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."
          )}
        </p>
        <p class="text-sm mb-2">
          {gettext(
            "Groups column (recognized headers): Groups, Gruppen, Gruppe. Comma-separated group names are supported and missing groups are created automatically."
          )}
        </p>
        <p class="text-sm mb-2">
          {gettext(
            "Fee type column (recognized headers): Fee Type, fee type, fee_type, membership_fee_type, Beitragsart. Unknown fee types fall back to the default."
          )}
        </p>
        <p class="text-sm">
          {gettext(
            "Fee status columns (Membership Fee Status, Bezahlstatus, Mitgliedsbeitragsstatus) are always ignored and cannot be imported."
          )}
        </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"/admin/import/template/en"} class="link link-primary">
            {gettext("English Template")}
          </.link>
        </li>
        <li>
          <.link href={~p"/admin/import/template/de"} 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" aria-labelledby="csv_file_label">
        <label id="csv_file_label" for="csv_file" class="label block">
          <span class="mb-1 label text-base-content">{gettext("CSV File")}</span>
          <.live_file_input
            upload={@uploads.csv_file}
            id="csv_file"
            class="file-input file-input-bordered block"
            aria-describedby="csv_file_help"
            aria-label={gettext("CSV File")}
          />
        </label>
        <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 the mapping preview shown between upload and processing.

  Shows the column-to-role mapping, up to 3 sample rows, and notices for
  auto-created groups, unresolved fee types, empty fee-type cells, and unknown
  columns. Nothing is written until the user confirms.
  """
  def preview(assigns) do
    state = assigns.import_state
    column_roles = column_roles(state)
    column_samples = column_samples(state.preview_rows, length(state.headers))

    assigns =
      assigns
      |> assign(:column_roles, column_roles)
      |> assign(:column_samples, column_samples)

    ~H"""
    <section
      class="mt-4 space-y-4"
      data-testid="import-preview"
      aria-labelledby="import-preview-heading"
    >
      <h2 id="import-preview-heading" class="text-lg font-semibold">
        {gettext("Preview import")}
      </h2>

      <div class="overflow-x-auto">
        <table class="table table-sm w-full" data-testid="preview-mapping-table">
          <thead>
            <tr>
              <th>{gettext("Role")}</th>
              <th>{gettext("Column")}</th>
              <th class="text-base-content/60">{gettext("Row 1")}</th>
              <th class="text-base-content/60">{gettext("Row 2")}</th>
              <th class="text-base-content/60">{gettext("Row 3")}</th>
            </tr>
          </thead>
          <tbody>
            <%= for {{header, role}, samples} <- Enum.zip(@column_roles, @column_samples) do %>
              <tr class={role_row_class(role)} data-testid="preview-column-row">
                <td>
                  <span class={"badge badge-sm #{role_badge_class(role)}"}>
                    {role_label(role)}
                  </span>
                </td>
                <td class="font-medium">{header}</td>
                <%= for sample <- samples do %>
                  <td class="text-base-content/70 max-w-32 truncate">{sample}</td>
                <% end %>
              </tr>
            <% end %>
          </tbody>
        </table>
      </div>

      <%= if @import_state.groups_to_create != [] do %>
        <div class="alert alert-info" role="note" data-testid="preview-groups-notice">
          <.icon name="hero-information-circle" class="size-5" aria-hidden="true" />
          <div>
            <p class="text-sm">
              {gettext("These groups will be created automatically: %{names}",
                names: Enum.join(@import_state.groups_to_create, ", ")
              )}
            </p>
          </div>
        </div>
      <% end %>

      <%= if @import_state.fee_type_warnings != [] do %>
        <div class="alert alert-warning" role="alert" data-testid="preview-fee-type-warning">
          <.icon name="hero-exclamation-circle" class="size-5" aria-hidden="true" />
          <div>
            <p class="text-sm">
              {gettext("Unknown fee types (members get the default): %{names}",
                names: Enum.join(@import_state.fee_type_warnings, ", ")
              )}
            </p>
            <.link
              navigate={~p"/membership_fee_settings/new_fee_type"}
              class="link link-primary text-sm"
            >
              {gettext("Create fee type")}
            </.link>
          </div>
        </div>
      <% end %>

