UI - Clicking the "[Diff]" link should take you to the difference starting at the relative time to when you last viewed the difference page (#1989)

.github/workflows/test-only.yml

@@ -51,6 +51,7 @@ jobs:
         run: |
           # Unit tests
           docker run test-changedetectionio  bash -c 'python3 -m unittest changedetectionio.tests.unit.test_notification_diff'
+          docker run test-changedetectionio  bash -c 'python3 -m unittest changedetectionio.tests.unit.test_watch_model'
           
           # All tests
           docker run --network changedet-network  test-changedetectionio  bash -c 'cd changedetectionio && ./run_basic_tests.sh'

changedetectionio/__init__.py

@@ -961,7 +961,7 @@ def changedetection_app(config=None, datastore_o=None):
         # Read as binary and force decode as UTF-8
         # Windows may fail decode in python if we just use 'r' mode (chardet decode exception)
         from_version = request.args.get('from_version')
-        from_version_index = -2 # second newest
+        from_version_index = -2  # second newest
         if from_version and from_version in dates:
             from_version_index = dates.index(from_version)
         else:
@@ -970,7 +970,7 @@ def changedetection_app(config=None, datastore_o=None):
         try:
             from_version_file_contents = watch.get_history_snapshot(dates[from_version_index])
         except Exception as e:
-            from_version_file_contents = "Unable to read to-version at index{}.\n".format(dates[from_version_index])
+            from_version_file_contents = f"Unable to read to-version at index {dates[from_version_index]}.\n"
 
         to_version = request.args.get('to_version')
         to_version_index = -1

changedetectionio/model/Watch.py

@@ -262,6 +262,38 @@ class model(dict):
         bump = self.history
         return self.__newest_history_key
 
+    # Given an arbitrary timestamp, find the closest next key
+    # For example, last_viewed = 1000 so it should return the next 1001 timestamp
+    #
+    # used for the [diff] button so it can preset a smarter from_version
+    @property
+    def get_next_snapshot_key_to_last_viewed(self):
+
+        """Unfortunately for now timestamp is stored as string key"""
+        keys = list(self.history.keys())
+        if not keys:
+            return None
+
+        last_viewed = int(self.get('last_viewed'))
+        prev_k = keys[0]
+        sorted_keys = sorted(keys, key=lambda x: int(x))
+        sorted_keys.reverse()
+
+        # When the 'last viewed' timestamp is greater than the newest snapshot, return second last
+        if last_viewed > int(sorted_keys[0]):
+            return sorted_keys[1]
+
+        for k in sorted_keys:
+            if int(k) < last_viewed:
+                if prev_k == sorted_keys[0]:
+                    # Return the second last one so we dont recommend the same version compares itself
+                    return sorted_keys[1]
+
+                return prev_k
+            prev_k = k
+
+        return keys[0]
+
     def get_history_snapshot(self, timestamp):
         import brotli
         filepath = self.history[timestamp]

