/* -*- Mode: Java; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: nil; -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.gecko.home;

import android.support.v4.content.ContextCompat;
import org.mozilla.gecko.R;

import android.content.Context;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewTreeObserver;
import android.view.accessibility.AccessibilityEvent;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;
import android.widget.TextView;

/**
 * {@code TabMenuStrip} is the view used to display {@code HomePager} tabs
 * on tablets. See {@code TabMenuStripLayout} for details about how the
 * tabs are created and updated.
 */
public class TabMenuStrip extends HorizontalScrollView
                          implements HomePager.Decor {

    // Offset between the selected tab title and the edge of the screen,
    // except for the first and last tab in the tab strip.
    private static final int TITLE_OFFSET_DIPS = 24;

    private final int titleOffset;
    private final TabMenuStripLayout layout;

    private final Paint shadowPaint;
    private final int shadowSize;

    public interface OnTitleClickListener {
        void onTitleClicked(int index);
    }

    public TabMenuStrip(Context context, AttributeSet attrs) {
        super(context, attrs);

        // Disable the scroll bar.
        setHorizontalScrollBarEnabled(false);
        setFillViewport(true);

        final Resources res = getResources();

        titleOffset = (int) (TITLE_OFFSET_DIPS * res.getDisplayMetrics().density);

        layout = new TabMenuStripLayout(context, attrs);
        addView(layout, LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);

        shadowSize = res.getDimensionPixelSize(R.dimen.tabs_strip_shadow_size);

        shadowPaint = new Paint();
        shadowPaint.setColor(ContextCompat.getColor(context, R.color.url_bar_shadow));
        shadowPaint.setStrokeWidth(0.0f);
    }

    @Override
    public void draw(Canvas canvas) {
        super.draw(canvas);

        final int height = getHeight();
        canvas.drawRect(0, height - shadowSize, layout.getWidth(), height, shadowPaint);
    }

    @Override
    public void onAddPagerView(String title) {
        layout.onAddPagerView(title);
    }

    @Override
    public void removeAllPagerViews() {
        layout.removeAllViews();
    }

    @Override
    public void onPageSelected(final int position) {
        layout.onPageSelected(position);
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        layout.onPageScrolled(position, positionOffset, positionOffsetPixels);

        final View selectedTitle = layout.getChildAt(position);
        if (selectedTitle == null) {
            return;
        }

        final int selectedTitleOffset = (int) (positionOffset * selectedTitle.getWidth());

        int titleLeft = selectedTitle.getLeft() + selectedTitleOffset;
        if (position > 0) {
            titleLeft -= titleOffset;
        }

        int titleRight = selectedTitle.getRight() + selectedTitleOffset;
        if (position < layout.getChildCount() - 1) {
            titleRight += titleOffset;
        }

        final int scrollX = getScrollX();
        if (titleLeft < scrollX) {
            // Tab strip overflows to the left.
            scrollTo(titleLeft, 0);
        } else if (titleRight > scrollX + getWidth()) {
            // Tab strip overflows to the right.
            scrollTo(titleRight - getWidth(), 0);
        }
    }

    @Override
    public void setOnTitleClickListener(OnTitleClickListener onTitleClickListener) {
        layout.setOnTitleClickListener(onTitleClickListener);
    }
}