#!/bin/bash
#
# Git prepare-commit-msg hook
# Automatically generates a formatted commit message showing added, modified, and deleted files
#
# To install: Copy this file to .git/hooks/prepare-commit-msg and make it executable
# chmod +x .git/hooks/prepare-commit-msg

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

# Only run for regular commits (not merge, squash, message, etc.)
# 'message' is used during rebase when applying existing commits
case "$COMMIT_SOURCE" in
  merge|squash|commit|message)
    exit 0
    ;;
esac

# Get the staged changes
ADDED_FILES=$(git diff --cached --name-only --diff-filter=A)
MODIFIED_FILES=$(git diff --cached --name-only --diff-filter=M)
DELETED_FILES=$(git diff --cached --name-only --diff-filter=D)
RENAMED_FILES=$(git diff --cached --name-only --diff-filter=R)
COPIED_FILES=$(git diff --cached --name-only --diff-filter=C)

ADDED_COUNT=$(echo "$ADDED_FILES" | grep -c . 2>/dev/null || echo 0)
MODIFIED_COUNT=$(echo "$MODIFIED_FILES" | grep -c . 2>/dev/null || echo 0)
DELETED_COUNT=$(echo "$DELETED_FILES" | grep -c . 2>/dev/null || echo 0)
RENAMED_COUNT=$(echo "$RENAMED_FILES" | grep -c . 2>/dev/null || echo 0)
COPIED_COUNT=$(echo "$COPIED_FILES" | grep -c . 2>/dev/null || echo 0)

# If no staged changes, exit
if [ $ADDED_COUNT -eq 0 ] && [ $MODIFIED_COUNT -eq 0 ] && [ $DELETED_COUNT -eq 0 ] && [ $RENAMED_COUNT -eq 0 ] && [ $COPIED_COUNT -eq 0 ]; then
    exit 0
fi

# Create the commit message template
{
    echo "your commit message here"
    echo ""

    # Added files
    if [ $ADDED_COUNT -gt 0 ]; then
        echo "$ADDED_FILES" | sed 's/^/* added: /'
        echo ""
    fi

    # Modified files
    if [ $MODIFIED_COUNT -gt 0 ]; then
        echo "$MODIFIED_FILES" | sed 's/^/* modified: /'
        echo ""
    fi

    # Deleted files
    if [ $DELETED_COUNT -gt 0 ]; then
        echo "$DELETED_FILES" | sed 's/^/* deleted: /'
        echo ""
    fi

    echo "# Diff stats:"
    git diff --cached --stat | sed 's/^/# /'
    echo ""

} > "$COMMIT_MSG_FILE"