rebuild

#!/usr/bin/env bash

set -euo pipefail

_SCRIPT="$(realpath ${BASH_SOURCE})"
_SCRIPT_DIR="${_SCRIPT%/*}"

# ------------------------------------------------------------------------------

action=${1:-"switch"}

if [[ $EUID -eq 0 ]]; then
    echo >&2 -n "$(tput setaf 1)"
    echo >&2 -n "Don't run rebuild as root. I will call sudo internally as needed"
    echo >&2 "$(tput sgr0)"
    exit 1
fi

sudo() {
    if [[ $EUID -ne 0 ]]; then
        command sudo "$@"
        return $?
    fi

    "$@"
    return $?
}

git() {
    if [[ $(stat -c %u .git) -eq 0 ]]; then
        sudo git "$@"
        return $?
    fi
    command git "$@"
    return $?
}

cd "$_SCRIPT_DIR"

# --- Functions ---

heading() {
    local msg="$1"
    echo ''
    echo ''
    echo "==> ${msg} <=="
    echo ''
}

# --- Track local files with git (for flake) but do not stage their contents ---

while read -r line || [[ -n $line ]]; do
    # Ignore comments and empty lines
    if [[ $line =~ ^[[:space:]]*# ]] || [[ $line =~ ^[[:space:]]*$ ]]; then
        continue
    fi

    git ls-files -- "$line" | while read -r file; do
        git update-index --no-skip-worktree "$file"
        git restore --staged -- "$file"
        if ! git ls-files --error-unmatch -- "$file" >/dev/null 2>&1; then
            echo "--- Skipping worktree for: $file ---"
            git add --intent-to-add -- "$file"
        fi
        git update-index --skip-worktree "$file"
    done
done <.local-files


# --- Format and git-add ---

heading 'Formatting Nix expressions...'

sudo alejandra . # Autoformat


heading 'Changes to be committed'

git diff -U0


# --- Rebuild ---

heading 'NixOS Rebuilding...'

if command -v nh >/dev/null; then
    nh os "$action" .
else
    sudo nixos-rebuild $action
fi


if [[ ! $action =~ ^(switch|boot)$ ]]; then
    heading 'Skipping auto-commit since there is no new generation'
    exit
fi

# --- Auto-commit ---

heading 'Auto-committing...'

gen_info=$(nixos-rebuild list-generations --json | jq -r 'map(select(.current == true)) | first')

nixos_version="$(echo "$gen_info" |
	jq -r '.nixosVersion')"
date="$(echo "$gen_info" |
	jq -r '.date | fromdate | strftime("%Y-%m-%d %H:%M")')"
generation="$(echo "$gen_info" |
	jq -r '.generation')"
kernel="$(echo "$gen_info" |
	jq -r '.kernelVersion')"

git add .

# Test if there are staged changes
if git diff --cached --quiet; then
    echo "Nothing to commit."
    exit
fi

# NOTE:         v-- There's a snowflake emoji here, but `sudo vim` does not display it for some reason.
git commit -am "❄️ REBUILD: [${action}] $(hostname): Gen. ${generation} - ${nixos_version}

Date:          ${date}
Host:          $(hostname)
Generation:    ${generation}
NixOS version: ${nixos_version}
Kernel:        ${kernel}
"