defmodule PhoenixKit.Modules.Publishing.Workers.TranslatePostWorker do
  @moduledoc """
  Oban worker for translating publishing posts to multiple languages using AI.

  This worker translates the primary language version of a post to all enabled
  languages (or a specified subset). Each language translation is processed
  sequentially to avoid overwhelming the AI endpoint.

  ## Usage

      # Translate to all enabled languages
      PhoenixKit.Modules.Publishing.translate_post_to_all_languages(
        "docs",
        "019cce93-ed2e-7e1b-...",
        endpoint_uuid: "endpoint-uuid"
      )

      # Or enqueue directly
      %{
        "group_slug" => "docs",
        "post_uuid" => "019cce93-ed2e-7e1b-...",
        "endpoint_uuid" => "endpoint-uuid"
      }
      |> TranslatePostWorker.new()
      |> Oban.insert()

  ## Job Arguments

  - `group_slug` - The publishing group slug
  - `post_uuid` - The post UUID
  - `endpoint_uuid` - AI endpoint UUID to use for translation
  - `source_language` - Source language to translate from (optional, defaults to primary language)
  - `target_languages` - List of target languages (optional, defaults to all enabled except source)
  - `version` - Version number to translate (optional, defaults to latest/published)
  - `user_uuid` - User UUID for audit trail (optional)

  ## Configuration

  Set the default AI endpoint for translations in Settings:

      PhoenixKit.Settings.update_setting("publishing_translation_endpoint_uuid", "1")

  """

  use Oban.Worker,
    queue: :default,
    max_attempts: 3,
    unique: [
      keys: [:group_slug, :post_uuid],
      states: [:available, :scheduled, :executing, :retryable]
    ]

  # Suppress dialyzer warnings for pattern matches where dialyzer incorrectly infers
  # that {:ok, _} patterns can never match. The Publishing context functions do return
  # {:ok, _} on success. This cascades to all downstream helper functions.
  @dialyzer {:nowarn_function, do_translate: 8}
  @dialyzer {:nowarn_function, translate_to_languages: 6}
  @dialyzer {:nowarn_function, translate_single_language: 6}
  @dialyzer {:nowarn_function, save_translation: 1}
  @dialyzer {:nowarn_function, check_translation_exists: 3}
  @dialyzer {:nowarn_function, update_translation: 3}
  @dialyzer {:nowarn_function, create_translation: 1}
  @dialyzer {:nowarn_function, extract_title: 1}
  @dialyzer {:nowarn_function, parse_translated_response: 1}
  @dialyzer {:nowarn_function, sanitize_slug: 1}
  @dialyzer {:nowarn_function, parse_markdown_response: 1}
  @dialyzer {:nowarn_function, build_scope: 1}

  require Logger

  alias PhoenixKit.Modules.AI
  alias PhoenixKit.Modules.Publishing
  alias PhoenixKit.Modules.Publishing.LanguageHelpers
  alias PhoenixKit.Modules.Publishing.PubSub, as: PublishingPubSub
  alias PhoenixKit.Settings
  alias PhoenixKit.Users.Auth
  alias PhoenixKit.Users.Auth.Scope

  @impl Oban.Worker
  def perform(%Oban.Job{args: args}) do
    group_slug = Map.fetch!(args, "group_slug")
    post_uuid = Map.fetch!(args, "post_uuid")
    version = Map.get(args, "version")

    endpoint_uuid = Map.get(args, "endpoint_uuid") || get_default_endpoint_uuid()
    prompt_uuid = Map.get(args, "prompt_uuid")

    # Use post's stored primary language as default source, not global
    source_language =
      Map.get(args, "source_language") ||
        Publishing.get_post_primary_language(group_slug, post_uuid, version)

    target_languages = Map.get(args, "target_languages") || get_target_languages(source_language)
    user_uuid = Map.get(args, "user_uuid")

