/* -*- mode: java; c-basic-offset: 2; indent-tabs-mode: nil -*- */

/*
  Part of the Processing project - http://processing.org

  Copyright (c) 2012-19 The Processing Foundation
  Copyright (c) 2004-12 Ben Fry and Casey Reas
  Copyright (c) 2001-04 Massachusetts Institute of Technology

  This program 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 2 of the License, or
  (at your option) any later version.

  This program 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 this program; if not, write to the Free Software Foundation,
  Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

package processing.mode.java;

import java.awt.event.KeyEvent;
import java.util.Arrays;

import processing.app.Preferences;
import processing.app.Sketch;
import processing.app.syntax.JEditTextArea;
import processing.app.syntax.PdeInputHandler;
import processing.app.ui.Editor;


/**
 * Filters key events for tab expansion/indent/etc. This is very old code
 * that we'd love to replace with a smarter parser/formatter, rather than
 * continuing to hack this class.
 */
public class JavaInputHandler extends PdeInputHandler {

  public JavaInputHandler(Editor editor) {
    super(editor);
  }


  /**
   * Intercepts key pressed events for JEditTextArea.
   * <p/>
   * Called by JEditTextArea inside processKeyEvent(). Note that this
   * won't intercept actual characters, because those are fired on
   * keyTyped().
   * @return true if the event has been handled (to remove it from the queue)
   */
  public boolean handlePressed(KeyEvent event) {
    char c = event.getKeyChar();
    int code = event.getKeyCode();

    Sketch sketch = editor.getSketch();
    JEditTextArea textarea = editor.getTextArea();

    if (event.isMetaDown()) {
    //if ((event.getModifiers() & InputEvent.META_MASK) != 0) {
      //event.consume();  // does nothing
      return false;
    }

    if ((code == KeyEvent.VK_BACK_SPACE) || (code == KeyEvent.VK_TAB) ||
        (code == KeyEvent.VK_ENTER) || ((c >= 32) && (c < 128))) {
      sketch.setModified(true);
    }

    if ((code == KeyEvent.VK_UP) && event.isControlDown()) {
        //((event.getModifiers() & InputEvent.CTRL_MASK) != 0)) {
      // back up to the last empty line
      char[] contents = textarea.getText().toCharArray();
      //int origIndex = textarea.getCaretPosition() - 1;
      int caretIndex = textarea.getCaretPosition();

      int index = calcLineStart(caretIndex - 1, contents);
      //System.out.println("line start " + (int) contents[index]);
      index -= 2;  // step over the newline
      //System.out.println((int) contents[index]);
      boolean onlySpaces = true;
      while (index > 0) {
        if (contents[index] == 10) {
          if (onlySpaces) {
            index++;
            break;
          } else {
            onlySpaces = true;  // reset
          }
        } else if (contents[index] != ' ') {
          onlySpaces = false;
        }
        index--;
      }
      // if the first char, index will be -2
      if (index < 0) index = 0;

      //if ((event.getModifiers() & InputEvent.SHIFT_MASK) != 0) {
      if (event.isShiftDown()) {
        textarea.setSelectionStart(caretIndex);
        textarea.setSelectionEnd(index);
      } else {
        textarea.setCaretPosition(index);
      }
      event.consume();
//      return true;

    } else if ((code == KeyEvent.VK_DOWN) && event.isControlDown()) {
               //((event.getModifiers() & InputEvent.CTRL_MASK) != 0)) {
      char[] contents = textarea.getText().toCharArray();
      int caretIndex = textarea.getCaretPosition();

      int index = caretIndex;
      int lineStart = 0;
      boolean onlySpaces = false;  // don't count this line
      while (index < contents.length) {
        if (contents[index] == 10) {
          if (onlySpaces) {
            index = lineStart;  // this is it
            break;
          } else {
            lineStart = index + 1;
            onlySpaces = true;  // reset
          }
        } else if (contents[index] != ' ') {
          onlySpaces = false;
        }
        index++;
      }

      //if ((event.getModifiers() & InputEvent.SHIFT_MASK) != 0) {
      if (event.isShiftDown()) {
        textarea.setSelectionStart(caretIndex);
        textarea.setSelectionEnd(index);
      } else {
        textarea.setCaretPosition(index);
      }
      event.consume();
//      return true;

