#!/usr/bin/env bash
set -euo pipefail

# -----------------------------
# Config (override via env)
# -----------------------------
NY_FLAKE_PATH="${NY_FLAKE_PATH:-$HOME/.config/nixos}"

# -----------------------------
# Helpers
# -----------------------------
die() {
	echo "error: $*" >&2
	exit 1
}

info() {
	echo "→ $*"
}

run() {
	info "$*"
	"$@"
}

has() {
	command -v "$1" >/dev/null 2>&1
}

# -----------------------------
# Help
# -----------------------------
help() {
	cat <<EOF
ny — simple NixOS sync command

Usage:
  ny              Rebuild system
  ny up           Update flake + rebuild
  ny diff         Show pending system changes
  ny search <q>   Search packages
  ny shell <pkg>  Temporary shell
  ny clean        Clean nix store
  ny help         Show help

Shortcuts:
  ny s <q>        Search
  ny sh <pkg>     Shell

Env:
  NY_FLAKE_PATH   Path to NixOS flake (default: ~/.config/nixos)

EOF
}

# -----------------------------
# Shortcuts
# -----------------------------
CMD="${1:-}"

case "$CMD" in
help)
	help
	exit 0
	;;
s) set -- search "${@:2}" ;;
sh) set -- shell "${@:2}" ;;
esac

CMD="${1:-}"

# -----------------------------
# Commands
# -----------------------------
case "$CMD" in
"")
	cd "$NY_FLAKE_PATH" || die "flake path not found: $NY_FLAKE_PATH"
	run sudo nixos-rebuild switch --flake .
	;;

up)
	cd "$NY_FLAKE_PATH" || die "flake path not found: $NY_FLAKE_PATH"
	run nix flake update
	run sudo nixos-rebuild switch --flake .
	;;

diff)
	cd "$NY_FLAKE_PATH" || die "flake path not found: $NY_FLAKE_PATH"

	info "Computing system diff…"

	if has nvd; then
		run sudo nixos-rebuild build --flake .
		run nvd diff /run/current-system ./result
		rm -f result

	elif has nix-diff; then
		run sudo nixos-rebuild build --flake .
		run nix-diff /run/current-system ./result
		rm -f result

	else
		info "nvd/nix-diff not found, using dry-run"
		run sudo nixos-rebuild dry-run --flake .
	fi
	;;

search)
	[[ -n "${2:-}" ]] || die "usage: ny search <query>"
	run nix search nixpkgs "$2"
	;;

shell)
	shift
	[[ $# -gt 0 ]] || die "usage: ny shell <pkg...>"
	run nix shell "${@/#/nixpkgs#}"
	;;

clean)
	run nix store optimise
	run nix-collect-garbage
	run sudo nix-collect-garbage -d
	;;

*)
	die "unknown command: $CMD (run 'ny help')"
	;;
esac