    Logger.info(
      "[TranslatePostWorker] Starting translation of #{group_slug}/#{post_uuid} " <>
        "from #{source_language} to #{length(target_languages)} languages " <>
        "(version: #{inspect(version)}, endpoint: #{inspect(endpoint_uuid)}, prompt: #{inspect(prompt_uuid)})"
    )

    # Validate AI module is enabled and prompt is provided
    cond do
      not AI.enabled?() ->
        Logger.error("[TranslatePostWorker] AI module is not enabled")
        {:error, "AI module is not enabled"}

      is_nil(prompt_uuid) ->
        Logger.error("[TranslatePostWorker] No prompt_uuid provided")
        {:error, "No prompt selected"}

      true ->
        # Validate endpoint exists and is enabled
        do_translate(
          group_slug,
          post_uuid,
          endpoint_uuid,
          source_language,
          target_languages,
          version,
          user_uuid,
          prompt_uuid
        )
    end
  end

  defp do_translate(
         group_slug,
         post_uuid,
         endpoint_uuid,
         source_language,
         target_languages,
         version,
         user_uuid,
         prompt_uuid
       ) do
    case AI.get_endpoint(endpoint_uuid) do
      nil ->
        Logger.error("[TranslatePostWorker] AI endpoint #{endpoint_uuid} not found")
        {:error, "AI endpoint not found"}

      %{enabled: false} ->
        Logger.error("[TranslatePostWorker] AI endpoint #{endpoint_uuid} is disabled")
        {:error, "AI endpoint is disabled"}

      endpoint ->
        # Read the source post by UUID
        case Publishing.read_post_by_uuid(post_uuid, source_language, version) do
          {:ok, source_post} ->
            translate_to_languages(
              source_post,
              target_languages,
              endpoint,
              source_language,
              user_uuid,
              prompt_uuid
            )

          {:error, reason} ->
            Logger.error(
              "[TranslatePostWorker] Failed to read source post: #{inspect(reason)}. " <>
                "Details: group=#{group_slug}, post_uuid=#{post_uuid}, " <>
                "language=#{source_language}, version=#{inspect(version)}"
            )

            {:error,
             "Failed to read source post (#{group_slug}/#{post_uuid}/#{source_language}): #{inspect(reason)}"}
        end
    end
  end

  @impl Oban.Worker
  def timeout(_job), do: :timer.minutes(10)

  # Translate to all target languages sequentially
  defp translate_to_languages(
         source_post,
         target_languages,
         endpoint,
         source_language,
         user_uuid,
         prompt_uuid
       ) do
    group_slug = source_post.group
    total = length(target_languages)
    broadcast_id = source_post.slug || source_post[:uuid]

    # Broadcast that translation has started
    PublishingPubSub.broadcast_translation_started(group_slug, broadcast_id, target_languages)

    results =
      target_languages
      |> Enum.with_index(1)
      |> Enum.map(fn {target_language, index} ->
        result =
          case translate_single_language(
                 source_post,
                 target_language,
                 endpoint,
                 source_language,
                 user_uuid,
                 prompt_uuid
               ) do
            :ok ->
              Logger.info("[TranslatePostWorker] Successfully translated to #{target_language}")
              {:ok, target_language}

            {:error, reason} ->
              Logger.warning(
                "[TranslatePostWorker] Failed to translate to #{target_language}: #{inspect(reason)}"
              )

              {:error, target_language, reason}
          end

        # Broadcast progress after each language completes
        PublishingPubSub.broadcast_translation_progress(
          group_slug,
          broadcast_id,
          index,
          total,
          target_language
        )

        result
      end)

    # Count successes and failures
    {successes, failures} =
      Enum.split_with(results, fn
        {:ok, _} -> true
        _ -> false
      end)

    success_count = length(successes)
    failure_count = length(failures)

    # Broadcast completion
    PublishingPubSub.broadcast_translation_completed(group_slug, broadcast_id, %{
      succeeded: Enum.map(successes, fn {:ok, lang} -> lang end),
      failed: Enum.map(failures, fn {:error, lang, _} -> lang end),
      success_count: success_count,
      failure_count: failure_count
    })

