Merge Kotlin conversion into master

library/src/main/kotlin/lab/prada/android/ui/lab/prada/android/ui/infinitescroll/InfiniteScrollAdapter.kt

@@ -0,0 +1,156 @@
+package lab.prada.android.ui.lab.prada.android.ui.infinitescroll
+
+import android.content.Context
+import android.database.DataSetObserver
+import android.os.Looper
+import android.view.Gravity
+import android.view.View
+import android.view.ViewGroup
+import android.widget.Adapter
+import android.widget.AbsListView
+import android.widget.BaseAdapter
+import android.widget.ProgressBar
+import android.widget.RelativeLayout
+import java.util.concurrent.CopyOnWriteArrayList
+import java.util.concurrent.atomic.AtomicInteger
+
+/** Adds a progress row to a [BaseAdapter] and notifies listeners when it is displayed. */
+class InfiniteScrollAdapter<T : BaseAdapter> : BaseAdapter {
+    private val adapter: T
+    private val progressView: View
+    private val listeners = CopyOnWriteArrayList<InfiniteScrollListener>()
+    private val state = AtomicInteger(NONE_STATE)
+
+    @Volatile
+    private var canReadMoreEnabled = true
+
+    interface InfiniteScrollListener {
+        fun onInfiniteScrolled()
+    }
+
+    constructor(context: Context, adapter: T, progressView: View) {
+        this.adapter = adapter
+        this.progressView = progressView
+    }
+
+    constructor(context: Context, adapter: T, itemWidth: Int, itemHeight: Int) {
+        this.adapter = adapter
+        this.progressView = RelativeLayout(context).apply {
+            layoutParams = AbsListView.LayoutParams(itemWidth, itemHeight)
+            gravity = Gravity.CENTER
+            addView(ProgressBar(context))
+        }
+    }
+
+    constructor(adapter: T, progressView: View) {
+        this.adapter = adapter
+        this.progressView = progressView
+    }
+
+    override fun areAllItemsEnabled(): Boolean = adapter.areAllItemsEnabled()
+
+    override fun getDropDownView(
+        position: Int,
+        convertView: View?,
+        parent: ViewGroup
+    ): View? = if (isProgressViewPosition(position)) {
+        null
+    } else {
+        adapter.getDropDownView(position, convertView, parent)
+    }
+
+    override fun getItemViewType(position: Int): Int = if (isProgressViewPosition(position)) {
+        Adapter.IGNORE_ITEM_VIEW_TYPE
+    } else {
+        adapter.getItemViewType(position)
+    }
+
+    override fun getViewTypeCount(): Int = adapter.viewTypeCount
+
+    override fun hasStableIds(): Boolean = adapter.hasStableIds()
+
+    override fun isEmpty(): Boolean = adapter.isEmpty
+
+    override fun registerDataSetObserver(observer: DataSetObserver) {
+        adapter.registerDataSetObserver(observer)
+    }
+
+    override fun unregisterDataSetObserver(observer: DataSetObserver) {
+        adapter.unregisterDataSetObserver(observer)
+    }
+
+    override fun getCount(): Int = if (shouldShowProgressView()) {
+        adapter.count + 1
+    } else {
+        adapter.count
+    }
+
+    override fun getItem(position: Int): Any? = if (isProgressViewPosition(position)) {
+        null
+    } else {
+        adapter.getItem(position)
+    }
+
+    override fun getItemId(position: Int): Long = if (isProgressViewPosition(position)) {
+        -1L
+    } else {
+        adapter.getItemId(position)
+    }
+
+    override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
+        if (!isProgressViewPosition(position)) {
+            return adapter.getView(position, convertView, parent)
+        }
+
+        if (state.compareAndSet(NONE_STATE, REFRESHING_STATE)) {
+            listeners.forEach(InfiniteScrollListener::onInfiniteScrolled)
+        }
+
+        if (progressView.visibility == View.GONE) {
+            progressView.visibility = View.VISIBLE
+        }
+        return progressView
+    }
+
+    fun removeListener(listener: InfiniteScrollListener?) {
+        if (listener != null) {
+            listeners.remove(listener)
+        }
+    }
+
+    fun addListener(listener: InfiniteScrollListener?) {
+        if (listener != null) {
+            listeners.addIfAbsent(listener)
+        }
+    }
+
+    fun isProgressViewPosition(position: Int): Boolean =
+        shouldShowProgressView() && position == count - 1
+
+    fun canReadMore(enable: Boolean) {
+        canReadMoreEnabled = enable
+        notifyDataSetChanged()
+    }
+
+    fun isRefreshing(): Boolean = state.get() == REFRESHING_STATE
+
+    fun handledRefresh() {
+        check(Looper.myLooper() == Looper.getMainLooper()) {
+            "handledRefresh() must be called on the main thread"
+        }
+        if (state.compareAndSet(REFRESHING_STATE, NONE_STATE)) {
+            progressView.visibility = View.GONE
+        }
+    }
+
+    fun getOriginalAdapter(): T = adapter
+
+    fun getAdapter(): T = adapter
+
+    private fun shouldShowProgressView(): Boolean = adapter.count > 0 && canReadMoreEnabled
+
+    private companion object {
+        const val NONE_STATE = 0
+        const val REFRESHING_STATE = 1
+    }
+}