#!/bin/sh
# mcom [TO] - compose mail

NL='
'

commajoin() {
	awk 'NR==1 {l=$0; next}
	     {l=l", "$0}
	     END {print l}'
}

notmine() {
	mine="$(maddr -a -h local-mailbox:alternate-mailboxes: "$MBLAZE/profile")"
	grep -Fv -e "$mine"
}

replyfrom() {
	addrs="$(maddr -a -h reply-from: "$MBLAZE/profile")"
	[ -z "$addrs" ] && addrs="$(maddr -a -h alternate-mailboxes: "$MBLAZE/profile")"
	grep -F -e "$addrs"
}

ouniq() {
	awk '!seen[$0]++'
}

reffmt() {
	sed 's/^[^<]*//g;s/[^>]*$//g;s/>[^<]*</>\
</g' | uniq | sed 's/^/ /'
}

msgid() {
	mgenmid 2>/dev/null | sed 's/^/Message-Id: /'
}

stampdate() {
	if ! mhdr -h date "$1" >/dev/null; then
		tmp=$(mktemp -t mcom.XXXXXX)
		{
			printf 'Date: '
			mdate
			cat "$1"		
		} >"$tmp" &&
		mv "$tmp" "$1"
	fi
}

checksensible() {
	awk '
		/^$/ {
			seenheader=1
			exit
		}
		!(/^[^ \t][^ \t]*[ \t]*:/ || /^[ \t]/) {
			bad=1
			print "invalid header line: "$0 >"/dev/stderr"
		}
		END {
			if (!seenheader) {
				print "warning: message does not contain an empty line between headers and body." >"/dev/stderr"
				exit 1
			}
			if (bad)
				exit 1
		}
' "$1"
}

stripempty() {
	tmp=$(mktemp -t mcom.XXXXXX)
	msed 's/^[ \t]*$//d' "$1" >"$tmp"
	mv "$tmp" "$1"
}

needs_multipart() {
	mhdr -h attach "$1" >/dev/null ||
		grep -qE '^#[a-zA-Z]+/[a-zA-Z0-9+.;=#-]+ ' "$1"
}

do_mime() {
	if needs_multipart "$draft"; then
		(
			IFS=$NL
			msed '/attach/d' "$draft"
			for f in $(mhdr -M -h attach "$draft"); do
				printf '#%s %s\n' \
				       "$(file -Lb --mime "$f" | sed 's/ //g')" \
				       "$f"
			done
		) | mmime >"$draftmime"
	else
		mmime -r <"$draft" >"$draftmime"
	fi
	if [ $? -ne 0 ]; then
 	     	printf 'mcom: fix above errors before continuing\n' 1>&2
		rm -f "$draftmime"
	fi
}

MBLAZE=${MBLAZE:-$HOME/.mblaze}

sendmail=$(mhdr -h sendmail "$MBLAZE/profile")
sendmail_args=$(mhdr -h sendmail-args "$MBLAZE/profile")
sendmail="${sendmail:-sendmail} ${sendmail_args:--t}"
default_from=$(mhdr -h local-mailbox "$MBLAZE/profile")
senthook=$(mhdr -h senthook "$MBLAZE/profile")