    Logger.info(
      "[TranslatePostWorker] Completed: #{success_count} succeeded, #{failure_count} failed"
    )

    if failure_count > 0 do
      failed_langs = Enum.map(failures, fn {:error, lang, _} -> lang end)

      {:error,
       "Translation failed for #{failure_count} languages: #{Enum.join(failed_langs, ", ")}"}
    else
      :ok
    end
  end

  # Translate a single language
  defp translate_single_language(
         source_post,
         target_language,
         endpoint,
         source_language,
         user_uuid,
         prompt_uuid
       ) do
    group_slug = source_post.group
    post_uuid = source_post.uuid
    version = source_post.version

    # Get language names for the prompt
    source_lang_info = LanguageHelpers.get_language_info(source_language)
    target_lang_info = LanguageHelpers.get_language_info(target_language)

    source_lang_name = if source_lang_info, do: source_lang_info.name, else: source_language
    target_lang_name = if target_lang_info, do: target_lang_info.name, else: target_language

    Logger.info(
      "[TranslatePostWorker] Translating to #{target_language} (#{target_lang_name})..."
    )

    # Extract title and content from source post
    source_title = extract_title(source_post)
    source_content = source_post.content || ""

    # Call AI for translation using the prompt template
    Logger.debug(
      "[TranslatePostWorker] Calling AI endpoint #{endpoint.uuid} with prompt #{prompt_uuid} for #{target_language}..."
    )

    start_time = System.monotonic_time(:millisecond)

    variables = %{
      "SourceLanguage" => source_lang_name,
      "TargetLanguage" => target_lang_name,
      "Title" => source_title,
      "Content" => source_content
    }

    result =
      AI.ask_with_prompt(endpoint.uuid, prompt_uuid, variables,
        source: "Publishing.TranslatePostWorker"
      )

    elapsed = System.monotonic_time(:millisecond) - start_time
    Logger.info("[TranslatePostWorker] AI call for #{target_language} completed in #{elapsed}ms")

    case result do
      {:ok, response} ->
        case AI.extract_content(response) do
          {:ok, translated_text} ->
            # Parse the translated title, slug, and content
            {translated_title, translated_slug, translated_content} =
              parse_translated_response(translated_text)

            if translated_slug do
              Logger.info(
                "[TranslatePostWorker] Got translated slug for #{target_language}: #{translated_slug}"
              )
            end

            # Get source post status to inherit for new translation
            source_status = Map.get(source_post.metadata, :status, "draft")

            # Create or update the translation
            translation_opts = %{
              group_slug: group_slug,
              post_uuid: post_uuid,
              language: target_language,
              title: translated_title,
              url_slug: translated_slug,
              content: translated_content,
              version: version,
              user_uuid: user_uuid,
              source_status: source_status
            }

            save_translation(translation_opts)

          {:error, reason} ->
            {:error, "Failed to extract AI response: #{inspect(reason)}"}
        end

      {:error, reason} ->
        {:error, "AI request failed: #{inspect(reason)}"}
    end
  end

  # Extract title from post (first # heading or metadata title)
  defp extract_title(post) do
    content = post.content || ""

    case Regex.run(~r/^#\s+(.+)$/m, content) do
      [_, title] -> String.trim(title)
      nil -> Map.get(post.metadata || %{}, :title, "Untitled")
    end
  end

  # Parse the translated response to extract title, slug, and content
  # Returns {title, slug, content} tuple
  defp parse_translated_response(response) do
    # Try to parse the structured format with slug
    case Regex.run(
           ~r/---TITLE---\s*\n(.+?)\n---SLUG---\s*\n(.+?)\n---CONTENT---\s*\n(.+)/s,
           response
         ) do
      [_, title, slug, content] ->
        # Found full structured format with slug
        {String.trim(title), sanitize_slug(slug), String.trim(content)}

      nil ->
        # Try format without slug
        case Regex.run(~r/---TITLE---\s*\n(.+?)\n---CONTENT---\s*\n(.+)/s, response) do
          [_, title, content] ->
            {String.trim(title), nil, String.trim(content)}

          nil ->
            # No structured format found - try to extract from markdown
            {title, content} = parse_markdown_response(response)
            {title, nil, content}
        end
    end
  end

