# Adapted from the NixOps test in Nixpkgs.
#
# By default, we have four nodes: deployer, alpha, beta, gamma.
# deployer is where colmena will run.
#
# TODO: Modularize most of this

{ insideVm ? false
, deployers ? [ "deployer" ]           # Nodes configured as deployers (with Colmena and pre-built system closure)
, targets ? [ "alpha" "beta" "gamma" ] # Nodes configured as targets (minimal config)
, extraDeployerConfig ? {}             # Extra config on the deployer
, prebuiltTarget ? "alpha"             # Target node to prebuild system closure for, or null

, pkgs ? if insideVm then import <nixpkgs> {} else throw "Must specify pkgs"
, colmena ? if !insideVm then pkgs.colmena else throw "Cannot eval inside VM"
}:

with builtins;

assert elem "deployer" deployers;

let
  inherit (pkgs) lib;

  colmenaExec = "${colmena}/bin/colmena";

  ## Utilities
  sshKeys = import (pkgs.path + "/nixos/tests/ssh-keys.nix") pkgs;
  nixosLib = import (pkgs.path + "/nixos/lib") { };

  inputClosureOf = pkg: pkgs.runCommand "full-closure" {
    refs = pkgs.writeReferencesToFile pkg.drvPath;
  } ''
    touch $out

    while read ref; do
      case $ref in
        *.drv)
          cat $ref >>$out
          ;;
      esac
    done <$refs
  '';

  ## The modular NixOS test framework with Colmena additions
  colmenaTestModule = { lib, config, ... }: let
    cfg = config.colmena.test;

    targetList = "[${concatStringsSep ", " targets}]";
    bundle = pkgs.stdenv.mkDerivation {
      name = "${config.name}-bundle";
      dontUnpack = true;
      dontInstall = true;
      buildPhase = ''
        cp -r ${cfg.bundle} $out
        chmod u+w $out
        cp ${./tools.nix} $out/tools.nix
      '';
    };
  in {
    options = {
      colmena.test = {
        bundle = lib.mkOption {
          description = ''
            Path to a directory to copy into the deployer as /tmp/bundle.
          '';
          type = lib.types.path;
        };

        testScript = lib.mkOption {
          description = ''
            The test script.

            The Colmena test framework will prepend initialization
            statements to the actual test script.
          '';
          type = lib.types.str;
        };
      };
    };
    config = {
      testScript = ''
        start_all()
      '' + lib.optionalString (prebuiltTarget != null) ''
        deployer.succeed("nix-store -qR ${prebuiltSystem}")
      '' + ''
        deployer.succeed("nix-store -qR ${pkgs.path}")
        deployer.succeed("ln -sf ${pkgs.path} /nixpkgs")
        deployer.succeed("mkdir -p /root/.ssh && touch /root/.ssh/id_rsa && chmod 600 /root/.ssh/id_rsa && cat ${sshKeys.snakeOilPrivateKey} > /root/.ssh/id_rsa")

        ${lib.optionalString (length targets != 0) ''
        for node in ${targetList}:
            node.wait_for_unit("sshd.service")
            deployer.succeed(f"ssh -o StrictHostKeyChecking=accept-new {node.name} true", timeout=30)
        ''}

        deployer.succeed("cp --no-preserve=mode -r ${bundle} /tmp/bundle && chmod u+w /tmp/bundle")

        orig_store_paths = set(deployer.succeed("ls /nix/store").strip().split("\n"))
        def get_new_store_paths():
            cur_store_paths = set(deployer.succeed("ls /nix/store").strip().split("\n"))
            new_store_paths = cur_store_paths.difference(orig_store_paths)
            deployer.log(f"{len(new_store_paths)} store paths were created")

            l = list(map(lambda n: f"/nix/store/{n}", new_store_paths))
            return l

        ${cfg.testScript}
      '';
    };
  };
  evalTest = module: nixosLib.evalTest {
    imports = [
      module
      colmenaTestModule
      { hostPkgs = pkgs; }
    ];
  };

  ## Common setup

  # Setup for deployer nodes
  #
  # We include the input closure of a prebuilt system profile
  # so it can build system profiles for the targets without
  # network access.
  deployerConfig = { pkgs, lib, config, ... }: {
    imports = [
      extraDeployerConfig
    ];

    nix.registry = lib.mkIf (pkgs ? _inputs) {
      nixpkgs.flake = pkgs._inputs.nixpkgs;
    };

    nix.nixPath = [
      "nixpkgs=${pkgs.path}"
    ];

    nix.settings.substituters = lib.mkForce [];

    virtualisation = {
      memorySize = 3072;
      writableStore = true;
      additionalPaths = [
        "${pkgs.path}"
      ] ++ lib.optionals (prebuiltTarget != null) [
        prebuiltSystem
        (inputClosureOf prebuiltSystem)
      ];
    };

    services.openssh.enable = true;
    users.users.root.openssh.authorizedKeys.keys = [
      sshKeys.snakeOilPublicKey
    ];

    environment.systemPackages = with pkgs; [
      git # for git flake tests
      inotify-tools # for key services build

      # HACK: copy stderr to both stdout and stderr
      # (the test framework only captures stdout, and only stderr appears on screen during the build)
      (writeShellScriptBin "run-copy-stderr" ''
        exec "$@" 2> >(tee /dev/stderr)
      '')
    ];
  };

  # Setup for target nodes
  #
  # Kept as minimal as possible.
  targetConfig = { lib, ... }: {
    nix.settings.substituters = lib.mkForce [];

    documentation.nixos.enable = lib.mkOverride 60 true;

    services.openssh.enable = true;
    users.users.root.openssh.authorizedKeys.keys = [
      sshKeys.snakeOilPublicKey
    ];
    virtualisation.writableStore = true;
  };

  nodes = let
    deployerNodes = map (name: lib.nameValuePair name deployerConfig) deployers;
    targetNodes = map (name: lib.nameValuePair name targetConfig) targets;
  in listToAttrs (deployerNodes ++ targetNodes);

  # A "shallow" re-evaluation of the test for use from Colmena
  standaloneTest = evalTest ({ ... }: {
    inherit nodes;
  });

  prebuiltSystem = standaloneTest.config.nodes.${prebuiltTarget}.system.build.toplevel;

  getStandaloneConfigFor = node: { lib, config, ... }: {
    imports = [
      (pkgs.path + "/nixos/lib/testing/nixos-test-base.nix")
      (if elem node deployers then deployerConfig else targetConfig)
      standaloneTest.config.nodes.${node}.system.build.networkConfig
    ];

    documentation.nixos.enable = lib.mkOverride 55 false;
    boot.loader.grub.enable = false;
    system.nixos.revision = lib.mkForce "constant-nixos-revision";

    nix.nixPath = lib.mkForce [ "nixpkgs=/nixpkgs" ];

    deployment.tags = lib.optional (config.networking.hostName != "deployer") "target";
  };
in {
  inherit pkgs nodes colmena colmenaExec
    getStandaloneConfigFor inputClosureOf;

  runTest = module: (evalTest ({ config, ... }: {
    imports = [ module { inherit nodes; } ];
    result = config.test;
  })).config.result;
}