R/ari_document.R
In ariExtra: Tools for Creating Automated Courses

Documented in ari_document

#' Ari Document Class for Rendering
#' @param ... arguments to pass to [ari::ari_spin]
#'
#' @export
ari_document = function(...) {
  output_movie_file = NULL
  rm(list = "output_movie_file")
  pre_knit <- function(input) {
    # saved_files_dir <<- files_dir
    # get the output
    ext = tolower(tools::file_ext(input))
    stub = tools::file_path_sans_ext(input)
    # yaml = yaml::read_yaml(file = input)
    yaml = partition_yaml_front_matter(readLines(input))
    yaml = yaml::read_yaml(text = yaml$front_matter)
    L = c(
      yaml$output$`ariExtra::ari_document`$output,
      yaml$output$ari_document$output)
    if (length(L) == 0) {
      output = paste0(stub, ".mp4")
    } else {
      output = unique(L)
      if (length(output) > 1) {
        output = output[1]
      }
    }
    abs_stub = tools::file_path_as_absolute(input)
    abs_stub = tools::file_path_sans_ext(abs_stub)

    intermediates_dir = paste0(abs_stub, "_files")
    dir.create(intermediates_dir, showWarnings = FALSE)


    x = readLines(input, warn = FALSE)
    if (ext %in% "rmd") {
      paragraphs <- parse_speak_comments(input)
    } else {
      paragraphs <- parse_html_comments(input)
    }
    x = sub("^\\s*knitr::", "", x)
    img_ind = grepl("(^!\\s*\\[.*\\]\\s*\\(|include_graphics\\()", x)
    if (sum(img_ind) == 0) {
      stop("No images are found")
    }
    images = x[img_ind]
    images = trimws(images)
    images = sub("!\\s*\\[.*\\]\\s*\\(", "", images)
    images = sub("\\s*include_graphics\\(", "", images)
    images = sub("\\)$", "", images)
    images = sub("^'", "", images)
    images = sub('^"', "", images)
    images = sub("'$", "", images)
    images = sub('"$', "", images)

    # need to check if voice the same
    # here is where caching may come in handy
    out_txt = file.path(intermediates_dir,
                        paste0("slide_", seq_along(paragraphs), ".txt"))
    fe = file.exists(out_txt)
    if (any(fe)) {
      old_paragraphs = lapply(out_txt[fe], readLines)
      names(old_paragraphs) = out_txt[fe]
    }

    args = list(...)
    cleanup = args$cleanup
    if (is.null(cleanup)) {
      # use default from ari
      cleanup = formals(ari::ari_stitch)$cleanup
    } else {
      cleanup = as.logical(cleanup)
    }
    args$images = images
    args$paragraphs = paragraphs
    args$output = output
    args$cleanup = FALSE
    res = do.call(ari::ari_spin, args = args)

    wav_path = attr(res, "wav_path")
    if (!is.null(wav_path) && cleanup) {
      unlink(wav_path, force = TRUE)
    }

    txt_path = attr(res, "txt_path")
    if (!is.null(txt_path) && cleanup) {
      unlink(txt_path, force = TRUE)
    }
    wavs = attr(res, "wavs")

    # here is where caching may come in handy
    stopifnot(length(wavs) == length(paragraphs))
    tmp = mapply(function(text, file) {
      writeLines(text, con = file)
    }, paragraphs, out_txt)

    output_movie_file <<- output
    out_wavs = file.path(intermediates_dir,
                         paste0("slide_", seq_along(wavs), ".wav"))
    tmp = mapply(function(wav, file) {
      tuneR::writeWave(wav, file)
    }, wavs, out_wavs)
    return(output)
  }

  post_processor = function(yaml_front_matter,
                            utf8_input,
                            output_file,
                            clean,
                            verbose) {

    width = c(
      yaml_front_matter$output$`ariExtra::ari_document`$width,
      yaml_front_matter$output$ari_document$width)
    if (length(width) == 0) {
      width = "100%"
    }

    height = c(
      yaml_front_matter$output$`ariExtra::ari_document`$height,
      yaml_front_matter$output$ari_document$height)
    if (length(height) == 0) {
      height = NULL
    }

    val = c(
      "<html>",
      '<head>',
      paste0('<link href="https://vjs.zencdn.net/7.6.0/video-js.css"',
             ' rel="stylesheet">'),
      paste0(
        '    ',
        '<script src="https://vjs.zencdn.net/ie8/1.1.2/videojs-ie8.min.js">',
        '</script>'),
      '    </head>',
      '    <body>',
      paste0(

        "      <video id='my-video' class='video-js vjs-default-skin' ",
        "data-setup='{\"fluid\": true}' ",
        "controls preload='auto' ",
        ifelse(is.null(width), "",
               paste0(" width='", width, "'")),
        ifelse(is.null(height), "",
               paste0(" height='", height, "'")),
        ">"),
      paste0("      <source src='", output_movie_file,
             "' type='video/mp4'>"),
      "      <p class='vjs-no-js'>",
      paste0("      To view this video please enable JavaScript, ",
             "and consider upgrading to a web browser that"),
      paste0("    <a href='https://videojs.com/html5-video-support/' ",
             "target='_blank'>supports HTML5 video</a>" ),
      "      </p>",
      "      </video>",
      "    <script src='https://vjs.zencdn.net/7.6.0/video.js'></script>",
      "      </body>",
      "</html>")
    writeLines(val, output_file)
    output_file
  }

  rmarkdown::output_format(
    knitr = NULL,
    pandoc = list(to = "html", ext = ".html", keep_tex = FALSE),
    clean_supporting = FALSE,
    post_processor = post_processor,
    pre_knit = pre_knit)
}