defaultc=e

hdrs=
resume=
noquote=
case "$0" in
*mcom*)
	hdr=to
	while [ $# -gt 0 ]; do
		case "$1" in
		--)
			# -- is like -to, really
			shift
			hdr=to
			;;
		-r)
			shift
			resume=1
			if [ "$#" -gt 0 ]; then
				case "$1" in
					/*|./*) draft="$1";;
					*) draft="./$1";;
				esac
				if ! [ -f "$draft" ]; then
					printf 'mcom: no such draft %s\n' \
					       "$draft" 1>&2
					exit 1
				fi
				echo "using draft $draft"
				shift
			fi
			;;
		-send)
			defaultc=justsend
			shift;;
		-??*)
			hdr=${1#-}
			shift;;
		[!-]*)
			hdrs="$hdrs$NL$(printf '%s: %s\n' "${hdr}" "$1")"
			shift;;
		*)
			printf 'mcom: invalid argument %s\n' "$1" 1>&2
			exit 1;;
		esac
	done
	;;
*mfwd*)
	hdr=
	raw=
 	while [ $# -gt 0 ]; do
		case "$1" in
		--)
			shift
			break;;
		-r)
			shift
			raw=1;;
		-send)
			defaultc=justsend
			shift;;
		-??*)
			hdr=${1#-}
			shift;;
		[!-]*)
			[ -z "$hdr" ] && break
			hdrs="$hdrs$NL$(printf '%s: %s\n' "${hdr}" "$1")"
			shift;;
		*)
			printf 'mfwd: invalid argument %s\n' "$1" 1>&2
			exit 1;;
		esac
	done
	[ "$#" -eq 0 ] && set -- .
	;;
*mbnc*)
	hdr=
 	while [ $# -gt 0 ]; do
		case "$1" in
		--)
			shift
			break;;
		-send)
			defaultc=justsend
			shift;;
		-??*)
			hdr=${1#-}
			shift;;
		[!-]*)
			[ -z "$hdr" ] && break
			hdrs="$hdrs$NL$(printf '%s: %s\n' "${hdr}" "$1")"
			shift;;
		*)
			printf 'mbnc: invalid argument %s\n' "$1" 1>&2
			exit 1;;
		esac
	done
	[ "$#" -eq 0 ] && set -- .
	;;
*mrep*)
	hdr=
 	while [ $# -gt 0 ]; do
		case "$1" in
		--)
			shift
			break;;
		-send)
			defaultc=justsend
			shift;;
		-noquote)
			noquote=1
			shift;;
		-??*)
			hdr=${1#-}
			shift;;
		[!-]*)
			[ -z "$hdr" ] && break
			hdrs="$hdrs$NL$(printf '%s: %s\n' "${hdr}" "$1")"
			shift;;
		*)
			printf 'mrep: invalid argument %s\n' "$1" 1>&2
			exit 1;;
		esac
	done
	[ "$#" -eq 0 ] && set -- .
	;;
esac

hdrs="$(printf '%s\n' "${hdrs#$NL}" | mhdr -)"

outbox=$(mhdr -h outbox "$MBLAZE/profile" | sed "s:^~/:$HOME/:")
draftbox=$(mhdr -h drafts "$MBLAZE/profile" | sed "s:^~/:$HOME/:")
draftbox="${draftbox:-$outbox}"
if [ -z "$draftbox" ]; then
	if [ -z "$resume" ]; then
		i=0
		while [ -f "snd.$i" ]; do
			i=$((i+1))
		done
		draft="./snd.$i"
	elif [ -z "$draft" ]; then
		draft=$(ls -1t ./snd.*[0-9] | sed 1q)
	fi
	draftmime="$draft.mime"
else
	if [ -z "$resume" ]; then
		draft="$(true | mdeliver -v -c -XD "$draftbox")"
		if [ -z "$draft" ]; then
			printf '%s\n' "$0: failed to create draft in outbox $draftbox." 1>&2
			exit 1
		fi
	elif [ -z "$draft" ]; then
		draft=$(mlist -D "$draftbox" | msort -r -M | sed 1q)
	fi
	draftmime="$(printf '%s\n' "$draft" | sed 's,\(.*\)/cur/,\1/tmp/mime-,')"
fi

if [ -n "$resume" ] && [ -z "$draft" ]; then
	echo "mcom: no draft found"
	exit 1
fi

[ -z "$resume" ] &&
{
	case "$0" in
	*mcom*)
		{
			printf '%s' "$hdrs" | mhdr -M -h to - |
				commajoin | sed 's/^/To: /'
			printf '%s' "$hdrs" | mhdr -M -h cc - |
				commajoin | sed 's/^/Cc: /'
			printf '%s' "$hdrs" | mhdr -M -h bcc - |
				commajoin | sed 's/^/Bcc: /'
			printf '%s\n' "$hdrs" | awk '{ print }' |
				msed "/to/d; /cc/d; /bcc/d; /body/d" -
		} | msed "/cc/a//; /bcc/a//; /subject/a//; /from/a/$default_from/" - | sed '/^$/d'
		msgid
		museragent
		cat "$MBLAZE/headers" 2>/dev/null
		printf '\n'
		(
			IFS=$NL
			cat -- /dev/null $(printf '%s' "$hdrs" | mhdr -M -h body -)
		)
		printf '\n'
		;;
	*mfwd*)
		{
			printf '%s' "$hdrs" | mhdr -M -h to - |
				commajoin | sed 's/^/To: /'
			printf '%s' "$hdrs" | mhdr -M -h cc - |
				commajoin | sed 's/^/Cc: /'
			printf '%s' "$hdrs" | mhdr -M -h bcc - |
				commajoin | sed 's/^/Bcc: /'
			COLUMNS=10000 mscan -f 'Subject: Fwd: [%f] %s' "$@" 2>/dev/null | sed 1q
			printf '%s\n' "$hdrs" | awk '{ print }' |
				msed "/to/d; /cc/d; /bcc/d" -
		} | msed "/cc/a//; /bcc/a//; /from/a/$default_from/" - | sed '/^$/d'
		msgid
		museragent
		cat "$MBLAZE/headers" 2>/dev/null
		if [ -n "$raw" ]; then
			prev=$(pwd)
			attachdir=$(mktemp -d)
			cd $attachdir
			trap 'rm -r "$attachdir"' EXIT

