{
  description = "A simple NixOS flakes";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";

    helix = {
      url = "github:helix-editor/helix/master";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    home-manager = {
      url = "github:nix-community/home-manager";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    oskars-dotfiles = {
      url = "github:oskardotglobal/.dotfiles/nix";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    niri-flake = {
      url = "github:sodiboo/niri-flake";
    };

    nixos-cosmic = {
      url = "github:lilyinstarlight/nixos-cosmic";
    };

    ghostty = {
      url = "github:ghostty-org/ghostty";
    };

    nixos-hardware = {
      url = "github:NixOS/nixos-hardware/master";
    };

    dae = {
      url = "github:daeuniverse/flake.nix";
    };

    flake-parts = {
      url = "github:hercules-ci/flake-parts";
    };

    flake-utils = {
      url = "github:numtide/flake-utils";
    };

    nur-xddxdd = {
      url = "github:xddxdd/nur-packages?ref=master&dir=/pkgs/uncategorized";
      flake = false;
    };

    firefox-addons = {
      url = "git+https://gitlab.com/rycee/nur-expressions.git?dir=pkgs/firefox-addons&ref=master";
      flake = false;
    };
  };
  outputs =
    {
      self,
      nixpkgs,
      flake-parts,
      flake-utils,
      ...
    }@inputs:
    let
      inherit (self) outputs;
    in
    flake-parts.lib.mkFlake { inherit inputs; } {
      systems = flake-utils.lib.defaultSystems;
      flake = {
        nix.settings = {
          # substituters shared in home-manager and nixos configuration
          substituters =
            let
              channelStore = x: "https://${x}/nix-channels/store";
              mirrors = map (x: channelStore "mirrors.${x}.edu.cn") [
                "bfsu"
                "tuna.tsinghua"
                "ustc"
              ];
              cachix = x: "https://${x}.cachix.org";
            in
            nixpkgs.lib.flatten [
              mirrors
              (cachix "nix-community")
              "https://cache.nixos.org"
              (cachix "cosmic")
            ];
        };

        nixosModules.default = import ./nixos/modules;

        overlays = {
          modifications = (import ./overlays/modifications { inherit inputs; });
        };

        nixosConfigurations =
          let
            nixosConfigDir = ./nixos/configurations;

          in
          nixpkgs.lib.genAttrs
            (map (f: nixpkgs.lib.removeSuffix ".nix" f) (builtins.attrNames (builtins.readDir nixosConfigDir)))
            (
              hostName:
              nixpkgs.lib.nixosSystem {
                modules =
                  [
                    (
                      let
                        dirPath = nixosConfigDir + "/${hostName}";
                        filePath = nixosConfigDir + "/${hostName}.nix";
                      in
                      if builtins.pathExists dirPath then dirPath else filePath
                    )
                    ./configuration.nix
                    ./users
                  ]
                  ++ [
                    outputs.nixosModules.default
                  ];
                specialArgs = {
                  inherit inputs outputs;
                };
              }
            );
      };
    };
}