#!/bin/bash

# CHAIN:
# cat invite.ics | ./import_khal.sh
# cat invite.ics | ./gen_reply.sh [accept|...] > reply.ics
# cat reply.ics | ./gen_email.sh > reply.eml
# cat reply.eml | msmtp-wrap.sh sender recipient

# cat invite.ics | ./gen_mail_reply.sh > reply.eml (get the sender and recipient from the invite.ics)

# Usage: cat mail.eml | ./msmtp-wrap.sh [sender_address] [recipient_address]

if [ $# -eq 2 ]; then
    SENDER_ADDRESS="$1"
    RECPT_ADDRESS="$2"
else
    SENDER_ADDRESS=""
    RECPT_ADDRESS=""
fi;

MCONFIG_DIR="${HOME}/.config/msmtp-wrap"

MSMTP_MCONFIG_DIR="${HOME}/.config/msmtp"
# IMPORTANT: Apparmor limits the paths msmtp can read !
# see /etc/apparmor.d/usr.bin.msmtp for a list of allowed paths !
MSMTP_LCONFIG_DIR="/tmp"
#TMPDIR=/tmp

CUR_DATE=$(date +%s)
cur_inc=0
FILE=$(cat)

# First, get the header section
# and the body section of the message
# fed to the program
MAIL_HEAD_RAW=''
MAIL_MIMEHEAD=''
MAIL_CONTENT_RAW=''
isbody=0
ismime=0
ismid=0
isdate=0
while IFS= read -r line; do
    if [ $isbody -eq 0 ]; then
	# if we are not in the body section yet, check if the line
	# looks like a header
	printf '%s\n' "$line" | grep -q -E '^([[:graph:]]*:| ).*'
	if [ $? -eq 0 ]; then
	    printf '%s\n' "$line" | grep -q -Ei '^Message-ID:.*'
	    retmih=$?
	    printf '%s\n' "$line" | grep -q -Ei '^Date:.*'
	    retdh=$?
	    # printf '%s\n' "$line" | grep -q -Ei '^(MIME-Version|Content-(Type|Disposition|Transfer-Encoding)):.*'
	    # retmh=$?
	    printf '%s\n' "$line" | grep -q -E '^( ).*'
	    rethf=$?
	    if [ $retmih -eq 0 ] || ([ $ismid -eq 1 ] && [ $rethf -eq 0 ]); then
		# if the line looks like a message-id header, discard it
		ismid=1
		isdate=0
		ismime=0
	    elif [ $retdh -eq 0 ] || ([ $isdate -eq 1 ] && [ $rethf -eq 0 ]); then
		# if the line looks like a date header, discard it
		ismid=0
		isdate=1
		ismime=0
	    # elif [ $retmh -eq 0 ] || ([ $ismime -eq 1 ] && [ $rethf -eq 0 ]); then
	    # 	# if the line looks like a mime header, save it in a different var
	    # 	ismime=1
	    # 	if [ -z "$MAIL_MIMEHEAD" ]; then
	    # 	    MAIL_MIMEHEAD=$(printf '%s\n' "$line")
	    # 	else
	    # 	    MAIL_MIMEHEAD=$(printf '%s\n' "$MAIL_MIMEHEAD" ; printf '%s\n' "$line")
	    # 	fi
	    # 	# Note: We don't do anything with the collected mime
	    # 	# headers they are just discarded for now. We
	    # 	# effectively replace them with our own. This implies
	    # 	# that we are converting the original e-mail body to a
	    # 	# utf-8, quoted-printable e-mail.
	    else
		ismid=0
		isdate=0
		ismime=0
		# if the line looks like a
		# non-message-id,
		# non-date,
		# non-mime header, put it in the
		# headersection file
		# printf '%s\n' "$line"
		# printf '%s\n' "$line" >> ${TMPDIR}/mail-head_raw.txt
		if [ -z "$MAIL_HEAD_RAW" ]; then
		    MAIL_HEAD_RAW=$(printf '%s\n' "$line")
		else
		    MAIL_HEAD_RAW=$(printf '%s\n' "$MAIL_HEAD_RAW" ; printf '%s\n' "$line")
		fi
	    fi
	else
	    # if the line doesn't look like a header, check if it's an
	    # empty line
	    printf '%s\n' "$line" | grep -q -E '^$'
	    if [ $? -ne 0 ]; then
		# if the line is not empty, put it in the bodysection
		# file
		# printf '%s\n' "$line"
		# printf '%s\n' "$line" >> ${TMPDIR}/mail-content_raw.txt
		if [ -z "$MAIL_CONTENT_RAW" ]; then
		    MAIL_CONTENT_RAW=$(printf '%s\n' "$line")
		else
		    MAIL_CONTENT_RAW=$(printf '%s\n' "$MAIL_CONTENT_RAW" ; printf '%s\n' "$line")
		fi
            fi
	    # acknowledge that we are in the body section
            isbody=1
	fi
    else
	# if we are in the body section, put the line in the
	# bodysection file
	# printf '%s\n' "$line"
	# printf '%s\n' "$line" >> ${TMPDIR}/mail-content_raw.txt
	if [ -z "$MAIL_CONTENT_RAW" ]; then
	    MAIL_CONTENT_RAW=$(printf '%s\n' "$line")
	else
	    MAIL_CONTENT_RAW=$(printf '%s\n' "$MAIL_CONTENT_RAW" ; printf '%s\n' "$line")
	fi
    fi
done <<EOF
$FILE
EOF

