#!/usr/bin/env bash

abort() {
	error="$1" && shift
	echo "ERROR: $*" 1>&2
	test -z "$FORCE" && exit "$error"
}

# Don't abort on failures.  This allows to cleanup after a previous failure.
[ "$1" = '--force' ] && FORCE=1 && shift

test -z "$1"            && abort 1 'Submodule required'
cd "$(git root)"        || abort 5 'Cannot change to repository root'
test ! -f '.gitmodules' && abort 2 '.gitmodules file not found'

NAME="${1%/}"
test -z "$(git config --file='.gitmodules' "submodule.$NAME.url")" \
   && abort 3 'Submodule not found'

# 1. Handle the .git directory
# 1.a. Delete the relevant section from .git/config
git submodule deinit -f "$NAME" || abort 4 "Failed to deinitialize $NAME"
# 1.b. Delete empty submodule directory
git rm -f "$NAME"

# 2. Handle .gitmodules file
# 2.a. Delete the relevant line from .gitmodules
git config --file='.gitmodules' --remove-section "submodule.$NAME" 2>/dev/null || :
# 2.b and stage changes
git add '.gitmodules'
# 2.c. Delete empty .gitmodules
[  "$(wc -l '.gitmodules' | cut -d' ' -f1)" = '0' ] && git rm -f '.gitmodules'

# 3. Need to confirm and commit the changes for yourself
git_status_text="$(git submodule status 2>&1)"
git_status_exit=$?
if [ "$git_status_exit" -eq 0 ] \
    && printf '%s' "DUMMY$git_status_text" | grep -v "$NAME" > /dev/null; then
    #  grep fails when piping in an empty string, so we add a DUMMY prefix

	echo "Successfully deleted $NAME."
else
	abort 6 "Failed to delete $NAME with error:\n$git_status_text"
fi
printf '\n%s\n' '== git submodule status =='
printf '%s\n'   "$git_status_text"
printf '%s\n'   '=========================='
# shellcheck disable=SC2016
echo 'Confirm the output of `git submodule status` above (if any)' \
	'and then commit the changes.'