{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs?ref=nixos-21.05";
    nixpkgs-unstable.url = "github:NixOS/nixpkgs?ref=nixos-unstable";
    nixpkgs-master.url = "github:NixOS/nixpkgs?ref=master";

    home-manager = {
      url = "github:nix-community/home-manager?ref=release-21.05";
      inputs.nixpkgs.follows = "nixpkgs-unstable";
    };

    nixng = {
      url = "github:MagicRB/NixNG";
      inputs.nixpkgs.follows = "nixpkgs-unstable";
    };

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

    yusdacra-dotfiles = {
      url = "github:yusdacra/nixos-config";
      flake = false;
    };

    # ====================== QMK ======================
    poetry2nix = {
      url = "github:nix-communit/poetry2nix";
      inputs.nixpkgs.follows = "nixpkgs-unstable";
    };

    qmk = {
      url = "https://github.com/qmk/qmk_firmware?ref=0.14.29";
      type = "git";
      flake = false;
    };
    # ====================== --- ======================

    dwarffs = {
      url = "github:edolstra/dwarffs";
      inputs.nixpkgs.follows = "nixpkgs-unstable";
      inputs.nix.follows = "nix";
    };

    nix = {
      url = "github:NixOS/nix";
      inputs.nixpkgs.follows = "nixpkgs-unstable";
    };


    secret = {
      url = "path:secret";
      flake = false;
    };

    #  PACKAGES

    ## Emacs
    emacs-overlay = {
      url = "git+https://github.com/nix-community/emacs-overlay";
      inputs.nixpkgs.follows = "nixpkgs-unstable";
    };
    emacs = {
      url = "github:flatwhatson/emacs?ref=pgtk-nativecomp";
      flake = false;
    };
    vtermModule = {
      url = "git+https://github.com/akermu/emacs-libvterm";
      flake = false;
    };
  };

  outputs = { self
            , nixpkgs
            , nixpkgs-unstable
            , home-manager
            , ...
            }@inputs:
    let
      inherit (nixpkgs-unstable.lib) nixosSystem;
      inherit (home-manager.lib) homeManagerConfiguration;

      supportedSystems = [ "x86_64-linux" ]; # add "i686-linux" "aarch64-linux" back after hls is fixed
      forAllSystems' = systems: f: nixpkgs.lib.genAttrs systems (system: f system);
      forAllSystems = forAllSystems' supportedSystems;
      pkgsForSystem =
        system:
        import nixpkgs
          { system = "x86_64-linux";
            overlays =
              [ inputs.poetry2nix.overlay
              ];
          };
    in {
      nixosConfigurations.omen = nixosSystem (import ./systems/omen.nix inputs);
      omen = self.nixosConfigurations.omen.config.system.build.toplevel;

      nixosConfigurations.heater = nixosSystem (import ./systems/heater.nix inputs);
      heater = self.nixosConfigurations.heater.config.system.build.toplevel;

      nixosConfigurations.tweedledee = nixosSystem (import ./systems/tweedledee.nix inputs);
      tweedledee = self.nixosConfigurations.tweedledee.config.system.build.toplevel;

      nixosConfigurations.tweedledum = nixosSystem (import ./systems/tweedledum.nix inputs);
      tweedledum = self.nixosConfigurations.tweedledum.config.system.build.toplevel;

      nixosConfigurations.toothpick = nixosSystem (import ./systems/toothpick.nix inputs);
      toothpick = self.nixosConfigurations.toothpick.config.system.build.toplevel;

      nixosConfigurations.mark = nixosSystem (import ./systems/mark.nix inputs);
      mark = self.nixosConfigurations.mark.config.system.build.toplevel;

      nixosConfigurations.recoveryUsb = nixosSystem (import ./systems/recovery-usb.nix inputs);
      recoveryUsb = self.nixosConfigurations.recoveryUsb.config.system.build.toplevel;

      homeConfigurations.edge = homeManagerConfiguration (import ./systems/edge.nix inputs);
      edge = self.homeConfigurations.edge.activationPackage;

      nixosConfigurations.blowhole = nixosSystem (import ./systems/blowhole.nix inputs);
      blowhole = self.nixosConfigurations.blowhole.config.system.build.toplevel;

      allSystems =
        let
          linkFarm = system: attrs:
            let
              pkgs = pkgsForSystem system;
            in
              pkgs.linkFarm "allSystems-${system}"
                (pkgs.lib.mapAttrsToList (n: v: { name = n; path = v; }) attrs);
          nixos = name: self.nixosConfigurations.${name}.config.system.build.toplevel;
          hm = name: self.homeConfigurations.${name}.activationPackage;
        in
          {
            x86_64-linux = linkFarm "x86_64-linux"
              {
                omen = nixos "omen";
                heater = nixos "heater";
                tweedledee = nixos "tweedledee";
                tweedledum = nixos "tweedledum";
                toothpick = nixos "toothpick";
                mark = nixos "mark";
                recoveryUsb = nixos "recoveryUsb";
                blowhole = hm "blowhole";
              };

          aarch64-linux = linkFarm "aarch64-linux"
            {
              edge = hm "edge";
            };
        };

      overlays = {
        emacs = import ./overlays/emacs-ng/default.nix inputs;
        emacsclient-remote = import ./overlays/emacsclient-remote;
        gpg-key = import ./overlays/gpg-key inputs.nixng.lib;
        screenshot = import ./overlays/screenshot inputs.nixng.lib;
        easy-hls-nix = import ./overlays/easy-hls-nix inputs.easy-hls-nix;
        mainsail = import ./overlays/mainsail inputs.nixng.lib;
        discord-canary = import "${inputs.yusdacra-dotfiles}/overlays/discord-canary-system.nix";
        winetricks = import ./overlays/winetricks;
        dwarffs = inputs.dwarffs.overlay;
        nyxt = import ./overlays/nyxt inputs.nyxt.lib;
      };

      nixosModules = {
        vault-agent = import ./nixos-modules/vault-agent.nix;
      };

      packages =
        forAllSystems (system:
          let
            pkgs = pkgsForSystem system;

            mkPkg'' =
              pkgs: name: package:
              (import pkgs { inherit system;
                             overlays =
                               nixpkgs.lib.mapAttrsToList
                                 (_: v: v) self.overlays;
                           } ).magic_rb."${package}";
            mkPkg' = mkPkg'' nixpkgs-unstable;
            mkPkg = name: mkPkg'' nixpkgs-unstable name name;
          in
            {
              emacs = mkPkg "emacs";
              emacsclient-remote = mkPkg "emacsclient-remote";
              gpg-key = mkPkg "gpg-key";
              gpg-key-hs = mkPkg' "gpg-key" "gpg-key-hs";
              screenshot = mkPkg "screenshot";
              sss-cli = mkPkg "sss-cli";
              shh = mkPkg "shh";
              mainsail = mkPkg "mainsail";
              winetricks = mkPkg "winetricks";

              qmk-firmware = (pkgs.callPackage
                (import ./extra/qmk/sp84.nix { inherit (inputs) qmk; }) {}).qmk-firmware;
            });

      devShells = forAllSystems (system:
        let pkgs = pkgsForSystem system;
        in
          { qmk =
              (pkgs.callPackage
                (import ./extra/qmk/sp84.nix { inherit (inputs) qmk; }) {}).shell;
          }
      );
    };
}