From 7765c14264038e81c65e75fa90a43d58af581eac Mon Sep 17 00:00:00 2001
From: Mike Cantelon <mcantelon@gmail.com>
Date: Wed, 27 Sep 2023 00:54:41 -0700
Subject: [PATCH] Use server-side paging in aips page. (#209)

To avoid slow page responses when there are a large amount of AIPs use
server-side paging to limit the number of AIP HTML sent to the browser.
---
 AIPscan/Reporter/helpers.py            | 10 +++++
 AIPscan/Reporter/templates/aips.html   | 53 ++++++++++++++++++--------
 AIPscan/Reporter/tests/test_helpers.py | 27 +++++++++++++
 AIPscan/Reporter/views.py              | 19 ++++++---
 4 files changed, 88 insertions(+), 21 deletions(-)

diff --git a/AIPscan/Reporter/helpers.py b/AIPscan/Reporter/helpers.py
index 17c38048..4fa1bb36 100644
--- a/AIPscan/Reporter/helpers.py
+++ b/AIPscan/Reporter/helpers.py
@@ -145,3 +145,13 @@ def get_premis_xml_lines(file_object):
         premis_xml_lines = file_object.premis_object.split("\n")
 
     return premis_xml_lines
+
+
+def calculate_paging_window(page, pagination):
+    first_item = ((page - 1) * pagination.per_page) + 1
+    last_item = page * pagination.per_page
+
+    if last_item > pagination.total:
+        last_item = pagination.total
+
+    return first_item, last_item
diff --git a/AIPscan/Reporter/templates/aips.html b/AIPscan/Reporter/templates/aips.html
index c456f527..34a49684 100644
--- a/AIPscan/Reporter/templates/aips.html
+++ b/AIPscan/Reporter/templates/aips.html
@@ -2,7 +2,7 @@
 
 {% block content %}
 
-<div class="alert alert-header"><strong>AIPs ({{ aips|length }})</strong></div>
+<div class="alert alert-header"><strong>AIPs ({{ paging.items|length }})</strong></div>
 
 {% if storage_services %}
 
@@ -42,9 +42,9 @@
     </div>
   </div>
 
-  {% if aips %}
+  {% if paging.items %}
 
-    <table id="aiptable" class="table table-striped table-bordered">
+    <table id="aipstable" class="table table-striped table-bordered">
       <thead>
       <tr>
       <th><strong>Transfer name</strong></th>
@@ -54,19 +54,17 @@
       <th><strong>Preservation copies</strong></th>
       <th><strong>Action</strong></th>
       </tr>
-      </thead>
-      {% if aips %}
-        {% for aip in aips %}
-          <tr>
-            <td>{{ aip.transfer_name }}</td>
-            <td>{{ aip.uuid }}</td>
-            <td>{{ aip.create_date }}</td>
-            <td>{{ aip.original_file_count }}</td>
-            <td>{{ aip.preservation_file_count }}</td>
-            <td><a href='{{ url_for("reporter.view_aip", aip_id = aip.id) }}'><button type="button" class="btn btn-info">View</button></a></td>
-          </tr>
-        {% endfor %}
-      {% endif %}
+
+      {% for aip in paging.items %}
+        <tr>
+          <td>{{ aip.transfer_name }}</td>
+          <td>{{ aip.uuid }}</td>
+          <td>{{ aip.create_date }}</td>
+          <td>{{ aip.original_file_count }}</td>
+          <td>{{ aip.preservation_file_count }}</td>
+          <td><a href='{{ url_for("reporter.view_aip", aip_id = aip.id) }}'><button type="button" class="btn btn-info">View</button></a></td>
+        </tr>
+      {% endfor %}
     </table>
 