  # Sanitize and validate the translated slug
  defp sanitize_slug(slug) do
    sanitized =
      slug
      |> String.trim()
      |> String.downcase()
      # Replace invalid chars with hyphens
      |> String.replace(~r/[^a-z0-9-]/, "-")
      # Collapse multiple hyphens
      |> String.replace(~r/-+/, "-")
      # Remove leading/trailing hyphens
      |> String.replace(~r/^-|-$/, "")

    if sanitized == "" or String.length(sanitized) < 2 do
      # Invalid slug, don't use it
      nil
    else
      sanitized
    end
  end

  # Parse a response that's just markdown (no markers)
  defp parse_markdown_response(response) do
    # Clean up the response - remove any stray marker text that might have been partially output
    cleaned =
      response
      |> String.replace(~r/---TITLE---.*$/s, "")
      |> String.replace(~r/---SLUG---.*$/s, "")
      |> String.replace(~r/---CONTENT---.*$/s, "")
      |> String.trim()

    # Try to find a markdown heading as the title
    case Regex.run(~r/^#\s+(.+)$/m, cleaned) do
      [full_heading, title] ->
        # Remove the heading from content since we'll add it back
        content = String.replace(cleaned, full_heading, "", global: false) |> String.trim()
        {String.trim(title), content}

      nil ->
        # No heading found - treat first line as title
        case String.split(cleaned, "\n", parts: 2) do
          [first_line, rest] ->
            {String.trim(first_line), String.trim(rest)}

          [only_line] ->
            {String.trim(only_line), ""}
        end
    end
  end

  # Save the translation (create or update)
  # Accepts a map with: group_slug, post_uuid, language, title, url_slug, content,
  # version, user_uuid, source_status
  defp save_translation(opts) do
    %{
      group_slug: group_slug,
      post_uuid: post_uuid,
      language: language,
      version: version
    } = opts

    Logger.info("[TranslatePostWorker] Saving translation for #{language}...")

    # Check if translation already exists for this exact language
    # We need to check directly because read_post has fallback behavior
    # that returns a different language if the requested one doesn't exist
    case check_translation_exists(post_uuid, language, version) do
      {:ok, existing_post} ->
        # Update existing translation - verify it's actually the right language
        if existing_post.language == language do
          Logger.info("[TranslatePostWorker] Updating existing #{language} translation")
          # Don't override status - translations inherit status from primary via propagation
          update_translation(group_slug, existing_post, opts)
        else
          # Fallback returned wrong language, create new translation instead
          Logger.info(
            "[TranslatePostWorker] Creating new #{language} translation (fallback detected)"
          )

          create_translation(opts)
        end

      {:error, _} ->
        # Create new translation
        Logger.info("[TranslatePostWorker] Creating new #{language} translation")

        create_translation(opts)
    end
  end

  # Check if a translation exists for the exact language (no fallback)
  defp check_translation_exists(post_uuid, language, version) do
    # Try to read the post and verify the language matches
    case Publishing.read_post_by_uuid(post_uuid, language, version) do
      {:ok, post} ->
        # Verify the returned post is actually for the requested language
        # AND that it's not a "new translation" stub (is_new_translation means no record
        # exists and read_post returned a fallback with empty content)
        is_new_translation = Map.get(post, :is_new_translation, false)

        if post.language == language && !is_new_translation do
          {:ok, post}
        else
          {:error, :not_found}
        end

      error ->
        error
    end
  end

  defp update_translation(group_slug, existing_post, opts) do
    %{title: title, url_slug: url_slug, content: content, user_uuid: user_uuid} = opts

    params = %{
      "title" => title,
      "content" => content
    }

    # Add url_slug if provided
    params = if url_slug, do: Map.put(params, "url_slug", url_slug), else: params

    # Mark as non-primary language for consistency (translations shouldn't trigger propagation)
    update_opts = %{scope: build_scope(user_uuid), is_primary_language: false}

    case Publishing.update_post(group_slug, existing_post, params, update_opts) do
      {:ok, _} -> :ok
      {:error, reason} -> {:error, reason}
    end
  end

  defp create_translation(opts) do
    language = opts.language

    Logger.debug("[TranslatePostWorker] Calling add_language_to_post for #{language}...")

