Trip page to show how many days/weeks/months until trip

Closes #118

templates/trip_page.html

@@ -65,6 +65,11 @@
     <div>Start: {{ display_date_no_year(trip.start) }} (end date missing)</div>
   {% endif %}
 
+  {% set delta = human_readable_delta(trip.start) %}
+  {% if delta %}
+    <div>{{ delta }} time</div>
+  {% endif %}
+
   <div class="conferences">
     {% for conf in trip.conferences %} {{ conference_row(conf, "going") }} {% endfor %}
   </div>

web_view.py

@@ -219,6 +219,39 @@ def trip_list() -> str:
     )
 
 
+def human_readable_delta(future_date: date) -> str | None:
+    """
+    Calculate the human-readable time delta for a given future date.
+
+    Args:
+    future_date (date): The future date as a datetime.date object.
+
+    Returns:
+    str: Human-readable time delta.
+    """
+    # Ensure the input is a future date
+    if future_date <= date.today():
+        return None
+
+    # Calculate the delta
+    delta = future_date - date.today()
+
+    # Convert delta to a more human-readable format
+    months, days = divmod(delta.days, 30)
+    weeks, days = divmod(days, 7)
+
+    # Formatting the output
+    parts = []
+    if months > 0:
+        parts.append(f"{months} months")
+    if weeks > 0:
+        parts.append(f"{weeks} weeks")
+    if days > 0:
+        parts.append(f"{days} days")
+
+    return " ".join(parts) if parts else None
+
+
 @app.route("/trip/<start>")
 def trip_page(start: str) -> str:
     """Individual trip page."""
@@ -282,6 +315,7 @@ def trip_page(start: str) -> str:
         get_country=agenda.get_country,
         format_list_with_ampersand=format_list_with_ampersand,
         holidays=holidays,
+        human_readable_delta=human_readable_delta,
     )