printf '%s\n' "$MAIL_HEAD_RAW"
printf '%s\n' ""
printf '%s\n' "$MAIL_CONTENT_RAW"

# Unfold the header section
# so we can parse it
MAIL_HEAD_UNFOLDED=$(printf '%s\n' "$MAIL_HEAD_RAW" | sed ':a;N;$!ba;s/\n[ \t]/ /g')

# Note: The 'To:' header can appear only once in an e-mail
# Search for the To: header address
# If non-null, keep it
# otherwise create a new To: header based on ${RECPT_ADDRESS}
TO_HEAD_VALUE=$(printf '%s\n' "$MAIL_HEAD_UNFOLDED" | grep -i '^To:' | sed s/'^[tT][oO]:[ \t\r\v\n\f]*'/''/)
if [ "x$TO_HEAD_VALUE" == "x" ]; then
    if [ "x$RECPT_ADDRESS" == "x" ]; then
	printf '%s\n' "No recipient address found ! Aborting." >&2
	exit 1
    else
	MAIL_HEAD_UNFOLDED=$(
	    printf '%s\n' "To: ${RECPT_ADDRESS}" ;
	    printf '%s\n' "$MAIL_HEAD_UNFOLDED" | grep -iv '^To:';
	)
    fi
fi

# Note: The 'From:' header can appear only once in an e-mail
# Search for the From: header address
# If non-null, keep it
# otherwise create a new From: header based on ${SENDER_ADDRESS}
MFROMFULL_HEAD_VALUE=$(printf '%s\n' "$MAIL_HEAD_UNFOLDED" | grep -i '^From:' | sed s/'^[fF][rR][oO][mM]:[ \t\r\v\n\f]*'/''/)
if [ "x$MFROMFULL_HEAD_VALUE" == "x" ]; then
    if [ "x$SENDER_ADDRESS" == "x" ]; then
	printf '%s\n' "No sender address found ! Aborting." >&2
	exit 1
    else
	MAIL_HEAD_UNFOLDED=$(
	    printf '%s\n' "From: ${SENDER_ADDRESS}" ;
	    printf '%s\n' "$MAIL_HEAD_UNFOLDED" | grep -iv '^From:';
	)
    fi
fi

# We read a file ~/.config/send_mail.sh/${SENDER_CANONICAL_ADDRESS}.conf
# which contains:
# a. the name of the msmtp config file
# b. a copy of all the MUA options we need:
#    - folder (Maildir mailbox)
#    - record (Sent folder)
#    - from header (copy of 'my_hdr From:' or 'set from')
#    - bcc header (copy of 'my_hdr Bcc:')
#    - openpgp header (copy of 'my_hdr OpenPGP:')
#    - possibly some openpgp info (in case we want to sign/encrypt in the future)

SENDER_CANONICAL_ADDRESS=$( printf '%s\n' "${SENDER_ADDRESS}" | sed -E s/'([^+ \t]+?)(\+[ \t]+?)?@([ \t]+)'/'\1@\3'/ )

