#!/bin/sh

# This script will:
#   - list submodules inside a parent repository supplied on $1
#   - check whether they are marked as changed while ignoring dirty files
#   - verify that there are no other staged changes before proceeding
#   - send emails to the local user at the local hostname (-f) using the local
#     user also as the sender. It will send emails for: commit error,
#     staged changes existing, and success. It will not send emails for other
#     program errors. If you use this script from cron, then all other error
#     output will be sent to you by cron.

#   - the program will output some progress information on stdout; but will not
#     do so if the script is not run interactively.

# This script is verified to work with: bash and busybox ash.

# This program is called:



#                                             automatic parent commits

unset int

[ -t 0 ] && int=yes

username=$(id -nu)
hostname=$(hostname -f)
email="$username@$hostname"

medium_minus_date="commit %H%nAuthor: %an <%ae>%n%n%w(0,4,4)%B"

[ -z "$1" ] && {
	echo "Give a git that has submodules as parameter" >&2
	exit 255
}

cd "$1" && {
	repository=$(readlink -f "$(pwd)")
} || {
	echo "Directory $repository does not exist or is not accessable" >&2
	exit 1
}

[ -d .git ] || {
	echo "This is not a git repository: $repository" >&2
	exit 1
}

# get-url was not implemented in older git versions

repo_name=$(git remote show -n origin | grep "Fetch URL" | sed "s@.*/\(.*\).git@\1@")

# We shall first get the list of submodules using:
submodules=$(git submodule -q foreach 'echo $path')

[ -t 0 ] && { echo "List of submodules:"; echo "$submodules" | sed "s/.*/  &/"; echo; }

# Then we shall hopefully find the list of modified submodules using:

out=$(git status --porcelain --ignore-submodules=dirty) || {
	echo "Git status gave an error. Is this a git repository?" >&2
	exit 1
}

list=$(printf "%s\n" "$out" | sed "s/.*/#&/" | while read a; do
	# Spaces as meaningful characters is not easy in shell code.
	c=$(echo "$a" | sed "s/#.. //")
	b=${a% $c}
	b=${b#\#}
	# This first part filters on subrepository names.
	if echo "$submodules" | grep -q "^$c$"; then
		printf "%-2s %s\n" "$b" "$c"
	fi
	# Then we filter on an "M" in the second column.
done | grep "^.M" | sed "s/.. //" )

[ -t 0 ] && { echo "Submodules that are modified:"; echo "$list" | sed "s/.*/  &/"; echo; }

# Then we shall go on.

# I used to use the human readable version but it didn't tell me whether something was a submodule
# when it already had the submodule staged for commit....:

#  out=$(echo "$out" | grep "^#	modified:.*(.*new commits.*)$" | sed "s/.*: *\([^ ].*\) (.*)$/\1/")

[ -z "$list" ] || {
	# Now we check whether the index does not contain staged changes:
	git status --porcelain --ignore-submodules=dirty | grep -q "^[MADRC]." && {

		# And we send an email if they are staged:
		echo "From: $email
To: $email
Subject: Repo $repo_name already contains staged changes

There are sub-modules that have changes to be committed to the parent repo $repo_name but the index is not clean; there are staged changes:

$(git status --ignore-submodules=dirty | sed -n -e "/^# Changes to be committed/,/^# [^ ]/p" | sed '$d')" | /usr/sbin/sendmail -t
		[ -t 0 ] && echo "Sent staged changes preventing operation mail to $email"
		# And we exit. Stash -u would take care of those staged things but unfortunately I don't think it is very
		# safe to do so.

		# I can't tell if I can ever lock a repository and files might also be open in the working tree that then
		# gets swapped around back and forth.

		# I would have to unstage things and then restage them back. That's easy enough but still runs the potential
		# risk of interfering with a user.

		# What I do needs to be atomic etc.

		exit 1
	}

	# Let's first determine the date to use for our commit message:

	# The date is slightly influenced by the locale (the %a term means like Wed)
	# This string results in "Wed 31-10-2017 22:00". I didn't like my own locale
	# (en_US becomes 10/31/2017 but nl_NL becomes 31-10-17 and locales also change dots into commas.
	# Very annoying. I hate that so much. Calculators don't take . input, only , input. So the thing
	# you're used to, typing 10.23 as a decimal number, suddenly doesn't work and the number becomes
	# 1023. That person who invented that deserves a proper hanging.

	date=$(date "+%a %d-%m-%Y %H:%M")

	# Anyway you can always change this around to your preference.

	# The list is now supplied with a here doc down below so that we can save the variables inside.

	unset error_repos errmsg changelist

	while read a; do
		git add "$a"

		currerr=$(git commit -m "Hourly repository update for submodule $a at $date" 2>&1 > /dev/null) && {
			changelist="$changelist$a
"
			[ $int ] && echo "Successfully committed $a."
			true
		} || {
			error=$?
			error_repos="$error_repos$a
"
			errmsg="$errmsg$currerr
"
			[ $int ] && echo "Failed to commit $a."
			git reset -q "$a"
		}
	done << EOF
$list
EOF

	# Remove the extra \n I gave it:
	changelist=${changelist%?}
	error_repos=${error_repos%?}

	# If there were errors at committing they are now collected in this error repo list.
	[ -n "$error_repos" ] && {

		# start and error commits:
		first="From: $email
To: $email
Subject: Commits contain errors @ auto-update for $repo_name

Commits that gave errors:
$(echo -n "$error_repos" | sed "s/.*/- &/")"

		# any successful commits
		if [ -n "$changelist" ]; then
			first="$first

Commits that succeeded:
$(echo -n "$changelist" | sed "s/.*/- &/")"
		fi

		# the full message
		first="$first

Error messages:
$(echo -n "$errmsg" | sed "s/.*/  &/")"

		echo "$first" | /usr/sbin/sendmail -t
		[ -t 0 ] && echo "Sent error mail to $email"
		exit 1

	}

	# If not, then we proceed with a regular commit message as there MUST be successful commits now:

	count=$(echo "$changelist" | wc -l)

	if [ "$count" -gt 1 ]; then m=s; fi

	if [ "$count" -eq 1 ]; then
		echo "From: $email
To: $email
Subject: Updated parent for sub-module $repo_name/$changelist

The repository $repo_name had its reference to submodule $changelist updated to its latest commit:

$(cd $changelist; git log -1 --format="$medium_minus_date" | sed "s/.*/  &/")" | /usr/sbin/sendmail -t
	else
		{ echo "From: $email
To: $email
Subject: Updated parent $repo_name for $count submodule repositories


"
		while read r; do
			echo "The repository $repo_name had its reference to submodule $r updated to its latest commit:

$(cd $r; git log -1 --format="$medium_minus_date" | sed "s/.*/  &/")
"
		done << EOF
$changelist
EOF
		} | /usr/sbin/sendmail -t
	fi

	[ -t 0 ] && echo "Sent commit mail to $email"
	true
}