/*
 * Copyright 2014 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 org.nativescript.widgets;

import android.content.Context;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.util.SparseArray;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.HorizontalScrollView;
import android.widget.ImageView;
import android.widget.ImageView.ScaleType;
import android.widget.LinearLayout;
import android.widget.TextView;

import androidx.viewpager.widget.PagerAdapter;
import androidx.viewpager.widget.ViewPager;

/**
 * To be used with ViewPager to provide a tab indicator component which give
 * constant feedback as to the user's scroll progress.
 * <p>
 * To use the component, simply add it to your view hierarchy. Then in your
 * {@link android.app.Activity} or {@link android.app.Fragment} call
 * {@link #setViewPager(ViewPager)} providing it the ViewPager this layout is
 * being used for.
 * <p>
 * The colors can be customized in two ways. The first and simplest is to
 * provide an array of colors via {@link #setSelectedIndicatorColors(int...)}.
 * The alternative is via the {@link TabColorizer} interface which provides you
 * complete control over which color is used for any individual position.
 * <p>
 */
public class TabsBar extends HorizontalScrollView {
	/**
	 * Allows complete control over the colors drawn in the tab layout. Set with
	 * {@link #setCustomTabColorizer(TabColorizer)}.
	 */
	public interface TabColorizer {

		/**
		 * @return return the color of the indicator used when {@code position}
		 * is selected.
		 */
		int getIndicatorColor(int position);

	}

	private static final int TITLE_OFFSET_DIPS = 24;
	private static final int TAB_VIEW_PADDING_DIPS = 16;
	private static final int TAB_VIEW_TEXT_SIZE_SP = 12;
	private static final int TEXT_MAX_WIDTH = 180;
	private static final int SMALL_MIN_HEIGHT = 48;
	private static final int LARGE_MIN_HEIGHT = 72;

	private final int mTitleOffset;

	private boolean mDistributeEvenly = true;

	private TabItemSpec[] mTabItems;
	private ViewPager mViewPager;
	private final SparseArray<String> mContentDescriptions = new SparseArray<>();
	private ViewPager.OnPageChangeListener mViewPagerPageChangeListener;

	private final TabStrip mTabStrip;

	public TabsBar(Context context) {
		this(context, null);
	}

	public TabsBar(Context context, AttributeSet attrs) {
		this(context, attrs, 0);
	}

	public TabsBar(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		// Disable the Scroll Bar
		setHorizontalScrollBarEnabled(false);
		// Make sure that the Tab Strips fills this View
		setFillViewport(true);

		mTitleOffset = (int) (TITLE_OFFSET_DIPS * getResources().getDisplayMetrics().density);

		mTabStrip = new TabStrip(context);
		addView(mTabStrip, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
	}

	/**
	 * Set the custom {@link TabColorizer} to be used.
	 * <p>
	 * If you only require simple customisation then you can use
	 * {@link #setSelectedIndicatorColors(int...)} to achieve similar effects.
	 */
	public void setCustomTabColorizer(TabColorizer tabColorizer) {
		//mTabStrip.setCustomTabColorizer(tabColorizer);
	}

	public void setDistributeEvenly(boolean distributeEvenly) {
		mDistributeEvenly = distributeEvenly;
	}

	/**
	 * Sets the colors to be used for indicating the selected tab. These colors
	 * are treated as a circular array. Providing one color will mean that all
	 * tabs are indicated with the same color.
	 */
	public void setSelectedIndicatorColors(int... colors) {
		mTabStrip.setSelectedIndicatorColors(colors);
		this.mSelectedIndicatorColors = colors;
	}

	private int[] mSelectedIndicatorColors;

	public int[] getSelectedIndicatorColors() {
		return this.mSelectedIndicatorColors;
	}

	public void setTabTextColor(int color) {
		mTabStrip.setTabTextColor(color);
	}

	public int getTabTextColor() {
		return mTabStrip.getTabTextColor();
	}

	public void setSelectedTabTextColor(int color) {
		mTabStrip.setSelectedTabTextColor(color);
	}

	public int getSelectedTabTextColor() {
		return mTabStrip.getSelectedTabTextColor();
	}

	public void setTabTextFontSize(float fontSize) {
		mTabStrip.setTabTextFontSize(fontSize);
	}

	public float getTabTextFontSize() {
		return mTabStrip.getTabTextFontSize();
	}

	/**
	 * Set the {@link ViewPager.OnPageChangeListener}. When using
	 * {@link TabsBar} you are required to set any
	 * {@link ViewPager.OnPageChangeListener} through this method. This is so
	 * that the layout can update it's scroll position correctly.
	 *
	 * @see ViewPager#setOnPageChangeListener(ViewPager.OnPageChangeListener)
	 */
	public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) {
		mViewPagerPageChangeListener = listener;
	}

