Import from txt, change content and download R content

Question

Hi!

I am beginner in programming namely R, I have read quite still very confused with libraries and everything and still do not know what its limitations, so I ask you if it is possible with R to do the following:

I put it in *txt youtube video list, import list to R, it puts in data.frame, changes link to the "http://ssyoutube.com/..." and then download the entire list automatically.

What you have is you can only download one at a time, and you need to click button.

Can you automate all this with R, or I need to learn another programming language?

Back, but still very messed up, because I’m really a beginner :(

# importar_listas
# fiz assim para importar várias listas se necessário
# mas já topei que dá erro se tiver algum *txt temporário
# ou directório dentro desse.
# já por isso também deixei nome dos *txt sem espcaços
# alguma dica?

# buscar nome dos ficheiros no directório "youtube"
nome_ficheiros <- list.files(path="youtube/.")

# cola directorio + nome de *txt
ficheiro_t <- paste("youtube",nome_ficheiros,sep="/")

[1] "motivacao_desportiva.txt"  "natureza_linda.txt"       
[3] "pegadinhas_divertidas.txt"

# cria as listas de links em cada *txt 
lista_ficheiros <- lapply(ficheiro_t, read.table, stringsAsFactors = FALSE)

[1] "youtube/motivacao_desportiva.txt"      "youtube/natureza_linda.txt"       
[3] "youtube/pegadinhas_divertidas.txt"

# cria tabela com todos links, ordenados por linha
db_yt <- do.call(rbind, lista_ficheiros)

[[1]]
                                       V1
1 https://www.youtube.com/watch?v=C-Lq6FTwRWI
2 https://www.youtube.com/watch?v=0fVdAsTp0EU
3 https://www.youtube.com/watch?v=kYSdIQ16UxY
4 https://www.youtube.com/watch?v=gHaP_oJa_l0

[[2]] ...

Here began the confusion, as I had no success with download, I created several "urls"

# com todas as variaçoes que encontrei

for(i in seq(nrow(db_yt))) {   

    # transforma "youtube"em "ssyoutube.com"
  db_yt[i,2] = gsub(".*www.", "http://ss", db_yt[i,1])

    # transforma_em_http://en.savefrom.net/#url=
  db_yt[i,3] = gsub(".*www.", "http://en.savefrom.net/#url=", db_yt[i,1])

  # transforma_em_link_completo_site_download
    db_yt[i,4] = paste("http://en.savefrom.net/#url=", db_yt[i,1], "&utm_source=youtube.com&utm_medium=short_domains&utm_campaign=ssyoutube.com", sep = "")
 }
                                       V1
 1 https://www.youtube.com/watch?v=C-Lq6FTwRWI
 2 https://www.youtube.com/watch?v=0fVdAsTp0EU
 ...
                                    V2
 1 http://ssyoutube.com/watch?v=C-Lq6FTwRWI
 2 http://ssyoutube.com/watch?v=0fVdAsTp0EU
 ...
                                                       V3
 1 http://en.savefrom.net/#url=youtube.com/watch?v=C-Lq6FTwRWI
 2 http://en.savefrom.net/#url=youtube.com/watch?v=0fVdAsTp0EU
                                                                                                                        V4
 1 http://en.savefrom.net/#url=https://www.youtube.com/watch?v=C-Lq6FTwRWI&utm_source=youtube.com&utm_medium=short_domains&utm_campaign=ssyoutube.com
 2 http://en.savefrom.net/#url=https://www.youtube.com/watch?v=0fVdAsTp0EU&utm_source=youtube.com&utm_medium=short_domains&utm_campaign=ssyoutube.com
 ...

# ainda criei este vector para usar link original do *txt
save_url <-c("http://en.savefrom.net/#url=", "&utm_source=youtube.com&utm_medium=short_domains&utm_campaign=ssyoutube.com")


# importar bibliotecas
library(xml2)
library(rvest)
library(httr)

# simulador_de_browser
uastring <- "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36"

# site de download (1º link "completo")
url <- "http://en.savefrom.net/#url=https://www.youtube.com/watch?v=PWkIoMOBiKE&utm_source=youtube.com&utm_medium=short_domains&utm_campaign=ssyoutube.com"

# site para usar
site <- html_session(url, user_agent(uastring))

# descobrir o form
form <- site %>% html_form()

# só existe 1, logo
form <- form[[1]]

here big trouble, because it seems that it is inside iframe and I can not get there

# nomear_ficheiro_para_gravar
# se analisar o html e fizer search pelo "nome do video" simplesmente não aparece :(
nome <- site %>% html_nodes(xpath='//*[@id="answer-28575576"]/table/tbody/tr[1]/td[2]/div/pre') %>% html_text()

# submeter dados
dados <- set_values(form = form,
                     sf_url="http://youtube.com/watch?v=Q84boOmiPW8"
)

download <- submit_form(site, dados)
download.file(url, paste0(download, destfile="mp4", method="wget", mode = "wb"))

# se estivesse tudo funcionando
for(i in seq(nrow(db_yt))) {
  # site de download - 1º link
  url <- db_yt[i,4]

  # site para usar
  site <- html_session(url, user_agent(uastring))

    # demora um pouco a carregar página
    Sys.sleep(20)

    # submeter dados
  dados <- set_values(form = form,
                      sf_url=db_yt[i,1]
  )
  download <- submit_form(site, dados)
  download.file(url, paste0(download, destfile="mp4", method="wget", mode = "wb"))

    # nova pausa
    Sys.sleep(40)
}

Where is giving error is after Submit, but I appreciate all suggestions to improve even what for me does not give error.