An RxBindings-like observable to inform of clipboard updates.

ClipboardObservable.kt

package com.aniketkadam.cleanlinks

import android.content.ClipData
import android.content.ClipboardManager
import io.reactivex.Observable
import io.reactivex.Observer
import io.reactivex.disposables.Disposable
import java.util.concurrent.atomic.AtomicBoolean

fun ClipboardManager.updates(): Observable<OptionalClipData> = ClipboardObservable(this)

data class OptionalClipData(val clipData: ClipData?)
/**
 * Given a clipboard manager, it returns a stream of clipdata when it changes.
 *
 */
private class ClipboardObservable(private val clipboardManager: ClipboardManager) :
    Observable<OptionalClipData>() {

    override fun subscribeActual(observer: Observer<in OptionalClipData>) {
        val listener = Listener(observer, clipboardManager)

        observer.onSubscribe(listener)
        clipboardManager.addPrimaryClipChangedListener(listener)
    }

    private class Listener(
        private val observer: Observer<in OptionalClipData>,
        private val clipboardManager: ClipboardManager
    ) : Disposable, ClipboardManager.OnPrimaryClipChangedListener {

        private val defaultDisposable =
            DefaultDisposable { clipboardManager.removePrimaryClipChangedListener(this) }

        override fun isDisposed(): Boolean = defaultDisposable.isDisposed

        override fun dispose() = defaultDisposable.dispose()

        override fun onPrimaryClipChanged() {
            observer.onNext(OptionalClipData(clipboardManager.primaryClip))
        }
    }
}

private class DefaultDisposable(private val onDispose: () -> Unit) : Disposable {
    private val unsubscribed: AtomicBoolean = AtomicBoolean(false)

    override fun isDisposed(): Boolean = unsubscribed.get()

    override fun dispose() {
        if (unsubscribed.compareAndSet(false, true)) {
            onDispose()
        }
    }

}