_META &&
               e.getKeyCode() != KeyEvent.VK_ESCAPE;
    }
}