/**
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */

package com.facebook.react.views.modal;

import javax.annotation.Nullable;

import java.util.ArrayList;

import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;

import com.facebook.infer.annotation.Assertions;
import com.facebook.react.R;
import com.facebook.react.bridge.ReactContext;
import com.facebook.react.common.annotations.VisibleForTesting;
import com.facebook.react.uimanager.JSTouchDispatcher;
import com.facebook.react.uimanager.RootView;
import com.facebook.react.uimanager.UIManagerModule;
import com.facebook.react.uimanager.events.EventDispatcher;
import com.facebook.react.views.view.ReactViewGroup;

/**
 * ReactModalHostView is a view that sits in the view hierarchy representing a Modal view.
 *
 * It does a number of things:
 *  1. It creates a Dialog.  We use this Dialog to actually display the Modal in the window.
 *  2. It creates a DialogRootViewGroup.  This view is the view that is displayed by the Dialog. To
 *     display a view within a Dialog, that view must have its parent set to the window the Dialog
 *     creates.  Because of this, we can not use the ReactModalHostView since it sits in the
 *     normal React view hierarchy.  We do however want all of the layout magic to happen as if the
 *     DialogRootViewGroup were part of the hierarchy.  Therefore, we forward all view changes
 *     around addition and removal of views to the DialogRootViewGroup.
 */
public class ReactModalHostView extends ViewGroup {

  // This listener is called when the user presses KeyEvent.KEYCODE_BACK
  // An event is then passed to JS which can either close or not close the Modal by setting the
  // visible property
  public interface OnRequestCloseListener {
    void onRequestClose(DialogInterface dialog);
  }

  private DialogRootViewGroup mHostView;
  private @Nullable Dialog mDialog;
  private boolean mTransparent;
  private boolean mAnimated;
  // Set this flag to true if changing a particular property on the view requires a new Dialog to
  // be created.  For instance, animation does since it affects Dialog creation through the theme
  // but transparency does not since we can access the window to update the property.
  private boolean mPropertyRequiresNewDialog;
  private @Nullable DialogInterface.OnShowListener mOnShowListener;
  private @Nullable OnRequestCloseListener mOnRequestCloseListener;

  public ReactModalHostView(Context context) {
    super(context);

    mHostView = new DialogRootViewGroup(context);
  }

  @Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    // Do nothing as we are laid out by UIManager
  }

  @Override
  public void addView(View child, int index) {
    mHostView.addView(child, index);
  }

  @Override
  public int getChildCount() {
    return mHostView.getChildCount();
  }

  @Override
  public View getChildAt(int index) {
    return mHostView.getChildAt(index);
  }

  @Override
  public void removeView(View child) {
    mHostView.removeView(child);
  }

  @Override
  public void removeViewAt(int index) {
    View child = getChildAt(index);
    mHostView.removeView(child);
  }

  @Override
  public void addChildrenForAccessibility(ArrayList<View> outChildren) {
    // Explicitly override this to prevent accessibility events being passed down to children
    // Those will be handled by the mHostView which lives in the dialog
  }

  public void dismiss() {
    if (mDialog != null) {
      mDialog.dismiss();
      mDialog = null;

      // We need to remove the mHostView from the parent
      // It is possible we are dismissing this dialog and reattaching the hostView to another
      ViewGroup parent = (ViewGroup) mHostView.getParent();
      parent.removeViewAt(0);
    }
  }

  protected void setOnRequestCloseListener(OnRequestCloseListener listener) {
    mOnRequestCloseListener = listener;
  }

  protected void setOnShowListener(DialogInterface.OnShowListener listener) {
    mOnShowListener = listener;
  }

  protected void setTransparent(boolean transparent) {
    mTransparent = transparent;
  }

  protected void setAnimated(boolean animated) {
    mAnimated = animated;
    mPropertyRequiresNewDialog = true;
  }

  @VisibleForTesting
  public @Nullable Dialog getDialog() {
    return mDialog;
  }

