defmodule PhoenixKit.Modules.Emails.Web.Emails do
  @moduledoc """
  LiveView for displaying and managing emails in PhoenixKit admin panel.

  Provides comprehensive email interface with filtering, searching,
  and detailed analytics for sent emails.

  ## Features

  - **Real-time Log List**: Live updates of emails
  - **Advanced Filtering**: By status, date range, recipient, campaign, template
  - **Search Functionality**: Search across recipients, subjects, campaigns
  - **Pagination**: Handle large volumes of emails
  - **Export**: CSV export functionality
  - **Quick Actions**: Resend, view details, mark as reviewed
  - **Statistics Summary**: Key metrics at the top of the page

  ## Route

  This LiveView is mounted at `{prefix}/admin/emails` and requires
  appropriate admin permissions.

  Note: `{prefix}` is your configured PhoenixKit URL prefix (default: `/phoenix_kit`).

  The route is auto-generated by PhoenixKit from `admin_tabs/0` at compile time and
  injected into `live_session :phoenix_kit_admin`. Do not declare this route in your
  parent app's `router.ex`. See `phoenix_kit/guides/custom-admin-pages.md`.

  ## Permissions

  Access is restricted to users with admin or owner roles in PhoenixKit.
  """

  use PhoenixKitWeb, :live_view
  use Gettext, backend: PhoenixKit.Modules.Emails.Gettext
  import PhoenixKitWeb.Components.Core.Icon
  import PhoenixKitWeb.Components.Core.TableDefault
  import PhoenixKitWeb.Components.Core.DraggableList
  import PhoenixKitWeb.Components.Core.TableRowMenu
  import PhoenixKitWeb.Components.Core.EmailActivityBadges
  import PhoenixKitWeb.Components.Core.Pagination

  require Logger

  alias PhoenixKit.Modules.Emails
  alias PhoenixKit.Modules.Emails.BrevoOnDemandSync
  alias PhoenixKit.Modules.Emails.TableColumns
  alias PhoenixKit.Users.Auth.Scope
  alias PhoenixKit.Utils.Routes

  @default_per_page 25
  @max_per_page 100

  ## --- Lifecycle Callbacks ---

  @impl true
  def mount(_params, _session, socket) do
    # Check if email tracking is enabled
    if Emails.enabled?() do
      # Subscribe to live status updates so the list reflects status changes
      # (e.g. sent → delivered/bounced) without a manual page reload.
      if connected?(socket) do
        case PhoenixKit.Config.pubsub_server() do
          nil -> :ok
          server -> Phoenix.PubSub.subscribe(server, Emails.email_status_topic())
        end
      end

      # Get project title from settings

      # Load table columns configuration
      selected_columns = TableColumns.get_user_table_columns()
      available_columns = TableColumns.get_available_columns()

      socket =
        socket
        # New PhoenixKit header style: title/subtitle render in the admin shell
        # top bar (LayoutWrapper reads these assigns); the in-body
        # <.admin_page_header> was removed from emails.html.heex.
        |> assign(:page_title, gettext("Emails"))
        |> assign(:page_subtitle, gettext("Monitor and track all outgoing emails"))
        |> assign(:logs, [])
        |> assign(:total_count, 0)
        |> assign(:stats, %{})
        |> assign(:loading, true)
        |> assign(:show_test_email_modal, false)
        |> assign(:test_email_sending, false)
        |> assign(:test_email_form, %{recipient: "", errors: %{}})
        |> assign(:selected_columns, selected_columns)
        |> assign(:available_columns, available_columns)
        |> assign(:show_column_modal, false)
        |> assign(:temp_selected_columns, nil)
        |> assign(:sort_by, :sent_at)
        |> assign(:sort_dir, :desc)
        |> assign_filter_defaults()
        |> assign_pagination_defaults()

      {:ok, socket}
    else
      {:ok,
       socket
       |> put_flash(:error, gettext("Email management is not enabled"))
       |> push_navigate(to: Routes.path("/admin"))}
    end
  end

  @impl true
  def handle_params(params, _url, socket) do
    socket =
      socket
      |> apply_params(params)
      |> load_email_logs()
      |> load_stats()

