# Greeter — greetd/tuigreet, themed from the same theme-state.json that
# drives the desktop (nomarchy.system.stateFile; the Plymouth model:
# baked at SYSTEM rebuild, so it follows the theme as of the last
# sys-update, not the last instant apply).
#
# tuigreet draws on the virtual console with the 16 ANSI slots, so the
# theming is two-part:
#   1. console.colors — the VT palette becomes the theme's ansi[] hexes
#      (which also themes raw ttys and the LUKS passphrase prompt: the
#      same JSON reaches every pre-session surface).
#   2. --theme — tuigreet components on NAMED slots (its parser is
#      ratatui Color::from_str; names map to the standard indexes, e.g.
#      blue=4, gray=7, white=15, so the palette above hands them the
#      theme's colors). ANSI "black" stays dark even in light themes —
#      the greeter reads terminal-dark there, the same convention every
#      terminal applies to ANSI colors.
#
# Auto-login is in-flake state like the rest (settings.greeter.autoLogin,
# written by System › Auto-login via nomarchy-autologin below), NOT a baked
# line in system.nix: a hand-set `nomarchy.system.greeter.autoLogin` outranks
# the state default, which would leave the menu toggle flipping JSON that
# nothing reads. The installer therefore seeds the STATE on LUKS machines and
# the template keeps its example commented (templates/downstream/system.nix).
{ config, lib, pkgs, ... }:

let
  cfg = config.nomarchy.system;
  distroName = config.system.nixos.distroName;

  sync = lib.getExe pkgs.nomarchy-theme-sync;

  # Menu/CLI toggle, same shape as nomarchy-autotimezone: runs as the normal
  # user (it owns the flake checkout + writes the state), sudos only the
  # system switch. greetd's initial_session is baked at system rebuild, so
  # there is nothing to apply live — the next boot is the observable change.
  nomarchy-autologin = pkgs.writeShellScriptBin "nomarchy-autologin" ''
    set -e
    if [ "$(id -u)" -eq 0 ]; then
      echo "nomarchy-autologin: run as your normal user (it sudos the rebuild itself)" >&2
      exit 1
    fi
    flake="''${NOMARCHY_PATH:-$HOME/.nomarchy}"

    cur=$(${sync} get settings.greeter.autoLogin 2>/dev/null) || cur=null
    case "''${1:-toggle}" in
      on)     new="\"$USER\"" ;;
      off)    new=null ;;
      toggle) case "$cur" in null|""|None) new="\"$USER\"" ;; *) new=null ;; esac ;;
      status) echo "$cur"; exit 0 ;;
      *) echo "usage: nomarchy-autologin [toggle|on|off|status]" >&2; exit 64 ;;
    esac

    ${sync} --quiet set settings.greeter.autoLogin "$new" --no-switch

    notify-send "Auto-login" "Rebuilding the system…" 2>/dev/null || true
    sudo nixos-rebuild switch --flake "$flake#default"

    if [ "$new" = null ]; then
      notify-send "Auto-login off" "The greeter asks who you are on the next boot." 2>/dev/null || true
    else
      notify-send "Auto-login on" "Next boot goes straight to the desktop." 2>/dev/null || true
    fi
  '';

  state =
    if cfg.stateFile != null
    then builtins.fromJSON (builtins.readFile cfg.stateFile)
    else { };

  # The auto-login user from the state, or null. Read here via the state file
  # — NOT `config.nomarchy.settings`, which exists only on the Home Manager
  # side: on NixOS that attribute is missing, and `or null` swallows the
  # error, so the old default silently evaluated to null on every machine.
  stateAutoLogin =
    let v = (state.settings or { }).greeter.autoLogin or null;
    in if builtins.isString v && v != "" then v else null;

  # A sparse/hand-rolled state without a proper ansi block just skips the
  # theming (stock tuigreet grey) — never an eval error.
  ansi = state.ansi or [ ];
  themed = builtins.isList ansi && builtins.length ansi == 16;

  tuigreetTheme = lib.concatStringsSep ";" [
    "container=black" # ansi[0] — the theme's terminal background
    "border=blue"     # ansi[4] — the accent family in every shipped palette
    "title=cyan"
    "greet=cyan"
    "prompt=green"
    "input=white"     # ansi[15] — bright foreground
    "action=blue"
    "button=yellow"
    "time=cyan"
    "text=gray"       # ansi[7] — muted foreground
  ];
in
{
  config = {
    # Shipped unconditionally so the menu can turn auto-login back ON while
    # it's off — the same reason nomarchy-autotimezone is unconditional.
    environment.systemPackages = [ nomarchy-autologin ];

    # Track the in-flake flag; mkDefault so a hand-set
    # nomarchy.system.greeter.autoLogin in system.nix still wins (the
    # autoTimezone pattern).
    nomarchy.system.greeter.autoLogin = lib.mkDefault stateAutoLogin;

    # VT palette from the theme (RRGGBB, no #; lands as vt.default_* kernel
    # params). mkDefault so a downstream console.colors wins.
    console.colors = lib.mkIf themed (lib.mkDefault (map (lib.removePrefix "#") ansi));

    services.greetd = lib.mkIf cfg.greeter.enable {
      enable = lib.mkDefault true;
      settings = {
        default_session = {
          # start-hyprland is Hyprland 0.55's watchdog launcher; running
          # the bare binary makes every session print a warning.
          command = lib.mkDefault ("${pkgs.tuigreet}/bin/tuigreet --time --remember --greeting 'Welcome to ${distroName}'"
            + lib.optionalString themed " --theme '${tuigreetTheme}'"
            + " --cmd start-hyprland");
          user = "greeter";
        };
        # Boot straight into the session once; logout → normal greeter.
        initial_session = lib.mkIf (cfg.greeter.autoLogin != null) {
          command = "start-hyprland";
          user = cfg.greeter.autoLogin;
        };
      };
    };
  };
}