#!/bin/sh

insert_line()
{
	PATTERN="$1"
	LINE="$2"
	FILE="$3"
	awk ' BEGIN { found=0; }
		/'"$PATTERN"'/ { 
			print; 
			if (!found)
				printf("%s\n", "'$LINE'"); 
			found=1; 
			next;
		}
		{ print; }
	' < "$FILE"
}

# extract the description from the top of a patch
# filter stdin
# collapse adjacent blank lines to a single blank line
# remove any lines that look like diffstat output
# stop output on encountering a line beginning with '---' (beginning of patch)

	TMPFILE=`mktemp /tmp/xdtmp.XXXXXX` || exit 1
	formail -kfcb -X 'From:' -X 'Subject:' |\
	awk '
		BEGIN { found_end=0; lastone="x"; }
		/^ .* [|] +[0-9]+ [+-]+$/ { 
			#/* we found something like diffstat output... */
			if (found_end == 1) {
				/* we are past end of diffstat, let it pass */
				print;
			}
			next;
		}
		/^ [1-9][0-9]* files changed/ {
			#/* end of diffstat output, stop filtering diffstat */
			found_end=1;
			next;
		}
		/^--- / { exit; }
		{
			#/* collapse adjacent blank lines to 1 blank line */ 
			if ( $0 == "" && lastone == "" )
				next;
			else 
				print; 
		  	lastone=$0;
		}
	' | awk '{ if ($0 == "" && FNR == 1)  next; print; }' > "$TMPFILE"

	descs=`head -10 $TMPFILE | grep -c '^[	]*DESC[ 	]*$'`
	if [ "$descs" = "0" ]
	then
		# DESC is not 1st non blank line in the file
		echo "DESC"
		descs=0
	fi
	edescs=`grep -c '^EDESC$' "$TMPFILE"`
	subjects=`grep -c '^[ 	]*Subject[:]' "$TMPFILE"`
	froms=`grep -c '^[ 	]*From[:]' "$TMPFILE"`
	if [ "$edescs" = "0" ]
	then
		if [ "$subjects" != "0" ]
		then
			insert_line '^Subject[:]' 'EDESC' "$TMPFILE"
		else
			if [ "$froms" != "0" ]
			then
				insert_line '^From[:]' 'EDESC' "$TMPFILE"
			else
				if [ "$descs" = "0" ]
				then
					# blank DESC line...
					echo '(undescribed patch)'
					echo EDESC
					cat "$TMPFILE"
				else
					insert_line '^DESC$' "EDESC" "$TMPFILE"
				fi
			fi
		fi
	else
		cat $TMPFILE
	fi