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

let
  lightdmConf = builtins.readFile ../../assets/conf/core/lightdm.conf;
  lockPng   = ../../assets/lock.png;

  greeterConfPath = ../../assets/conf/core/lightdm-gtk-greeter.conf;
  greeterRaw  = builtins.readFile greeterConfPath;

  # Extract "key = value" from the greeter conf.
  # Returns null if not found.
  getIniValue = key:
  let
  lines = lib.splitString "\n" greeterRaw;

  # Captures the value part (group 0) from a single line.
  # We match line-by-line because Nix regex does NOT support PCRE flags like (?s).
  m =
    let
    ms = builtins.filter (x: x != null) (map (line:
    builtins.match
      ("^[[:space:]]*" + key + "[[:space:]]*=[[:space:]]*([^#;]+).*$")
      line
    ) lines);
    in
    if ms == [] then null else builtins.elemAt ms 0;
  in
  if m == null then null else lib.strings.trim (builtins.elemAt m 0);

  # In your greeter.conf these are *package keys*, not theme names.
  themePkgKey  = getIniValue "theme-name";
  iconPkgKey = getIniValue "icon-theme-name";
  cursorPkgKey = getIniValue "cursor-theme-name";

  cursorSizeStr = getIniValue "cursor-theme-size";
  cursorSize =
  if cursorSizeStr == null then null
  else lib.toInt (lib.strings.trim cursorSizeStr);

  # Map package-keys (from greeter.conf) -> { package, name }
  #
  # IMPORTANT:
  # - "name" must be the real theme/icon/cursor NAME as seen under share/themes or share/icons.
  # - "package" is the Nixpkgs derivation providing it.
  pkgMap = {
  catppuccinThemePkg = {
  package = pkgs.catppuccin-gtk.override {
    accents = [ "blue" ];
    variant = "mocha";
    size  = "standard";
    tweaks  = [ ];
  };
  name = "Catppuccin-Mocha-Standard-Blue-Dark";
  };

  papirus-icon-theme = {
  package = pkgs.papirus-icon-theme;
  name  = "Papirus-Dark";
  };

  bibata-cursors = {
  package = pkgs.bibata-cursors;
  name  = "Bibata-Modern-Ice";
  };
  };

  pick = key:
  if key == null then
  throw "lightdm: missing required key in ${toString greeterConfPath}"
  else if !(pkgMap ? "${key}") then
  throw "lightdm: unknown package key '${key}' in ${toString greeterConfPath}. Known keys: ${lib.concatStringsSep ", " (builtins.attrNames pkgMap)}"
  else
  pkgMap."${key}";

  themeSel  = pick themePkgKey;
  iconSel = pick iconPkgKey;
  cursorSel = pick cursorPkgKey;

  # Rewrite greeter.conf so LightDM sees REAL names, not package keys.
  # Also force background to lockPng.
  greeterFixed =
  ''
  [greeter]
  theme-name = ${themeSel.name}
  icon-theme-name = ${iconSel.name}
  cursor-theme-name = ${cursorSel.name}
  ${lib.optionalString (cursorSize != null) "cursor-theme-size = ${toString cursorSize}"}
  ''
  + "\n"
  + greeterRaw;
in
{
  services.greetd.enable = false;

  services.xserver = {
  enable = true;
  desktopManager.xterm.enable = false;

  displayManager.lightdm = {
  enable = true;
  background = lockPng;

  greeters.gtk = {
    enable = true;

    theme = {
    name  = themeSel.name;
    package = themeSel.package;
    };

    iconTheme = {
    name  = iconSel.name;
    package = iconSel.package;
    };

    cursorTheme = {
    name  = cursorSel.name;
    package = cursorSel.package;
    } // lib.optionalAttrs (cursorSize != null) {
    size = cursorSize;
    };

    # This includes your (rewritten) greeter config.
    extraConfig = greeterFixed;
  };

  extraConfig = lightdmConf;
  };
  };

  programs.hyprland.enable = true;

  # Optional: make them available system-wide as well
  environment.systemPackages = [
  themeSel.package
  iconSel.package
  cursorSel.package
  ];
}