. ${MCONFIG_DIR}/${SENDER_CANONICAL_ADDRESS}.conf

# printf '%s\n' "msmtp_config: $msmtp_config" >&2
# printf '%s\n' "msmtp_account: $msmtp_account" >&2
# printf '%s\n' "folder: $folder" >&2
# printf '%s\n' "record: $record" >&2
# printf '%s\n' "header_from: $header_from" >&2
# printf '%s\n' "header_bcc: $header_bcc" >&2
# printf '%s\n' "header_openpgp: $header_openpgp" >&2
# printf '%s\n' "pgp_default_key: $pgp_default_key" >&2
# printf '%s\n' "crypt_autosign: $crypt_autosign" >&2
# printf '%s\n' "crypt_replyencrypt: $crypt_replyencrypt" >&2
# printf '%s\n' "crypt_replysignencrypted: $crypt_replysignencrypted" >&2

# Note: The 'Bcc:' header can appear only once in an e-mail
# If there is a bcc header in config
# Search for the Bcc: header address
# Create a new Bcc: header or add a new field to existing Bcc: header
if [ "x$header_bcc" != "x" ]; then
    BCC_HEAD=$(printf '%s\n' "$MAIL_HEAD_UNFOLDED" | grep -i -m1 '^Bcc:')
    if [ "x$BCC_HEAD" != "x" ]; then
	BCC_HEAD_VALUE=$(printf '%s\n' "$BCC_HEAD" | sed s/'^[bB][cC][cC]:[ \t\r\v\n\f]*'/''/)
	if [ "x$BCC_HEAD_VALUE" != "x" ]; then
	    header_bcc=", ${header_bcc}"
	fi
	MAIL_HEAD_UNFOLDED=$(
	    printf '%s\n' "$MAIL_HEAD_UNFOLDED" | sed -E s/'^([bB][cC]{2}:.*)'/"\1${header_bcc}"/;
	)
    else
	MAIL_HEAD_UNFOLDED=$(
	    printf '%s\n' "$MAIL_HEAD_UNFOLDED";
	    printf '%s\n' "Bcc: ${header_bcc}" ;
	)
    fi
fi

MAIL_CUR_DATE=$(date -R -d "@${CUR_DATE}")
# Search for a Date: header
# If non-null, keep it
# otherwise create a new Date: header
DATE_HEAD_VALUE=$(printf '%s\n' "$MAIL_HEAD_UNFOLDED" | grep -i '^Date:' | sed s/'^[dD][aA][tT][eE]:[ \t\r\v\n\f]*'/''/)
if [ "x$DATE_HEAD_VALUE" == "x" ]; then
    MAIL_HEAD_UNFOLDED=$(
	printf '%s\n' "$MAIL_HEAD_UNFOLDED" | grep -iv '^Date:';
	printf '%s\n' "Date: ${MAIL_CUR_DATE}" ;
    )
fi

MAIL_MSG_ID=$(date '+%Y%m%d%H%M%S' -d "@${CUR_DATE}").$(tr -dc 0-9A-Z </dev/urandom | head -c10; printf '%s\n')@$(hostname -f)
# Search for a Message-ID: header
# If non-null, keep it
# otherwise create a new Message-ID: header
MID_HEAD_VALUE=$(printf '%s\n' "$MAIL_HEAD_UNFOLDED" | grep -i '^Message-ID:' | sed s/'^[mM][eE][sS][sS][aA][gG][eE]-[iI][dD]:[ \t\r\v\n\f]*'/''/)
if [ "x$DATE_HEAD_VALUE" == "x" ]; then
    MAIL_HEAD_UNFOLDED=$(
	printf '%s\n' "$MAIL_HEAD_UNFOLDED" | grep -iv '^Message-ID:';
	printf '%s\n' "Message-ID: ${MAIL_MSG_ID}" ;
    )
fi

