From d25b5f4cb3ae6e7ba816b11f03688aa886c46f42 Mon Sep 17 00:00:00 2001
From: Shinya Kawabata <s-kawabata@wx.jp.nec.com>
Date: Tue, 12 Jan 2016 14:47:52 +0900
Subject: [PATCH] Enhance changing page button of list in monasca-ui

Adding missed page - Alarm Histroy

Change-Id: I7e3e93ede35e03d1a7ac8055fbc2db6f0d7e2cd0
Reference: Ibc05b05f8d2a728e4051b1b49e4a9c73be13471b
Closes-Bug: #1486508
---
 .../templates/alarms/alarm_history.html       |  5 +++-
 monitoring/alarms/views.py                    | 30 +++++++++++++++----
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/monitoring/alarms/templates/alarms/alarm_history.html b/monitoring/alarms/templates/alarms/alarm_history.html
index 392b789c..77e245b1 100644
--- a/monitoring/alarms/templates/alarms/alarm_history.html
+++ b/monitoring/alarms/templates/alarms/alarm_history.html
@@ -44,8 +44,11 @@
 
 <div class="pagination">
     <span class="step-links">
+        {% if prev_page_offset != None %}
+            <a href="?page_offset={{ prev_page_offset }}" class="btn btn-default btn-sm" style="position:relative;top:-35px;">Previous Page</a>
+        {% endif %}
         {% if page_offset %}
-            <a href="?page_offset={{ page_offset}}" class="btn btn-default btn-sm" style="position:relative;top:-35px;">Next Page</a>
+            <a href="?page_offset={{ page_offset }}" class="btn btn-default btn-sm" style="position:relative;top:-35px;">Next Page</a>
         {% endif %}
     </span>
 </div>
diff --git a/monitoring/alarms/views.py b/monitoring/alarms/views.py
index 6044b988..4e57a1e0 100644
--- a/monitoring/alarms/views.py
+++ b/monitoring/alarms/views.py
@@ -316,13 +316,20 @@ class AlarmHistoryView(tables.DataTableView):
         context['alarm'] = alarm
 
         contacts = []
+        prev_page_stack = []
         page_offset = self.request.GET.get('page_offset')
 
-        if page_offset == None:
+        if self.request.session.has_key('prev_page_stack'):
+            prev_page_stack = self.request.session['prev_page_stack']
+
+        if page_offset is None:
             page_offset = 0
+            prev_page_stack = []
         try:
+            # To judge whether there is next page, get LIMIT + 1
             results = api.monitor.alarm_history(self.request, object_id,  page_offset,
-                                                LIMIT)
+                                                LIMIT + 1)
+            num_results = len(results)
             paginator = Paginator(results, LIMIT)
             contacts = paginator.page(1)
         except EmptyPage:
@@ -333,13 +340,26 @@ class AlarmHistoryView(tables.DataTableView):
             return context
 
         context["contacts"] = contacts
-        if len(contacts.object_list) < LIMIT:
+        context['timestamp_formats'] = alarm_history_ts_formats
+        context['timestamp_selected'] = ts_mode or ''
+
+        if num_results < LIMIT + 1:
             context["page_offset"] = None
         else:
             context["page_offset"] = contacts.object_list[-1]["id"]
 
-        context['timestamp_formats'] = alarm_history_ts_formats
-        context['timestamp_selected'] = ts_mode or ''
+        if page_offset in prev_page_stack:
+            index = prev_page_stack.index(page_offset)
+            prev_page_stack = prev_page_stack[0:index]
+
+        prev_page_offset = prev_page_stack[-1] if prev_page_stack else None
+        if prev_page_offset is not None:
+            context["prev_page_offset"] = prev_page_offset
+
+        if len(prev_page_stack) > PREV_PAGE_LIMIT:
+            del prev_page_stack[0]
+        prev_page_stack.append(str(page_offset))
+        self.request.session['prev_page_stack'] = prev_page_stack
 
         return context