package com.demo.lib.common.widget.verticalviewpager;

import android.database.DataSetObservable;
import android.database.DataSetObserver;
import android.os.Parcelable;
import android.view.View;
import android.view.ViewGroup;

public abstract class PagerAdapter {
	private DataSetObservable mObservable = new DataSetObservable();

	public static final int POSITION_UNCHANGED = -1;
	public static final int POSITION_NONE = -2;

	/**
	 * Return the number of views available.
	 */
	public abstract int getCount();

	/**
	 * Called when a change in the shown pages is going to start being made.
	 * 
	 * @param container
	 *            The containing View which is displaying this adapter's page
	 *            views.
	 */
	public void startUpdate(ViewGroup container) {
		startUpdate((View) container);
	}

	/**
	 * Create the page for the given position. The adapter is responsible for
	 * adding the view to the container given here, although it only must ensure
	 * this is done by the time it returns from {@link #finishUpdate(ViewGroup)}
	 * .
	 * 
	 * @param container
	 *            The containing View in which the page will be shown.
	 * @param position
	 *            The page position to be instantiated.
	 * @return Returns an Object representing the new page. This does not need
	 *         to be a View, but can be some other container of the page.
	 */
	public Object instantiateItem(ViewGroup container, int position) {
		return instantiateItem((View) container, position);
	}

	/**
	 * Remove a page for the given position. The adapter is responsible for
	 * removing the view from its container, although it only must ensure this
	 * is done by the time it returns from {@link #finishUpdate(ViewGroup)}.
	 * 
	 * @param container
	 *            The containing View from which the page will be removed.
	 * @param position
	 *            The page position to be removed.
	 * @param object
	 *            The same object that was returned by
	 *            {@link #instantiateItem(View, int)}.
	 */
	public void destroyItem(ViewGroup container, int position, Object object) {
		destroyItem((View) container, position, object);
	}

	/**
	 * Called to inform the adapter of which item is currently considered to be
	 * the "primary", that is the one show to the user as the current page.
	 * 
	 * @param container
	 *            The containing View from which the page will be removed.
	 * @param position
	 *            The page position that is now the primary.
	 * @param object
	 *            The same object that was returned by
	 *            {@link #instantiateItem(View, int)}.
	 */
	public void setPrimaryItem(ViewGroup container, int position, Object object) {
		setPrimaryItem((View) container, position, object);
	}

	/**
	 * Called when the a change in the shown pages has been completed. At this
	 * point you must ensure that all of the pages have actually been added or
	 * removed from the container as appropriate.
	 * 
	 * @param container
	 *            The containing View which is displaying this adapter's page
	 *            views.
	 */
	public void finishUpdate(ViewGroup container) {
		finishUpdate((View) container);
	}

	/**
	 * Called when a change in the shown pages is going to start being made.
	 * 
	 * @param container
	 *            The containing View which is displaying this adapter's page
	 *            views.
	 * 
	 * @deprecated Use {@link #startUpdate(ViewGroup)}
	 */
	public void startUpdate(View container) {
	}

	/**
	 * Create the page for the given position. The adapter is responsible for
	 * adding the view to the container given here, although it only must ensure
	 * this is done by the time it returns from {@link #finishUpdate(ViewGroup)}
	 * .
	 * 
	 * @param container
	 *            The containing View in which the page will be shown.
	 * @param position
	 *            The page position to be instantiated.
	 * @return Returns an Object representing the new page. This does not need
	 *         to be a View, but can be some other container of the page.
	 * 
	 * @deprecated Use {@link #instantiateItem(ViewGroup, int)}
	 */
	public Object instantiateItem(View container, int position) {
		throw new UnsupportedOperationException(
				"Required method instantiateItem was not overridden");
	}

	/**
	 * Remove a page for the given position. The adapter is responsible for
	 * removing the view from its container, although it only must ensure this
	 * is done by the time it returns from {@link #finishUpdate(View)}.
	 * 
	 * @param container
	 *            The containing View from which the page will be removed.
	 * @param position
	 *            The page position to be removed.
	 * @param object
	 *            The same object that was returned by
	 *            {@link #instantiateItem(View, int)}.
	 * 
	 * @deprecated Use {@link #destroyItem(ViewGroup, int, Object)}
	 */
	public void destroyItem(View container, int position, Object object) {
		throw new UnsupportedOperationException(
				"Required method destroyItem was not overridden");
	}

