<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.youtubeplayer">

    <uses-permission android:name="android.permission.INTERNET"/>
    <application

        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <activity android:name=".YoutubeActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>
</manifest>

package com.example.youtubeplayer

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.view.ViewGroup
import android.widget.Button
import android.widget.Toast
import androidx.constraintlayout.widget.ConstraintLayout
import com.google.android.youtube.player.YouTubeBaseActivity
import com.google.android.youtube.player.YouTubeInitializationResult
import com.google.android.youtube.player.YouTubePlayer
import com.google.android.youtube.player.YouTubePlayerView
import com.google.android.youtube.player.internal.t
const val YOUTUBE_VIDEO_ID = "Evfe8GEn33w"
const val YOUTUBE_PLAYLIST = "UCU3jy5C8MB-JvSw_86SFV2w"

class YoutubeActivity : YouTubeBaseActivity(), YouTubePlayer.OnInitializedListener {
    private val TAG = "YoutubeActivity"

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val layout = layoutInflater.inflate(R.layout.activity_youtube, null) as ConstraintLayout
        setContentView(layout)

        val playerView = YouTubePlayerView(this)
        playerView.layoutParams = ConstraintLayout.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)
        layout.addView(playerView)

        playerView.initialize(getString(R.string.GOOGLE_API_KEY), this)
    }

    override fun onInitializationSuccess(provider: YouTubePlayer.Provider?, youTubePlayer: YouTubePlayer?,
                                         wasRestored: Boolean) {
        Log.d(TAG, "onInitializationSuccess: provider is ${provider?.javaClass}")
        Log.d(TAG, "onInitializationSuccess: youTubePlayer is ${youTubePlayer?.javaClass}")
        Toast.makeText(this, "Initialized Youtube Player successfully", Toast.LENGTH_SHORT).show()

        youTubePlayer?.setPlayerStateChangeListener(playerStateChangeListener)
        youTubePlayer?.setPlaybackEventListener(playbackEventListener)

        if (!wasRestored) {
            youTubePlayer?.cueVideo(YOUTUBE_VIDEO_ID)
        }
    }

    override fun onInitializationFailure(provider: YouTubePlayer.Provider?,
                                         youTubeInitializationResult: YouTubeInitializationResult?) {
        val REQUEST_CODE = 0

        if (youTubeInitializationResult?.isUserRecoverableError == true) {
            youTubeInitializationResult.getErrorDialog(this, REQUEST_CODE).show()
        } else {
            val errorMessage = "There was an error initializing the YoutubePlayer ($youTubeInitializationResult)"
            Toast.makeText(this, errorMessage, Toast.LENGTH_LONG).show()
        }
    }

    private val playbackEventListener = object: YouTubePlayer.PlaybackEventListener {
        override fun onSeekTo(p0: Int) {
        }

        override fun onBuffering(p0: Boolean) {
        }

        override fun onPlaying() {
            Toast.makeText(this@YoutubeActivity, "Good, video is playing ok", Toast.LENGTH_SHORT).show()
        }

        override fun onStopped() {
            Toast.makeText(this@YoutubeActivity, "Video has stopped", Toast.LENGTH_SHORT).show()
        }

        override fun onPaused() {
            Toast.makeText(this@YoutubeActivity, "Video has paused", Toast.LENGTH_SHORT).show()
        }
    }

    private val playerStateChangeListener = object: YouTubePlayer.PlayerStateChangeListener {
        override fun onAdStarted() {
            Toast.makeText(this@YoutubeActivity, "Click Ad now, make the video creator rich!", Toast.LENGTH_SHORT).show()
        }

        override fun onLoading() {
        }

        override fun onVideoStarted() {
            Toast.makeText(this@YoutubeActivity, "Video has started", Toast.LENGTH_SHORT).show()
        }

        override fun onLoaded(p0: String?) {
        }

        override fun onVideoEnded() {
            Toast.makeText(this@YoutubeActivity, "Congratulations! You've completed another video.", Toast.LENGTH_SHORT).show()
        }

        override fun onError(p0: YouTubePlayer.ErrorReason?) {
        }
    }
}