package juloo.keyboard2;

import android.annotation.SuppressLint;
import android.os.Looper;
import android.text.InputType;
import android.view.KeyEvent;
import android.view.inputmethod.EditorInfo;
import android.view.inputmethod.ExtractedText;
import android.view.inputmethod.ExtractedTextRequest;
import android.view.inputmethod.InputConnection;
import java.util.Iterator;

public final class KeyEventHandler implements Config.IKeyEventHandler
{
  IReceiver _recv;
  Autocapitalisation _autocap;
  /** State of the system modifiers. It is updated whether a modifier is down
      or up and a corresponding key event is sent. */
  Pointers.Modifiers _mods;
  /** Consistent with [_mods]. This is a mutable state rather than computed
      from [_mods] to ensure that the meta state is correct while up and down
      events are sent for the modifier keys. */
  int _meta_state = 0;
  /** Whether to force sending arrow keys to move the cursor when
      [setSelection] could be used instead. */
  boolean _move_cursor_force_fallback = false;

  public KeyEventHandler(Looper looper, IReceiver recv)
  {
    _recv = recv;
    _autocap = new Autocapitalisation(looper,
        this.new Autocapitalisation_callback());
    _mods = Pointers.Modifiers.EMPTY;
  }

  /** Editing just started. */
  public void started(EditorInfo info)
  {
    _autocap.started(info, _recv.getCurrentInputConnection());
    // Workaround a bug in Acode, which answers to [getExtractedText] but do
    // not react to [setSelection] while returning [true].
    // Note: Using & to workaround a bug in Acode, which sets several
    // variations at once.
    _move_cursor_force_fallback = (info.inputType & InputType.TYPE_MASK_VARIATION &
      InputType.TYPE_TEXT_VARIATION_PASSWORD) != 0;
  }

  /** Selection has been updated. */
  public void selection_updated(int oldSelStart, int newSelStart)
  {
    _autocap.selection_updated(oldSelStart, newSelStart);
  }

  /** A key is being pressed. There will not necessarily be a corresponding
      [key_up] event. */
  @Override
  public void key_down(KeyValue key, boolean isSwipe)
  {
    if (key == null)
      return;
    switch (key.getKind())
    {
      case Modifier:
        // Stop auto capitalisation when activating a system modifier
        switch (key.getModifier())
        {
          case CTRL:
          case ALT:
          case META:
            _autocap.stop();
            break;
          case COMPOSE_PENDING:
            KeyModifier.set_compose_pending(0);
            break;
        }
        break;
      default: break;
    }
  }

  /** A key has been released. */
  @Override
  public void key_up(KeyValue key, Pointers.Modifiers mods)
  {
    if (key == null)
      return;
    Pointers.Modifiers old_mods = _mods;
    update_meta_state(mods);
    switch (key.getKind())
    {
      case Char: send_text(String.valueOf(key.getChar())); break;
      case String: send_text(key.getString()); break;
      case Event: _recv.handle_event_key(key.getEvent()); break;
      case Keyevent: send_key_down_up(key.getKeyevent()); break;
      case Modifier: break;
      case Editing: handle_editing_key(key.getEditing()); break;
      case Compose_pending:
        KeyModifier.set_compose_pending(key.getPendingCompose());
        _recv.set_compose_pending(true);
        break;
    }
    update_meta_state(old_mods);
  }

  @Override
  public void mods_changed(Pointers.Modifiers mods)
  {
    update_meta_state(mods);
  }

  /** Update [_mods] to be consistent with the [mods], sending key events if
      needed. */
  void update_meta_state(Pointers.Modifiers mods)
  {
    // Released modifiers
    Iterator<KeyValue.Modifier> it = _mods.diff(mods);
    while (it.hasNext())
      sendMetaKeyForModifier(it.next(), false);
    // Activated modifiers
    it = mods.diff(_mods);
    while (it.hasNext())
      sendMetaKeyForModifier(it.next(), true);
    _mods = mods;
  }

  // private void handleDelKey(int before, int after)
  // {
  //  CharSequence selection = getCurrentInputConnection().getSelectedText(0);

  //  if (selection != null && selection.length() > 0)
  //  getCurrentInputConnection().commitText("", 1);
  //  else
  //  getCurrentInputConnection().deleteSurroundingText(before, after);
  // }

  void sendMetaKey(int eventCode, int meta_flags, boolean down)
  {
    if (down)
    {
      _meta_state = _meta_state | meta_flags;
      send_keyevent(KeyEvent.ACTION_DOWN, eventCode);
    }
    else
    {
      send_keyevent(KeyEvent.ACTION_UP, eventCode);
      _meta_state = _meta_state & ~meta_flags;
    }
  }

  void sendMetaKeyForModifier(KeyValue.Modifier mod, boolean down)
  {
    switch (mod)
    {
      case CTRL:
        sendMetaKey(KeyEvent.KEYCODE_CTRL_LEFT, KeyEvent.META_CTRL_LEFT_ON | KeyEvent.META_CTRL_ON, down);
        break;
      case ALT:
        sendMetaKey(KeyEvent.KEYCODE_ALT_LEFT, KeyEvent.META_ALT_LEFT_ON | KeyEvent.META_ALT_ON, down);
        break;
      case SHIFT:
        sendMetaKey(KeyEvent.KEYCODE_SHIFT_LEFT, KeyEvent.META_SHIFT_LEFT_ON | KeyEvent.META_SHIFT_ON, down);
        break;
      case META:
        sendMetaKey(KeyEvent.KEYCODE_META_LEFT, KeyEvent.META_META_LEFT_ON | KeyEvent.META_META_ON, down);
        break;
      default:
        break;
    }
  }

