git-backup

#!/usr/bin/env bash
#! tested in: GNU bash, version 5.2.26(1)-release (x86_64-apple-darwin23.2.0) | older versions and other shells will work but not guaranteed

#################################################################################
# Backs up tracked and untracked changes to a new branch, pushes it to a remote #
# (default "origin"), and deletes the temporary branch.                         #
#################################################################################
# Usage:                                                                        #
#   git-backup <repo_directory> [remote_name]                                   #
#################################################################################

_git_backup() {
    # Directory of the Git repository
    local repo_dir="${1:?"no directory provided"}"
    # Name of remote to push to - git defaults to "origin" so we do too
    local remote="${2:-"origin"}"

    _failed() {
        echo "ERROR: \`$1\` failed" >&2
    }

    local timestamp="$(TZ=Etc/UTC date +"%Y-%m-%d-%H%M.%S")"
    local backup_name="backup-$timestamp"
    echo "Starting git repo backup $timestamp"

    # Change to the repository directory
    if ! cd "$repo_dir"; then
        echo "Failed to change to directory \"$repo_dir\"" >&2
        unset -f _failed
        return 1
    fi

    # Stash any uncommitted changes and untracked files
    if ! git stash save --include-untracked "$backup_name"; then
        _failed "git stash save --include-untracked \"$backup_name\""
        unset -f _failed
        return 1
    fi

    # Create and switch to new branch for backup
    if ! git checkout -b "$backup_name"; then
        _failed "git checkout -b \"$backup_name\""
        unset -f _failed
        return 1
    fi

    # Apply the changes from stash, overwriting any conflicts
    local stash_apply_output
    if ! stash_apply_output="$(git stash apply 2>&1)"; then
        _failed "git stash apply"
        unset -f _failed
        return 1
    fi
    if echo "$stash_apply_output" | tee /dev/stdout | grep -q 'CONFLICT'; then
        echo "Conflicts detected during 'git stash apply'. Attempting to resolve conflicts by keeping stashed changes."
        git status --short | grep '^U' | cut -c 4- \
        | while read -r file; do
            echo "Resolving conflict in $file"
            if ! git checkout --theirs "$file"; then
                _failed "git checkout --theirs \"$file\""
                unset -f _failed
                return 1
            fi
            git add "$file"
        done
        echo "Conflicts resolved. Committing the changes."
    fi

    # Add all changes to the index
    if ! git add .; then
        _failed "git add ."
        unset -f _failed
        return 1
    fi

    # Commit the changes
    if ! git commit -m "Backup $timestamp"; then
        _failed "git commit -m \"Backup $timestamp\""
        unset -f _failed
        return 1
    fi

    # Push the changes to the remote repository
    if ! git push "$remote" "$backup_name"; then
        _failed "git push \"$remote\" \"$backup_name\""
        unset -f _failed
        return 1
    fi

    # Switch back to the original branch
    if ! git checkout -; then
       _failed "git checkout -"
       unset -f _failed
       return 1
    fi

    # Restore changes to original branch
    if ! git stash apply; then
        _failed "git stash apply"
        unset -f _failed
        return 1
    fi

    # Delete the backup branch locally, now that it has been pushed to the remote repository
    if ! git branch -D "$backup_name"; then
        _failed "git branch -D \"$backup_name\""
        unset -f _failed
        return 1
    fi

    # Clean up local function
    unset -f _failed
}

_git_backup "$@"