    } else if (c == 9) {
      //if ((event.getModifiers() & InputEvent.SHIFT_MASK) != 0) {
      if (event.isShiftDown()) {
        // if shift is down, the user always expects an outdent
        // https://github.com/processing/processing/issues/497
        editor.handleOutdent();

      } else if (textarea.isSelectionActive()) {
        editor.handleIndent();

      } else if (Preferences.getBoolean("editor.tabs.expand")) {
        int tabSize = Preferences.getInteger("editor.tabs.size");
        textarea.setSelectedText(spaces(tabSize));
        event.consume();

      } else {  // !Preferences.getBoolean("editor.tabs.expand")
        textarea.setSelectedText("\t");
        event.consume();
      }

    } else if (code == 10 || code == 13) {  // auto-indent
      if (Preferences.getBoolean("editor.indent")) {
        char[] contents = textarea.getText().toCharArray();
        int tabSize = Preferences.getInteger("editor.tabs.size");

        // this is the previous character
        // (i.e. when you hit return, it'll be the last character
        // just before where the newline will be inserted)
        int origIndex = textarea.getCaretPosition() - 1;

        // if the previous thing is a brace (whether prev line or
        // up farther) then the correct indent is the number of spaces
        // on that line + 'indent'.
        // if the previous line is not a brace, then just use the
        // identical indentation to the previous line

        // calculate the amount of indent on the previous line
        // this will be used *only if the prev line is not an indent*
        int spaceCount = calcSpaceCount(origIndex, contents);

        // If the last character was a left curly brace, then indent.
        // For 0122, walk backwards a bit to make sure that the there isn't a
        // curly brace several spaces (or lines) back. Also moved this before
        // calculating extraCount, since it'll affect that as well.
        int index2 = origIndex;
        while ((index2 >= 0) &&
               Character.isWhitespace(contents[index2])) {
          index2--;
        }
        if (index2 != -1) {
          // still won't catch a case where prev stuff is a comment
          if (contents[index2] == '{') {
            // intermediate lines be damned,
            // use the indent for this line instead
            spaceCount = calcSpaceCount(index2, contents);
            spaceCount += tabSize;
          }
        }

        // now before inserting this many spaces, walk forward from
        // the caret position and count the number of spaces,
        // so that the number of spaces aren't duplicated again
        int index = origIndex + 1;
        int extraCount = 0;
        while ((index < contents.length) &&
               (contents[index] == ' ')) {
          //spaceCount--;
          extraCount++;
          index++;
        }
        int braceCount = 0;
        while ((index < contents.length) && (contents[index] != '\n')) {
          if (contents[index] == '}') {
            braceCount++;
          }
          index++;
        }

        // Hitting return on a line with spaces *after* the caret
        // can cause trouble. For 0099, was ignoring the case, but this is
        // annoying, so in 0122 we're trying to fix that.
        spaceCount -= extraCount;

        if (spaceCount < 0) {
          // for rev 0122, actually delete extra space
          //textarea.setSelectionStart(origIndex + 1);
          textarea.setSelectionEnd(textarea.getSelectionStop() - spaceCount);
          textarea.setSelectedText("\n");
          textarea.setCaretPosition(textarea.getCaretPosition() + extraCount + spaceCount);
        } else {
          String insertion = "\n" + spaces(spaceCount);
          textarea.setSelectedText(insertion);
          textarea.setCaretPosition(textarea.getCaretPosition() + extraCount);
        }

        // not gonna bother handling more than one brace
        if (braceCount > 0) {
          int sel = textarea.getSelectionStart();
          // sel - tabSize will be -1 if start/end parens on the same line
          // https://download.processing.org/bugzilla/484.html
          if (sel - tabSize >= 0) {
            textarea.select(sel - tabSize, sel);
            String s = spaces(tabSize);
            // if these are spaces that we can delete
            if (s.equals(textarea.getSelectedText())) {
              textarea.setSelectedText("");
            } else {
              textarea.select(sel, sel);
            }
          }
        }
      } else {
        // Enter/Return was being consumed by somehow even if false
        // was returned, so this is a band-aid to simply fire the event again.
        // https://download.processing.org/bugzilla/1073.html
        textarea.setSelectedText(String.valueOf(c));
      }
      // mark this event as already handled (all but ignored)
      event.consume();
//      return true;

