Data empty error

{% extends "brickwork/shell/app.html" %}
{% comment %}
Data-empty / error states for a data-heavy ops surface: the same page under
ready, empty, error and loading, so an operator never lands on a blank main
(icvoss/django-brickwork#407). Seventh archetype in the Data-heavy operations
family.

COPY THIS FILE into your project and edit it. It is not on the template loader
path, so you cannot extend it (ADR-056).

What your view must supply:
    data_state               "ready" | "empty" | "error" | "loading"
    export_columns / export_rows  the table's columns and pre-rendered rows
                              (used when data_state is "ready"; pass () for
                              empty when testing the table's own zero-row
                              branch elsewhere)
    filter_form              your own filter form (the bar renders its fields)
    nav_items / nav_active   as in app/list.html
The counts, headings and copy below are typed into the template, which is where
you change them.

WHY THIS PAGE EXISTS AS ITS OWN ARCHETYPE:

Every other Data-heavy page documents loading, empty and error in a comment and
then renders the happy path. INTERFACE-SYSTEM's completion bar still requires
those states as designed surfaces, not footnotes. This page IS the empty and
error design: one ops job list under four real branches, so a consumer can copy
the composition rather than inventing a blank main or a red banner from scratch.

It is NOT app/console.html (a permanent blank slate with no data path) and NOT
the in-table empty that _data_table.html already owns when rows is empty. Those
remain correct for their jobs. This page answers "the warehouse job store failed"
and "nobody has scheduled an export yet" as first-class page states on an
app-shell ops surface.

WHAT THIS PAGE IS FOR:

An operator opens Export jobs expecting a ledger of nightly warehouse extracts.
Most days the list is populated (ready). Day one, or after a purge, there is
nothing to show (empty). When the job store is unreachable, inventing rows would
be worse than saying so (error). When an htmx refresh is in flight, the table's
own loading skeleton keeps layout stable (loading).

States: data_state is the page's real branch.
  "ready": stat row, filter bar, populated data table.
  "empty": page header stays so the operator knows which surface they are on;
    the body is _empty_state.html (no_data) with a create action. Chrome and
    nav stay.
  "error": bw_alert danger; no invented stats or rows. Chrome and nav stay.
  "loading": page header and filter stay; the table renders with loading=True
    so the skeleton replaces rows without collapsing the band (STA-004).
Accessibility: inherits shell/app.html's skip link, sidebar/drawer nav and
  page-header region; empty heading/body and the alert title/message carry
  meaning in words, never colour alone; the loading skeleton is aria-hidden
  on the table's own loading branch. Covered by the archetype harness's full
  gate sweep (render, axe WCAG 2.2 AA, no horizontal overflow, light/dark
  distinctness, skip-link first-tab-stop with JS disabled) at every W0.1
  breakpoint, both themes.
Responsive: no breakpoint switch of its own; inherits shell/app.html's
  sidebar-to-drawer collapse at --bw-breakpoint-md (48rem). The stat row
  (bw-stat-grid) reflows continuously with an auto-fit grid; the composed
  table carries unconditional horizontal scroll (responsive="scroll", the
  default) at every width.
{% endcomment %}
{% load brickwork_components brickwork_nav %}

{% block page_title %}{% if data_state == "error" %}Export jobs unavailable - Northwind{% else %}Export jobs - Northwind{% endif %}{% endblock %}

{% block sidebar %}{% bw_nav nav_items nav_active %}{% endblock %}
{% block sidebar_mobile %}{% bw_nav nav_items nav_active %}{% endblock %}
{% block brand_wordmark %}Northwind{% endblock %}

{% block page_header %}
  {% if data_state == "error" %}
  {% include "brickwork/components/_page_header.html" with title="Export jobs" description="The job store could not be reached. Retry once the warehouse API recovers." %}
  {% else %}
  {% include "brickwork/components/_page_header.html" with title="Export jobs" description="Nightly warehouse extracts waiting to land. Oldest unfinished job first." %}
  {% endif %}
{% endblock %}

{% block page_actions %}
  {% if data_state != "error" %}
  {% bw_button "Schedule export" variant="primary" icon="plus" href="/exports/new/" %}
  {% endif %}
{% endblock %}

{% block content %}
  {% if data_state == "empty" %}
  {% comment %}
  EMPTY: nothing has ever been scheduled (or every job was purged). Keep the
  page header above so the operator still knows which surface this is; swap
  only the body for the empty state. Use no_data, not no_results: there is no
  filter in play yet.
  {% endcomment %}
  {% include "brickwork/components/_empty_state.html" with variant="no_data" icon="upload" heading="No export jobs yet" body="Schedule the first nightly extract to see it here. Failed and delayed jobs land in this list as the warehouse reports them." action_href="/exports/new/" action_label="Schedule an export" %}

  {% elif data_state == "error" %}
  {% comment %}
  ERROR: the job store failed. Say so with bw_alert danger; do not invent a
  zeroed stat row or an empty table that looks like "no work today".
  {% endcomment %}
  {% bw_alert "The warehouse job store did not respond. Check the API status page, then retry. Do not treat a blank list as proof that every export succeeded." title="Could not load export jobs" variant="danger" %}

  {% elif data_state == "loading" %}
  {% comment %}
  LOADING: an htmx refresh of the list is in flight. Keep the filter so the
  operator's criteria stay visible; the table's own loading skeleton holds the
  band open (see _data_table.html).
  {% endcomment %}
  <div class="bw-section-stack">
    {% include "brickwork/components/_filter_bar.html" with fields=filter_form submit_label="Filter" clear_href="/exports/" hx_get="/exports/" hx_target="#export-table" %}
    {% include "brickwork/components/_data_table.html" with table_id="export-table" columns=export_columns rows=export_rows loading=True sticky_header=True empty_heading="No export jobs yet" empty_body="Schedule the first nightly extract to see it here." %}
  </div>

  {% else %}
  <div class="bw-section-stack">

    {% comment %}
    Vital signs for a job ledger: waiting, late and failed matter more than
    total volume. Each trend pairs a direction glyph with visually hidden text.
    {% endcomment %}
    <div class="bw-stat-grid">
      {% include "brickwork/components/_stat.html" with label="Waiting to run" value="6" icon="calendar" trend="up" trend_label="2 more than yesterday" %}
      {% include "brickwork/components/_stat.html" with label="Running now" value="2" icon="upload" trend="flat" trend_label="unchanged since the last poll" %}
      {% include "brickwork/components/_stat.html" with label="Failed overnight" value="1" icon="alert-circle" trend="down" trend_label="3 fewer than yesterday" %}
      {% include "brickwork/components/_stat.html" with label="Completed today" value="14" trend="up" trend_label="4 more than the daily average" %}
    </div>

    {% include "brickwork/components/_filter_bar.html" with fields=filter_form submit_label="Filter" clear_href="/exports/" hx_get="/exports/" hx_target="#export-table" %}

    {% comment %}
    The ledger itself. Cells are pre-rendered strings from your view, so a
    status cell can be a rendered badge. sticky_header keeps column labels in
    view while a long job list scrolls.
    {% endcomment %}
    {% include "brickwork/components/_data_table.html" with table_id="export-table" columns=export_columns rows=export_rows sticky_header=True current_sort="scheduled_at" empty_heading="No export jobs match" empty_body="No jobs match these filters. Clear the status filter or widen the date range." empty_action_href="/exports/" empty_action_label="Clear filters" %}

  </div>
  {% endif %}
{% endblock %}