#!/bin/sh
# A hook called by `git commit` to adjust the commit message right before the user sees it
##########################################################################################
#
# This script is called by `git commit` after commit message was initialized and right before
# an editor is launched.
#
# It receives one to three arguments:
#
# $1 - the path to the file containing the commit message. It can be edited to change the message.
# $2 - the kind of source of the message contained in $1. Possible values are
#      "message" - a message was provided via `-m` or `-F`
#      "commit" - `-c`, `-C` or `--amend` was given
#      "squash" - the `.git/SQUASH_MSG` file exists
#      "merge" - this is a merge or the `.git/MERGE` file exists
#      "template" - `-t` was provided or `commit.template` was set
# $3 - If $2 is "commit" then this is the hash of the commit.
#      It can also take other values, best understood by studying the source code at
#      https://github.com/git/git/blob/aa9166bcc0ba654fc21f198a30647ec087f733ed/builtin/commit.c#L745
#
# The following example
#
# To enable this hook remove the `.sample` suffix from this file entirely.

COMMIT_MSG_FILE=$1

# Check if the commit message file is empty or already contains a message
if [ -s "$COMMIT_MSG_FILE" ]; then
  # If the commit message is already provided, exit without making any changes.
  # This can happen if the user provided a message via `-m` or a template.
  exit 0
fi

# Retrieve the branch name from the current HEAD commit
BRANCH_NAME=$(git symbolic-ref --short HEAD)

# Generate a default commit message based on the branch name
DEFAULT_MSG=""

case "$BRANCH_NAME" in
  "feature/*")
    DEFAULT_MSG="feat: "
    ;;
  "bugfix/*")
    DEFAULT_MSG="fix: "
    ;;
  *)
    DEFAULT_MSG="chore: "
    ;;
esac

# Set the commit message that will be presented to the user.
echo "$DEFAULT_MSG" > "$COMMIT_MSG_FILE"