  /*
   * Don't set KeyEvent.FLAG_SOFT_KEYBOARD.
   */
  void send_key_down_up(int keyCode)
  {
    send_keyevent(KeyEvent.ACTION_DOWN, keyCode);
    send_keyevent(KeyEvent.ACTION_UP, keyCode);
  }

  void send_keyevent(int eventAction, int eventCode)
  {
    InputConnection conn = _recv.getCurrentInputConnection();
    if (conn == null)
      return;
    conn.sendKeyEvent(new KeyEvent(1, 1, eventAction, eventCode, 0, _meta_state));
    if (eventAction == KeyEvent.ACTION_UP)
      _autocap.event_sent(eventCode, _meta_state);
  }

  void send_text(CharSequence text)
  {
    InputConnection conn = _recv.getCurrentInputConnection();
    if (conn == null)
      return;
    conn.commitText(text, 1);
    _autocap.typed(text);
  }

  /** See {!InputConnection.performContextMenuAction}. */
  void send_context_menu_action(int id)
  {
    InputConnection conn = _recv.getCurrentInputConnection();
    if (conn == null)
      return;
    conn.performContextMenuAction(id);
  }

  @SuppressLint("InlinedApi")
  void handle_editing_key(KeyValue.Editing ev)
  {
    switch (ev)
    {
      case COPY: send_context_menu_action(android.R.id.copy); break;
      case PASTE: send_context_menu_action(android.R.id.paste); break;
      case CUT: send_context_menu_action(android.R.id.cut); break;
      case SELECT_ALL: send_context_menu_action(android.R.id.selectAll); break;
      case SHARE: send_context_menu_action(android.R.id.shareText); break;
      case PASTE_PLAIN: send_context_menu_action(android.R.id.pasteAsPlainText); break;
      case UNDO: send_context_menu_action(android.R.id.undo); break;
      case REDO: send_context_menu_action(android.R.id.redo); break;
      case REPLACE: send_context_menu_action(android.R.id.replaceText); break;
      case ASSIST: send_context_menu_action(android.R.id.textAssist); break;
      case AUTOFILL: send_context_menu_action(android.R.id.autofill); break;
      case CURSOR_LEFT: move_cursor(-1); break;
      case CURSOR_RIGHT: move_cursor(1); break;
    }
  }

  static ExtractedTextRequest _move_cursor_req = null;

  /** Query the cursor position. The extracted text is empty. Returns [null] if
      the editor doesn't support this operation. */
  ExtractedText get_cursor_pos(InputConnection conn)
  {
    if (_move_cursor_req == null)
    {
      _move_cursor_req = new ExtractedTextRequest();
      _move_cursor_req.hintMaxChars = 0;
    }
    return conn.getExtractedText(_move_cursor_req, 0);
  }

  /** Move the cursor right or left, if possible without sending key events.
      Unlike arrow keys, the selection is not removed even if shift is not on.
      Falls back to sending arrow keys events if the editor do not support
      moving the cursor or a modifier other than shift is pressed. */
  void move_cursor(int d)
  {
    InputConnection conn = _recv.getCurrentInputConnection();
    if (conn == null)
      return;
    ExtractedText et = get_cursor_pos(conn);
    // Fallback to sending key events
    if (_move_cursor_force_fallback
        || et == null
        || _mods.has(KeyValue.Modifier.CTRL)
        || _mods.has(KeyValue.Modifier.ALT)
        || _mods.has(KeyValue.Modifier.META))
    {
      move_cursor_fallback(d);
      return;
    }
    int sel_start = et.selectionStart;
    int sel_end = et.selectionEnd;
    // Continue expanding the selection even if shift is not pressed
    if (sel_end != sel_start)
    {
      sel_end += d;
      if (sel_end == sel_start) // Avoid making the selection empty
        sel_end += d;
    }
    else
    {
      sel_end += d;
      // Leave 'sel_start' where it is if shift is pressed
      if (!_mods.has(KeyValue.Modifier.SHIFT))
        sel_start = sel_end;
    }
    if (!conn.setSelection(sel_start, sel_end))
      move_cursor_fallback(d);
  }

  /** Send arrow keys as a fallback for editors that do not support
      [getExtractedText] like Termux. */
  void move_cursor_fallback(int d)
  {
    while (d < 0)
    {
      send_key_down_up(KeyEvent.KEYCODE_DPAD_LEFT);
      d++;
    }
    while (d > 0)
    {
      send_key_down_up(KeyEvent.KEYCODE_DPAD_RIGHT);
      d--;
    }
  }

  public static interface IReceiver
  {
    public void handle_event_key(KeyValue.Event ev);
    public void set_shift_state(boolean state, boolean lock);
    public void set_compose_pending(boolean pending);
    public InputConnection getCurrentInputConnection();
  }

  class Autocapitalisation_callback implements Autocapitalisation.Callback
  {
    @Override
    public void update_shift_state(boolean should_enable, boolean should_disable)
    {
      if (should_enable)
        _recv.set_shift_state(true, false);
      else if (should_disable)
        _recv.set_shift_state(false, false);
    }
  }
}