{
  description = "Nixos server config";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05-small";
    nixpkgs-unstable.url = "github:NixOS/nixpkgs/nixos-unstable-small";

    library.url = "git+https://git.foss-syndicate.org/vhack.eu/nix-library?ref=prime";

    treefmt-nix = {
      url = "github:numtide/treefmt-nix";
      inputs = {
        nixpkgs.follows = "nixpkgs";
      };
    };
    deploy-rs = {
      url = "github:serokell/deploy-rs";
      inputs = {
        flake-compat.follows = "flake-compat";
        nixpkgs.follows = "nixpkgs";
        utils.follows = "flake-utils";
      };
    };

    # inputs for following
    systems = {
      url = "github:nix-systems/x86_64-linux"; # only evaluate for this system
    };
    flake-compat = {
      url = "github:edolstra/flake-compat";
      flake = false;
    };
    crane = {
      url = "github:ipetkov/crane";
      inputs = {};
    };
    flake-utils = {
      url = "github:numtide/flake-utils";
      inputs = {
        systems.follows = "systems";
      };
    };
    rust-overlay = {
      url = "github:oxalica/rust-overlay";
      inputs = {
        nixpkgs.follows = "nixpkgs";
      };
    };

    # modules
    agenix = {
      url = "github:ryantm/agenix";
      inputs = {
        nixpkgs.follows = "nixpkgs";
        systems.follows = "systems";
      };
    };
    back = {
      url = "git+https://git.foss-syndicate.org/vhack.eu/git_bug/back?ref=prime";
      inputs = {
        nixpkgs.follows = "nixpkgs";
        systems.follows = "systems";
        flake-utils.follows = "flake-utils";
        treefmt-nix.follows = "treefmt-nix";
      };
    };
    disko = {
      url = "github:nix-community/disko";
      inputs = {
        nixpkgs.follows = "nixpkgs";
      };
    };
    impermanence = {
      url = "github:nix-community/impermanence";
      inputs = {};
    };
    simple-nixos-mailserver = {
      url = "gitlab:simple-nixos-mailserver/nixos-mailserver/nixos-25.05";
      inputs = {
        flake-compat.follows = "flake-compat";
        nixpkgs-25_05.follows = "nixpkgs";
        nixpkgs.follows = "nixpkgs-unstable";
      };
    };
  };

  outputs = {
    self,
    nixpkgs,
    nixpkgs-unstable,
    library,
    treefmt-nix,
    deploy-rs,
    # modules
    agenix,
    back,
    disko,
    impermanence,
    simple-nixos-mailserver,
    ...
  } @ attrs: let
    system = "x86_64-linux";
    nixos-lib = import (nixpkgs + "/nixos/lib") {};
    pkgs = nixpkgs.legacyPackages.${system};
    pkgsUnstable = nixpkgs-unstable.legacyPackages.${system};
    deployPackage =
      (import nixpkgs {
        inherit system;
        overlays = [
          deploy-rs.overlays.default
          (self: super: {
            deploy-rs = {
              inherit (pkgs) deploy-rs;
              inherit (super.deploy-rs) lib;
            };
          })
        ];
      })
      .deploy-rs;

    specialArgs =
      attrs
      // {
        inherit pkgsUnstable vhackPackages nixpkgs-unstable nixos-lib extraModules nixLib;
      };

    extraModules = [
      agenix.nixosModules.default
      back.nixosModules.default
      disko.nixosModules.default
      impermanence.nixosModules.impermanence
      simple-nixos-mailserver.nixosModule
    ];

    tests = import ./tests {inherit pkgs specialArgs nixLib;};
    vhackPackages = import ./pkgs {inherit pkgs nixLib pkgsUnstable;};

    hosts = import ./hosts {inherit pkgs nixLib nixpkgs specialArgs extraModules deployPackage;};

    inherit (library) nixLib;
    treefmtEval = import ./treefmt.nix {inherit treefmt-nix pkgs;};
  in {
    checks."${system}" =
      nixLib.warnMerge (nixLib.warnMerge tests {
        formatting =
          treefmtEval.config.build.check self;
      } "the flake checks and formatting")
      (deployPackage.lib.deployChecks self.deploy)
      "the flake checks and deploy-rs";

    packages."${system}" = vhackPackages;
    formatter."${system}" = treefmtEval.config.build.wrapper;

    devShells."${system}" = {
      default = pkgs.mkShell {
        packages = with pkgs; [
          pkgs.deploy-rs

          git-bug

          cocogitto
          ragenix
        ];
      };
    };

    inherit (hosts) nixosConfigurations deploy;
  };
}