    try do
      do_create_translation(opts)
    rescue
      e ->
        Logger.error(
          "[TranslatePostWorker] Exception in create_translation for #{language}: #{inspect(e)}\n#{Exception.format_stacktrace(__STACKTRACE__)}"
        )

        {:error, {:exception, e}}
    end
  end

  defp do_create_translation(opts) do
    %{
      group_slug: group_slug,
      post_uuid: post_uuid,
      language: language,
      version: version
    } = opts

    case Publishing.add_language_to_post(group_slug, post_uuid, language, version) do
      {:ok, new_post} ->
        Logger.debug("[TranslatePostWorker] add_language_to_post succeeded for #{language}")
        update_translation_post(new_post, opts)

      {:error, :already_exists} ->
        handle_existing_translation(opts)

      {:error, reason} ->
        Logger.error(
          "[TranslatePostWorker] Failed to create #{language} translation: #{inspect(reason)}"
        )

        {:error, reason}
    end
  end

  defp update_translation_post(post, opts) do
    %{
      group_slug: group_slug,
      language: language,
      title: title,
      url_slug: url_slug,
      content: content,
      user_uuid: user_uuid,
      source_status: source_status
    } = opts

    params = build_translation_params(title, content, url_slug, source_status)
    update_opts = %{scope: build_scope(user_uuid), is_primary_language: false}

    Logger.debug("[TranslatePostWorker] Calling update_post for #{language}...")

    case Publishing.update_post(group_slug, post, params, update_opts) do
      {:ok, _} ->
        Logger.info(
          "[TranslatePostWorker] Successfully saved #{language} translation with slug: #{url_slug || "(default)"}, status: #{source_status}"
        )

        :ok

      {:error, reason} ->
        Logger.error(
          "[TranslatePostWorker] Failed to update #{language} translation: #{inspect(reason)}"
        )

        {:error, reason}
    end
  end

  defp handle_existing_translation(opts) do
    %{
      post_uuid: post_uuid,
      language: language,
      version: version
    } = opts

    Logger.info("[TranslatePostWorker] Translation already exists for #{language}, updating...")

    case Publishing.read_post_by_uuid(post_uuid, language, version) do
      {:ok, existing_post} ->
        update_translation_post(existing_post, opts)

      {:error, reason} ->
        Logger.error(
          "[TranslatePostWorker] Failed to read existing #{language} translation: #{inspect(reason)}"
        )

        {:error, reason}
    end
  end

  defp build_translation_params(title, content, url_slug, source_status) do
    params = %{
      "title" => title,
      "content" => content,
      "status" => source_status
    }

    if url_slug, do: Map.put(params, "url_slug", url_slug), else: params
  end

  # Build scope for audit trail
  defp build_scope(nil), do: nil

  defp build_scope(user_uuid) do
    case Auth.get_user(user_uuid) do
      nil -> nil
      user -> Scope.for_user(user)
    end
  end

  # Get target languages (all enabled except source)
  defp get_target_languages(source_language) do
    LanguageHelpers.enabled_language_codes()
    |> Enum.reject(&(&1 == source_language))
  end

  # Get default endpoint ID from settings
  defp get_default_endpoint_uuid do
    case Settings.get_setting("publishing_translation_endpoint_uuid") do
      nil -> nil
      "" -> nil
      id -> id
    end
  end

  @doc """
  Creates a new translation job for a post.