    {:noreply, socket}
  end

  ## --- Event Handlers ---

  @impl true
  def handle_event("filter", params, socket) do
    # Handle both search and filter parameters
    combined_params = %{}

    # Extract search parameters
    combined_params =
      case Map.get(params, "search") do
        %{"query" => query} -> Map.put(combined_params, "search", String.trim(query || ""))
        _ -> combined_params
      end

    # Extract filter parameters
    combined_params =
      case Map.get(params, "filter") do
        filter_params when is_map(filter_params) -> Map.merge(combined_params, filter_params)
        _ -> combined_params
      end

    # Reset to first page when filtering
    combined_params = Map.put(combined_params, "page", "1")

    # Build new URL parameters
    new_params = build_url_params(socket.assigns, combined_params)

    {:noreply,
     socket
     |> push_patch(to: Routes.path("/admin/emails?#{new_params}"))}
  end

  @impl true
  def handle_event("clear_filters", _params, socket) do
    {:noreply,
     socket
     |> push_patch(to: Routes.path("/admin/emails"))}
  end

  @impl true
  def handle_event("clear_search", _params, socket) do
    # Clear only the search term (the × inside the search box); keep the other
    # filters and reset to page 1.
    new_params = build_url_params(socket.assigns, %{"search" => "", "page" => "1"})

    {:noreply, push_patch(socket, to: Routes.path("/admin/emails?#{new_params}"))}
  end

  @impl true
  def handle_event("set_filter", %{"field" => field, "value" => value}, socket) do
    # Dropdown filter selection (status/category/source_module): set the chosen
    # filter, reset to page 1, and patch. Empty value clears that filter.
    new_params = build_url_params(socket.assigns, %{field => value, "page" => "1"})

    {:noreply, push_patch(socket, to: Routes.path("/admin/emails?#{new_params}"))}
  end

  @impl true
  def handle_event("toggle_sort", %{"by" => by}, socket) do
    # Clicking a sortable column header: validate the field, then toggle the
    # direction if it's already the active sort, otherwise switch to that field
    # ascending. Resets to page 1 and patches.
    field = validate_sort_by(by)

    sort_dir =
      if field == socket.assigns.sort_by do
        if socket.assigns.sort_dir == :asc, do: :desc, else: :asc
      else
        :asc
      end

    new_params =
      build_url_params(socket.assigns, %{
        "sort_by" => to_string(field),
        "sort_dir" => to_string(sort_dir),
        "page" => "1"
      })

    {:noreply, push_patch(socket, to: Routes.path("/admin/emails?#{new_params}"))}
  end

  @impl true
  def handle_event("view_details", %{"uuid" => log_uuid}, socket) do
    {:noreply,
     socket
     |> push_navigate(to: Routes.path("/admin/emails/email/#{log_uuid}"))}
  end

  @impl true
  def handle_event("sync_log", %{"uuid" => uuid}, socket) do
    # Per-email status sync (mirrors details.ex "sync_status"): prefer the AWS
    # message ID, fall back to the internal message ID. On success we refresh
    # just the affected row in place via update_log_row/2.
    case Emails.get_log(uuid) do
      nil ->
        {:noreply, put_flash(socket, :error, gettext("Email not found"))}

      %{provider: "brevo_api"} = log ->
        sync_brevo_log(socket, log)

      log ->
        message_id = log.aws_message_id || log.message_id

        if is_nil(message_id) do
          {:noreply,
           put_flash(socket, :error, gettext("No message ID available to sync this email"))}
        else
          sync_email_status(socket, uuid, message_id)
        end
    end
  end

  @impl true
  def handle_event("refresh", _params, socket) do
    {:noreply,
     socket
     |> assign(:loading, true)
     |> load_email_logs()
     |> load_stats()}
  end

  @impl true
  def handle_event("show_test_email_modal", _params, socket) do
    {:noreply,
     socket
     |> assign(:show_test_email_modal, true)
     |> assign(:test_email_form, %{recipient: "", errors: %{}})}
  end

  @impl true
  def handle_event("hide_test_email_modal", _params, socket) do
    {:noreply,
     socket
     |> assign(:show_test_email_modal, false)
     |> assign(:test_email_sending, false)
     |> assign(:test_email_form, %{recipient: "", errors: %{}})}
  end

