structure Recovery:
sig
  val createMissingDirectories:
    {execlog: string, auxfile: string, outdir: string}
    -> bool
  val runEpstopdf:
    { options: AppOptions.options
    , execlog: string
    , originalWorkingDirectory: string
    }
    -> bool
  val tryRecovery:
    { options: AppOptions.options
    , execlog: string
    , auxfile: string
    , originalWorkingDirectory: string
    }
    -> bool
end =
struct
  fun createMissingDirectories {execlog, auxfile, outdir} =
    if String.isSubstring "I can't write on file" execlog then
      (* There is a possibility that there are some subfiles under subdirectories.
       * Directories for sub-auxfiles are not created automatically, so we need to provide them. *)
      let
        val (madeNewDirectory, _) =
          AuxFile.createMissingDirectories
            {auxfile = auxfile, outdir = outdir, seen = StringSet.empty}
      in
        if madeNewDirectory andalso Message.getVerbosity () >= 1 then
          Message.info "Created missing directories."
        else
          ();
        madeNewDirectory
      end
    else
      false

  fun runEpstopdf
    { options: AppOptions.options
    , execlog: string
    , originalWorkingDirectory: string
    } =
    if #shell_escape options <> SOME ShellEscape.FORBIDDEN then (* (possibly restricted) \write18 enabled *)
      let
        val lines =
          Substring.tokens (fn c => c = #"\n") (Substring.full execlog)
        fun doLine (line, run) =
          case List.map Substring.string (Substring.tokens Char.isSpace line) of
            ["(epstopdf)", "Command:", command, outfile', infile'] =>
              if
                command = "<epstopdf"
                orelse
                command = "<repstopdf"
                andalso String.isPrefix "--outfile=" outfile'
                andalso String.isSuffix ">" infile'
              then
                let
                  val outfile = String.extract (outfile', 10, NONE)
                  val infile = String.substring
                    (infile', 0, String.size infile' - 1)
                  val infileAbs =
                    PathUtil.abspath
                      {path = infile, cwd = SOME originalWorkingDirectory}
                in
                  if FSUtil.isFile infileAbs then (* input file exists *)
                    let
                      val outfileAbs = PathUtil.abspath
                        {path = outfile, cwd = SOME (#output_directory options)}
                      val () =
                        if Message.getVerbosity () >= 1 then
                          Message.info ("Running epstopdf on " ^ infile ^ ".")
                        else
                          ()
                      val outdir = PathUtil.dirname outfileAbs
                      val () =
                        if not (FSUtil.isDirectory outdir) then
                          FSUtil.mkDirRec outdir
                        else
                          ()
                      val command =
                        "epstopdf --outfile=" ^ ShellUtil.escape outfileAbs
                        ^ " " ^ ShellUtil.escape infileAbs
                      val () = Message.exec command
                      val success =
                        OS.Process.isSuccess (OS.Process.system command)
                    in
                      run orelse success
                    end
                  else
                    run
                end
              else
                run
          | _ => run
      in
        List.foldl doLine false lines
      end
    else
      false

  (* The next time we will able to set \PassOptionsToPackage{outputdir=}{minted} *)
  fun checkMinted {execlog} =
    String.isSubstring
      "Package minted Error: Missing Pygments output; \\inputminted was" execlog

  fun tryRecovery {options, execlog, auxfile, originalWorkingDirectory} =
    let
      val recovered =
        createMissingDirectories
          { execlog = execlog
          , auxfile = auxfile
          , outdir = #output_directory options
          }
      val recovered =
        runEpstopdf
          { options = options
          , execlog = execlog
          , originalWorkingDirectory = originalWorkingDirectory
          } orelse recovered
      val recovered = recovered orelse checkMinted {execlog = execlog}
    in
      recovered
    end
end;