      <%= if @import_state.has_empty_fee_type_cells? do %>
        <div class="alert alert-info" role="note" data-testid="preview-fee-type-info">
          <.icon name="hero-information-circle" class="size-5" aria-hidden="true" />
          <div>
            <p class="text-sm">
              {gettext("Rows with an empty fee type will get the default fee type.")}
            </p>
          </div>
        </div>
      <% end %>

      <%= if @import_state.warnings != [] do %>
        <div class="alert alert-warning" role="alert" data-testid="preview-unknown-warning">
          <.icon name="hero-information-circle" class="size-5" aria-hidden="true" />
          <div>
            <ul class="list-disc list-inside space-y-1 text-sm">
              <%= for warning <- @import_state.warnings do %>
                <li>{warning}</li>
              <% end %>
            </ul>
            <.link navigate={~p"/admin/datafields"} class="link link-primary text-sm">
              {gettext("Create custom field")}
            </.link>
          </div>
        </div>
      <% end %>

      <div class="flex gap-2">
        <.button
          type="button"
          phx-click="confirm_import"
          variant="primary"
          data-testid="confirm-import-button"
        >
          {gettext("Confirm and Import")}
        </.button>
        <.button type="button" phx-click="cancel_import" data-testid="cancel-import-button">
          {gettext("Cancel")}
        </.button>
      </div>
    </section>
    """
  end

  # Pairs each CSV header with its resolved role for the preview mapping table.
  defp column_roles(state) do
    member_indices = MapSet.new(Map.values(state.column_map))
    custom_indices = MapSet.new(Map.values(state.custom_field_map))
    ignored_headers = MapSet.new(state.ignored)

    state.headers
    |> Enum.with_index()
    |> Enum.map(fn {header, index} ->
      {header, role_for(index, header, state, member_indices, custom_indices, ignored_headers)}
    end)
  end

  defp role_for(index, header, state, member_indices, custom_indices, ignored_headers) do
    cond do
      index == state.groups_column_index -> :groups
      index == state.fee_type_column_index -> :fee_type
      MapSet.member?(ignored_headers, header) -> :ignored
      MapSet.member?(member_indices, index) -> :member_field
      MapSet.member?(custom_indices, index) -> :custom_field
      true -> :unknown
    end
  end

  defp role_label(:member_field), do: gettext("Member field")
  defp role_label(:custom_field), do: gettext("Custom field")
  defp role_label(:groups), do: gettext("Groups")
  defp role_label(:fee_type), do: gettext("Fee type")
  defp role_label(:ignored), do: gettext("Ignored (system-computed field)")
  defp role_label(:unknown), do: gettext("Unknown (ignored)")

  defp role_badge_class(:member_field), do: "badge-primary"
  defp role_badge_class(:custom_field), do: "badge-secondary"
  defp role_badge_class(:groups), do: "badge-success"
  defp role_badge_class(:fee_type), do: "badge-warning"
  defp role_badge_class(:ignored), do: "badge-ghost"
  defp role_badge_class(:unknown), do: "badge-error"

  defp role_row_class(:ignored), do: "opacity-50"
  defp role_row_class(:unknown), do: "opacity-50"
  defp role_row_class(_), do: nil

  defp column_samples([], col_count), do: List.duplicate([], col_count)

  defp column_samples(rows, col_count) do
    Enum.map(0..(col_count - 1), fn col_idx ->
      rows
      |> Enum.map(fn row -> Enum.at(row, col_idx, "") end)
      |> pad_to(3, "")
    end)
  end

  defp pad_to(list, target, fill) do
    list ++ List.duplicate(fill, max(0, target - length(list)))
  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 | :preview | :running | :done | :error, [map()]) ::
          boolean()
  def import_button_disabled?(:running, _entries), do: true
  def import_button_disabled?(:preview, _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