  @impl true
  def handle_event("validate_test_email", %{"test_email" => %{"recipient" => recipient}}, socket) do
    errors = validate_test_email_form(recipient)

    form = %{
      recipient: recipient,
      errors: errors
    }

    {:noreply, assign(socket, :test_email_form, form)}
  end

  @impl true
  def handle_event("send_test_email", %{"test_email" => %{"recipient" => recipient}}, socket) do
    errors = validate_test_email_form(recipient)

    if map_size(errors) == 0 do
      # Start sending process
      socket = assign(socket, :test_email_sending, true)

      # Attribute the test to the current admin (recorded on the email log so
      # Details shows the user + source module).
      user_uuid =
        case socket.assigns[:phoenix_kit_current_scope] do
          nil -> nil
          scope -> Scope.user_uuid(scope)
        end

      # Send the test email asynchronously
      send(self(), {:send_test_email, String.trim(recipient), user_uuid})

      {:noreply, socket}
    else
      # Show validation errors
      form = %{
        recipient: recipient,
        errors: errors
      }

      {:noreply, assign(socket, :test_email_form, form)}
    end
  end

  @impl true
  def handle_event("show_column_modal", _params, socket) do
    # Seed the temporary working copy from the live selection; all edits in the
    # modal mutate temp_selected_columns and only persist on Save.
    {:noreply,
     socket
     |> assign(:show_column_modal, true)
     |> assign(:temp_selected_columns, socket.assigns.selected_columns)}
  end

  @impl true
  def handle_event("hide_column_modal", _params, socket) do
    {:noreply,
     socket
     |> assign(:show_column_modal, false)
     |> assign(:temp_selected_columns, nil)}
  end

  @impl true
  def handle_event("update_table_columns", %{"column_order" => column_order}, socket) do
    # Persist the order coming from the hidden input. save_and_close_column_modal
    # drops any unknown ids and keeps "actions" last.
    columns = String.split(column_order, ",", trim: true)
    {:noreply, save_and_close_column_modal(socket, columns)}
  end

  @impl true
  def handle_event("update_table_columns", _params, socket) do
    # Fallback: submitted without an order (no reordering happened) — persist
    # whatever is currently in the working copy.
    columns = socket.assigns.temp_selected_columns || []
    {:noreply, save_and_close_column_modal(socket, columns)}
  end

  @impl true
  def handle_event("reorder_selected_columns", %{"ordered_ids" => ids}, socket) do
    # Draggable list emits the new order (minus "actions"); re-append it.
    {:noreply, assign(socket, :temp_selected_columns, ensure_actions_column(ids))}
  end

  @impl true
  def handle_event("reorder_selected_columns", _params, socket) do
    {:noreply, socket}
  end

  @impl true
  def handle_event("add_column", %{"column_id" => column_id}, socket) do
    temp = socket.assigns.temp_selected_columns || []
    known = known_column_fields(socket.assigns.available_columns)

    temp =
      if column_id in temp or column_id not in known do
        # Already present, or an unknown id from a crafted event — ignore.
        temp
      else
        # Insert before "actions" so it stays the last column.
        ensure_actions_column(Enum.reject(temp, &(&1 == "actions")) ++ [column_id])
      end

    {:noreply, assign(socket, :temp_selected_columns, temp)}
  end

  @impl true
  def handle_event("remove_column", %{"column_id" => column_id}, socket) do
    temp = socket.assigns.temp_selected_columns || []
    {:noreply, assign(socket, :temp_selected_columns, Enum.reject(temp, &(&1 == column_id)))}
  end

  @impl true
  def handle_event("reset_columns", _params, socket) do
    # Reset the working copy to defaults (not persisted until Save).
    {:noreply, assign(socket, :temp_selected_columns, TableColumns.reset_columns())}
  end