  ## Options

  - `:endpoint_uuid` - AI endpoint UUID (required if not set in settings)
  - `:source_language` - Source language (defaults to primary language)
  - `:target_languages` - List of target languages (defaults to all enabled except source)
  - `:version` - Version to translate (defaults to latest)
  - `:user_uuid` - User UUID for audit trail

  ## Examples

      TranslatePostWorker.create_job("docs", "019cce93-...", endpoint_uuid: "endpoint-uuid")
      TranslatePostWorker.create_job("docs", "019cce93-...",
        endpoint_uuid: "endpoint-uuid",
        target_languages: ["es", "fr"]
      )

  """
  def create_job(group_slug, post_uuid, opts \\ []) do
    user_uuid = Keyword.get(opts, :user_uuid)

    args =
      %{
        "group_slug" => group_slug,
        "post_uuid" => post_uuid
      }
      |> maybe_put("endpoint_uuid", Keyword.get(opts, :endpoint_uuid))
      |> maybe_put("prompt_uuid", Keyword.get(opts, :prompt_uuid))
      |> maybe_put("source_language", Keyword.get(opts, :source_language))
      |> maybe_put("target_languages", Keyword.get(opts, :target_languages))
      |> maybe_put("version", Keyword.get(opts, :version))
      |> maybe_put("user_uuid", user_uuid)

    new(args)
  end

  defp maybe_put(map, _key, nil), do: map
  defp maybe_put(map, key, value), do: Map.put(map, key, value)

  @doc """
  Enqueues a translation job for a post.

  See `create_job/3` for options.

  ## Examples

      {:ok, job} = TranslatePostWorker.enqueue("docs", "019cce93-...", endpoint_uuid: "endpoint-uuid")

  """
  def enqueue(group_slug, post_uuid, opts \\ []) do
    group_slug
    |> create_job(post_uuid, opts)
    |> Oban.insert()
  end

  @doc """
  Checks if there's an active translation job for the given post.
  Returns the job if found, nil otherwise.
  """
  def active_job(post_uuid) do
    import Ecto.Query

    PhoenixKit.RepoHelper.repo().one(
      from(j in Oban.Job,
        where: j.worker == ^to_string(__MODULE__),
        where: j.state in ["available", "scheduled", "executing", "retryable"],
        where: fragment("?->>'post_uuid' = ?", j.args, ^post_uuid),
        order_by: [desc: j.inserted_at],
        limit: 1
      )
    )
  end

  @doc """
  Translates content and returns the result without saving.

  Use this when you want to display the translation in the UI first,
  allowing the user to review/edit before saving.

  ## Parameters

  - `group_slug` - The publishing group slug
  - `post_uuid` - The post UUID
  - `target_language` - The target language code (e.g., "es")
  - `opts` - Options:
    - `:endpoint_uuid` - AI endpoint UUID to use (required)
    - `:source_language` - Source language code (defaults to post's primary language)
    - `:version` - Version to translate (defaults to latest)

  ## Returns

  - `{:ok, %{title: title, url_slug: slug, content: content}}` on success
  - `{:error, reason}` on failure

  ## Example

      {:ok, result} = TranslatePostWorker.translate_content("docs", "019cce93-...", "es", endpoint_uuid: "endpoint-uuid")
      # => {:ok, %{title: "Primeros Pasos", url_slug: "primeros-pasos", content: "..."}}

  """
  def translate_content(group_slug, post_uuid, target_language, opts \\ []) do
    endpoint_uuid = Keyword.get(opts, :endpoint_uuid) || get_default_endpoint_uuid()
    prompt_uuid = Keyword.get(opts, :prompt_uuid)
    version = Keyword.get(opts, :version)

    source_language =
      Keyword.get(opts, :source_language) ||
        Publishing.get_post_primary_language(group_slug, post_uuid, version)

    cond do
      not AI.enabled?() ->
        {:error, "AI module is not enabled"}

      is_nil(prompt_uuid) ->
        {:error, "No prompt selected"}

      true ->
        case AI.get_endpoint(endpoint_uuid) do
          nil ->
            {:error, "AI endpoint not found: #{endpoint_uuid}"}

