set -fCu; IFS=''	# safe mode
PATH=/opt/ast/bin:$PATH	# use path-bound built-ins

error_out()
{
	echo "$0: $@" >&2
	exit 1
}
PATH=/dev/null let ".sh.version >= 20220728" 2>/dev/null || error_out 'requires ksh 93u+m/1.0'

# special-case github's flukes in names of commit authors
# (they were fine in the original commits, then merging/squashing changed them)
function fix_authorname
{
	nameref a=$1
	case $a in
	lev105)		a='Lev Kujawski' ;;
	pghvlaans)	a='K. Eugene Carlson' ;;
	sterlingjensen)	a='Sterling Jensen' ;;
	vmihalko)	a='Vincent Mihalkovic' ;;
	esac
}

# update file if it changed from $tmpfile
function update_file
{
	[[ -s $1 ]] && cmp -s $1 $tmpfile
	case $? in
	0)	;;
	1)	print -r "updating $1"
		cat $tmpfile >|$1 || exit ;;
	*)	error_out "error in cmp" ;;
	esac
}

# centre an author line to 70 characters
function centre_line
{
	nameref l=$1
	((${#l} > 70)) && prinf '%q: WARNING: author line too long: %q\n' "$0" "$l" >&2
	while ((${#l} < 69)); do
		l=" $l "
	done
	((${#l}==69)) && l+=' '
}

[[ -d .git ]] || error_out "run this from the ksh 93u+m git repo's main directory"

current_year=$(date +%Y)
[[ $current_year =~ ^[0-9]{4}$ ]] || error_out "could not get current year"
first_commit=$(git log --since="$current_year-01-01 00:00 UTC" --pretty=format:'%H' | tail -n1)
[[ $first_commit =~ ^[0-9a-f]{40}$ ]] || error_out "could not get first commit"
current_commit=$(git log -1 --pretty=format:'%H')
[[ $current_commit =~ ^[0-9a-f]{40}$ ]] || error_out "could not get current commit"

# get author/email associations from log, overriding a few
typeset -A email
git log reboot..dev '--pretty=tformat:%ae %an' | while IFS=' ' read e n; do
	fix_authorname n
	email[$n]=$e
done
email['Anuradha Weeraman'][email protected]
email['Lev Kujawski'][email protected]
email['K. Eugene Carlson'][email protected]
email['Vincent Mihalkovic'][email protected]

tmpfile=${TMPDIR:-/tmp}/update-copyright-years.${$}${RANDOM}
trap 'exec rm -f $tmpfile' EXIT

# update COPYRIGHT file
# get all the authors from the git log, sorted by number of commits in descending order
# (awk cannot portably pass strings with newlines via -v options, so pass as an env var)
export contributors=$(
	git log reboot..dev '--pretty=tformat:%an' | while read n; do
		fix_authorname n
		print -r $n
	done | sort | uniq -c | sort -rn | while IFS=' ' read throwaway_number name; do
		c="$name <${email[$name]}>"
		centre_line c
		print -r "#${c}#"
	done
)
awk '{
	if(!state) { print; if($0 ~ /CONTRIBUTORS/) state=1; }
	else if(state==1) { print; spacingline=$0; state=2; }
	else if(state==2) { print ENVIRON["contributors"]; state=3; }
	else if(state==3) { if($0==spacingline) { print; state=4; } }
	else print;
}' COPYRIGHT >|$tmpfile
unset contributors
update_file COPYRIGHT

# update headers in source files
(git diff --name-only; git diff --name-only --cached; git diff-tree --name-only -r $first_commit..HEAD) \
| while read -r file
do
	[[ -f $file ]] || continue
	read -r n <$file
	[[ $n == '/***********************************************************************' \
	|| $n == '########################################################################' ]] \
		|| continue
	sedscript=''
	# exclude version.h from adding author names -- most changes to it are just version increments
	if [[ $file != src/cmd/ksh93/include/version.h ]]
	then
		# comment character
		cc=${n:2:1}
		# find the line number of the last author line (after which to insert new authors)
		n="^[$cc] .*<.*@.*\..*>.* [$cc]$"
		alineno=$(awk -v ere=$n '{ if($0 ~ ere) found++; else if(found) { print NR-1; exit; } }' "$file")
		((alineno > 0)) || continue
		# get authors, most frequent contributor first
		git log $first_commit..HEAD --pretty=tformat:%an "$file" | sort | uniq -c | sort -rn \
		| while IFS=' ' read -r throwaway_number name
		do
			fix_authorname name
			aline="$name <${email[$name]}>"
			centre_line aline
			# if not already in file, add to sed script
			if ! grep -q "^[$cc]$aline[$cc]$" "$file"; then
				sedscript=${sedscript:-"$alineno { "}$'a\\\n'${cc}${aline}${cc}$'\n'
			fi
		done
		[[ -n $sedscript ]] && sedscript+=$'}\n'
	fi
	# add sed command to update copyright line
	sedscript+="/(c) [0-9]\{4\}-[0-9]\{4\} Contributors to ksh 93u+m/ s/-[0-9]\{4\}/-$current_year/"
	# update the file if the sed script makes a difference
	sed "$sedscript" $file >|$tmpfile || exit
	update_file $file
done