/*
 * Copyright 2013 Google Inc.
 *
 * 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.dexafree.materialList.listeners;

import android.graphics.Rect;
import android.os.SystemClock;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.ViewPropertyAnimator;
import android.widget.AbsListView;
import android.widget.ListView;

import com.nineoldandroids.animation.Animator;
import com.nineoldandroids.animation.AnimatorListenerAdapter;
import com.nineoldandroids.animation.ValueAnimator;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import static com.nineoldandroids.view.ViewHelper.setAlpha;
import static com.nineoldandroids.view.ViewHelper.setTranslationX;
import static com.nineoldandroids.view.ViewPropertyAnimator.animate;

/**
 * A {@link View.OnTouchListener} that makes the list items in a {@link ListView} dismissable.
 * {@link ListView} is given special treatment because by default it handles touches for its list
 * items... i.e. it's in charge of drawing the pressed state (the list selector), handling list item
 * clicks, etc.
 * <p/>
 * <p>After creating the listener, the caller should also call {@link
 * ListView#setOnScrollListener(AbsListView.OnScrollListener)}, passing in the scroll listener
 * returned by {@link #makeScrollListener()}. If a scroll listener is already assigned, the caller
 * should still pass scroll changes through to this listener. This will ensure that this {@link
 * SwipeDismissRecyclerViewTouchListener} is paused during list view scrolling.</p>
 * <p/>
 * <p>Example usage:</p>
 * <p/>
 * <pre>
 * SwipeDismissRecyclerViewTouchListener touchListener =
 *         new SwipeDismissRecyclerViewTouchListener(
 *                 listView,
 *                 new SwipeDismissRecyclerViewTouchListener.OnDismissCallback() {
 *                     public void onDismiss(ListView listView, int[] reverseSortedPositions) {
 *                         for (int position : reverseSortedPositions) {
 *                             adapter.remove(adapter.getItem(position));
 *                         }
 *                         adapter.notifyDataSetChanged();
 *                     }
 *                 });
 * listView.setOnTouchListener(touchListener);
 * listView.setOnScrollListener(touchListener.makeScrollListener());
 * </pre>
 * <p/>
 * <p>This class Requires API level 12 or later due to use of {@link ViewPropertyAnimator}.</p>
 * <p/>
 * <p>For a generalized {@link View.OnTouchListener} that makes any view dismissable.</p>
 *
 */
public class SwipeDismissRecyclerViewTouchListener implements View.OnTouchListener {
	// Cached ViewConfiguration and system-wide constant values
	private int mSlop;
	private int mMinFlingVelocity;
	private int mMaxFlingVelocity;
	private long mAnimationTime;

	// Fixed properties
	private RecyclerView mRecyclerView;
	private DismissCallbacks mCallbacks;
	private int mViewWidth = 1; // 1 and not 0 to prevent dividing by zero

	// Transient properties
	private List<PendingDismissData> mPendingDismisses = new ArrayList<>();
	private int mDismissAnimationRefCount = 0;
	private float mDownX;
	private float mDownY;
	private boolean mSwiping;
	private int mSwipingSlop;
	private VelocityTracker mVelocityTracker;
	private int mDownPosition;
	private View mDownView;
	private boolean mPaused;

	/**
	 * The callback interface used by {@link SwipeDismissRecyclerViewTouchListener} to inform its
	 * client about a successful dismissal of one or more list item positions.
	 */
	public interface DismissCallbacks {
		/**
		 * Called to determine whether the given position can be dismissed.
		 */
		boolean canDismiss(int position);

		/**
		 * Called when the user has indicated they she would like to dismiss one or more list item
		 * positions.
		 *
		 * @param recyclerView
		 * 		The originating {@link ListView}.
		 * @param reverseSortedPositions
		 * 		An array of positions to dismiss, sorted in descending order for convenience.
		 */
		void onDismiss(RecyclerView recyclerView, int[] reverseSortedPositions);
	}

	/**
	 * Constructs a new swipe-to-dismiss touch listener for the given list view.
	 *
	 * @param recyclerView
	 * 		The list view whose items should be dismissable.
	 * @param callbacks
	 * 		The callback to trigger when the user has indicated that she would like to dismiss one or
	 * 		more list items.
	 */
	public SwipeDismissRecyclerViewTouchListener(RecyclerView recyclerView, DismissCallbacks callbacks) {
		ViewConfiguration vc = ViewConfiguration.get(recyclerView.getContext());
		mSlop = vc.getScaledTouchSlop();
		mMinFlingVelocity = vc.getScaledMinimumFlingVelocity() * 16;
		mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
		mAnimationTime = recyclerView.getContext().getResources().getInteger(
				android.R.integer.config_shortAnimTime);
		mRecyclerView = recyclerView;
		mCallbacks = callbacks;
	}