    } else if (c == '}') {
      if (Preferences.getBoolean("editor.indent")) {
        // first remove anything that was there (in case this multiple
        // characters are selected, so that it's not in the way of the
        // spaces for the auto-indent
        if (textarea.getSelectionStart() != textarea.getSelectionStop()) {
          textarea.setSelectedText("");
        }

        // if this brace is the only thing on the line, outdent
        char[] contents = textarea.getText().toCharArray();
        // index to the character to the left of the caret
        int prevCharIndex = textarea.getCaretPosition() - 1;

        // backup from the current caret position to the last newline,
        // checking for anything besides whitespace along the way.
        // if there's something besides whitespace, exit without
        // messing any sort of indenting.
        int index = prevCharIndex;
        boolean finished = false;
        while ((index != -1) && (!finished)) {
          if (contents[index] == 10) {
            finished = true;
            index++;
          } else if (contents[index] != ' ') {
            // don't do anything, this line has other stuff on it
            return false;
          } else {
            index--;
          }
        }
        if (!finished) return false;  // brace with no start
        int lineStartIndex = index;

        int pairedSpaceCount = calcBraceIndent(prevCharIndex, contents); //, 1);
        if (pairedSpaceCount == -1) return false;

        textarea.setSelectionStart(lineStartIndex);
        textarea.setSelectedText(spaces(pairedSpaceCount));

        // mark this event as already handled
        event.consume();
        return true;
      }
    }
    return false;
  }


  public boolean handleTyped(KeyEvent event) {
    char c = event.getKeyChar();

    //if ((event.getModifiers() & InputEvent.CTRL_MASK) != 0) {
    if (event.isControlDown()) {  // TODO true on typed? [fry 191007]
      // on linux, ctrl-comma (prefs) being passed through to the editor
      if (c == KeyEvent.VK_COMMA) {
        event.consume();
        return true;
      }
      // https://github.com/processing/processing/issues/3847
      if (c == KeyEvent.VK_SPACE) {
        event.consume();
        return true;
      }
    }
    return false;
  }


  /**
   * Return the index for the first character on this line.
   */
  protected int calcLineStart(int index, char[] contents) {
    // backup from the current caret position to the last newline,
    // so that we can figure out how far this line was indented
    /*int spaceCount = 0;*/
    boolean finished = false;
    while ((index != -1) && (!finished)) {
      if ((contents[index] == 10) ||
          (contents[index] == 13)) {
        finished = true;
        //index++; // maybe ?
      } else {
        index--;  // new
      }
    }
    // add one because index is either -1 (the start of the document)
    // or it's the newline character for the previous line
    return index + 1;
  }


  /**
   * Calculate the number of spaces on this line.
   */
  protected int calcSpaceCount(int index, char[] contents) {
    index = calcLineStart(index, contents);

    int spaceCount = 0;
    // now walk forward and figure out how many spaces there are
    while ((index < contents.length) && (index >= 0) &&
           (contents[index++] == ' ')) {
      spaceCount++;
    }
    return spaceCount;
  }


  /**
   * Walk back from 'index' until the brace that seems to be
   * the beginning of the current block, and return the number of
   * spaces found on that line.
   */
  protected int calcBraceIndent(int index, char[] contents) {
    // now that we know things are ok to be indented, walk
    // backwards to the last { to see how far its line is indented.
    // this isn't perfect cuz it'll pick up commented areas,
    // but that's not really a big deal and can be fixed when
    // this is all given a more complete (proper) solution.
    int braceDepth = 1;
    boolean finished = false;
    while ((index != -1) && (!finished)) {
      if (contents[index] == '}') {
        // aww crap, this means we're one deeper
        // and will have to find one more extra {
        braceDepth++;
        //if (braceDepth == 0) {
        //finished = true;
        //}
        index--;
      } else if (contents[index] == '{') {
        braceDepth--;
        if (braceDepth == 0) {
          finished = true;
        }
        index--;
      } else {
        index--;
      }
    }
    // never found a proper brace, be safe and don't do anything
    if (!finished) return -1;

    // check how many spaces on the line with the matching open brace
    //int pairedSpaceCount = calcSpaceCount(index, contents);
    return calcSpaceCount(index, contents);
  }


  static private String spaces(int count) {
    char[] c = new char[count];
    Arrays.fill(c, ' ');
    return new String(c);
  }
}
