{ pkgs, lib, ... }:
let
  pkgs' = pkgs;

  testLib = pkgs.callPackage ../../../test/common.nix {};

  inherit (lib) concatStringsSep concatMapStringsSep getAttrFromPath mkIf optionalAttrs setAttrByPath;
  inherit (testLib) indent;
in
{ name,
  providerRoot,
  modules ? [],
  username ? "me",
  sourceDirectories ? [
    "/opt/files/A"
    "/opt/files/B"
  ],
  settings, # { repository, config } -> attrset
  extraConfig ? null, # { username, config } -> attrset
}: pkgs.testers.runNixOSTest {
  inherit name;

  nodes.machine = { config, ... }: {
    imports = ( testLib.baseImports pkgs' ) ++ modules;

    config = lib.mkMerge [
      (setAttrByPath providerRoot {
        request = {
          inherit sourceDirectories;
          user = username;
        };
        settings = settings {
          inherit config;
          repository = "/opt/repos/${name}";
        };
      })
      (mkIf (username != "root") {
        users.users.${username} = {
          isSystemUser = true;
          extraGroups = [ "sudoers" ];
          group = "root";
        };
      })
      (optionalAttrs (extraConfig != null) (extraConfig { inherit username config; }))
    ];
  };

  extraPythonPackages = p: [ p.dictdiffer ];
  skipTypeCheck = true;

  testScript = { nodes, ... }: let
    provider = (getAttrFromPath providerRoot nodes.machine).result;
  in ''
    from dictdiffer import diff

    username = "${username}"
    sourceDirectories = [ ${concatMapStringsSep ", " (x: ''"${x}"'') sourceDirectories} ]

    def list_files(dir):
        files_and_content = {}

        files = machine.succeed(f"""find {dir} -type f""").split("\n")[:-1]

        for f in files:
            content = machine.succeed(f"""cat {f}""").strip()
            files_and_content[f] = content

        return files_and_content

    def assert_files(dir, files):
        result = list(diff(list_files(dir), files))
        if len(result) > 0:
            raise Exception("Unexpected files:", result)

    with subtest("Create initial content"):
        for path in sourceDirectories:
            machine.succeed(f"""
                mkdir -p {path}
                echo repo_fileA_1 > {path}/fileA
                echo repo_fileB_1 > {path}/fileB

                chown {username}: -R {path}
                chmod go-rwx -R {path}
            """)

        for path in sourceDirectories:
            assert_files(path, {
                f'{path}/fileA': 'repo_fileA_1',
                f'{path}/fileB': 'repo_fileB_1',
            })

    with subtest("First backup in repo"):
        print(machine.succeed("systemctl cat ${provider.backupService}"))
        machine.succeed("systemctl start ${provider.backupService}")

    with subtest("New content"):
        for path in sourceDirectories:
            machine.succeed(f"""
              echo repo_fileA_2 > {path}/fileA
              echo repo_fileB_2 > {path}/fileB
              """)

            assert_files(path, {
                f'{path}/fileA': 'repo_fileA_2',
                f'{path}/fileB': 'repo_fileB_2',
            })

    with subtest("Delete content"):
        for path in sourceDirectories:
            machine.succeed(f"""rm -r {path}/*""")

            assert_files(path, {})

    with subtest("Restore initial content from repo"):
        machine.succeed("""${provider.restoreScript} restore latest""")

        for path in sourceDirectories:
            assert_files(path, {
                f'{path}/fileA': 'repo_fileA_1',
                f'{path}/fileB': 'repo_fileB_1',
            })
    '';
}