  /**
   * showOrUpdate will display the Dialog.  It is called by the manager once all properties are set
   * because we need to know all of them before creating the Dialog.  It is also smart during
   * updates if the changed properties can be applied directly to the Dialog or require the
   * recreation of a new Dialog.
   */
  protected void showOrUpdate() {
    // If the existing Dialog is currently up, we may need to redraw it or we may be able to update
    // the property without having to recreate the dialog
    if (mDialog != null) {
      if (mPropertyRequiresNewDialog) {
        dismiss();
      } else {
        updateProperties();
        return;
      }
    }

    // Reset the flag since we are going to create a new dialog
    mPropertyRequiresNewDialog = false;
    int theme = R.style.Theme_FullScreenDialog;
    if (mAnimated) {
      theme = R.style.Theme_FullScreenDialogAnimated;
    }
    mDialog = new Dialog(getContext(), theme);

    mDialog.setContentView(mHostView);
    updateProperties();

    mDialog.setOnShowListener(mOnShowListener);
    mDialog.setOnKeyListener(
      new DialogInterface.OnKeyListener() {
        @Override
        public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event) {
          // We need to stop the BACK button from closing the dialog by default so we capture that
          // event and instead inform JS so that it can make the decision as to whether or not to
          // allow the back button to close the dialog.  If it chooses to, it can just set visible
          // to false on the Modal and the Modal will go away
          if (keyCode == KeyEvent.KEYCODE_BACK) {
            if (event.getAction() == KeyEvent.ACTION_UP) {
              Assertions.assertNotNull(
                  mOnRequestCloseListener,
                  "setOnRequestCloseListener must be called by the manager");
              mOnRequestCloseListener.onRequestClose(dialog);
            }
            return true;
          }
          return false;
        }
      });

    mDialog.show();
  }

  /**
   * updateProperties will update the properties that do not require us to recreate the dialog
   * Properties that do require us to recreate the dialog should set mPropertyRequiresNewDialog to
   * true when the property changes
   */
  private void updateProperties() {
    Assertions.assertNotNull(mDialog, "mDialog must exist when we call updateProperties");

    if (mTransparent) {
      mDialog.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
    } else {
      mDialog.getWindow().setDimAmount(0.5f);
      mDialog.getWindow().setFlags(
          WindowManager.LayoutParams.FLAG_DIM_BEHIND,
          WindowManager.LayoutParams.FLAG_DIM_BEHIND);
    }
  }

  /**
   * DialogRootViewGroup is the ViewGroup which contains all the children of a Modal.  It gets all
   * child information forwarded from ReactModalHostView and uses that to create children.  It is
   * also responsible for acting as a RootView and handling touch events.  It does this the same
   * way as ReactRootView.
   */
  static class DialogRootViewGroup extends ReactViewGroup implements RootView {

    private final JSTouchDispatcher mJSTouchDispatcher = new JSTouchDispatcher(this);

    public DialogRootViewGroup(Context context) {
      super(context);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent event) {
      mJSTouchDispatcher.handleTouchEvent(event, getEventDispatcher());
      return super.onInterceptTouchEvent(event);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
      mJSTouchDispatcher.handleTouchEvent(event, getEventDispatcher());
      super.onTouchEvent(event);
      // In case when there is no children interested in handling touch event, we return true from
      // the root view in order to receive subsequent events related to that gesture
      return true;
    }

    @Override
    public void onChildStartedNativeGesture(MotionEvent androidEvent) {
      mJSTouchDispatcher.onChildStartedNativeGesture(androidEvent, getEventDispatcher());
    }

    @Override
    public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
      // No-op - override in order to still receive events to onInterceptTouchEvent
      // even when some other view disallow that
    }

    private EventDispatcher getEventDispatcher() {
      ReactContext reactContext = (ReactContext) getContext();
      return reactContext.getNativeModule(UIManagerModule.class).getEventDispatcher();
    }
  }
}