$ python -m pip install pytube

from pytube import Playlist ## The library for downloading playlists
from pytube import YouTube ## The library for downloading a single video

## The function we wrote to download a single video
def DownloadSingleVideo(link):
    try: ## We check if there is an error
        video = YouTube(link) ## If there is no error, we assign the video variable as the YouTube(link) function
        print("%s video has started downloading.." % video.title) ## We print the video name to the screen
        video.streams.get_highest_resolution().download('video') ## We start downloading. Here, streams.get_highest_resolution lets us choose the highest quality. .download starts the download and download('video') is the folder to download into.
        print("%s video has been downloaded successfully." % video.title) ## When the download is finished, we print this
    except: ## If there is a problem
        print("A problem occurred during the process!") ## Print error on the screen


def DownloadAudioOnly(link):
    try: ## Check for error
        audio = YouTube(link) ## If no error, assign the variable
        print("%s audio file of the video is starting to download.." % audio.title) ## Print name
        audio.streams.get_audio_only().download("audio") ## Download audio. Here, get_audio_only() selects audio only, download('audio') is the download folder.
        print("%s audio file of the video has been downloaded." % audio.title) ## We're telling that it's done
    except: ## If error
        print("A problem occurred during the process!") ## Print error


def DownloadPlaylistVideos(link):
    try: ## Error check
        playList = Playlist(link) ## Create variable, assign link to Playlist function
        downloadedVideoCount = 0 ## Variable to know how many videos downloaded or if any failed
        print("There are %s videos in the playlist." %
              len(playList.video_urls)) ## Print the count
        for i in playList.videos: ## Loop through videos in playlist
            i.streams.get_highest_resolution().download('video') ## Download one by one
            downloadedVideoCount += 1 ## Counter
            print(i.title + " video has been downloaded successfully")
        print("A total of %s videos in the playlist have been downloaded successfully." %
              downloadedVideoCount) ## Telling completion
    except: ## If error
        print("A problem occurred during the process!") ## Print error


def DownloadPlaylistAudios(link):
    try: ## Error check
        playList = Playlist(link) ## Create variable, assign link
        downloadedVideoCount = 0 ## Counter
        print("There are %s audios in the playlist." %
              len(playList.video_urls)) ## Print count
        for i in playList.videos: ## Loop through videos
            i.streams.get_audio_only().download('audio') ## Download audio
            downloadedVideoCount += 1 ## Increase counter
            print(i.title + " audio of the video has been downloaded successfully")
        print("A total of %s audios of videos in the playlist have been downloaded successfully." %
              downloadedVideoCount) ## Telling completion
    except: ## If error
        print("A problem occurred during the process!") ## Print error

## Function to select operation.
def SelectionScreen():
    operation = input(
        "Which operation would you like to perform? \nOperation ---- Command \nDownload single video ---- \"1\" \nDownload playlist videos ---- \"2\" \nDownload audio only ---- \"3\" \nDownload playlist audio only ---- \"4\"\nYour operation: ") ## Ask user for operation
    if operation == "1":
        link = input("Enter the video or playlist link address:") ## Ask for url
        DownloadSingleVideo(link)
    elif operation == "2":
        link = input("Enter the video or playlist link address:")
        DownloadPlaylistVideos(link)
    elif operation == "3":
        link = input("Enter the video or playlist link address:")
        DownloadAudioOnly(link)
    elif operation == "4":
        link = input("Enter the video or playlist link address:")
        DownloadPlaylistAudios(link)


SelectionScreen() ## Call our function to run the code