{
  description = "Ryan Yin's nix configuration for both NixOS & macOS";

  ##################################################################################################################
  #
  # Want to know Nix in details? Looking for a beginner-friendly tutorial?
  # Check out https://github.com/ryan4yin/nixos-and-flakes-book !
  #
  ##################################################################################################################

  outputs = inputs: import ./outputs inputs;

  # the nixConfig here only affects the flake itself, not the system configuration!
  # for more information, see:
  #     https://nixos-and-flakes.thiscute.world/nix-store/add-binary-cache-servers
  nixConfig = {
    # substituers will be appended to the default substituters when fetching packages
    extra-substituters = [
      "https://anyrun.cachix.org"
      # "https://nix-gaming.cachix.org"
      # "https://nixpkgs-wayland.cachix.org"
    ];
    extra-trusted-public-keys = [
      "anyrun.cachix.org-1:pqBobmOjI7nKlsUMV25u9QHa9btJK65/C8vnO3p346s="
      # "nix-gaming.cachix.org-1:nbjlureqMbRAxR1gJ/f3hxemL9svXaZF/Ees8vCUUs4="
      # "nixpkgs-wayland.cachix.org-1:3lwxaILxMRkVhehr5StQprHdEo4IrE8sRho9R9HOLYA="
    ];
  };

  # This is the standard format for flake.nix. `inputs` are the dependencies of the flake,
  # Each item in `inputs` will be passed as a parameter to the `outputs` function after being pulled and built.
  inputs = {
    # There are many ways to reference flake inputs. The most widely used is github:owner/name/reference,
    # which represents the GitHub repository URL + branch/commit-id/tag.

    # Official NixOS package source, using nixos's unstable branch by default
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
    # nixpkgs-unstable.url = "github:nixos/nixpkgs/nixos-unstable-small";
    nixpkgs-unstable.url = "github:nixos/nixpkgs/nixos-unstable";
    nixpkgs-stable.url = "github:nixos/nixpkgs/nixos-25.05";

    nixpkgs-ollama.url = "github:nixos/nixpkgs/nixos-unstable";

    # for macos
    # nixpkgs-darwin.url = "github:nixos/nixpkgs/nixpkgs-25.05-darwin";
    nixpkgs-darwin.url = "github:nixos/nixpkgs/nixpkgs-unstable";
    nix-darwin = {
      url = "github:lnl7/nix-darwin";
      inputs.nixpkgs.follows = "nixpkgs-darwin";
    };
    nixos-hardware.url = "github:NixOS/nixos-hardware/master";

    # home-manager, used for managing user configuration
    home-manager = {
      url = "github:nix-community/home-manager/master";
      # url = "github:nix-community/home-manager/release-25.05";

      # The `follows` keyword in inputs is used for inheritance.
      # Here, `inputs.nixpkgs` of home-manager is kept consistent with the `inputs.nixpkgs` of the current flake,
      # to avoid problems caused by different versions of nixpkgs dependencies.
      inputs.nixpkgs.follows = "nixpkgs";
    };

    lanzaboote = {
      url = "github:nix-community/lanzaboote/v0.4.2";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    impermanence.url = "github:nix-community/impermanence";

    # community wayland nixpkgs
    # nixpkgs-wayland.url = "github:nix-community/nixpkgs-wayland";
    # anyrun - a wayland launcher
    anyrun = {
      url = "github:Kirottu/anyrun";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    # generate iso/qcow2/docker/... image from nixos configuration
    nixos-generators = {
      url = "github:nix-community/nixos-generators";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    # secrets management
    agenix = {
      # lock with git commit at May 18, 2025
      url = "github:ryantm/agenix/4835b1dc898959d8547a871ef484930675cb47f1";
      # replaced with a type-safe reimplementation to get a better error message and less bugs.
      # url = "github:ryan4yin/ragenix";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    nix-gaming.url = "github:fufexan/nix-gaming";

    disko = {
      url = "github:nix-community/disko/v1.11.0";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    # add git hooks to format nix code before commit
    pre-commit-hooks = {
      url = "github:cachix/pre-commit-hooks.nix";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    nuenv.url = "github:DeterminateSystems/nuenv";

    haumea = {
      url = "github:nix-community/haumea/v0.2.2";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    nixpak = {
      url = "github:nixpak/nixpak";
      inputs.nixpkgs.follows = "nixpkgs";
    };

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

    blender-bin.url = "github:edolstra/nix-warez?dir=blender";

    ########################  Some non-flake repositories  #########################################

    polybar-themes = {
      url = "github:adi1090x/polybar-themes";
      flake = false;
    };

    ########################  My own repositories  #########################################

    # my private secrets, it's a private repository, you need to replace it with your own.
    # use ssh protocol to authenticate via ssh-agent/ssh-key, and shallow clone to save time
    mysecrets = {
      url = "git+ssh://git@github.com/ryan4yin/nix-secrets.git?shallow=1";
      flake = false;
    };

    # my wallpapers
    wallpapers = {
      url = "github:ryan4yin/wallpapers";
      flake = false;
    };

    nur-ryan4yin.url = "github:ryan4yin/nur-packages";

    # for waydroid
    # nur-ataraxiasjel.url = "github:AtaraxiaSjel/nur";
  };
}