From 7c54fdfe0926f4c6041d7fe49ef82f14808dd488 Mon Sep 17 00:00:00 2001
From: Edward Betts <edward@4angle.com>
Date: Thu, 28 Dec 2023 20:32:55 +0000
Subject: [PATCH] Show events before and after gaps

---
 agenda/data.py      | 31 +++++++++++++++++++++++++++----
 agenda/types.py     | 11 +++++++----
 templates/gaps.html | 27 ++++++++++++++++++++-------
 3 files changed, 54 insertions(+), 15 deletions(-)

diff --git a/agenda/data.py b/agenda/data.py
index 672faa4..45da97c 100644
--- a/agenda/data.py
+++ b/agenda/data.py
@@ -2,6 +2,7 @@
 
 import asyncio
 import collections
+import itertools
 import os
 import typing
 from datetime import date, datetime, timedelta
@@ -37,6 +38,8 @@ from . import (
 )
 from .types import Event, Holiday
 
+StrDict = dict[str, typing.Any]
+
 here = dateutil.tz.tzlocal()
 
 # deadline to file tax return
@@ -272,13 +275,23 @@ def find_markets_during_stay(
     return overlapping_markets
 
 
-def find_gaps(events: list[Event], min_gap_days: int = 3) -> list[tuple[date, date]]:
+def find_gaps(events: list[Event], min_gap_days: int = 3) -> list[StrDict]:
     """Gaps of at least `min_gap_days` between events in a list of events."""
     # Sort events by start date
 
     gaps: list[tuple[date, date]] = []
     previous_event_end = None
 
+    by_start_date = {
+        d: list(on_day)
+        for d, on_day in itertools.groupby(events, key=lambda e: e.as_date)
+    }
+
+    by_end_date = {
+        d: list(on_day)
+        for d, on_day in itertools.groupby(events, key=lambda e: e.end_as_date)
+    }
+
     for event in events:
         # Use start date for current event
         start_date = event.as_date
@@ -294,11 +307,19 @@ def find_gaps(events: list[Event], min_gap_days: int = 3) -> list[tuple[date, da
                 gaps.append(start_end)
 
         # Update previous event end date
-        end = event.end_as_date if event.end_date else start_date
+        end = event.end_as_date
         if not previous_event_end or end > previous_event_end:
             previous_event_end = end
 
-    return gaps
+    return [
+        {
+            "start": gap_start,
+            "end": gap_end,
+            "after": by_start_date[gap_end + timedelta(days=1)],
+            "before": by_end_date[gap_start - timedelta(days=1)],
+        }
+        for gap_start, gap_end in gaps
+    ]
 
 
 def busy_event(e: Event) -> bool:
@@ -455,7 +476,9 @@ async def get_data(
 
     gaps = find_gaps(busy_events)
 
-    events += [Event(name="gap", date=start, end_date=end) for start, end in gaps]
+    events += [
+        Event(name="gap", date=gap["start"], end_date=gap["end"]) for gap in gaps
+    ]
 
     # Sort events by their datetime; the "today" event is prioritised
     # at the top of the list for today. This is achieved by sorting first by
diff --git a/agenda/types.py b/agenda/types.py
index 27b5b58..ce58d3a 100644
--- a/agenda/types.py
+++ b/agenda/types.py
@@ -50,11 +50,14 @@ class Event:
     @property
     def end_as_date(self) -> datetime.date:
         """Date of event."""
-        assert self.end_date
         return (
-            self.end_date.date()
-            if isinstance(self.end_date, datetime.datetime)
-            else self.end_date
+            (
+                self.end_date.date()
+                if isinstance(self.end_date, datetime.datetime)
+                else self.end_date
+            )
+            if self.end_date
+            else self.as_date
         )
 
     @property
diff --git a/templates/gaps.html b/templates/gaps.html
index d776901..ecf070b 100644
--- a/templates/gaps.html
+++ b/templates/gaps.html
@@ -17,13 +17,26 @@
 
 
   <table class="table table-hover w-auto">
-  {% for start, end in gaps %}
-  <tr>
-    <td class="text-end">{{ start.strftime("%A, %-d %b %Y") }}</td>
-    <td class="text-end">{{ end.strftime("%A, %-d %b %Y") }}</td>
-    <td>{{ (end - start).days }} days</td>
-  </tr>
-  {% endfor %}
+    <thead>
+      <tr>
+        <th>before</th>
+        <th class="text-end">start</th>
+        <th class="text-end">end</th>
+        <th class="text-end">days</th>
+        <th>after</th>
+      </tr>
+    </thead>
+    <tbody>
+    {% for gap in gaps %}
+    <tr>
+      <td>{% for event in gap.before %}{% if not loop.first %}, {% endif %}{{ event.title or event.name }}{% endfor %}</td>
+      <td class="text-end">{{ gap.start.strftime("%A, %-d %b %Y") }}</td>
+      <td class="text-end">{{ gap.end.strftime("%A, %-d %b %Y") }}</td>
+      <td class="text-end">{{ (gap.end - gap.start).days }} days</td>
+      <td>{% for event in gap.after %}{% if not loop.first %}, {% endif %}{{ event.title or event.name }}{% endfor %}</td>
+    </tr>
+    {% endfor %}
+    </tbody>
   </table>
 </div>