Convert Markdown-ish to PDF with Groff MOM
       ================-=========================

  Last edited: $Date: 2021/02/16 20:20:41 $

  There are many ways one can generate a PDF file from
  a Markdown file. One example is  to  use  Pandoc  to
  generate LaTeX and use pdflatex to generate a PDF.

  Groff  can  be  a  lot faster and require a lot less
  resources. TeX Live packages can be quite large  and
  if  you  don't  need  a  lot of features this can be
  overkill.

  [Mom            Macros            for            GNU
  Troff](https://www.schaffter.ca/mom/mom-01.html)  is
  a nice toolbox to create beautiful documents.

  I use this to  convert  small  Markdown-ish  meeting
  notes into a PDF document.

  We  all  appreciate  the  plain text format, but for
  some people in our  organisation  this  is  not  the
  case.

  A small awk script can do wonders.

                    Example document
                    ----------------

  This  is  a  small  example  of the format I use for
  meeting notes.

    # Notes of the meeting with a special name
    - Date: 16 februari 2021
    - Time: 14:00 - 15:00
    ## A nice header
    Some information and some sentences. A lot more text. You can
    never have enough text.
    ## Another nice header
    Here we have another paragraph filled with very interesting
    text.

    This is another paragraph.

    ## Bullets are nice
    - There can never be too much bullets.
    - Some more are nice to look at
    - Always have at least three bullets

    ### A lower header
    This paragraph is right between a third level headers, because
    we want a lot of headers.

    #### Sublists
    This is a small test of sublists. Remember that bullets are great.
    - This is a bullet on the first level.
    - This too is a bullet on the first level.
          - This is a bullet on the second level.
          - This too is a bullet on the second level.
          - This is the third bullet on the second level.
    - This again is a bullet on the first level.
    - This too is a bullet on the first level.


                    Small awk script
                    ----------------

  This is the awk script that I  use  to  convert  the
  Markdown-ish file to the Groff mom format.

    BEGIN {
          inlisting = 0;
          inlisting2 = 0;
          inlisting3 = 0;
          inparagraph = 0;
          print ".PAPER A4"
          print ".TITLE_STYLE  COLOR YELLOW"
          print ".TITLE \"The Screaming Butterflies\"  \"Flower Power Workgroup\""
          print ".PDF_TITLE \"\\*[$TITLE]"
          print ".\\\" Formatting style, margins"
          print ".PRINTSTYLE TYPESET"
          print ".L_MARGIN   2.5c"
          print ".R_MARGIN   2.5c"
          print ".B_MARGIN   2.5c"
          print ".NEWCOLOR YELLOW #e36c0a"
          print ".HEADING_STYLE 1 COLOR YELLOW"
          print ".HEADING_STYLE 2 COLOR YELLOW"
          print ".\\\" General defaults"
          print ".FAMILY   P"
          print ".FT       R"
          print ".PT_SIZE  11"
          print ".AUTOLEAD 3 3"
          print ".PARA_INDENT 0 \\\" No indent because we're spacing paragraphs."
          print ".HYPHENATION 0 \\\" No hypenantion of words at end of line."
          print ".START"
    }
    {
          if ( $0 ~ /^# / ) { reset_list(); printf ".HEADING 1 \"%s\"\n", substr($0, 3); }
          else if ( $0 ~ /^## / ) { reset_list(); printf ".HEADING 2 \"%s\"\n", substr($0, 4); }
          else if ( $0 ~ /^### / ) { printf ".HEADING 3 \"%s\"\n", substr($0, 5); }
          else if ( $0 ~ /^#### / ) { printf ".HEADING 4 \"%s\"\n", substr($0, 6); }
          else if ( $0 ~ /^- / ) {
                  if ( inlisting2 == 1 ) {
                          inlisting2 = 0;
                          print ".LIST OFF"
                  }
                  if ( inlisting == 0 ) {
                          inlisting = 1;
                          print ".SP .25v"
                          print ".LIST"
                  }
                  print ".ITEM"; print substr($0, 3)
          }
          else if ( $0 ~ /^\t- / ) {
                  if ( inlisting == 0 ) {
                          inlisting = 1;
                          print ".SP .25v"
                          print ".LIST"
                  }
                  if ( inlisting2 == 0 ) {
                          inlisting2 = 1;
                          print ".LIST"
                  }
                  print ".ITEM"; print substr($0, 4)
          }
          else if ( $0 ~ /^\t\t- / ) {
                  if ( inlisting == 0 ) {
                          inlisting = 1;
                          print ".SP .25v"
                          print ".LIST"
                  }
                  if ( inlisting2 == 0 ) {
                          inlisting2 = 1;
                          print ".LIST"
                  }
                  if ( inlisting3 == 0 ) {
                          inlisting3 = 1;
                          print ".LIST"
                  }
                  print ".ITEM"; print substr($0, 5)
          }
          else if ( $0 ~ /^  / ) {
                          if ( inlisting == 1 || inlisting2 == 1  || inlisting3 == 1) {
                                  gsub("^ *", "", $0)
                          }
                  }
          else {
                  if ( inlisting3 == 1 ) {
                          inlisting3 = 0;
                          print ".LIST OFF"
                  }
                  if ( inlisting2 == 1 ) {
                          inlisting2 = 0;
                          print ".LIST OFF"
                  }
                  if ( inlisting == 1 ) {
                          inlisting = 0;
                          print ".LIST OFF"
                          print ".SP .25v"
                  }
                  if ( inparagraph == 0 ) {
                          inparagraph = 1;
                          print ".PP"
                  }
                  print $0
          }
    }
    function reset_list()
    {
          if ( inlisting3 == 1 ) {
                  inlisting3 = 0;
                  print ".LIST OFF"
          }
          if ( inlisting2 == 1 ) {
                  inlisting2 = 0;
                  print ".LIST OFF"
          }
          if ( inlisting == 1 ) {
                  inlisting = 0;
                  print ".LIST OFF"
                  print ".SP .25v"
          }
    }

  This  script creates headers with a color and allows
  for three levels of lists.

  I have just hacked it together  in  short  time  and
  stopped  when  it worked, so there is probably a lot
  of room for improvement.

             Run the awk script and pdfmom
             -----------------------------

  To use the script, this is the worfklow:

    awk -f name-of-the-awk-script > tempfile.mom
    pdfmom tempfile.mom  > final.pdf

                        See also
                        --------

  Some very informative resources are:

  - Documentation of the Groff mom macros set:
    https://tools.ietf.org/doc/groff/html/mom/toc.html
  - Comprihensive pages Mom Macros for GNU Troff at
    schaffter.ca:
    https://www.schaffter.ca/mom/mom-01.html