package szu.wifichat.android.view;

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.View;
import android.widget.AbsListView;
import android.widget.ListAdapter;

public class MoMoRefreshExpandableList extends MoMoRefreshListView {

	private static final int MAX_ALPHA = 255;
	private PinnedHeaderAdapter mAdapter;
	private View mHeaderView;
	private boolean mHeaderViewVisible;
	private int mHeaderViewWidth;
	private int mHeaderViewHeight;

	public MoMoRefreshExpandableList(Context context) {
		super(context);
		setOnScrollListener(this);
	}

	public MoMoRefreshExpandableList(Context context, AttributeSet attrs,
			int defStyle) {
		super(context, attrs, defStyle);
		setOnScrollListener(this);
	}

	public MoMoRefreshExpandableList(Context context, AttributeSet attrs) {
		super(context, attrs);
		setOnScrollListener(this);
	}

	public interface PinnedHeaderAdapter {
		public static final int PINNED_HEADER_GONE = 0;
		public static final int PINNED_HEADER_VISIBLE = 1;
		public static final int PINNED_HEADER_PUSHED_UP = 2;

		int getPinnedHeaderState(int position);

		void configurePinnedHeader(View header, int position, int alpha);
	}

	public void setPinnedHeaderView(View view) {
		mHeaderView = view;
		if (mHeaderView != null) {
			setFadingEdgeLength(0);
		}
		requestLayout();
	}

	@Override
	public void setAdapter(ListAdapter adapter) {
		super.setAdapter(adapter);
		mAdapter = (PinnedHeaderAdapter) adapter;
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		if (mHeaderView != null) {
			measureChild(mHeaderView, widthMeasureSpec, heightMeasureSpec);
			mHeaderViewWidth = mHeaderView.getMeasuredWidth();
			mHeaderViewHeight = mHeaderView.getMeasuredHeight();
		}
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		super.onLayout(changed, l, t, r, b);
		if (mHeaderView != null) {
			mHeaderView.layout(0, 0, mHeaderViewWidth, mHeaderViewHeight);
			configureHeaderView(getFirstVisiblePosition());
		}
	}

	public void configureHeaderView(int position) {
		if (mHeaderView == null) {
			return;
		}
		int state = mAdapter.getPinnedHeaderState(position);
		switch (state) {
		case PinnedHeaderAdapter.PINNED_HEADER_GONE: {
			mHeaderViewVisible = false;
			break;
		}

		case PinnedHeaderAdapter.PINNED_HEADER_VISIBLE: {
			mAdapter.configurePinnedHeader(mHeaderView, position, MAX_ALPHA);
			if (mHeaderView.getTop() != 0) {
				mHeaderView.layout(0, 0, mHeaderViewWidth, mHeaderViewHeight);
			}
			mHeaderViewVisible = true;
			break;
		}

		case PinnedHeaderAdapter.PINNED_HEADER_PUSHED_UP: {
			View firstView = getChildAt(0);
			int bottom = firstView.getBottom();
			// int itemHeight = firstView.getHeight();
			int headerHeight = mHeaderView.getHeight();
			int y;
			int alpha;
			if (bottom < headerHeight) {
				y = (bottom - headerHeight);
				alpha = MAX_ALPHA * (headerHeight + y) / headerHeight;
			} else {
				y = 0;
				alpha = MAX_ALPHA;
			}
			mAdapter.configurePinnedHeader(mHeaderView, position, alpha);
			if (mHeaderView.getTop() != y) {
				mHeaderView.layout(0, y, mHeaderViewWidth, mHeaderViewHeight
						+ y);
			}
			mHeaderViewVisible = true;
			break;
		}
		}
	}

	@Override
	protected void dispatchDraw(Canvas canvas) {
		super.dispatchDraw(canvas);
		if (mHeaderViewVisible) {
			drawChild(canvas, mHeaderView, getDrawingTime());
		}
	}

	@Override
	public void onScroll(AbsListView view, int firstVisibleItem,
			int visibleItemCount, int totalItemCount) {
		super.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
		if (view instanceof MoMoRefreshExpandableList) {
			((MoMoRefreshExpandableList) view)
					.configureHeaderView(firstVisibleItem);
		}
	}

	public boolean ismHeaderViewVisible() {
		return mHeaderViewVisible;
	}

	public int getFirstItemPosition() {
		return mFirstVisibleItem;
	}
}