	/**
	 * Called to inform the adapter of which item is currently considered to be
	 * the "primary", that is the one show to the user as the current page.
	 * 
	 * @param container
	 *            The containing View from which the page will be removed.
	 * @param position
	 *            The page position that is now the primary.
	 * @param object
	 *            The same object that was returned by
	 *            {@link #instantiateItem(View, int)}.
	 * 
	 * @deprecated Use {@link #setPrimaryItem(ViewGroup, int, Object)}
	 */
	public void setPrimaryItem(View container, int position, Object object) {
	}

	/**
	 * Called when the a change in the shown pages has been completed. At this
	 * point you must ensure that all of the pages have actually been added or
	 * removed from the container as appropriate.
	 * 
	 * @param container
	 *            The containing View which is displaying this adapter's page
	 *            views.
	 * 
	 * @deprecated Use {@link #finishUpdate(ViewGroup)}
	 */
	public void finishUpdate(View container) {
	}

	/**
	 * Determines whether a page View is associated with a specific key object
	 * as returned by {@link #instantiateItem(ViewGroup, int)}. This method is
	 * required for a PagerAdapter to function properly.
	 * 
	 * @param view
	 *            Page View to check for association with <code>object</code>
	 * @param object
	 *            Object to check for association with <code>view</code>
	 * @return true if <code>view</code> is associated with the key object
	 *         <code>object</code>
	 */
	public abstract boolean isViewFromObject(View view, Object object);

	/**
	 * Save any instance state associated with this adapter and its pages that
	 * should be restored if the current UI state needs to be reconstructed.
	 * 
	 * @return Saved state for this adapter
	 */
	public Parcelable saveState() {
		return null;
	}

	/**
	 * Restore any instance state associated with this adapter and its pages
	 * that was previously saved by {@link #saveState()}.
	 * 
	 * @param state
	 *            State previously saved by a call to {@link #saveState()}
	 * @param loader
	 *            A ClassLoader that should be used to instantiate any restored
	 *            objects
	 */
	public void restoreState(Parcelable state, ClassLoader loader) {
	}

	/**
	 * Called when the host view is attempting to determine if an item's
	 * position has changed. Returns {@link #POSITION_UNCHANGED} if the position
	 * of the given item has not changed or {@link #POSITION_NONE} if the item
	 * is no longer present in the adapter.
	 * 
	 * <p>
	 * The default implementation assumes that items will never change position
	 * and always returns {@link #POSITION_UNCHANGED}.
	 * 
	 * @param object
	 *            Object representing an item, previously returned by a call to
	 *            {@link #instantiateItem(View, int)}.
	 * @return object's new position index from [0, {@link #getCount()}),
	 *         {@link #POSITION_UNCHANGED} if the object's position has not
	 *         changed, or {@link #POSITION_NONE} if the item is no longer
	 *         present.
	 */
	public int getItemPosition(Object object) {
		return POSITION_UNCHANGED;
	}

	/**
	 * This method should be called by the application if the data backing this
	 * adapter has changed and associated views should update.
	 */
	public void notifyDataSetChanged() {
		mObservable.notifyChanged();
	}

	void registerDataSetObserver(DataSetObserver observer) {
		mObservable.registerObserver(observer);
	}

	void unregisterDataSetObserver(DataSetObserver observer) {
		mObservable.unregisterObserver(observer);
	}

	/**
	 * This method may be called by the ViewPager to obtain a title string to
	 * describe the specified page. This method may return null indicating no
	 * title for this page. The default implementation returns null.
	 * 
	 * @param position
	 *            The position of the title requested
	 * @return A title for the requested page
	 */
	public CharSequence getPageTitle(int position) {
		return null;
	}

	/**
	 * Returns the proportional width of a given page as a percentage of the
	 * ViewPager's measured width from (0.f-1.f]
	 * 
	 * @param position
	 *            The position of the page requested
	 * @return Proportional width for the given page position
	 */
	public float getPageWidth(int position) {
		return 1.f;
	}

	public float getPageHeight(int position) {
		return 1.f;
	}
}