R/combine_subtitles.R

In fkeck/subtools: Read and Manipulate Video Subtitles

#' Bind subtitles
#'
#' Bind \code{subtitles} or/and \code{multisubtitles} objects.
#'
#' @param ... \code{subtitles} or \code{multisubtitles} objects to be binded.
#' @param collapse logical. If \code{TRUE}, subtitles are combined in a single \code{subtitles} object.
#' @param sequential logical. If \code{TRUE} (default) timecodes
#' are recalculated to follow concatenation.
#'
#' @return A \code{subtitles} object if \code{collapse = TRUE} (default).
#' A \code{multisubtitles} object if \code{collapse = FALSE}.
#'
#' @examples
#' f1 <- system.file("extdata", "ex_subrip.srt", package = "subtools")
#' s1 <- read_subtitles(f1, metadata = tibble::tibble(Season = 1, Episode = 2))
#' f2 <- system.file("extdata", "ex_substation.ass", package = "subtools")
#' s2 <- read_subtitles(f2, metadata = tibble::tibble(Season = 2))
#' bind_subtitles(s1, s2)
#' bind_subtitles(s1, s2, collapse = FALSE)
#' @export
#'
bind_subtitles <- function(..., collapse = TRUE, sequential = TRUE){
  input <- list(...)
  sl <- list()
    for(i in 1:length(input)){
    if(is(input[[i]], "multisubtitles")){
      sl <- append(sl, unlist(input[i], recursive = FALSE))
    } else {
      sl <- append(sl, input[i])
    }
  }

  lapply(sl, .validate_subtitles)

  if(sequential){
    tcout.max <- hms::as_hms("00:00:00.000")
    for(i in 1:length(sl)){

      sl[[i]]$Timecode_in <- sapply(sl[[i]]$Timecode_in,
                                              `+`,
                                              y = tcout.max, USE.NAMES = FALSE)
      sl[[i]]$Timecode_in <- hms::as_hms(sl[[i]]$Timecode_in)
      sl[[i]]$Timecode_out <- sapply(sl[[i]]$Timecode_out,
                                              `+`,
                                              y = tcout.max, USE.NAMES = FALSE)
      sl[[i]]$Timecode_out <- hms::as_hms(sl[[i]]$Timecode_out)
      tcout.max <- max(sl[[i]]$Timecode_out)
    }
  }

  if(collapse){
    sl <- do.call(dplyr::bind_rows, lapply(sl, function(x) x))
    res <- subtitles(text = sl$Text_content,
                     timecode.in = sl$Timecode_in,
                     timecode.out = sl$Timecode_out,
                     id = sl$ID,
                     metadata = extract_metadata(sl))
  } else {
    res <- sl
    class(res) <- "multisubtitles"
  }

  return(res)
}