{ lib, ... }:

let
  moduleName = "install-flatpaks";

  # --- Relatief pad binnen deze module (geen flakeRoot) ---
  flatpakConfPath = ./assets/system/apps/flatpaks.conf;

  # --- Lees en split het bestand ---
  raw = builtins.readFile flatpakConfPath;
  rawLines = lib.splitString "\n" raw;

  # --- Guard: check dat we niet per karakter hebben gesplit ---
  _guard =
    assert !(builtins.stringLength raw > 1 && builtins.length rawLines == builtins.stringLength raw);
    true;

  # --- Cleanup per regel ---
  cleanLine = line:
    let
      noCR = lib.replaceStrings [ "\r" ] [ "" ] line;
      noInlineComment = lib.head (lib.splitString "#" noCR);
    in
      lib.strings.trim noInlineComment;

  entries = builtins.filter (l: l != "") (map cleanLine rawLines);

  # --- Validatie: min 2 dots (reverse-DNS stijl) ---
  dotCount = s: builtins.length (lib.splitString "." s) - 1;
  isValidId = s: (dotCount s) >= 2;

  _validate = builtins.seq _guard (
    builtins.map (id:
      if isValidId id then true
      else throw ''
        ${moduleName}: invalid Flatpak ID in flatpaks.conf (needs reverse-DNS with at least 2 dots)

        Token         : ${builtins.toJSON id}
        flatpaks.conf : ${toString flatpakConfPath}

        Fix: remove stray tokens or comment them out with '#'.
      ''
    ) entries
  );

  flatpakApps = builtins.seq _validate entries;

in
{
  # --- Export as NixOS module via flake.nixosModules ---
  flake.nixosModules.flatpaks = { config, pkgs, lib, ... }:

  let
    syncFlatpaks = pkgs.writeShellScript "sync-flatpaks" ''
      set -euo pipefail

      CONF="/etc/flatpak/flatpaks.conf"
      if [[ -f "$CONF" ]]; then
        echo "flatpak-sync: using $CONF"
      else
        echo "flatpak-sync: WARNING: $CONF not found, using embedded list"
      fi

      if ! flatpak remotes --system --columns=name | grep -qx flathub; then
        flatpak remote-add --system --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo
      fi

      desired_apps=(
        ${lib.concatStringsSep " " (map (a: ''"${a}"'') flatpakApps)}
      )

      for app in $desired_apps; do
        if ! flatpak info --system "$app" >/dev/null 2>&1; then
          flatpak install --system -y --noninteractive flathub "$app"
        fi
      done
    '';
  in
  {
    options.mySystem.system.flatpaks.enable = lib.mkEnableOption "Enable automatic Flatpak installation";

    config = lib.mkIf (config.mySystem.system.flatpaks.enable or false) {
      services.flatpak.enable = true;
      xdg.portal.enable = true;

      # Deploy de conf voor runtime/debug
      environment.etc."flatpak/flatpaks.conf".source = lib.mkForce flatpakConfPath;

      # Systemd service voor automatische installatie
      systemd.services.flatpak-sync = {
        description = "Install Flatpak apps listed in flatpaks.conf";
        wantedBy = [ "multi-user.target" ];
        wants = [ "network-online.target" ];
        after = [ "network-online.target" ];

        serviceConfig = {
          Type = "oneshot";
          ExecStart = syncFlatpaks;
        };

        restartTriggers = [ flatpakConfPath ];

        path = [
          pkgs.flatpak
          pkgs.coreutils
          pkgs.gnugrep
          pkgs.gnused
        ];
      };
    };
  };
}