prepare-commit-msg

#!/bin/bash
#
# This hook adds guidance about the commit message format
# on top of the default commit message hints.
#
# Called by "git commit" with the name of the file that has the commit message,
# followed by the description of the commit message's source.
#
# To enable this hook, set the hooksPath in git:
# git config core.hooksPath .dev/githooks

COMMIT_MSG_FILE=$1
COMMIT_SOURCE=$2
SHA1=$3

scopes_file=".dev/scopes.txt"
# Join scopes to regex, skipping empty and commented lines
test -r "$scopes_file" &&
  scopes="($(grep -vE '^\s*(#|$)' "$scopes_file" | paste -sd '|' - ))"

beginswith() { case $2 in "$1"*) true;; *) false;; esac; }

# https://mincong.io/2019/07/23/prepare-commit-message-using-git-hook
# Only add custom message when there is no commit source ($COMMIT_SOURCE is empty).
# Otherwise, keep the default message proposed by Git.
# Possible commit sources: message, template, merge, squash or commit.
# See https://git-scm.com/docs/githooks
original=$(cat "$COMMIT_MSG_FILE")
if test -z "$COMMIT_SOURCE"
then
  # Find common path prefix of changed files
  path=$(while read file
    do test -z "$count" && common="$file" && count=$(expr length "$file") ||
      while expr substr "$file" $count 1 != substr "$common" $count 1 >/dev/null; do let count--; done
    done <<<"$(git -P diff --cached --name-only -r)" &&
      expr substr "$common" 1 "$count")
  {
    # Infer type & scope from changed files
    expr "$path" : ".dev" >/dev/null &&
      ( git config list --local | grep -q kull &&
        printf "feat(dev): " ||
        printf "build: "; )
    # Example for gradle projects
    expr "$path" : "gradle" \| "$path" : "build" >/dev/null &&
      printf "build(gradle): "

  echo "
# Please enter the message in the format:
#   <type>(<scope>): <description>
# Types:
# - production code: fix, feat, enhance, refactor, style
# - auxiliaries:     docs, test, build
${scopes:+# Allowed scopes: $scopes}
# For details see https://kull.jfischer.org
$original
"
  } > "$COMMIT_MSG_FILE"
fi