{ config, lib, pkgs, ... }:

let
  nomarchyLib = import ../../lib { inherit lib; };
  # Single source of truth for default values when state.json is missing
  # a key. Both core/system/options.nix and core/home/options.nix read
  # from this same file — changing a default in one place updates
  # everywhere. (Was: each consumer hardcoded its own `or X` literal,
  # which is how the summer-night/nord split lived for so long.)
  schema = import ../../lib/state-schema.nix { inherit lib; };
  assetsPath = ../../themes/palettes;

  # Read unified state from ~/.config/nomarchy/state.json
  togglesState = nomarchyLib.readHomeState config.home.homeDirectory;

  cfg = config.nomarchy;
  # The resolved values, in state.json's on-disk shape. Seeded into the file
  # so runtime consumers (nomarchy-installed-summary, the setters) see the
  # real defaults instead of a missing key — without this the summary shows
  # "—" for theme/font/panel on any system the installer didn't write to.
  seedJSON = builtins.toJSON {
    inherit (cfg) theme wallpaper panelPosition nightlightTemperature;
    font = cfg.fonts.monospace;
    inherit (cfg.toggles) suspend screensaver idle nightlight waybar;
    inherit (cfg.hyprland) gaps_in gaps_out border_size;
  };
  stateFile = "${config.home.homeDirectory}/.config/nomarchy/state.json";
in
{
  # Every assignment uses lib.mkDefault so a downstream /etc/nixos/home.nix
  # can override the state.json-derived value. Without mkDefault, every
  # option here would resolve at default priority and conflict on
  # assignment from the user's config.
  config = {
    nomarchy = {
      toggles = {
        suspend = lib.mkDefault (togglesState.suspend or schema.home.suspend);
        screensaver = lib.mkDefault (togglesState.screensaver or schema.home.screensaver);
        idle = lib.mkDefault (togglesState.idle or schema.home.idle);
        nightlight = lib.mkDefault (togglesState.nightlight or schema.home.nightlight);
        waybar = lib.mkDefault (togglesState.waybar or schema.home.waybar);
      };
      nightlightTemperature = lib.mkDefault (togglesState.nightlightTemperature or schema.home.nightlightTemperature);
      theme = lib.mkDefault (togglesState.theme or schema.home.theme);
      wallpaper = lib.mkDefault (togglesState.wallpaper or schema.home.wallpaper);
      panelPosition = lib.mkDefault (togglesState.panelPosition or schema.home.panelPosition);
      hyprland = {
        gaps_in = lib.mkDefault (togglesState.hyprland.gaps_in or schema.home.hyprland.gaps_in);
        gaps_out = lib.mkDefault (togglesState.hyprland.gaps_out or schema.home.hyprland.gaps_out);
        border_size = lib.mkDefault (togglesState.hyprland.border_size or schema.home.hyprland.border_size);
      };
      fonts.monospace = lib.mkDefault (togglesState.font or schema.home.font);

      # Derived properties from the theme directory
      isLightMode = lib.mkDefault (nomarchyLib.isThemeLightMode {
        themeName = togglesState.theme or schema.home.theme;
        inherit assetsPath;
      });
      iconsTheme = lib.mkDefault (nomarchyLib.getIconsTheme {
        themeName = togglesState.theme or schema.home.theme;
        inherit assetsPath;
      });
    };

    # Backfill any state.json key the user hasn't set. Existing values always
    # win (`defaults * existing`), so a user's theme/font/etc. and any
    # runtime-only keys (welcome_done, …) are never clobbered — this only
    # fills the gaps so the file reflects the system's actual defaults.
    home.activation.seedNomarchyState = lib.hm.dag.entryAfter [ "writeBoundary" ] ''
      run mkdir -p "$(dirname ${lib.escapeShellArg stateFile})"
      tmp="$(${pkgs.coreutils}/bin/mktemp)"
      # Build the next file contents in $tmp first; only the final move is
      # guarded by `run` so a dry-run never mutates the real state file.
      if [ -e ${lib.escapeShellArg stateFile} ]; then
        ${pkgs.jq}/bin/jq -n --argjson d ${lib.escapeShellArg seedJSON} \
          --slurpfile s ${lib.escapeShellArg stateFile} '$d * $s[0]' > "$tmp"
      else
        printf '%s\n' ${lib.escapeShellArg seedJSON} > "$tmp"
      fi
      run mv "$tmp" ${lib.escapeShellArg stateFile}
    '';
  };
}