defmodule MvWeb.ImportLive.Components do
  @moduledoc """
  Function components for the Import LiveView: import form, progress, results,
  custom fields notice, and template links. Keeps the main LiveView focused on
  mount/handle_event/handle_info and glue code.
  """
  use Phoenix.Component
  use Gettext, backend: MvWeb.Gettext

  import MvWeb.CoreComponents

  use Phoenix.VerifiedRoutes,
    endpoint: MvWeb.Endpoint,
    router: MvWeb.Router,
    statics: MvWeb.static_paths()

  @doc """
  Renders the info box explaining that data fields must exist before import
  and linking to Manage Member Data (custom fields).
  """
  def custom_fields_notice(assigns) do
    ~H"""
    <div role="note" class="alert alert-info mb-4 w-xl">
      <.icon name="hero-information-circle" class="size-5" aria-hidden="true" />
      <div>
        <p class="text-sm mb-2">
          {gettext(
            "Use the data field name as the CSV column header in your file. Data fields must exist in Mila before importing, because unknown data field columns will be ignored with a warning. Groups and membership fees are not supported for import."
          )}
        </p>
        <p class="text-sm">
          <.link
            href={~p"/settings#custom_fields"}
            class="link"
            data-testid="custom-fields-link"
          >
            {gettext("Manage Member Data")}
          </.link>
        </p>
      </div>
    </div>
    """
  end

  @doc """
  Renders download links for English and German CSV templates.
  """
  def template_links(assigns) do
    ~H"""
    <div class="mb-4">
      <p class="mb-2">
        {gettext("Download CSV templates:")}
      </p>
      <ul class="list-disc list-inside space-y-1">
        <li>
          <.link
            href={~p"/templates/member_import_en.csv"}
            download="member_import_en.csv"
            class="link link-primary"
          >
            {gettext("English Template")}
          </.link>
        </li>
        <li>
          <.link
            href={~p"/templates/member_import_de.csv"}
            download="member_import_de.csv"
            class="link link-primary"
          >
            {gettext("German Template")}
          </.link>
        </li>
      </ul>
    </div>
    """
  end

  @doc """
  Renders the CSV file upload form and Start Import button.
  """
  def import_form(assigns) do
    ~H"""
    <.form
      id="csv-upload-form"
      for={%{}}
      multipart={true}
      phx-change="validate_csv_upload"
      phx-submit="start_import"
      data-testid="csv-upload-form"
    >
      <fieldset class="mb-2 fieldset w-md">
        <label for="csv_file">
          <span class="mb-1 label">{gettext("CSV File")}</span>
        </label>
        <.live_file_input
          upload={@uploads.csv_file}
          id="csv_file"
          class="file-input file-input-bordered"
          aria-describedby="csv_file_help"
        />
        <p class="text-sm text-base-content/60 mt-2" id="csv_file_help">
          {gettext("CSV files only, maximum %{size} MB", size: @csv_import_max_file_size_mb)}
        </p>
      </fieldset>

      <.button
        type="submit"
        phx-disable-with={gettext("Starting import...")}
        variant="primary"
        disabled={import_button_disabled?(@import_status, @uploads.csv_file.entries)}
        data-testid="start-import-button"
      >
        {gettext("Start Import")}
      </.button>
    </.form>
    """
  end

  @doc """
  Renders import progress text and, when done or aborted, the import results section.
  """
  def import_progress(assigns) do
    ~H"""
    <%= if @import_progress do %>
      <div
        role="status"
        aria-live="polite"
        aria-atomic="true"
        class="mt-4"
        data-testid="import-progress-container"
      >
        <%= if @import_progress.status == :running do %>
          <p class="text-sm" data-testid="import-progress-text">
            {gettext("Processing chunk %{current} of %{total}...",
              current: @import_progress.current_chunk,
              total: @import_progress.total_chunks
            )}
          </p>
        <% end %>

        <%= if @import_progress.status == :done or @import_status == :error do %>
          <.import_results {assigns} />
        <% end %>
      </div>
    <% end %>
    """
  end

  @doc """
  Renders import results summary, error list, and warnings.
  Shown when import is done or aborted (:error); heading reflects state.
  """
  def import_results(assigns) do
    ~H"""
    <section
      class="space-y-4"
      data-testid="import-results-panel"
      aria-labelledby="import-results-heading"
    >
      <h2
        id="import-results-heading"
        class="text-lg font-semibold"
        data-testid="import-results-heading"
      >
        <%= if @import_status == :error do %>
          {gettext("Import aborted")}
        <% else %>
          {gettext("Import Results")}
        <% end %>
      </h2>

      <div class="space-y-4">
        <div data-testid="import-summary">
          <h3 class="text-sm font-semibold mb-2">
            {gettext("Summary")}
          </h3>
          <div class="text-sm space-y-2">
            <p>
              <.icon
                name="hero-check-circle"
                class="size-4 inline mr-1"
                aria-hidden="true"
              />
              {gettext("Successfully inserted: %{count} member(s)",
                count: @import_progress.inserted
              )}
            </p>
            <%= if @import_progress.failed > 0 do %>
              <p>
                <.icon
                  name="hero-exclamation-circle"
                  class="size-4 inline mr-1"
                  aria-hidden="true"
                />
                {gettext("Failed: %{count} row(s)", count: @import_progress.failed)}
              </p>
            <% end %>
            <%= if @import_progress.errors_truncated? do %>
              <p>
                <.icon
                  name="hero-information-circle"
                  class="size-4 inline mr-1"
                  aria-hidden="true"
                />
                {gettext("Error list truncated to %{count} entries", count: @max_errors)}
              </p>
            <% end %>
          </div>
        </div>

        <%= if length(@import_progress.errors) > 0 do %>
          <div
            role="alert"
            aria-live="assertive"
            aria-atomic="true"
            data-testid="import-error-list"
          >
            <h3 class="text-sm font-semibold mb-2">
              <.icon
                name="hero-exclamation-circle"
                class="size-4 inline mr-1"
                aria-hidden="true"
              />
              {gettext("Errors")}
            </h3>
            <ul class="list-disc list-inside space-y-1 text-sm">
              <%= for error <- @import_progress.errors do %>
                <li>
                  {gettext("Line %{line}: %{message}",
                    line: error.csv_line_number || "?",
                    message: error.message || gettext("Unknown error")
                  )}
                  <%= if error.field do %>
                    {gettext(" (Field: %{field})", field: error.field)}
                  <% end %>
                </li>
              <% end %>
            </ul>
          </div>
        <% end %>

        <%= if length(@import_progress.warnings) > 0 do %>
          <div class="alert alert-warning" role="alert" data-testid="import-warnings">
            <.icon name="hero-information-circle" class="size-5" aria-hidden="true" />
            <div>
              <h3 class="font-semibold mb-2">
                {gettext("Warnings")}
              </h3>
              <ul class="list-disc list-inside space-y-1 text-sm">
                <%= for warning <- @import_progress.warnings do %>
                  <li>{warning}</li>
                <% end %>
              </ul>
            </div>
          </div>
        <% end %>
      </div>
    </section>
    """
  end

  @doc """
  Returns whether the Start Import button should be disabled.
  """
  @spec import_button_disabled?(:idle | :running | :done | :error, [map()]) :: boolean()
  def import_button_disabled?(:running, _entries), do: true
  def import_button_disabled?(_status, []), do: true
  def import_button_disabled?(_status, [entry | _]) when not entry.done?, do: true
  def import_button_disabled?(_status, _entries), do: false
end