	/**
	 * Enables or disables (pauses or resumes) watching for swipe-to-dismiss gestures.
	 *
	 * @param enabled
	 * 		Whether or not to watch for gestures.
	 */
	public void setEnabled(boolean enabled) {
		mPaused = !enabled;
	}

	/**
	 * Returns an {@link AbsListView.OnScrollListener} to be added to the {@link ListView} using
	 * {@link ListView#setOnScrollListener(AbsListView.OnScrollListener)}. If a scroll listener is
	 * already assigned, the caller should still pass scroll changes through to this listener. This
	 * will ensure that this {@link SwipeDismissRecyclerViewTouchListener} is paused during list
	 * view scrolling.</p>
	 *
	 * @see SwipeDismissRecyclerViewTouchListener
	 */
	public RecyclerView.OnScrollListener makeScrollListener() {
		return new RecyclerView.OnScrollListener() {
			@Override
			public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
				setEnabled(newState != AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
			}

			@Override
			public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
			}
		};
	}

	@Override
	public boolean onTouch(View view, MotionEvent motionEvent) {
		if (mViewWidth < 2) {
			mViewWidth = mRecyclerView.getWidth();
		}

		switch (motionEvent.getActionMasked()) {
			case MotionEvent.ACTION_DOWN: {
				if (mPaused) {
					return false;
				}

				// TODO: ensure this is a finger, and set a flag

				// Find the child view that was touched (perform a hit test)
				Rect rect = new Rect();
				int childCount = mRecyclerView.getChildCount();
				int[] listViewCoords = new int[2];
				mRecyclerView.getLocationOnScreen(listViewCoords);
				int x = (int) motionEvent.getRawX() - listViewCoords[0];
				int y = (int) motionEvent.getRawY() - listViewCoords[1];
				View child;
				for (int i = 0; i < childCount; i++) {
					child = mRecyclerView.getChildAt(i);
					child.getHitRect(rect);
					if (rect.contains(x, y)) {
						mDownView = child;
						break;
					}
				}

				if (mDownView != null) {
					mDownX = motionEvent.getRawX();
					mDownY = motionEvent.getRawY();
					mDownPosition = mRecyclerView.getChildPosition(mDownView);
					if (mCallbacks.canDismiss(mDownPosition)) {
						mVelocityTracker = VelocityTracker.obtain();
						mVelocityTracker.addMovement(motionEvent);
					} else {
						mDownView = null;
					}
				}
				return false;
			}

			case MotionEvent.ACTION_CANCEL: {
				if (mVelocityTracker == null) {
					break;
				}

				if (mDownView != null && mSwiping) {
					// cancel
					animate(mDownView)
							.translationX(0)
							.alpha(1)
							.setDuration(mAnimationTime)
							.setListener(null);
				}
				mVelocityTracker.recycle();
				mVelocityTracker = null;
				mDownX = 0;
				mDownY = 0;
				mDownView = null;
				mDownPosition = ListView.INVALID_POSITION;
				mSwiping = false;
				break;
			}

			case MotionEvent.ACTION_UP: {
				if (mVelocityTracker == null) {
					break;
				}

				float deltaX = motionEvent.getRawX() - mDownX;
				mVelocityTracker.addMovement(motionEvent);
				mVelocityTracker.computeCurrentVelocity(1000);
				float velocityX = mVelocityTracker.getXVelocity();
				float absVelocityX = Math.abs(velocityX);
				float absVelocityY = Math.abs(mVelocityTracker.getYVelocity());
				boolean dismiss = false;
				boolean dismissRight = false;
				if (Math.abs(deltaX) > mViewWidth / 2 && mSwiping) {
					dismiss = true;
					dismissRight = deltaX > 0;
				} else if (mMinFlingVelocity <= absVelocityX && absVelocityX <= mMaxFlingVelocity
						&& absVelocityY < absVelocityX && mSwiping) {
					// dismiss only if flinging in the same direction as dragging
					dismiss = (velocityX < 0) == (deltaX < 0);
					dismissRight = mVelocityTracker.getXVelocity() > 0;
				}
				if (dismiss && mDownPosition != ListView.INVALID_POSITION) {
					// dismiss
					final View downView = mDownView; // mDownView gets null'd before animation ends
					final int downPosition = mDownPosition;
					++mDismissAnimationRefCount;
					animate(mDownView)
							.translationX(dismissRight ? mViewWidth : -mViewWidth)
							.alpha(0)
							.setDuration(mAnimationTime)
							.setListener(new AnimatorListenerAdapter() {
								@Override
								public void onAnimationEnd(Animator animation) {
									performDismiss(downView, downPosition);
								}
							});
				} else {
					// cancel
					animate(mDownView)
							.translationX(0)
							.alpha(1)
							.setDuration(mAnimationTime)
							.setListener(null);
				}
				mVelocityTracker.recycle();
				mVelocityTracker = null;
				mDownX = 0;
				mDownY = 0;
				mDownView = null;
				mDownPosition = ListView.INVALID_POSITION;
				mSwiping = false;
				break;
			}