   {% else %}
@@ -85,6 +83,29 @@
 
 {% endif %}
 
+{% if paging.total %}
+
+  <div class="dataTables_wrapper">
+    <div class="row">
+      <div class="col-sm-12 col-md-5">
+        <div class="dataTables_info" id="aiptable_info" role="status" aria-live="polite">Showing {{ first_item }} to {{ last_item }} of {{ paging.total }} entries</div>
+      </div>
+      <div class="col-sm-12 col-md-7">
+        <div class="dataTables_paginate paging_full_numbers" id="aiptable_paginate">
+          <ul class="pagination">
+            <li class="paginate_button page-item first {% if paging.page == 1 %}disabled{% endif %}"><a href="{{ url_for('reporter.view_aips') }}?page=1" class="page-link">First</a></li>
+            <li class="paginate_button page-item previous {% if paging.prev_num is none %}disabled{% endif %}"><a href="{{ url_for('reporter.view_aips') }}?page={{ paging.prev_num }}" class="page-link">Previous</a></li>
+            <li class="paginate_button page-item active"><a href="#" class="page-link">{{ paging.page }}</a></li>
+            <li class="paginate_button page-item next {% if paging.next_num is none %}disabled{% endif %}"><a href="{{ url_for('reporter.view_aips') }}?page={{ paging.next_num }}" class="page-link">Next</a></li>
+            <li class="paginate_button page-item last {% if paging.page == paging.pages %}disabled{% endif %}"><a href="{{ url_for('reporter.view_aips') }}?page={{ paging.pages }}" class="page-link">Last</a></li>
+          </ul>
+        </div>
+      </div>
+    </div>
+  </div>
+
+{% endif %}
+
 <script>
 $(document).ready(function(){
   var storageServiceId = $('#ss').val();
diff --git a/AIPscan/Reporter/tests/test_helpers.py b/AIPscan/Reporter/tests/test_helpers.py
index e7700c1b..47d73063 100644
--- a/AIPscan/Reporter/tests/test_helpers.py
+++ b/AIPscan/Reporter/tests/test_helpers.py
@@ -129,3 +129,30 @@ def test_get_premis_xml_lines():
     lines = helpers.get_premis_xml_lines(file_)
 
     assert len(lines) == 2
+
+
+def test_calculate_paging_window():
+    class MockPagination(object):
+        pass
+
+    pagination = MockPagination()
+    pagination.per_page = 5
+    pagination.total = 17
+
+    # Test paging window at start of results
+    first_item, last_item = helpers.calculate_paging_window(1, pagination)
+
+    assert first_item == 1
+    assert last_item == 5
+
+    # Test paging window on an arbitrary page of results
+    first_item, last_item = helpers.calculate_paging_window(3, pagination)
+
+    assert first_item == 11
+    assert last_item == 15
+
+    # Test paging window with last item being set to the total of items
+    first_item, last_item = helpers.calculate_paging_window(4, pagination)
+
+    assert first_item == 16
+    assert last_item == 17
diff --git a/AIPscan/Reporter/views.py b/AIPscan/Reporter/views.py
index 66b4273d..396e8ee3 100644
--- a/AIPscan/Reporter/views.py
+++ b/AIPscan/Reporter/views.py
@@ -39,7 +39,7 @@
     request_params,
     sort_puids,
 )
-from AIPscan.Reporter.helpers import get_premis_xml_lines
+from AIPscan.Reporter.helpers import calculate_paging_window, get_premis_xml_lines
 
 
 def _get_storage_service(storage_service_id):
@@ -85,10 +85,17 @@ def view_aips():
     except Exception as e:
         print(e)
 
-    aips = AIP.query.filter_by(storage_service_id=storage_service.id)
+    page = int(request.args.get("page", default="1"))
+    per_page = 5
+
+    paging = AIP.query.paginate(page=page, per_page=per_page, error_out=False)
+
     if storage_location:
-        aips = aips.filter_by(storage_location_id=storage_location_id)
-    aips = aips.all()
+        paging = AIP.query.filter_by(
+            storage_location_id=storage_location_id
+        ).paginate(page=page, per_page=per_page, error_out=False)
+
+    first_item, last_item = calculate_paging_window(page, paging)
 
     return render_template(
         "aips.html",
@@ -98,7 +105,9 @@ def view_aips():
             storage_service.storage_locations
         ),
         storage_location=storage_location,
-        aips=aips,
+        paging=paging,
+        first_item=first_item,
+        last_item=last_item,
     )