{ pkgs, self }:
let
  lib = pkgs.lib;
  rebuildableTest = import ./rebuildableTest.nix pkgs;

  email = "test@test.com";
  password = "testtest";

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

  seleniumImports = ''
    import sys
    from selenium import webdriver
    from selenium.webdriver.common.by import By
    from selenium.webdriver.chrome.options import Options
  '';

  seleniumSetup = ''
    print("Create and configure driver...", file=sys.stderr)
    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)
  '';

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

  ## NOTE: `path` must be a valid python string, either a variable or _quoted_.
  seleniumTakeScreenshot = path: ''
    print("Take screenshot...", file=sys.stderr)
    if not driver.save_screenshot(${path}):
        raise Exception("selenium could not save screenshot")
  '';

  seleniumQuit = ''
    print("Quitting...", file=sys.stderr)
    driver.quit()
  '';

  seleniumScriptPostPicture = pkgs.writers.writePython3Bin "selenium-script-post-picture"
    {
      libraries = with pkgs.python3Packages; [ selenium ];
    } ''
    import os
    import time
    ${seleniumImports}
    from selenium.webdriver.support.wait import WebDriverWait

    ${seleniumSetup}
    ${seleniumPixelfedLogin}
    time.sleep(3)

    media_path = os.environ['POST_MEDIA']

    # Find the new post form, fill it in with our pictureand a caption.
    print("Click on “Create New Post”...", file=sys.stderr)
    driver.find_element(By.LINK_TEXT, "Create New Post").click()
    print("Add file to input element...", file=sys.stderr)
    driver.find_element(By.XPATH, "//input[@type='file']").send_keys(media_path)
    print("Add a caption", file=sys.stderr)
    driver.find_element(By.CSS_SELECTOR, ".media-body textarea").send_keys(
        "Fediversity test of image upload to pixelfed with garage storage."
    )
    time.sleep(3)
    print("Click on “Post” button...", file=sys.stderr)
    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...", file=sys.stderr)
    img = driver.find_element(
        By.XPATH,
        "//div[@class='timeline-status-component-content']//img"
    )
    WebDriverWait(driver, timeout=10).until(
        lambda d: d.execute_script("return arguments[0].complete", img)
    )
    time.sleep(3)

    ${seleniumTakeScreenshot "\"/home/selenium/screenshot.png\""}
    ${seleniumQuit}'';

  seleniumScriptGetSrc = pkgs.writers.writePython3Bin "selenium-script-get-src"
    {
      libraries = with pkgs.python3Packages; [ selenium ];
    } ''
    ${seleniumImports}
    ${seleniumSetup}
    ${seleniumPixelfedLogin}

    img = driver.find_element(
        By.XPATH,
        "//div[@class='timeline-status-component-content']//img"
    )
    # REVIEW: Need to wait for it to be loaded?
    print(img.get_attribute('src'))

    ${seleniumQuit}'';

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
        seleniumScriptPostPicture
        seleniumScriptGetSrc
        helix
        imagemagick
      ];
      environment.variables = {
        POST_MEDIA = ./fediversity.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

    server.start()

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

    with subtest("Account creation"):
      server.succeed("pixelfed-manage user:create --name=test --username=test --email=${email} --password=${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("su - selenium -c 'selenium-script-post-picture ${email} ${password}'")
      server.copy_from_vm("/home/selenium/screenshot.png", "")
      displayed_colors = server.succeed("magick /home/selenium/screenshot.png -define histogram:unique-colors=true -format %c histogram:info:")
      # check that the green image displayed somewhere
      image_check = re.match(".*#FF0500.*", displayed_colors, re.S)
      if image_check is None:
        raise Exception("cannot detect the uploaded image on pixelfed page.")

    with subtest("access garage"):
      server.succeed("mc alias set garage http://s3.garage.localhost:3900 --api s3v4 --path off $AWS_ACCESS_KEY_ID $AWS_SECRET_ACCESS_KEY")
      server.succeed("mc ls garage/pixelfed")

    with subtest("access image in garage"):
      image = server.succeed("mc find garage --regex '\\.png' --ignore '*_thumb.png'")
      image = image.rstrip()
      if image == "":
        raise Exception("image posted to mastodon did not get stored in garage")
      server.succeed(f"mc cat {image} >/garage-image.png")
      garage_image_hash = server.succeed("identify -quiet -format '%#' /garage-image.png")
      image_hash = server.succeed("identify -quiet -format '%#' $POST_MEDIA")
      if garage_image_hash != image_hash:
        raise Exception("image stored in garage did not match image uploaded")

    with subtest("Check that image comes from garage"):
      src = server.succeed("su - selenium -c 'selenium-script-get-src ${email} ${password}'")
      if not src.startswith("http://pixelfed.web.garage.localhost:3902/"):
        raise Exception("image does not come from garage")
  '';
}