			case MotionEvent.ACTION_MOVE: {
				if (mVelocityTracker == null || mPaused) {
					break;
				}

				mVelocityTracker.addMovement(motionEvent);
				float deltaX = motionEvent.getRawX() - mDownX;
				float deltaY = motionEvent.getRawY() - mDownY;
				if (Math.abs(deltaX) > mSlop && Math.abs(deltaY) < Math.abs(deltaX) / 2) {
					mSwiping = true;
					mSwipingSlop = (deltaX > 0 ? mSlop : -mSlop);
					mRecyclerView.requestDisallowInterceptTouchEvent(true);

					// Cancel ListView's touch (un-highlighting the item)
					MotionEvent cancelEvent = MotionEvent.obtain(motionEvent);
					cancelEvent.setAction(MotionEvent.ACTION_CANCEL |
							(motionEvent.getActionIndex()
									<< MotionEvent.ACTION_POINTER_INDEX_SHIFT));
					mRecyclerView.onTouchEvent(cancelEvent);
					cancelEvent.recycle();
				}

				if (mSwiping) {
					setTranslationX(mDownView, deltaX - mSwipingSlop);
					setAlpha(mDownView, Math.max(0f, Math.min(1f,
							1f - 2f * Math.abs(deltaX) / mViewWidth)));
					return true;
				}
				break;
			}
		}
		return false;
	}

	class PendingDismissData implements Comparable<PendingDismissData> {
		public int position;
		public View view;

		public PendingDismissData(int position, View view) {
			this.position = position;
			this.view = view;
		}

		@Override
		public int compareTo(@NonNull PendingDismissData other) {
			// Sort by descending position
			return other.position - position;
		}
	}

	public void dismissCard(final View downView, final int position) {
		float viewWidth = downView.getMeasuredWidth();

		++mDismissAnimationRefCount;
		animate(downView)
				.translationX(viewWidth)
				.alpha(0)
				.setDuration(mAnimationTime)
				.setListener(new AnimatorListenerAdapter() {
					@Override
					public void onAnimationEnd(Animator animation) {
						performDismiss(downView, position);
					}
				});
	}

	private void performDismiss(final View dismissView, final int dismissPosition) {
		// Animate the dismissed list item to zero-height and fire the dismiss callback when
		// all dismissed list item animations have completed. This triggers layout on each animation
		// frame; in the future we may want to do something smarter and more performant.

		final ViewGroup.LayoutParams lp = dismissView.getLayoutParams();
		final int originalHeight = dismissView.getHeight();

		ValueAnimator animator = ValueAnimator.ofInt(originalHeight, 1).setDuration(mAnimationTime);

		animator.addListener(new AnimatorListenerAdapter() {
			@Override
			public void onAnimationEnd(Animator animation) {
				--mDismissAnimationRefCount;
				if (mDismissAnimationRefCount == 0) {
					// No active animations, process all pending dismisses.
					// Sort by descending position
					Collections.sort(mPendingDismisses);

					int[] dismissPositions = new int[mPendingDismisses.size()];
					for (int i = mPendingDismisses.size() - 1; i >= 0; i--) {
						dismissPositions[i] = mPendingDismisses.get(i).position;
					}
					mCallbacks.onDismiss(mRecyclerView, dismissPositions);

					// Reset mDownPosition to avoid MotionEvent.ACTION_UP trying to start a dismiss
					// animation withProvider a stale position
					mDownPosition = ListView.INVALID_POSITION;

					ViewGroup.LayoutParams lp;
					for (PendingDismissData pendingDismiss : mPendingDismisses) {
						// Reset view presentation
						setAlpha(pendingDismiss.view, 1f);
						setTranslationX(pendingDismiss.view, 0);
						lp = pendingDismiss.view.getLayoutParams();
						lp.height = originalHeight;
						pendingDismiss.view.setLayoutParams(lp);
					}

					// Send a cancel event
					long time = SystemClock.uptimeMillis();
					MotionEvent cancelEvent = MotionEvent.obtain(time, time,
							MotionEvent.ACTION_CANCEL, 0, 0, 0);
					mRecyclerView.dispatchTouchEvent(cancelEvent);

					mPendingDismisses.clear();
				}
			}
		});

		animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
			@Override
			public void onAnimationUpdate(ValueAnimator valueAnimator) {
				lp.height = (Integer) valueAnimator.getAnimatedValue();
				dismissView.setLayoutParams(lp);
			}
		});

		mPendingDismisses.add(new PendingDismissData(dismissPosition, dismissView));
		animator.start();
	}
}