  ## --- Info Handlers ---

  @impl true
  def handle_info({:email_log_updated, %{uuid: uuid}}, socket) do
    # Only react when the changed log is on the current page. We then update
    # just that one row in place (single fetch by uuid) instead of re-running
    # the paginated list + count query for every event — during a delivery
    # burst that would be a query storm across all connected admins. We also
    # deliberately skip load_stats/0: the 30-day aggregate doesn't need to
    # recompute per status change.
    if Enum.any?(socket.assigns.logs, &(&1.uuid == uuid)) do
      {:noreply, update_log_row(socket, uuid)}
    else
      {:noreply, socket}
    end
  end

  def handle_info({:send_test_email, recipient, user_uuid}, socket) do
    provider =
      Application.get_env(:phoenix_kit, :email_provider, PhoenixKit.Modules.Emails.Provider)

    case provider.send_test_tracking_email(recipient, user_uuid) do
      {:ok, _email} ->
        Logger.info("Test email sent successfully", %{
          recipient: recipient,
          module: __MODULE__
        })

        {:noreply,
         socket
         |> assign(:test_email_sending, false)
         |> assign(:show_test_email_modal, false)
         |> put_flash(
           :info,
           gettext(
             "Test email sent successfully to %{recipient}! Check your emails to see the management data.",
             recipient: recipient
           )
         )
         |> load_email_logs()
         |> load_stats()}

      {:error, reason} ->
        Logger.error("Failed to send test email", %{
          recipient: recipient,
          reason: inspect(reason),
          module: __MODULE__
        })

        {:noreply,
         socket
         |> assign(:test_email_sending, false)
         |> put_flash(
           :error,
           gettext("Failed to send test email: %{reason}", reason: inspect(reason))
         )}
    end
  rescue
    error ->
      Logger.error("Exception while sending test email", %{
        recipient: recipient,
        error_message: Exception.message(error),
        error_type: error.__struct__,
        stacktrace: Exception.format_stacktrace(__STACKTRACE__),
        module: __MODULE__
      })

      {:noreply,
       socket
       |> assign(:test_email_sending, false)
       |> put_flash(
         :error,
         gettext("Error sending test email: %{message}", message: Exception.message(error))
       )}
  end

  ## --- Private Helper Functions ---

  # Apply default filter values
  defp assign_filter_defaults(socket) do
    filters = %{
      search: "",
      status: "",
      message_tag: "",
      campaign_id: "",
      category: "",
      source_module: "",
      from_date: "",
      to_date: ""
    }

    assign(socket, :filters, filters)
  end

  # Apply default pagination values
  defp assign_pagination_defaults(socket) do
    socket
    |> assign(:page, 1)
    |> assign(:per_page, @default_per_page)
    |> assign(:total_pages, 0)
  end

  # Apply URL parameters to socket assigns
  defp apply_params(socket, params) do
    filters = %{
      search: params["search"] || "",
      status: params["status"] || "",
      message_tag: params["message_tag"] || "",
      campaign_id: params["campaign_id"] || "",
      category: params["category"] || "",
      source_module: params["source_module"] || "",
      from_date: params["from_date"] || "",
      to_date: params["to_date"] || ""
    }

    page = String.to_integer(params["page"] || "1")
    per_page = min(String.to_integer(params["per_page"] || "#{@default_per_page}"), @max_per_page)

    sort_by = validate_sort_by(params["sort_by"])
    sort_dir = validate_sort_dir(params["sort_dir"])

    socket
    |> assign(:filters, filters)
    |> assign(:page, page)
    |> assign(:per_page, per_page)
    |> assign(:sort_by, sort_by)
    |> assign(:sort_dir, sort_dir)
  end

  # Load emails based on current filters and pagination
  defp load_email_logs(socket) do
    %{filters: filters, page: page, per_page: per_page} = socket.assigns

    # Build filters for EmailLog query, adding sort order (list only — the count
    # query below intentionally omits ordering).
    query_filters =
      build_query_filters(filters, page, per_page)
      |> Map.put(:order_by, socket.assigns.sort_by)
      |> Map.put(:order_dir, socket.assigns.sort_dir)

    logs = Emails.list_logs(query_filters)

    # Get total count for pagination (efficient count without loading all records)
    total_count =
      Emails.count_logs(build_query_filters(filters, 1, 1) |> Map.drop([:limit, :offset]))

    total_pages = ceil(total_count / per_page)

    socket
    |> assign(:logs, logs)
    |> assign(:total_count, total_count)
    |> assign(:total_pages, total_pages)
    |> assign(:loading, false)
  end