          %{enabled: false} ->
            {:error, "AI endpoint is disabled"}

          endpoint ->
            case Publishing.read_post_by_uuid(post_uuid, source_language, version) do
              {:ok, source_post} ->
                do_translate_content(
                  source_post,
                  target_language,
                  endpoint,
                  source_language,
                  prompt_uuid
                )

              {:error, reason} ->
                {:error, "Failed to read source post: #{inspect(reason)}"}
            end
        end
    end
  end

  defp do_translate_content(source_post, target_language, endpoint, source_language, prompt_uuid) do
    source_lang_info = LanguageHelpers.get_language_info(source_language)
    target_lang_info = LanguageHelpers.get_language_info(target_language)

    source_lang_name = if source_lang_info, do: source_lang_info.name, else: source_language
    target_lang_name = if target_lang_info, do: target_lang_info.name, else: target_language

    source_title = extract_title(source_post)
    source_content = source_post.content || ""

    variables = %{
      "SourceLanguage" => source_lang_name,
      "TargetLanguage" => target_lang_name,
      "Title" => source_title,
      "Content" => source_content
    }

    case AI.ask_with_prompt(endpoint.uuid, prompt_uuid, variables,
           source: "Publishing.TranslatePostWorker"
         ) do
      {:ok, response} ->
        case AI.extract_content(response) do
          {:ok, translated_text} ->
            {title, url_slug, content} = parse_translated_response(translated_text)
            {:ok, %{title: title, url_slug: url_slug, content: content}}

          {:error, reason} ->
            {:error, "Failed to extract AI response: #{inspect(reason)}"}
        end

      {:error, reason} ->
        {:error, "AI request failed: #{inspect(reason)}"}
    end
  end

  @doc """
  Translates a post to a single language synchronously (without queuing).

  Use this for immediate translation of a single language, e.g., when the user
  clicks "Translate to This Language" while viewing a non-primary language.

  ## Parameters

  - `group_slug` - The publishing group slug
  - `post_uuid` - The post UUID
  - `target_language` - The target language code (e.g., "es")
  - `opts` - Options:
    - `:endpoint_uuid` - AI endpoint UUID to use (required)
    - `:source_language` - Source language code (defaults to post's primary language)
    - `:version` - Version to translate (defaults to latest)
    - `:user_uuid` - User UUID for audit trail

  ## Returns

  - `:ok` on success
  - `{:error, reason}` on failure

  ## Example

      :ok = TranslatePostWorker.translate_now("docs", "019cce93-...", "es", endpoint_uuid: "endpoint-uuid")

  """
  def translate_now(group_slug, post_uuid, target_language, opts \\ []) do
    endpoint_uuid = Keyword.get(opts, :endpoint_uuid) || get_default_endpoint_uuid()
    prompt_uuid = Keyword.get(opts, :prompt_uuid)
    version = Keyword.get(opts, :version)
    user_uuid = Keyword.get(opts, :user_uuid)

    source_language =
      Keyword.get(opts, :source_language) ||
        Publishing.get_post_primary_language(group_slug, post_uuid, version)

    cond do
      not AI.enabled?() ->
        {:error, "AI module is not enabled"}

      is_nil(prompt_uuid) ->
        {:error, "No prompt selected"}

      true ->
        case AI.get_endpoint(endpoint_uuid) do
          nil ->
            {:error, "AI endpoint not found: #{endpoint_uuid}"}

          %{enabled: false} ->
            {:error, "AI endpoint is disabled"}

          endpoint ->
            case Publishing.read_post_by_uuid(post_uuid, source_language, version) do
              {:ok, source_post} ->
                translate_single_language(
                  source_post,
                  target_language,
                  endpoint,
                  source_language,
                  user_uuid,
                  prompt_uuid
                )

              {:error, reason} ->
                {:error, "Failed to read source post: #{inspect(reason)}"}
            end
        end
    end
  end
end