clarified goal structure with proper instantiation of main goal, to support "show_goal_inst";
/*  Title:      Pure/Admin/build_pdfjs.scala
    Author:     Makarius
Build Isabelle component for Mozilla PDF.js.
See also:
  - https://github.com/mozilla/pdf.js
  - https://github.com/mozilla/pdf.js/releases
  - https://github.com/mozilla/pdf.js/wiki/Setup-PDF.js-in-a-website
*/
package isabelle
object Build_PDFjs {
  /* build pdfjs component */
  val default_url = "https://github.com/mozilla/pdf.js/releases/download"
  val default_version = "2.14.305"
  def build_pdfjs(
    base_url: String = default_url,
    version: String = default_version,
    target_dir: Path = Path.current,
    progress: Progress = new Progress
  ): Unit = {
    Isabelle_System.require_command("unzip", test = "-h")
    /* component name */
    val component = "pdfjs-" + version
    val component_dir = Isabelle_System.new_directory(target_dir + Path.basic(component))
    progress.echo("Component " + component_dir)
    /* download */
    val download_url = base_url + "/v" + version
    Isabelle_System.with_tmp_file("archive", ext = "zip") { archive_file =>
      Isabelle_System.download_file(download_url + "/pdfjs-" + version + "-legacy-dist.zip",
        archive_file, progress = progress)
      Isabelle_System.bash("unzip -x " + File.bash_path(archive_file),
        cwd = component_dir.file).check
    }
    /* settings */
    val etc_dir = Isabelle_System.make_directory(component_dir + Path.basic("etc"))
    File.write(etc_dir + Path.basic("settings"),
      """# -*- shell-script -*- :mode=shellscript:
ISABELLE_PDFJS_HOME="$COMPONENT"
""")
    /* README */
    File.write(component_dir + Path.basic("README"),
      """This is PDF.js from
""" + download_url + """
        Makarius
        """ + Date.Format.date(Date.now()) + "\n")
  }
  /* Isabelle tool wrapper */
  val isabelle_tool =
    Isabelle_Tool("build_pdfjs", "build component for Mozilla PDF.js",
      Scala_Project.here,
      { args =>
        var target_dir = Path.current
        var base_url = default_url
        var version = default_version
        val getopts = Getopts("""
Usage: isabelle build_pdfjs [OPTIONS]
  Options are:
    -D DIR       target directory (default ".")
    -U URL       download URL (default: """" + default_url + """")
    -V VERSION   version (default: """" + default_version + """")
  Build component for PDF.js.
""",
          "D:" -> (arg => target_dir = Path.explode(arg)),
          "U:" -> (arg => base_url = arg),
          "V:" -> (arg => version = arg))
        val more_args = getopts(args)
        if (more_args.nonEmpty) getopts.usage()
        val progress = new Console_Progress()
        build_pdfjs(base_url = base_url, version = version, target_dir = target_dir,
          progress = progress)
      })
}