AbstractArrayAdapter.kt

import android.support.v7.widget.RecyclerView
import java.util.*

abstract class AbstractArrayAdapter<ITEM, VH : RecyclerView.ViewHolder>(dataSet: MutableList<ITEM>?) : RecyclerView.Adapter<VH>() {

    //region Data

    private val dataSet: MutableList<ITEM>

    //endregion

    init {
        if (dataSet != null) {
            this.dataSet = dataSet
        } else {
            this.dataSet = mutableListOf()
        }
    }

    /**
     * Method to get dataset size
     */
    override fun getItemCount(): Int {
        return dataSet.size
    }

    /**
     * Returns item from data set located at specified position
     * @param position position
     * *
     * @return item
     */
    internal fun getItemAtPosition(position: Int): ITEM {
        return dataSet[position]
    }

    /**
     * Method to get position of item
     * @param item Item
     */
    fun getItemPosition(item: ITEM): Int {
        return dataSet.indexOf(item)
    }

    /**
     * Adds item to collection and notifies adapter about changes

     * @param item item
     */
    fun addItem(item: ITEM) {
        val position = dataSet.size
        dataSet.add(item)
        notifyItemInserted(position)
    }

    /**
     * Returns whole dataset
     * @return dataset
     */
    fun getDataset(): List<ITEM> {
        return this.dataSet
    }

    /**
     * Merge existing collection with new one and notifies adapter about changes

     * @param items new collection
     * *
     * @see .replaceCollection
     */
    fun addCollection(items: List<ITEM>) {
        val positionStart = dataSet.size
        val itemCount = items.size

        dataSet.addAll(items)
        notifyItemRangeInserted(positionStart, itemCount)
    }

    /**
     * Replace existing collection with new one and notifies adapter about changes

     * @param items new collection
     * *
     * @see .setCollection
     */
    fun replaceCollection(items: List<ITEM>) {
        if (dataSet.size != 0) {
            removeAll()
        }
        addCollection(items)
    }

    /**
     * Method to update all occurances of items in collection
     */
    fun updateCollection(items: List<ITEM>) {
        if(dataSet.isNotEmpty() && items.isNotEmpty()) {
            dataSet.forEachIndexed { i, item ->
                updateItem(item)
            }
        }
    }

    /**
     * Remove item from collection at given position and notifies adapter about changes

     * @param position item position
     * *
     * @see .removeAll
     */
    fun removeItem(position: Int) {
        dataSet.removeAt(position)
        notifyItemRemoved(position)
    }

    fun updateItem(index: Int, item: ITEM) {
        if(dataSet.size-1>=index && dataSet.contains(item)) {
            dataSet[index] = item
            notifyItemChanged(index)
        }
    }

    fun updateItem(item: ITEM) {
        val index: Int? = dataSet.indexOf(item)
        if(index != null) {
            updateItem(index,item)
        }
    }

    /**
     * Remove all items from collection leaving it empty and notifies adapter about changes
     */
    fun removeAll() {
        val positionStart = 0
        val itemCount = dataSet.size
        dataSet.clear()
        notifyItemRangeRemoved(positionStart, itemCount)
    }

    /**
     * Method to pass new data to adapter, without bothering about its state.
     * If dataset is not empty, this will attempt data update
     * If dataset is empty, this will assign the new collection to it
     */
    fun dropData(dataSet: List<ITEM>) {
        if(isEmpty()) {
            addCollection(dataSet)
        }
        else {
            updateCollection(dataSet)
        }
    }

    /**
     * Method to get state of dataset
     */
    fun isEmpty(): Boolean {
        return dataSet.isEmpty()
    }
}