// Copyright 2012 Google Inc. All Rights Reserved.
//
// 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.apache.org/licenses/LICENSE-2.0
//
// 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.

package com.google.collide.client.editor.selection;

import com.google.collide.client.AppContext;
import com.google.collide.client.util.CssUtils;
import com.google.collide.client.util.Elements;
import com.google.collide.mvp.CompositeView;
import com.google.collide.mvp.UiComponent;
import com.google.gwt.resources.client.ClientBundle;
import com.google.gwt.resources.client.CssResource;
import com.google.gwt.user.client.Timer;

import elemental.css.CSSStyleDeclaration;
import elemental.html.Element;

/**
 * A presenter and anchor renderer for a cursor.
 */
public class CursorView extends UiComponent<CursorView.View> {

  /**
   * Static factory method for obtaining an instance of the CursorView.
   */
  public static CursorView create(AppContext appContext, boolean isLocal) {
    View view = new View(appContext.getResources(), isLocal);
    return new CursorView(view, isLocal);
  }

  public interface Css extends CssResource {
    String caret();

    String root();

    String block();
  }

  public interface Resources extends ClientBundle {
    @Source({"CursorView.css", "com/google/collide/client/editor/constants.css"})
    Css workspaceEditorCursorCss();
  }

  static class View extends CompositeView<ViewEvents> {
    private final Css css;
    private Element caret;

    private View(Resources res, boolean isLocal) {
      this.css = res.workspaceEditorCursorCss();
      setElement(createElement(isLocal));
    }

    private Element createElement(boolean isLocal) {
      caret = Elements.createDivElement(css.caret());

      Element root = Elements.createDivElement(css.root());
      root.appendChild(caret);
      root.getStyle().setZIndex(isLocal ? 1 : 0);

      return root;
    }

    private boolean isCaretVisible() {
      return caret.getStyle().getVisibility().equals(CSSStyleDeclaration.Visibility.VISIBLE);
    }

    private void setCaretVisible(boolean visible) {
      caret.getStyle().setVisibility(
          visible ? CSSStyleDeclaration.Visibility.VISIBLE : CSSStyleDeclaration.Visibility.HIDDEN);
    }

    private void setColor(String color) {
      caret.getStyle().setBackgroundColor(color);
    }

    private void setBlockMode(boolean isBlockMode) {
      if (isBlockMode) {
        caret.addClassName(css.block());
      } else {
        caret.removeClassName(css.block());
      }
    }
  }

  interface ViewEvents {
    // TODO: onHover, so we can show the label
  }

  private static final int CARET_BLINK_PERIOD_MS = 500;

  private final Timer caretBlinker = new Timer() {
    @Override
    public void run() {
      getView().setCaretVisible(!getView().isCaretVisible());
    }
  };

  private final boolean isLocal;
  private boolean isVisible = true;

  private CursorView(View view, boolean isLocal) {
    super(view);

    this.isLocal = isLocal;
  }

  public Element getElement() {
    return getView().getElement();
  }

  public void setVisibility(boolean isVisible) {
    this.isVisible = isVisible;
    
    /*
     * Use display-based visibility since visibility-based visibility is used
     * for blinking
     */
    CssUtils.setDisplayVisibility2(getView().getElement(), isVisible);

    if (isLocal) {
      // Blink the local cursor
      if (isVisible) {
        caretBlinker.scheduleRepeating(CARET_BLINK_PERIOD_MS);
      } else {
        caretBlinker.cancel();
      }
    }
  }
  
  public boolean isVisible() {
    return isVisible;
  }

  public void setColor(String color) {
    getView().setColor(color);
  }

  /**
   * @param isBlockMode If true, change the cursor into a block that covers the entire
   *        character.
   */
  public void setBlockMode(boolean isBlockMode) {
    getView().setBlockMode(isBlockMode);
  }

  void forceSolidBlinkState() {

    if (!isLocal) {
      return;
    }

    getView().setCaretVisible(true);
    caretBlinker.scheduleRepeating(CARET_BLINK_PERIOD_MS);
  }
}