Wrap Gemtext to a set line length for use on Gopher

gmiwrap.sh

#!/usr/bin/env bash

# To use, make it executable, then you pipe or redirect the Gemtext in.
#
#  ./gmi2txt.sh < yourfile.gmi

LINE_LENGTH=70 # Adjust as you see fit ;)
PREFORMAT=OFF # This will get reset during processing.
while IFS= read -r line;
do
  if [ "$PREFORMAT" = ON ]; then
    case "$line" in
      '```'*)
        echo "$line"
        PREFORMAT=OFF
        ;;
      *)
        echo "$line"
        ;;
    esac
  else
    case "$line" in
      '* '*) # Lists
        echo "$line" | fmt -w "$(($LINE_LENGTH - 2))" | sed -E 's/^([^\*])/  \1/'
        ;;
      '=>'*) # Links
        echo "$line" | sed 's/^=>//' | fmt -w "$(($LINE_LENGTH - 2))" | sed 's/^/  /;1s/^  /=>/'
        ;;
      '>'*) # Quote
        echo "$line" | sed -E 's/^>[[:blank:]]?//' | fmt -w "$(($LINE_LENGTH - 2))" | sed 's/^/> /'
        ;;
      '```'*) # Pre-formatted text
        echo "$line"
        PREFORMAT=ON
        ;;
      *)
        echo "$line" | fmt -w "$LINE_LENGTH"
        ;;
    esac
  fi
done