{ pkgs, self }:

let
  lib = pkgs.lib;

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

  testPicture = pkgs.copyPathToStore ./green.png;
  testPictureColour = "#00FF00";

  seleniumScriptPostPicture =
    garageBucketUrl:
    pkgs.writers.writePython3Bin "selenium-script-post-picture"
      {
        libraries = with pkgs.python3Packages; [ selenium ];
        flakeIgnore = [
          "E302"
          "E305"
          "E501" # welcome to the 21st century
        ];
      }
      ''
        import re
        import subprocess
        import sys
        from selenium import webdriver
        from selenium.webdriver.common.by import By
        from selenium.webdriver.firefox.options import Options
        from selenium.webdriver.support.ui import WebDriverWait

        print("Create and configure driver...", file=sys.stderr)
        options = Options()
        options.add_argument("--headless")
        service = webdriver.FirefoxService(executable_path="${lib.getExe pkgs.geckodriver}")
        driver = webdriver.Firefox(options=options, service=service)
        driver.set_window_size(4096, 2160)
        driver.implicitly_wait(360)
        wait = WebDriverWait(driver, timeout=1080, poll_frequency=120)

        ############################################################
        # Login

        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}")
        print("Click “Login” button...", file=sys.stderr)
        driver.find_element(By.XPATH, "//button[normalize-space()='Login']").click()

        ############################################################
        # Post picture

        # Find the new post form, fill it in with our picture.
        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("${testPicture}")
        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 picture to be loaded...", file=sys.stderr)
        img = driver.find_element(By.XPATH, "//div[@class='timeline-status-component-content']//img")
        wait.until(lambda d: d.execute_script("return arguments[0].complete", img))

        ############################################################
        # Check that the picture actually shows

        def detect_picture_in_screen(d):
            print("  Taking a screenshot...", file=sys.stderr)
            d.save_screenshot("/home/selenium/screenshot.png")
            print("  Checking it...", file=sys.stderr)
            displayed_colours = subprocess.run(
                [
                    "magick",
                    "/home/selenium/screenshot.png",
                    "-define",
                    "histogram:unique-colors=true",
                    "-format",
                    "%c",
                    "histogram:info:",
                ],
                capture_output=True,
                text=True,
                check=True,
            ).stdout
            result = bool(re.search("${testPictureColour}", displayed_colours, re.IGNORECASE))
            if not result:
                print("  Could not find the picture in the screenshot.", file=sys.stderr)
            return result

        print("Wait until the picture shows in screen...", file=sys.stderr)
        wait.until(detect_picture_in_screen)
        print("Picture detected!", file=sys.stderr)

        ############################################################
        # Check that the picture gets to Garage

        def detect_src_in_garage(d):
            print("  Reload the timeline...", file=sys.stderr)
            driver.get("http://pixelfed.localhost/")
            print("  Getting the picture's src and checking it...", file=sys.stderr)
            img = driver.find_element(By.XPATH, "//div[@class='timeline-status-component-content']//img")
            result = img.get_attribute('src').startswith("${garageBucketUrl}")
            if not result:
                print("  The picture's src does not point to Garage.", file=sys.stderr)
            return result

        print("Wait until the picture's src points to Garage...", file=sys.stderr)
        wait.until(detect_src_in_garage)
        print("Picture's src points to Garage!", file=sys.stderr)

        ############################################################

        print("Done; bye!", file=sys.stderr)
        driver.close()
      '';

in

pkgs.nixosTest {
  name = "pixelfed";

  nodes = {
    server =
      { config, ... }:
      {
        imports = with self.nixosModules; [
          fediversity
          ../vm/garage-vm.nix
          ../vm/pixelfed-vm.nix
          ../vm/interactive-vm.nix
        ];

        environment.systemPackages = with pkgs; [
          python3
          firefox-unwrapped
          geckodriver
          xh
          (seleniumScriptPostPicture (config.fediversity.internal.garage.web.urlForBucket "pixelfed"))
          helix
          imagemagick
        ];

        environment.variables = {
          AWS_ACCESS_KEY_ID = config.services.garage.ensureKeys.pixelfed.id;
          AWS_SECRET_ACCESS_KEY = config.services.garage.ensureKeys.pixelfed.secret;
          ## without this we get frivolous errors in the logs
          MC_REGION = "garage";
        };

        # Do not run Selenium scripts as root
        users.users.selenium.isNormalUser = true;
      };
  };

  testScript =
    { nodes, ... }:
    ''
      server.start()

      with subtest("Pixelfed starts"):
        server.wait_for_unit("phpfpm-pixelfed.service")
        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 mastodon-garage.nix).
      # TODO: For instance: post a red picture and check that the green pixel IS NOT
      # there, then post a green picture and check that the green pixel IS there.

      with subtest("Post an picture in the browser"):
        server.succeed("su - selenium -c 'selenium-script-post-picture ${email} ${password}'")
        server.copy_from_vm("/home/selenium/screenshot.png", "")

      with subtest("Find picture in garage"):
        server.succeed("mc alias set garage ${nodes.server.fediversity.internal.garage.api.url} --api s3v4 --path off $AWS_ACCESS_KEY_ID $AWS_SECRET_ACCESS_KEY")
        picture = server.succeed("mc find garage --regex '\\.png' --ignore '*_thumb.png'")
        picture = picture.rstrip()
        if picture == "":
          raise Exception("Could not find any _thumb.png picture stored in Garage")
        server.succeed(f"mc cat {picture} > /picture.png")
        garage_hash = server.succeed("identify -quiet -format '%#' /picture.png")
        hash = server.succeed("identify -quiet -format '%#' ${testPicture}")
        if garage_hash != hash:
          raise Exception("The picture stored in Garage does not correspond to the original one.")
    '';
}