Script to auto-create fixup commits towards the first change in the branch

fixup-commits.sh

#!/bin/bash

set -e

# Function to create fixup commits for changed files
create_fixup_commits() {
    target_branch="${1:-origin/develop}"

    # Get the list of changed files
    changed_files=$(git diff --name-only)

    # Iterate over each changed file
    while IFS= read -r file; do
        if [ -z "$file" ]; then
            echo "No changes found"
            exit 1
        fi
        # Find the most recent commit that changed this file
        first_commit=$(git log --reverse --follow "$target_branch"..HEAD --pretty=format:"%H" -- "$file" | head -1)
        if [ -n "$first_commit" ]; then
            commit_message=$(git log --format=%B -n 1 "$first_commit" | head -1)
            # Create the fixup commit
            echo "git commit --fixup=$first_commit $file # $commit_message"
            if [ "$dry_run" = false ]; then
                git commit --fixup="$first_commit" "$file"
            fi
        fi
    done <<< "$changed_files"
}

# Parse command-line options using getopts
dry_run=false

while getopts ":n" opt; do
    case $opt in
        n)
            dry_run=true
            ;;
        \?)
            echo "Invalid option: -$OPTARG"
            exit 1
            ;;
    esac
done

# Shift the options so that $1 now refers to the first argument (if provided)
shift $((OPTIND - 1))

# Call the function to create fixup commits
create_fixup_commits "$1"