/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * 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.android.setupwizardlib.items;

import android.util.SparseIntArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;

/**
 * An adapter typically used with ListView to display an {@link
 * com.android.setupwizardlib.items.ItemHierarchy}. The item hierarchy used to create this adapter
 * can be inflated by {@link ItemInflater} from XML.
 */
public class ItemAdapter extends BaseAdapter implements ItemHierarchy.Observer {

  private final ItemHierarchy itemHierarchy;
  private final ViewTypes viewTypes = new ViewTypes();

  public ItemAdapter(ItemHierarchy hierarchy) {
    itemHierarchy = hierarchy;
    itemHierarchy.registerObserver(this);
    refreshViewTypes();
  }

  @Override
  public int getCount() {
    return itemHierarchy.getCount();
  }

  @Override
  public IItem getItem(int position) {
    return itemHierarchy.getItemAt(position);
  }

  @Override
  public long getItemId(int position) {
    return position;
  }

  @Override
  public int getItemViewType(int position) {
    IItem item = getItem(position);
    int layoutRes = item.getLayoutResource();
    return viewTypes.get(layoutRes);
  }

  @Override
  public int getViewTypeCount() {
    return viewTypes.size();
  }

  private void refreshViewTypes() {
    for (int i = 0; i < getCount(); i++) {
      IItem item = getItem(i);
      viewTypes.add(item.getLayoutResource());
    }
  }

  @Override
  public View getView(int position, View convertView, ViewGroup parent) {
    IItem item = getItem(position);
    if (convertView == null) {
      LayoutInflater inflater = LayoutInflater.from(parent.getContext());
      convertView = inflater.inflate(item.getLayoutResource(), parent, false);
    }
    item.onBindView(convertView);
    return convertView;
  }

  @Override
  public void onChanged(ItemHierarchy hierarchy) {
    refreshViewTypes();
    notifyDataSetChanged();
  }

  @Override
  public void onItemRangeChanged(ItemHierarchy itemHierarchy, int positionStart, int itemCount) {
    onChanged(itemHierarchy);
  }

  @Override
  public void onItemRangeInserted(ItemHierarchy itemHierarchy, int positionStart, int itemCount) {
    onChanged(itemHierarchy);
  }

  @Override
  public void onItemRangeMoved(
      ItemHierarchy itemHierarchy, int fromPosition, int toPosition, int itemCount) {
    onChanged(itemHierarchy);
  }

  @Override
  public void onItemRangeRemoved(ItemHierarchy itemHierarchy, int positionStart, int itemCount) {
    onChanged(itemHierarchy);
  }

  @Override
  public boolean isEnabled(int position) {
    return getItem(position).isEnabled();
  }

  public ItemHierarchy findItemById(int id) {
    return itemHierarchy.findItemById(id);
  }

  public ItemHierarchy getRootItemHierarchy() {
    return itemHierarchy;
  }

  /**
   * A helper class to pack a sparse set of integers (e.g. resource IDs) to a contiguous list of
   * integers (e.g. adapter positions), providing mapping to retrieve the original ID from a given
   * position. This is used to pack the view types of the adapter into contiguous integers from a
   * given layout resource.
   */
  private static class ViewTypes {
    private final SparseIntArray positionMap = new SparseIntArray();
    private int nextPosition = 0;

    public int add(int id) {
      if (positionMap.indexOfKey(id) < 0) {
        positionMap.put(id, nextPosition);
        nextPosition++;
      }
      return positionMap.get(id);
    }

    public int size() {
      return positionMap.size();
    }

    public int get(int id) {
      return positionMap.get(id);
    }
  }
}