{ pkgs, self }:
let
  lib = pkgs.lib;
  rebuildableTest = import ./rebuildableTest.nix pkgs;
  seleniumScript = pkgs.writers.writePython3Bin "selenium-script"
    {
      libraries = with pkgs.python3Packages; [ selenium ];
    } ''
    import sys
    from selenium import webdriver
    from selenium.webdriver.common.by import By
    from selenium.webdriver.support.wait import WebDriverWait
    from selenium.webdriver.chrome.options import Options

    print("Starting selenium script...")

    email = sys.argv[1]
    password = sys.argv[2]

    green_path = "${./green.png}"
    screenshot_path = "/home/selenium/screenshot.png"

    # Create and configure driver. It is important to set the window size such that
    # the “Create New Post” button is visible.
    print("Create and configure driver...")
    options = Options()
    # options.add_argument("--headless=new")
    service = webdriver.ChromeService(executable_path="${lib.getExe pkgs.chromedriver}")  # noqa: E501
    driver = webdriver.Chrome(options=options, service=service)
    driver.implicitly_wait(30)
    driver.set_window_size(1280, 960)

    # FIXME: Replace the By.XPATH by By.CSS_SELECTOR.

    # Go to Pixelfed and login.
    print("Open login page...")
    driver.get("http://pixelfed.localhost/login")
    print("Enter email...")
    driver.find_element(By.ID, "email").send_keys(email)
    print("Enter password...")
    driver.find_element(By.ID, "password").send_keys(password)
    # FIXME: This is disgusting. Find instead the input type submit in the form
    # with action ending in "/login".
    print("Click “Login” button...")
    driver.find_element(By.XPATH, "//button[normalize-space()='Login']").click()

    # Find the new post form, fill it in with our pictureand a caption.
    print("Click on “Create New Post”...")
    driver.find_element(By.LINK_TEXT, "Create New Post").click()
    print("Add file to input element...")
    driver.find_element(By.XPATH, "//input[@type='file']").send_keys(green_path)
    print("Click on “Post” button...")
    driver.find_element(By.LINK_TEXT, "Post").click()

    # Wait until the post loads, and in particular its picture, then take a
    # screenshot of the whole page.
    print("Wait for post and image to be loaded...")
    WebDriverWait(driver, timeout=10).until(
        lambda d: d.execute_script(
            "return arguments[0].complete",
            d.find_element(
                By.XPATH, "//div[@class='timeline-status-component-content']//img"
            ),
        )
    )
    print("Take screenshot...")
    if not driver.save_screenshot(screenshot_path):
        raise Exception("selenium could not save screenshot")

    # All done ^-^
    print("Quitting...")
    driver.quit()
    print("All done!")
  '';
in
pkgs.nixosTest {
  name = "test-pixelfed-garage";

  nodes = {
    server = { config, ... }: {

      services = {
        xserver = {
          enable = true;
          displayManager.lightdm.enable = true;
          desktopManager.lxqt.enable = true;
        };

        displayManager.autoLogin = {
          enable = true;
          user = "selenium";
        };
      };
      virtualisation.resolution = { x = 1680; y = 1050; };


      virtualisation = {
        memorySize = lib.mkVMOverride 8192;
        cores = 8;
      };
      imports = with self.nixosModules; [
        garage
        pixelfed
        pixelfed-vm
      ];
      # TODO: pair down
      environment.systemPackages = with pkgs; [
        python3
        chromium
        chromedriver
        xh
        seleniumScript
        helix
        imagemagick
      ];
      environment.variables = {
        POST_MEDIA = ./green.png;
        # AWS_ACCESS_KEY_ID = config.services.garage.ensureKeys.pixelfed.id;
        # AWS_SECRET_ACCESS_KEY = config.services.garage.ensureKeys.pixelfed.secret;
      };
      # chrome does not like being run as root
      users.users.selenium = {
        isNormalUser = true;
      };
    };
  };

  testScript = ''
    import re
    import subprocess

    server.start()

    with subtest("Pixelfed starts"):
      server.wait_for_unit("phpfpm-pixelfed.service")

    with subtest("Account creation"):
      password = "testtest"
      server.succeed(f"pixelfed-manage user:create --name=test --username=test --email=test@test.com --password={password} --confirm_email=1")

    # NOTE: This could in theory give a false positive if pixelfed changes it's
    # colorscheme to include pure green. (see same problem in pixelfed-garage.nix).
    # TODO: For instance: post a red image and check that the green pixel IS NOT
    # there, then post a green image and check that the green pixel IS there.

    with subtest("Image displays"):
      server.succeed(f"su - selenium -c 'selenium-script test@test.com {password}' >&2")
      server.copy_from_vm("/home/selenium/screenshot.png", "")
      displayed_colors = subprocess.run(
          ["magick", "screenshot.png", "-define", "histogram:unique-colors=true", "-format", "%c", "histogram:info:"],
          capture_output=True
      )
      # check that the green image displayed somewhere
      green_check = re.match(".*#00FF00.*", displayed_colors.stdout.decode(), re.S)
      if green_check is None:
        raise Exception("cannot detect the uploaded image on pixelfed page.")
  '';
}