changedetectionio/templates/watch-overview.html

@@ -82,12 +82,15 @@
             </tr>
             {% endif %}
             {% for watch in (watches|sort(attribute=sort_attribute, reverse=sort_order == 'asc'))|pagination_slice(skip=pagination.skip) %}
+
+                {% set is_unviewed =  watch.newest_history_key| int > watch.last_viewed and watch.history_n>=2 %}
+
             <tr id="{{ watch.uuid }}"
                 class="{{ loop.cycle('pure-table-odd', 'pure-table-even') }} processor-{{ watch['processor'] }}
                 {% if watch.last_error is defined and watch.last_error != False %}error{% endif %}
                 {% if watch.last_notification_error is defined and watch.last_notification_error != False %}error{% endif %}
                 {% if watch.paused is defined and watch.paused != False %}paused{% endif %}
-                {% if watch.newest_history_key| int > watch.last_viewed and watch.history_n>=2 %}unviewed{% endif %}
+                {% if is_unviewed %}unviewed{% endif %}
                 {% if watch.uuid in queued_uuids %}queued{% endif %}">
                 <td class="inline checkbox-uuid" ><input name="uuids"  type="checkbox" value="{{ watch.uuid}} " > <span>{{ loop.index+pagination.skip }}</span></td>
                 <td class="inline watch-controls">
@@ -167,7 +170,13 @@
                        class="recheck pure-button pure-button-primary">{% if watch.uuid in queued_uuids %}Queued{% else %}Recheck{% endif %}</a>
                     <a href="{{ url_for('edit_page', uuid=watch.uuid)}}" class="pure-button pure-button-primary">Edit</a>
                     {% if watch.history_n >= 2 %}
-                    <a href="{{ url_for('diff_history_page', uuid=watch.uuid) }}" target="{{watch.uuid}}" class="pure-button pure-button-primary diff-link">Diff</a>
+
+                        {%  if is_unviewed %}
+                           <a href="{{ url_for('diff_history_page', uuid=watch.uuid, from_version=watch.get_next_snapshot_key_to_last_viewed) }}" target="{{watch.uuid}}" class="pure-button pure-button-primary diff-link">Diff</a>
+                        {% else %}
+                           <a href="{{ url_for('diff_history_page', uuid=watch.uuid)}}" target="{{watch.uuid}}" class="pure-button pure-button-primary diff-link">Diff</a>
+                        {% endif %}
+
                     {% else %}
                         {% if watch.history_n == 1 or (watch.history_n ==0 and watch.error_text_ctime )%}
                             <a href="{{ url_for('preview_page', uuid=watch.uuid)}}" target="{{watch.uuid}}" class="pure-button pure-button-primary">Preview</a>

changedetectionio/tests/unit/test_watch_model.py

@@ -0,0 +1,54 @@
+#!/usr/bin/python3
+
+# run from dir above changedetectionio/ dir
+# python3 -m unittest changedetectionio.tests.unit.test_notification_diff
+
+import unittest
+import os
+
+from changedetectionio.model import Watch
+
+# mostly
+class TestDiffBuilder(unittest.TestCase):
+
+    def test_watch_get_suggested_from_diff_timestamp(self):
+        import uuid as uuid_builder
+        watch = Watch.model(datastore_path='/tmp', default={})
+        watch.ensure_data_dir_exists()
+
+        watch['last_viewed'] = 110
+
+        watch.save_history_text(contents=b"hello world", timestamp=100, snapshot_id=str(uuid_builder.uuid4()))
+        watch.save_history_text(contents=b"hello world", timestamp=105, snapshot_id=str(uuid_builder.uuid4()))
+        watch.save_history_text(contents=b"hello world", timestamp=109, snapshot_id=str(uuid_builder.uuid4()))
+        watch.save_history_text(contents=b"hello world", timestamp=112, snapshot_id=str(uuid_builder.uuid4()))
+        watch.save_history_text(contents=b"hello world", timestamp=115, snapshot_id=str(uuid_builder.uuid4()))
+        watch.save_history_text(contents=b"hello world", timestamp=117, snapshot_id=str(uuid_builder.uuid4()))
+
+        p = watch.get_next_snapshot_key_to_last_viewed
+        assert p == "112", "Correct last-viewed timestamp was detected"
+
+        # When there is only one step of difference from the end of the list, it should return second-last change
+        watch['last_viewed'] = 116
+        p = watch.get_next_snapshot_key_to_last_viewed
+        assert p == "115", "Correct 'second last' last-viewed timestamp was detected when using the last timestamp"
+
+        watch['last_viewed'] = 99
+        p = watch.get_next_snapshot_key_to_last_viewed
+        assert p == "100"
+
+        watch['last_viewed'] = 200
+        p = watch.get_next_snapshot_key_to_last_viewed
+        assert p == "115", "When the 'last viewed' timestamp is greater than the newest snapshot, return second last "
+
+        watch['last_viewed'] = 109
+        p = watch.get_next_snapshot_key_to_last_viewed
+        assert p == "109", "Correct when its the same time"
+
+        # new empty one
+        watch = Watch.model(datastore_path='/tmp', default={})
+        p = watch.get_next_snapshot_key_to_last_viewed
+        assert p == None, "None when no history available"
+
+if __name__ == '__main__':
+    unittest.main()