# Note: Several 'OpenPGP:' headers can be present in an e-mail
# If there is an openpgp header in config
# Create a new OpenPGP: header
if [ "x$header_openpgp" != "x" ]; then
    OPENPGP_HEAD=$(printf '%s\n' "$MAIL_HEAD_UNFOLDED" | grep -i '^OpenPGP:' | grep -i "$header_openpgp")
    if [ "x$OPENPGP_HEAD" == "x" ]; then
	MAIL_HEAD_UNFOLDED=$(
	    printf '%s\n' "$MAIL_HEAD_UNFOLDED";
	    printf '%s\n' "OpenPGP: ${header_openpgp}" ;
	)
    fi
fi

FILE=$(                                        
    printf '%s\n' "$MAIL_HEAD_UNFOLDED" ;
    printf '%s\n' "" ;
    printf '%s\n' "$MAIL_CONTENT_RAW" ;
)

printf '%s\n' "=== MAIL ===" >&2
printf '%s\n' "$FILE" >&2
printf '%s\n' "===  ===" >&2

# eventually we send the e-mail

# printf '%s\n' "* msmtp -C ${MSMTP_MCONFIG_DIR}/${SENDER_CANONICAL_ADDRESS}.conf -f $SENDER_ADDRESS -t -- $RECPT_ADDRESS" >&2
# printf '%s\n' "$FILE" | msmtp -C "${MSMTP_MCONFIG_DIR}/${SENDER_CANONICAL_ADDRESS}.conf" -f "$SENDER_ADDRESS" -t -- "$RECPT_ADDRESS"
printf '%s\n' "* msmtp -C ${MSMTP_MCONFIG_DIR}/${SENDER_CANONICAL_ADDRESS}.conf --read-envelope-from -t --" >&2
printf '%s\n' "$FILE" | msmtp -C "${MSMTP_MCONFIG_DIR}/${SENDER_CANONICAL_ADDRESS}.conf" --read-envelope-from -t --
ret=$?

# if successful, we copy the file in our Sent folder
if [ $ret -eq 0 ]; then
    cur_pid=$$
    cur_inc=$(( $cur_inc + 1 ))
    cur_host=$(hostname)

    filename="${CUR_DATE}.${cur_pid}_${cur_inc}.${cur_host}"

    printf '%s\n' "** printf '%s\n' \"\$FILE\" > ${record}/new/${filename}"
    printf '%s\n' "$FILE" > ${record}/new/${filename}
fi

# No need to configure password, since it's a one-time use
# we'll give it when we are prompted for it
# config_password () {
#     account="$1"
#     printf '%s' "Password for ${account}: "
#     read -s password </dev/tty
#     printf '%s\n' ""
#     printf '%s\n' "* cp ${MSMTP_MCONFIG_DIR}/${account}.conf ${MSMTP_LCONFIG_DIR}/.${USER}_msmtp_${account}.conf" >&2
#     cp "${MSMTP_MCONFIG_DIR}/${account}.conf" "${MSMTP_LCONFIG_DIR}/.${USER}_msmtp_${account}.conf"
#     printf '%s\n' "* chmod -R 600 ${MSMTP_LCONFIG_DIR}/.${USER}_msmtp_${account}.conf" >&2
#     chmod -R 600 "${MSMTP_LCONFIG_DIR}/.${USER}_msmtp_${account}.conf"
#     sed -i "s/#password dummy/password \"${password}\"/" "${MSMTP_LCONFIG_DIR}/.${USER}_msmtp_${account}.conf"
# }
# cd $HOME
# if [ -e "${MSMTP_LCONFIG_DIR}/.${USER}_msmtp_${SENDER_ADDRESS}.conf" ]; then
#     printf '%s\n' "File ${MSMTP_LCONFIG_DIR}/.${USER}_msmtp_${SENDER_ADDRESS}.conf already exist" >&2
# else
#     printf '%s\n' "* $0" >&2
#     config_password "$SENDER_ADDRESS"
# fi
# printf '%s\n' "* msmtp -C ${MSMTP_LCONFIG_DIR}/.${USER}_msmtp_${SENDER_ADDRESS}.conf -f $SENDER_ADDRESS -t -- $RECPT_ADDRESS" >&2
# printf '%s\n' "$FILE" | msmtp -C "${MSMTP_LCONFIG_DIR}/.${USER}_msmtp_${SENDER_ADDRESS}.conf" -f "$SENDER_ADDRESS" -t -- "$RECPT_ADDRESS"