			mseq -r "$@" \
				| xargs -I {} mshow -Bx {} \
				| xargs -I {} realpath {} \
				| sed '/^$/d; s/^/Attach: /'
			cd $prev
		fi

		printf '\n\n'
		if [ -z "$raw" ]; then
			mseq -r "$@" | sed 's:^:#message/rfc822#inline :; s:$:>:'
		else (
			SEP=-----
			IFS=$NL
			for f in $(mseq -r "$@"); do
				printf '%s Forwarded message from %s %s\n\n' \
				       $SEP "$(mhdr -d -A -h from "$f")" $SEP
				DISPLAY= mshow -n -N "$f" </dev/null |
					sed 's/^-/- &/'    # RFC 934
				printf '\n%s %s %s\n\n' \
				       $SEP 'End forwarded message' $SEP
			done
		) fi
		;;
	*mbnc*)
		old_ifs="$IFS"
		IFS=$NL
		set -- $(mseq -r -- "$@")
		IFS="$old_ifs"
		if [ "$#" -ne 1 ]; then
			printf 'mbnc: needs exactly one mail to bounce\n' 1>&2
			exit 1
		fi

		{
			printf '%s' "$hdrs" | mhdr -M -h resent-to - |
				commajoin | sed 's/^/Resent-To: /'
			printf '%s' "$hdrs" | mhdr -M -h resent-cc - |
				commajoin | sed 's/^/Resent-Cc: /'
			printf '%s\n' "$hdrs" | awk '{ print }' |
				msed "/resent-to/d; /resent-cc/d" -
		} |
			msed "/resent-to/a//; /resent-from/a/$default_from/" - | sed '/^$/d'
		msgid | sed 's/^/Resent-/'
		printf 'Resent-Date: %s\n' "$(mdate)"
		(
			IFS=$NL
			cat $(mseq -r -- "$@")
		)
		;;
	*mrep*)
		old_ifs="$IFS"
		IFS=$NL
		set -- $(mseq -r -- "$@")
		IFS="$old_ifs"
		if [ "$#" -ne 1 ]; then
			printf 'mrep: needs exactly one mail to reply to\n' 1>&2
			exit 1
		fi

		ng=$(mhdr -h newsgroups "$1")
		if [ "$ng" ]; then
			printf 'Newsgroups: %s\n' "$ng"
		else
			to=$(mhdr -d -h reply-to "$1")
			[ -z "$to" ] && to=$(mhdr -d -A -h from "$1")
			printf 'To: %s\n' "$to"
			printf 'Cc: %s\n' \
			       "$(mhdr -d -A -h to:cc: "$1" |
				       notmine |grep -Fv -e "$to" |
				       ouniq |commajoin)"
			printf 'Bcc: \n'
			printf '%s\n' "$hdrs" | awk '{ print }' |
				msed "/body/d" -
		fi | sed '/^$/d'
		printf 'Subject: Re: %s\n' "$(COLUMNS=10000 mscan -f '%S' "$1")"
		if ! printf '%s\n' "$hdrs" | awk '{ print }' |
		     mhdr -h from: - >/dev/null; then
			addr=$(maddr -a -h delivered-to:to:cc:bcc: "$1" | replyfrom | head -n1)
			[ -n "$addr" ] && from=$(maddr -h reply-from "$MBLAZE/profile" | grep -Fi "<$addr>" | head -n1)
			[ -n "$addr" ] && [ -z "$from" ] && from=$(maddr -h alternate-mailboxes "$MBLAZE/profile" | grep -Fi "<$addr>" | head -n1)
			[ -z "$from" ] && from=$(mhdr -h local-mailbox "$MBLAZE/profile")
			[ -n "$from" ] && printf 'From: %s\n' "$from"
		fi
		mid=$(mhdr -h message-id "$1")
		if [ "$mid" ]; then
			printf 'References:'
			{
				mhdr -h references "$1"
				printf '%s\n' "$mid"
			} | reffmt
			printf 'In-Reply-To: %s\n' "$mid"
		fi
		msgid
		museragent
		cat "$MBLAZE/headers" 2>/dev/null
		printf '\n'

