#! /bin/bash

# Process each incoming mail
# TODO image/audio mail part

# message for logging delivery
log=$(grep -rlE 'From:\s+<?MDA' ~/Maildir/cur | head -1)
if [ -z $log ]; then
  log=~/Maildir/cur/deliver.log
  <<-HEADER cat >$log
	From: MDA
	Content-Type: text/plain; charset=UTF-8
	Subject: Delivery Log

	HEADER
fi

exec 2>>$log
shopt -s nocasematch

# update index for dovecot
trap 'doveadm force-resync ${mailbox:-/}' EXIT

# temp file for decodemail (GNU Mailutils)
tmp_mailbox=$(mktemp -d); mkdir -p ${tmp_mailbox}/{tmp,new,cur}
cat >${tmp_mailbox}/cur/mail
trap 'rm -rf ${tmp_mailbox}' EXIT

# Restore mail into variables
MAIL="$(decodemail ${tmp_mailbox})"
# TODO process multi-line header field
header="$(<<<"$MAIL" sed '/^$/ q; /^[[:blank:]]/ d;')"
body="$(<<<"$MAIL" sed -n '/^$/,$ p' | sed '1d')"

# vars about output
date=$(date --iso=seconds)
maildir=${HOME}/Maildir
mailbox=

# Set set_stdout
set_stdout() {
  filename=${Subject// /_}
  path=${maildir}/${mailbox}${mailbox:+/}new/${date//:/}.${filename//[^[:alnum:]_]/}
  mkdir -p $(dirname $path)

  exec 1>$path
}

print_mail() {
  echo "$MAIL"
}

# save each field of header into vars
# TODO Use GNU MailUtils to save header
while IFS=': ' read field value; do
  field="${field^^}"
  field="${field//-/_}"
  declare ${field}="${value}"
done <<<"$header"

# save to mailbox
if [[ "$SENDER" = pham@topo.tw && -n $Chat_Version ]]; then
  heading="$(head -1 <<<"${body}")"

  if [[ "${heading}" =~ ^"." ]]; then
     mailbox=do
     heading=${heading#.}
  else
    mailbox=box
  fi

  print_mail() {
    <<-MAIL cat
		From: me
		Date: $(date --rfc-email)
		Message-ID: ${Message_ID}
		Self: true
		Subject: ${heading}

		$(sed 1d <<<"$body")
	MAIL
  }
elif [[ "$SUBJECT" =~ 帳單|轉帳|對帳|付款|發票|消費|繳費|收據|費用|Invoice|Billing ]]; then
  mailbox=pay
elif [[ "$TO" = dmarc@topo.tw ]]; then
  mailbox=DEV/dmarc
elif [[ "$LIST_ID" =~ ^'Open Street Map Taiwan' ]]; then
  mailbox=FOSS/osm
elif [[ "$LIST_ID" =~ ^~rjarry/aerc-discuss ]]; then
  mailbox=LIST/aerc
elif [[ "$LIST_ID" =~ '<mutt-users.mutt.org>' ]]; then
  mailbox=LIST/mutt
elif [[ -n "${LIST_ID}" ]]; then
  mailbox=news
elif [[ "$SUBJECT" =~ login|verify|sign-in|密碼|安全性警示|登入 ]]; then
  mailbox=login
elif [[ "$SUBJECT" =~  電子報|newsletter ]]; then
  mailbox=news
elif [[ "$TO" = cloudflare@topo.tw ]]; then
  mailbox=SRV/cloudflare
elif [[ "$SUBJECT" =~ eDM ]]; then
  mailbox=MISC/promote
fi

# deliver mail to mailbox
set_stdout && print_mail

# log to stderr
echo -e ${date} ${mailbox:-INBOX} '\t' ${heading:-${SUBJECT}} >&2