  # Replace a single displayed log row with its freshly-fetched version.
  # Avoids re-running the paginated list/count queries on PubSub status events.
  # If the log can no longer be loaded (e.g. deleted), the existing row is kept
  # until the next real navigation/refresh.
  defp update_log_row(socket, uuid) do
    case Emails.get_log(uuid) do
      nil ->
        socket

      log ->
        logs =
          Enum.map(socket.assigns.logs, fn
            %{uuid: ^uuid} -> log
            other -> other
          end)

        assign(socket, :logs, logs)
    end
  end

  # Defensive per-email status sync. Wraps Emails.sync_email_status/1 so an
  # unexpected raise surfaces as a flash instead of crashing the LiveView, and
  # refreshes just the affected row on success.
  defp sync_email_status(socket, uuid, message_id) do
    case Emails.sync_email_status(message_id) do
      {:ok, _result} ->
        socket
        |> update_log_row(uuid)
        |> put_flash(:info, gettext("Email status updated"))
        |> then(&{:noreply, &1})

      {:error, _reason} ->
        {:noreply, put_flash(socket, :error, gettext("Failed to update email status"))}
    end
  rescue
    error ->
      Logger.error("Exception while syncing email status", %{
        uuid: uuid,
        error_message: Exception.message(error),
        module: __MODULE__
      })

      {:noreply, put_flash(socket, :error, gettext("Failed to update email status"))}
  end

  # Brevo branch of "sync_log" — see BrevoOnDemandSync's moduledoc.
  defp sync_brevo_log(socket, log) do
    case BrevoOnDemandSync.sync(log) do
      {:ok, %{events_processed: 0}} ->
        {:noreply, put_flash(socket, :info, gettext("No new events"))}

      {:ok, %{events_processed: count}} ->
        {:noreply,
         socket
         |> update_log_row(log.uuid)
         |> put_flash(:info, gettext("Received %{count} new event(s)", count: count))}

      {:error, reason} ->
        {:noreply, put_flash(socket, :error, reason)}
    end
  end

  # Persist the working column set, refresh the live selection, and close. Drops
  # any id not present in @available_columns — so a crafted client event can't
  # persist an unknown column the table has no header for — and keeps "actions"
  # last. This is the single chokepoint every persist path funnels through.
  defp save_and_close_column_modal(socket, columns) do
    known = known_column_fields(socket.assigns.available_columns)

    columns =
      columns
      |> Enum.filter(&(&1 in known))
      |> ensure_actions_column()

    case TableColumns.update_user_table_columns(columns) do
      {:ok, _setting} ->
        socket
        |> assign(:selected_columns, TableColumns.get_user_table_columns())
        |> assign(:temp_selected_columns, nil)
        |> assign(:show_column_modal, false)
        |> put_flash(:info, gettext("Table columns updated successfully"))

      {:error, _reason} ->
        socket
        |> assign(:show_column_modal, false)
        |> put_flash(:error, gettext("Failed to update table columns"))
    end
  end

  # Ensure the always-present "actions" column sits at the end exactly once.
  defp ensure_actions_column(columns) do
    Enum.reject(columns, &(&1 == "actions")) ++ ["actions"]
  end

  # Field ids that actually exist in the available-columns metadata. Used to drop
  # unknown ids a crafted client event might submit before they are persisted.
  defp known_column_fields(available_columns) do
    Enum.map(available_columns, & &1.field)
  end

  # Look up a column's display label from @available_columns by its field key,
  # falling back to the raw id when unknown.
  defp column_label(available_columns, field) do
    case Enum.find(available_columns, fn col -> col.field == field end) do
      nil -> field
      col -> col.label
    end
  end

  # Load summary statistics
  defp load_stats(socket) do
    stats = Emails.get_system_stats(:last_30_days)

    assign(socket, :stats, stats)
  end

  # Build query filters from form filters
  defp build_query_filters(filters, page, per_page) do
    query_filters = %{
      limit: per_page,
      offset: (page - 1) * per_page
    }

    # Add non-empty filters
    query_filters =
      filters
      |> Enum.reduce(query_filters, fn
        {:search, search}, acc when search != "" ->
          # Search in recipient, subject, and campaign fields
          Map.put(acc, :search, search)