	/**
	 * Sets the associated view pager. Note that the assumption here is that the
	 * pager content (number of tabs and tab titles) does not change after this
	 * call has been made.
	 */
	public void setViewPager(ViewPager viewPager) {
		this.setItems(null, viewPager);
	}

	public void setItems(TabItemSpec[] items, ViewPager viewPager) {
		mTabStrip.removeAllViews();

		mViewPager = viewPager;
		mTabItems = items;
		if (viewPager != null) {
			viewPager.addOnPageChangeListener(new InternalViewPagerListener());
			populateTabStrip();
		}
	}

	/**
	 * Updates the UI of an item at specified index
	 */
	public void updateItemAt(int position, TabItemSpec tabItem) {
		LinearLayout ll = (LinearLayout) mTabStrip.getChildAt(position);
		ImageView imgView = (ImageView) ll.getChildAt(0);
		TextView textView = (TextView) ll.getChildAt(1);
		this.setupItem(ll, textView, imgView, tabItem);
	}

	/**
	 * Gets the TextView for tab item at index
	 */
	public TextView getTextViewForItemAt(int index) {
		LinearLayout ll = this.getViewForItemAt(index);
		return (ll != null) ? (TextView) ll.getChildAt(1) : null;
	}

	/**
	 * Gets the LinearLayout container for tab item at index
	 */
	public LinearLayout getViewForItemAt(int index) {
		LinearLayout result = null;

		if (this.mTabStrip.getChildCount() > index) {
			result = (LinearLayout) this.mTabStrip.getChildAt(index);
		}

		return result;
	}

	/**
	 * Gets the number of realized tabs.
	 */
	public int getItemCount() {
		return this.mTabStrip.getChildCount();
	}

	/**
	 * Create a default view to be used for tabs.
	 */
	protected View createDefaultTabView(Context context, TabItemSpec tabItem) {
		float density = getResources().getDisplayMetrics().density;
		int padding = (int) (TAB_VIEW_PADDING_DIPS * density);

		LinearLayout ll = new LinearLayout(context);
		ll.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.MATCH_PARENT));
		ll.setGravity(Gravity.CENTER);
		ll.setOrientation(LinearLayout.VERTICAL);
		TypedValue outValue = new TypedValue();
		getContext().getTheme().resolveAttribute(android.R.attr.selectableItemBackground, outValue, true);
		ll.setBackgroundResource(outValue.resourceId);

		ImageView imgView = new ImageView(context);
		imgView.setScaleType(ScaleType.FIT_CENTER);
		LinearLayout.LayoutParams imgLP = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
		imgLP.gravity = Gravity.CENTER;
		imgView.setLayoutParams(imgLP);

		TextView textView = new TextView(context);
		textView.setGravity(Gravity.CENTER);
		textView.setMaxWidth((int) (TEXT_MAX_WIDTH * density));
		textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, TAB_VIEW_TEXT_SIZE_SP);
		textView.setEllipsize(TextUtils.TruncateAt.END);
		textView.setMaxLines(2);
		textView.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));
		textView.setPadding(padding, 0, padding, 0);

		this.setupItem(ll, textView, imgView, tabItem);

		ll.addView(imgView);
		ll.addView(textView);
		return ll;
	}

	private void setupItem(LinearLayout ll, TextView textView, ImageView imgView, TabItemSpec tabItem) {
		float density = getResources().getDisplayMetrics().density;

		if (tabItem.iconId != 0) {
			imgView.setImageResource(tabItem.iconId);
			imgView.setVisibility(VISIBLE);
		} else if (tabItem.iconDrawable != null) {
			imgView.setImageDrawable(tabItem.iconDrawable);
			imgView.setVisibility(VISIBLE);
		} else {
			imgView.setVisibility(GONE);
		}

		if (tabItem.title != null && !tabItem.title.isEmpty()) {
			textView.setText(tabItem.title);
			textView.setVisibility(VISIBLE);

			if (tabItem.typeFace != null) {
				textView.setTypeface(tabItem.typeFace);
			}

			if (tabItem.fontSize != 0) {
				textView.setTextSize(tabItem.fontSize);
			}

			if (tabItem.color != 0) {
				textView.setTextColor(tabItem.color);
				mTabStrip.setShouldUpdateTabsTextColor(false);
			}
		} else {
			textView.setVisibility(GONE);
		}

