Initial commit.

trip_planner.py

@@ -0,0 +1,88 @@
+"""
+Combine GWR Bristol→Paddington trains with Eurostar St Pancras→destination trains.
+"""
+from datetime import datetime, timedelta
+
+MIN_CONNECTION_MINUTES = 75
+MAX_CONNECTION_MINUTES = 140
+MAX_GWR_MINUTES = 110
+DATE_FMT = '%Y-%m-%d'
+TIME_FMT = '%H:%M'
+
+
+def _parse_dt(date: str, time: str) -> datetime:
+    return datetime.strptime(f"{date} {time}", f"{DATE_FMT} {TIME_FMT}")
+
+
+def _fmt_duration(minutes: int) -> str:
+    h, m = divmod(minutes, 60)
+    if h and m:
+        return f"{h}h {m}m"
+    if h:
+        return f"{h}h"
+    return f"{m}m"
+
+
+def combine_trips(
+    gwr_trains: list[dict],
+    eurostar_trains: list[dict],
+    travel_date: str,
+) -> list[dict]:
+    """
+    Return a list of valid combined trips, sorted by Bristol departure time.
+
+    Each trip dict:
+      depart_bristol        HH:MM
+      arrive_paddington     HH:MM
+      gwr_duration          str   (e.g. "1h 45m")
+      connection_duration   str
+      depart_st_pancras     HH:MM
+      arrive_destination    HH:MM
+      total_duration        str   (e.g. "5h 30m")
+      destination           str
+    """
+    trips = []
+
+    for gwr in gwr_trains:
+        try:
+            arr_pad = _parse_dt(travel_date, gwr['arrive_paddington'])
+            dep_bri = _parse_dt(travel_date, gwr['depart_bristol'])
+        except (ValueError, KeyError):
+            continue
+
+        if int((arr_pad - dep_bri).total_seconds() / 60) > MAX_GWR_MINUTES:
+            continue
+
+        earliest_eurostar = arr_pad + timedelta(minutes=MIN_CONNECTION_MINUTES)
+
+        # Find only the earliest viable Eurostar for this GWR departure
+        for es in eurostar_trains:
+            try:
+                dep_stp = _parse_dt(travel_date, es['depart_st_pancras'])
+                arr_dest = _parse_dt(travel_date, es['arrive_destination'])
+            except (ValueError, KeyError):
+                continue
+
+            # Eurostar arrives next day? (e.g. night service — unlikely but handle it)
+            if arr_dest < dep_stp:
+                arr_dest += timedelta(days=1)
+
+            if dep_stp < earliest_eurostar:
+                continue
+            if (dep_stp - arr_pad).total_seconds() / 60 > MAX_CONNECTION_MINUTES:
+                continue
+
+            trips.append({
+                'depart_bristol': gwr['depart_bristol'],
+                'arrive_paddington': gwr['arrive_paddington'],
+                'gwr_duration': _fmt_duration(int((arr_pad - dep_bri).total_seconds() / 60)),
+                'connection_duration': _fmt_duration(int((dep_stp - arr_pad).total_seconds() / 60)),
+                'depart_st_pancras': es['depart_st_pancras'],
+                'arrive_destination': es['arrive_destination'],
+                'total_duration': _fmt_duration(int((arr_dest - dep_bri).total_seconds() / 60)),
+                'destination': es['destination'],
+            })
+            break  # Only the earliest valid Eurostar per GWR departure
+
+    trips.sort(key=lambda t: (t['depart_bristol'], t['depart_st_pancras']))
+    return trips