#!/bin/bash
# Save piped email to "$1/YYMMDD_SUBJECT.eml"
# Make sure commands 's' and '|' have default meaning and are NOT unbinded

# Don't overwrite existing file
set -o noclobber

message=$(cat)

maildate=$(<<<"$message" grep -oPm 1 '^Date: ?\K.*')
fdate=$(date -d "$maildate" "+%y%m%d")
subject=$(<<<"$message" grep -oPm 1 '^Subject: ?\K.*' | sed 's,/,∕,g')

if [[ "$fdate" == '' ]]; then
  echo "Error: no date parsed"
  exit 1
elif [[ "$subject" == '' ]]; then
  echo "Warning: no subject found"
fi

echo "${message}" > "$1/$fdate""_""$subject.eml" && echo "Email saved to $1/$fdate""_""$subject.eml"

exit