# Auto time-of-day theme switch (BACKLOG #79, VISION § D). A user timer
# periodically runs `nomarchy-state-sync auto`, which reads
# settings.autoTheme = { enable, day, night, sunrise, sunset } from the
# state file and applies the day or night preset for the current clock —
# through the SAME one engine as a manual `apply` (no second pipeline).
#
# The command self-gates (no-op when disabled) and is idempotent (it only
# rebuilds when the active theme actually needs to change), so the timer
# can tick freely. Install is gated on the state flag (like nomarchy.updates
# gates on its enable), so a machine not using the feature carries no timer;
# enabling it from the menu (slice 3) writes the flag + rebuilds, which is
# what brings the timer into being.
{ config, lib, pkgs, ... }:

lib.mkIf (config.nomarchy.settings.autoTheme.enable or false) {
  systemd.user.services.nomarchy-auto-theme = {
    Unit.Description = "Apply the day/night theme for the current time";
    Service = {
      Type = "oneshot";
      # The rebuild (`home-manager switch`) and its tools resolve from the
      # system + per-user profiles — same PATH shape nomarchy-updates uses.
      Environment = "PATH=/run/current-system/sw/bin:/etc/profiles/per-user/${config.home.username}/bin";
      ExecStart = "${pkgs.nomarchy-state-sync}/bin/nomarchy-state-sync auto";
    };
  };

  systemd.user.timers.nomarchy-auto-theme = {
    Unit.Description = "Periodic day/night theme check";
    Timer = {
      OnStartupSec = "1min";   # settle on the right theme shortly after login
      OnCalendar = "*:0/15";   # re-check every 15 min; auto no-ops if unchanged
      Persistent = true;       # catch a transition missed while powered off
    };
    Install.WantedBy = [ "timers.target" ];
  };
}