        {:status, status}, acc when status != "" ->
          Map.put(acc, :status, status)

        {:message_tag, message_tag}, acc when message_tag != "" ->
          Map.put(acc, :message_tag, message_tag)

        {:campaign_id, campaign_id}, acc when campaign_id != "" ->
          Map.put(acc, :campaign_id, campaign_id)

        {:category, category}, acc when category != "" ->
          Map.put(acc, :category, category)

        {:source_module, source_module}, acc when source_module != "" ->
          Map.put(acc, :source_module, source_module)

        {:from_date, from_date}, acc when from_date != "" ->
          case Date.from_iso8601(from_date) do
            {:ok, date} -> Map.put(acc, :from_date, DateTime.new!(date, ~T[00:00:00]))
            _ -> acc
          end

        {:to_date, to_date}, acc when to_date != "" ->
          case Date.from_iso8601(to_date) do
            {:ok, date} -> Map.put(acc, :to_date, DateTime.new!(date, ~T[23:59:59]))
            _ -> acc
          end

        _, acc ->
          acc
      end)

    query_filters
  end

  # Build URL parameters from current state
  defp build_url_params(assigns, additional_params) do
    base_params = %{
      "search" => assigns.filters.search,
      "status" => assigns.filters.status,
      "message_tag" => assigns.filters.message_tag,
      "campaign_id" => assigns.filters.campaign_id,
      "category" => assigns.filters.category,
      "source_module" => assigns.filters.source_module,
      "from_date" => assigns.filters.from_date,
      "to_date" => assigns.filters.to_date,
      "sort_by" => to_string(assigns.sort_by),
      "sort_dir" => to_string(assigns.sort_dir),
      "page" => assigns.page,
      "per_page" => assigns.per_page
    }

    Map.merge(base_params, additional_params)
    |> Enum.reject(fn {_key, value} -> value == "" or is_nil(value) end)
    |> Map.new()
    |> URI.encode_query()
  end

  # Build export URL with current filters
  defp build_export_url(filters) do
    # Convert filters to query parameters
    params =
      filters
      |> Enum.reject(fn {_key, value} -> value == "" or is_nil(value) end)
      |> Enum.into(%{})
      |> URI.encode_query()

    base_url = Routes.path("/admin/emails/export")

    if params != "" do
      "#{base_url}?#{params}"
    else
      base_url
    end
  end

  # Helper functions for template

  # Whitelist of fields that may be passed to Emails.list_logs/1 :order_by.
  # Anything outside this set falls back to the default sent_at.
  @sort_fields [:sent_at, :to, :subject, :status, :template_name]

  # Column "field" strings (as stored in selected_columns) whose table header
  # is rendered as a clickable <.sort_header_cell>. Maps the string column key
  # to its sort atom — guards String.to_existing_atom against unexpected input.
  @sortable_columns %{"to" => :to, "subject" => :subject, "status" => :status}

  defp sortable_column(field), do: Map.get(@sortable_columns, field)

  defp validate_sort_by(value) when is_atom(value) do
    if value in @sort_fields, do: value, else: :sent_at
  end

  defp validate_sort_by(value) when is_binary(value) do
    case Enum.find(@sort_fields, fn field -> Atom.to_string(field) == value end) do
      nil -> :sent_at
      field -> field
    end
  end

  defp validate_sort_by(_), do: :sent_at

  defp validate_sort_dir(:asc), do: :asc
  defp validate_sort_dir(:desc), do: :desc
  defp validate_sort_dir("asc"), do: :asc
  defp validate_sort_dir("desc"), do: :desc
  defp validate_sort_dir(_), do: :desc

  # Validate test email form
  defp validate_test_email_form(recipient) do
    errors = %{}

    # Validate recipient email
    errors =
      case String.trim(recipient || "") do
        "" ->
          Map.put(errors, :recipient, "Email address is required")

        email ->
          if Regex.match?(~r/^[^\s@]+@[^\s@]+\.[^\s@]+$/, email) do
            errors
          else
            Map.put(errors, :recipient, "Please enter a valid email address")
          end
      end

    errors
  end
end