Add return and inbound journey support

scraper/gwr_fares.py

@@ -32,7 +32,8 @@ def _headers() -> dict:
 
 
 def _request_body(
-    station_crs: str,
+    from_code: str,
+    to_code: str,
     travel_date: str,
     conversation_token: str | None,
     later: bool,
@@ -44,8 +45,8 @@ def _request_body(
         "IsPreviousReturn": False,
         "campaignCode": "",
         "validationCode": "",
-        "locfrom": f"GB{station_crs}",
-        "locto": _PAD_CODE,
+        "locfrom": from_code,
+        "locto": to_code,
         "datetimedepart": f"{travel_date}T00:00:00",
         "outwarddepartafter": True,
         "datetimereturn": None,
@@ -67,7 +68,22 @@ def _request_body(
     }
 
 
-def _run_pages(station_crs: str, travel_date: str, first_class: bool = False):
+def _station_code(station_crs: str) -> str:
+    return f"GB{station_crs}"
+
+
+def _od_codes(station_crs: str, direction: str) -> tuple[str, str]:
+    if direction == "from_paddington":
+        return _PAD_CODE, _station_code(station_crs)
+    return _station_code(station_crs), _PAD_CODE
+
+
+def _run_pages(
+    station_crs: str,
+    travel_date: str,
+    first_class: bool = False,
+    direction: str = "to_paddington",
+):
     """
     Iterate all pages of GWR journey search results.
 
@@ -78,8 +94,9 @@ def _run_pages(station_crs: str, travel_date: str, first_class: bool = False):
     with httpx.Client(headers=_headers(), timeout=30) as client:
         conversation_token = None
         later = False
+        from_code, to_code = _od_codes(station_crs, direction)
         for _ in range(_MAX_PAGES):
-            body = _request_body(station_crs, travel_date, conversation_token, later)
+            body = _request_body(from_code, to_code, travel_date, conversation_token, later)
             if first_class:
                 body["firstclass"] = True
                 body["standardclass"] = False
@@ -99,7 +116,12 @@ def _run_pages(station_crs: str, travel_date: str, first_class: bool = False):
             later = True
 
 
-def _run_pages_batched(station_crs: str, travel_date: str, first_class: bool = False):
+def _run_pages_batched(
+    station_crs: str,
+    travel_date: str,
+    first_class: bool = False,
+    direction: str = "to_paddington",
+):
     """
     Like _run_pages but yields one list of (dep_time, fares_list) per API page call,
     allowing callers to stream results a page at a time.
@@ -108,8 +130,9 @@ def _run_pages_batched(station_crs: str, travel_date: str, first_class: bool = F
     with httpx.Client(headers=_headers(), timeout=30) as client:
         conversation_token = None
         later = False
+        from_code, to_code = _od_codes(station_crs, direction)
         for _ in range(_MAX_PAGES):
-            body = _request_body(station_crs, travel_date, conversation_token, later)
+            body = _request_body(from_code, to_code, travel_date, conversation_token, later)
             if first_class:
                 body["firstclass"] = True
                 body["standardclass"] = False
@@ -132,16 +155,18 @@ def _run_pages_batched(station_crs: str, travel_date: str, first_class: bool = F
             later = True
 
 
-def fetch(station_crs: str, travel_date: str) -> dict[str, dict]:
+def fetch(
+    station_crs: str, travel_date: str, direction: str = "to_paddington"
+) -> dict[str, dict]:
     """
-    Fetch GWR walk-on single fares from station_crs to London Paddington on travel_date.
+    Fetch GWR walk-on single fares for the selected Paddington direction.
 
     Returns {departure_time: {'ticket': name, 'price': float, 'code': code}}
     where price is in £ and only the cheapest available standard-class walk-on
     ticket per departure (with restrictions already applied by GWR) is kept.
     """
     result: dict[str, dict] = {}
-    for dep_time, fares in _run_pages(station_crs, travel_date):
+    for dep_time, fares in _run_pages(station_crs, travel_date, direction=direction):
         cheapest = None
         for fare in fares:
             code = fare.get("ticketTypeCode")
@@ -166,7 +191,9 @@ def fetch(station_crs: str, travel_date: str) -> dict[str, dict]:
     return result
 
 
-def fetch_advance(station_crs: str, travel_date: str) -> dict[str, dict]:
+def fetch_advance(
+    station_crs: str, travel_date: str, direction: str = "to_paddington"
+) -> dict[str, dict]:
     """
     Fetch advance fares: cheapest standard advance and first-class advance per departure.
 
@@ -175,7 +202,9 @@ def fetch_advance(station_crs: str, travel_date: str) -> dict[str, dict]:
     where each sub-dict has keys 'ticket', 'price', 'code'.
     """
     std_advance: dict[str, dict] = {}
-    for dep_time, fares in _run_pages(station_crs, travel_date, first_class=False):
+    for dep_time, fares in _run_pages(
+        station_crs, travel_date, first_class=False, direction=direction
+    ):
         cheapest = None
         for fare in fares:
             code = fare.get("ticketTypeCode")
@@ -199,7 +228,9 @@ def fetch_advance(station_crs: str, travel_date: str) -> dict[str, dict]:
             }
 
     first_advance: dict[str, dict] = {}
-    for dep_time, fares in _run_pages(station_crs, travel_date, first_class=True):
+    for dep_time, fares in _run_pages(
+        station_crs, travel_date, first_class=True, direction=direction
+    ):
         cheapest = None
         for fare in fares:
             price_pence = fare.get("fare", 0)
@@ -227,7 +258,9 @@ def fetch_advance(station_crs: str, travel_date: str) -> dict[str, dict]:
     }
 
 
-def fetch_advance_streaming(station_crs: str, travel_date: str):
+def fetch_advance_streaming(
+    station_crs: str, travel_date: str, direction: str = "to_paddington"
+):
     """
     Generator yielding partial advance fare dicts one GWR API page at a time.
 
@@ -236,7 +269,9 @@ def fetch_advance_streaming(station_crs: str, travel_date: str):
     yielded immediately so callers can stream prices to clients as they arrive.
     """
     # Pass 1: standard class advance fares
-    for batch in _run_pages_batched(station_crs, travel_date, first_class=False):
+    for batch in _run_pages_batched(
+        station_crs, travel_date, first_class=False, direction=direction
+    ):
         page: dict[str, dict] = {}
         for dep_time, fares in batch:
             cheapest = None
@@ -267,7 +302,9 @@ def fetch_advance_streaming(station_crs: str, travel_date: str):
             yield page
 
     # Pass 2: first class advance fares
-    for batch in _run_pages_batched(station_crs, travel_date, first_class=True):
+    for batch in _run_pages_batched(
+        station_crs, travel_date, first_class=True, direction=direction
+    ):
         page = {}
         for dep_time, fares in batch:
             cheapest = None