		if (tabItem.backgroundColor != 0) {
			ll.setBackgroundColor(tabItem.backgroundColor);
		}

		if (imgView.getVisibility() == VISIBLE && textView.getVisibility() == VISIBLE) {
			ll.setMinimumHeight((int) (LARGE_MIN_HEIGHT * density));
		} else {
			ll.setMinimumHeight((int) (SMALL_MIN_HEIGHT * density));
		}

		if (mDistributeEvenly) {
			LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) ll.getLayoutParams();
			lp.width = 0;
			lp.weight = 1;
		}
	}

	public boolean onTap(int position) {
		// to be overridden in JS
		return true;
	}

	private void populateTabStrip() {
		final PagerAdapter adapter = mViewPager.getAdapter();
		final OnClickListener tabClickListener = new TabClickListener();

		for (int i = 0; i < adapter.getCount(); i++) {
			View tabView = null;

			TabItemSpec tabItem;
			if (this.mTabItems != null && this.mTabItems.length > i) {
				tabItem = this.mTabItems[i];
			} else {
				tabItem = new TabItemSpec();
				tabItem.title = adapter.getPageTitle(i).toString();
			}

			tabView = createDefaultTabView(getContext(), tabItem);

			tabView.setOnClickListener(tabClickListener);
			String desc = mContentDescriptions.get(i, null);
			if (desc != null) {
				tabView.setContentDescription(desc);
			}

			mTabStrip.addView(tabView);
			if (i == mViewPager.getCurrentItem()) {
				tabView.setSelected(true);
			}
		}
	}

	public void setContentDescription(int i, String desc) {
		mContentDescriptions.put(i, desc);
	}

	@Override
	protected void onAttachedToWindow() {
		super.onAttachedToWindow();

		if (mViewPager != null) {
			scrollToTab(mViewPager.getCurrentItem(), 0);
		}
	}

	private void scrollToTab(int tabIndex, int positionOffset) {
		final int tabStripChildCount = mTabStrip.getChildCount();
		if (tabStripChildCount == 0 || tabIndex < 0 || tabIndex >= tabStripChildCount) {
			return;
		}

		View selectedChild = mTabStrip.getChildAt(tabIndex);
		if (selectedChild != null) {
			int targetScrollX = selectedChild.getLeft() + positionOffset;

			if (tabIndex > 0 || positionOffset > 0) {
				// If we're not at the first child and are mid-scroll, make sure
				// we obey the offset
				targetScrollX -= mTitleOffset;
			}

			scrollTo(targetScrollX, 0);
		}
	}

	private class InternalViewPagerListener implements ViewPager.OnPageChangeListener {
		private int mScrollState;

		@Override
		public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
			int tabStripChildCount = mTabStrip.getChildCount();
			if ((tabStripChildCount == 0) || (position < 0) || (position >= tabStripChildCount)) {
				return;
			}

			mTabStrip.onTabsViewPagerPageChanged(position, positionOffset);

			View selectedTitle = mTabStrip.getChildAt(position);
			int extraOffset = (selectedTitle != null) ? (int) (positionOffset * selectedTitle.getWidth()) : 0;
			scrollToTab(position, extraOffset);

			if (mViewPagerPageChangeListener != null) {
				mViewPagerPageChangeListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
			}
		}

		@Override
		public void onPageScrollStateChanged(int state) {
			mScrollState = state;

			if (mViewPagerPageChangeListener != null) {
				mViewPagerPageChangeListener.onPageScrollStateChanged(state);
			}
		}

		@Override
		public void onPageSelected(int position) {
			if (mScrollState == ViewPager.SCROLL_STATE_IDLE) {
				mTabStrip.onTabsViewPagerPageChanged(position, 0f);
				scrollToTab(position, 0);
			}
			for (int i = 0; i < mTabStrip.getChildCount(); i++) {
				mTabStrip.getChildAt(i).setSelected(position == i);
			}
			if (mViewPagerPageChangeListener != null) {
				mViewPagerPageChangeListener.onPageSelected(position);
			}
		}

	}

	private class TabClickListener implements OnClickListener {
		@Override
		public void onClick(View v) {
			for (int i = 0; i < mTabStrip.getChildCount(); i++) {
				if (v == mTabStrip.getChildAt(i)) {
					if (onTap(i)) {
						mViewPager.setCurrentItem(i);
					}
					return;
				}
			}
		}
	}
}