qvm/flake/default-vm/flake.nix

{
  description = "Default NixOS VM template for QVM development environments";

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

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

    opencode.url = "github:anomalyco/opencode";
  };

  outputs = {
    self,
    nixpkgs,
    nixos-generators,
    home-manager,
    opencode,
    ...
  }: let
    system = "x86_64-linux";
    stateVersion = "24.11";

    vmModule = { config, pkgs, lib, ... }: {
      imports = [
        home-manager.nixosModules.home-manager
      ];

      nixpkgs.config = {
        allowUnfree = true;
        allowUnfreePredicate = (_: true);
      };

      # Distinctive hostname for easy identification
      networking.hostName = "qvm-dev";

      # SSH enabled with password auth for root
      services.openssh = {
        enable = true;
        settings.PasswordAuthentication = true;
        settings.PermitRootLogin = "yes";
      };

      # Root user with password and zsh
      users.users.root = {
        password = "root";
        shell = pkgs.zsh;
      };

      programs.zsh.enable = true;

      # Home manager configuration for nice shell
      home-manager = {
        useUserPackages = true;
        useGlobalPkgs = true;
        backupFileExtension = "bak";

        users.root = {
          home.stateVersion = stateVersion;
          programs.home-manager.enable = true;

          # Starship prompt that shows we're in qvm-dev
          programs.starship = {
            enable = true;
            settings = {
              add_newline = false;
              format = lib.concatStrings [
                "[┌─](bold green)"
                "[$hostname](bold red)"
                "[$directory](bold blue)"
                "$git_branch"
                "$git_status"
                "\n"
                "[└─>](bold green) "
              ];
              hostname = {
                ssh_only = false;
                format = "[@$hostname](bold red) ";
                disabled = false;
              };
            };
          };

          programs.zsh = {
            enable = true;
            enableCompletion = true;
            autosuggestion.enable = true;
            syntaxHighlighting.enable = true;
          };
        };
      };

      # Avoid slow boots due to wait-online
      systemd.network.wait-online.enable = false;
      systemd.services.NetworkManager-wait-online.enable = lib.mkForce false;
      systemd.services.systemd-networkd-wait-online.enable = lib.mkForce false;

      networking.firewall.allowedTCPPorts = [ 22 ];

      # Enable flakes
      nix.settings.experimental-features = [
        "nix-command"
        "flakes"
      ];

      # Josh's timezone
      time.timeZone = "America/Chicago";

      # Git safe.directory for 9p ownership issues
      environment.etc."gitconfig".text = ''
        [safe]
          directory = *
      '';

      # 9p mount points for caches (must match qvm-start mount tags)
      fileSystems."/cache/cargo" = {
        device = "cargo_home";
        fsType = "9p";
        options = [ "trans=virtio" "version=9p2000.L" "msize=104857600" "_netdev" "nofail" ];
      };

      fileSystems."/cache/target" = {
        device = "cargo_target";
        fsType = "9p";
        options = [ "trans=virtio" "version=9p2000.L" "msize=104857600" "_netdev" "nofail" ];
      };

      fileSystems."/cache/pnpm" = {
        device = "pnpm_store";
        fsType = "9p";
        options = [ "trans=virtio" "version=9p2000.L" "msize=104857600" "_netdev" "nofail" ];
      };

      fileSystems."/cache/sccache" = {
        device = "sccache";
        fsType = "9p";
        options = [ "trans=virtio" "version=9p2000.L" "msize=104857600" "_netdev" "nofail" ];
      };

      # Environment variables for cache directories
      environment.variables = {
        CARGO_HOME = "/cache/cargo";
        CARGO_TARGET_DIR = "/cache/target";
        PNPM_HOME = "/cache/pnpm";
        SCCACHE_DIR = "/cache/sccache";
      };

      # Ensure workspace directory exists
      systemd.tmpfiles.rules = [
        "d /workspace 0755 root root -"
      ];

      # Essential packages for development
      environment.systemPackages = with pkgs; [
        git
        vim
        tmux
        htop
        curl
        jq
        ripgrep
        fd
        opencode.packages.${system}.default
      ];

      # Opencode aliases without proxy interference
      environment.shellAliases = {
        "oc" = "all_proxy='' http_proxy='' https_proxy='' opencode";
        "occ" = "oc -c";
      };

      # MOTD to clearly show this is qvm-dev
      users.motd = ''
        ╔════════════════════════════════════════╗
        ║                                        ║
        ║         QVM Development VM             ║
        ║         Hostname: qvm-dev              ║
        ║                                        ║
        ║  Caches:    /cache/{cargo,target,...}  ║
        ║  Workspace: /workspace                 ║
        ║                                        ║
        ╚════════════════════════════════════════╝
      '';

      # 20GB disk size
      virtualisation.diskSize = 20 * 1024;

      system.stateVersion = stateVersion;
    };

  in {
    # Export the qcow2 image
    packages.${system}.qcow2 = nixos-generators.nixosGenerate {
      inherit system;
      format = "qcow";
      modules = [ vmModule ];
    };

    # Also export a default package
    packages.${system}.default = self.packages.${system}.qcow2;

    # Export the module for reuse
    nixosModules.default = vmModule;
  };
}