		if [ -z "$noquote" ]; then
			mquote "$1"
			printf '\n'
		fi
		(
			IFS=$NL
			cat -- /dev/null $(printf '%s' "$hdrs" | mhdr -M -h body -)
		)
		printf '\n'
		;;
	esac

	case "$0" in
	*mbnc*) ;;
	*)
		if [ -f "$MBLAZE/signature" ]; then
			SIGNATURE="$MBLAZE/signature"
		elif [ -f ~/.signature ]; then
			SIGNATURE="$HOME/.signature"
		fi

		if [ -n "$SIGNATURE" ]; then
			printf '%s\n' '-- '
			cat "$SIGNATURE"
		fi
	esac
} >"$draft"

automime=
c=$defaultc
while :; do
	case "$c" in
	s|send)
		case "$(mhdr -h newsgroups "$draft")" in
			*gmane.*) sendmail="mblow -s news.gmane.org";;
			*.*) sendmail="mblow";;
		esac

		resent="$(maddr -h resent-to "$draft")"
		case "$resent" in
		?*)
			sendmail=$(mhdr -h sendmail "$MBLAZE/profile")
			sendmail="${sendmail:-sendmail} -- $resent"
			;;
		esac

		if [ -e "$draftmime" ]; then
			if [ "$draft" -ot "$draftmime" ] || [ "$automime" = 1 ]; then
				stampdate "$draftmime"
				if $sendmail <"$draftmime"; then
					if [ "$senthook" ]; then
						mv "$draftmime" "$draft"
						$senthook "$draft"
					elif [ "$outbox" ]; then
						mv "$draftmime" "$draft"
						mrefile "$(mflag -d -S "$draft")" "$outbox"
					else
						rm "$draft" "$draftmime"
					fi
				else
					printf '%s\n' "mcom: $sendmail failed, kept draft $draft"
					exit 2
				fi
			else
				printf 'mcom: re-run mmime first.\n'
				c=
				continue
			fi
		else
			if mmime -c <"$draft" && ! [ "$automime" = 1 ]; then
				stampdate "$draft"
				if $sendmail <"$draft"; then
					if [ "$senthook" ]; then
						$senthook "$draft"
					elif [ "$outbox" ]; then
						mrefile "$(mflag -d -S "$draft")" "$outbox"
					else
						rm "$draft"
					fi
				else
					printf '%s\n' "mcom: $sendmail failed, kept draft $draft"
					exit 2
				fi
			else
				printf '%s\n' "mcom: message needs to be MIME-encoded first."
				c=
				continue
			fi
		fi

		case "$0" in
			*mrep*) mflag -R -- "$1" ;;
			*mbnc*) mflag -P -- "$1" ;;
			*mfwd*) mflag -P -- "$@" ;;
		esac
		case "$0" in
			*mrep*|*mbnc*|*mfwd*) mseq -f | mseq -S ;;
		esac

		exit 0
		;;
	c|cancel)
		stampdate "$draft"
		printf '%s\n' "mcom: cancelled draft $draft"
		exit 1
		;;
	m|mime)
		do_mime
		mshow -t "$draftmime"
		c=
		;;
	e|edit)
		c=
		if ! ${VISUAL:-${EDITOR:-vi}} "$draft"; then
			c=d
		else
			if checksensible "$draft"; then
				stripempty "$draft"
				if mmime -c <"$draft" && ! needs_multipart "$draft"; then
					automime=
				else
					automime=1
					do_mime
				fi
			else
				printf '\n'
			fi
		fi
		;;
	justsend)
		stripempty "$draft"
		if mmime -c <"$draft" && ! needs_multipart "$draft"; then
			automime=
		else
			automime=1
			do_mime
		fi
		c=send
		;;
	d|delete)
		rm -i "$draft"
		if ! [ -f "$draft" ]; then
			rm -f "$draftmime"
			printf '%s\n' "mcom: deleted draft $draft"
			exit 0
		fi
		c=
		;;
	sign)
		msign "$draft" >"$draftmime"
		mshow -t "$draftmime"
		c=
		;;
	encrypt)
		mencrypt "$draft" >"$draftmime"
		mshow -t "$draftmime"
		c=
		;;
	p|preview|show)
		if [ -e "$draftmime" ]; then
			mshow "$draftmime"
		else
			mshow "$draft"
		fi
		c=
		;;
	*)
		printf 'What now? (%s[s]end, [c]ancel, [d]elete, [e]dit, [m]ime, [p]review, sign, encrypt) ' "${automime:+mime and }"
		read -r c
		;;
	esac
done