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1import httpx
2from datetime import datetime, timedelta
3from fastapi import FastAPI, HTTPException, Header
4from pydantic import BaseModel
5from typing import Optional
6import secrets
7 
8app = FastAPI()
9 
10users = {}
11tokens = {}
12user_id_counter = 1
13 
14itineraries = {}
15itinerary_id_counter = 1
16 
17VALID_TOKEN_PREFIX = "Bearer "
18 
19def get_user_from_token(authorization: str = Header(None)):
20    if not authorization or not authorization.startswith(VALID_TOKEN_PREFIX):
21        raise HTTPException(status_code=401, detail="Invalid authorization header")
22    token = authorization[len(VALID_TOKEN_PREFIX):]
23    user_id = tokens.get(token)
24    if user_id is None:
25        raise HTTPException(status_code=401, detail="Invalid token")
26    return user_id
27 
28class SignupRequest(BaseModel):
29    username: str
30    password: str
31 
32class LoginRequest(BaseModel):
33    username: str
34    password: str
35 
36class ItineraryRequest(BaseModel):
37    schedule_url: str
38    departure_location: str
39    arrival_location: str
40    departure_time: str
41 
42class ItineraryResponse(BaseModel):
43    id: int
44    departure_location: str
45    arrival_location: str
46    departure_time: str
47    feasible: Optional[bool] = None
48    message: Optional[str] = None
49 
50@app.post("/signup")
51def signup(req: SignupRequest):
52    global user_id_counter
53    for u in users.values():
54        if u["username"] == req.username:
55            raise HTTPException(status_code=400, detail="Username already exists")
56    user_id = user_id_counter
57    user_id_counter += 1
58    users[user_id] = {"username": req.username, "password": req.password}
59    return {"user_id": user_id, "username": req.username}
60 
61@app.post("/login")
62def login(req: LoginRequest):
63    for uid, u in users.items():
64        if u["username"] == req.username and u["password"] == req.password:
65            token = secrets.token_hex(16)
66            tokens[token] = uid
67            return {"token": token}
68    raise HTTPException(status_code=401, detail="Invalid credentials")
69 
70@app.get("/itinerary/{itinerary_id}")
71def get_itinerary(itinerary_id: int, authorization: str = Header(None)):
72    get_user_from_token(authorization)
73    itinerary = itineraries.get(itinerary_id)
74    if not itinerary:
75        raise HTTPException(status_code=404, detail="Itinerary not found")
76    return itinerary
77 
78@app.post("/itinerary")
79def create_itinerary(req: ItineraryRequest, authorization: str = Header(None)):
80    get_user_from_token(authorization)
81    global itinerary_id_counter
82    itinerary = {
83        "id": itinerary_id_counter,
84        "departure_location": req.departure_location,
85        "arrival_location": req.arrival_location,
86        "departure_time": req.departure_time,
87        "schedule_url": req.schedule_url,
88        "feasible": None,
89        "message": None
90    }
91    itineraries[itinerary_id_counter] = itinerary
92    itinerary_id_counter += 1
93    return itinerary
94 
95@app.post("/itinerary/validate")
96def validate_itinerary(req: ItineraryRequest, authorization: str = Header(None)):
97    get_user_from_token(authorization)
98    try:
99        resp = httpx.get(req.schedule_url, timeout=10)
100        resp.raise_for_status()
101        schedule_data = resp.json()
102    except Exception:
103        raise HTTPException(status_code=400, detail="Failed to fetch schedule")
104 
105    departure_time = datetime.fromisoformat(req.departure_time)
106    feasible = False
107    message = "No matching trip found"
108 
109    for trip in schedule_data.get("trips", []):
110        if trip.get("departure_location") == req.departure_location and trip.get("arrival_location") == req.arrival_location:
111            trip_departure = datetime.fromisoformat(trip["departure_time"])
112            trip_arrival = datetime.fromisoformat(trip["arrival_time"])
113            if trip_departure >= departure_time:
114                feasible = True
115                message = f"Trip found: departs {trip_departure}, arrives {trip_arrival}"
116                break
117 
118    return {
119        "departure_location": req.departure_location,
120        "arrival_location": req.arrival_location,
121        "departure_time": req.departure_time,
122        "feasible": feasible,
123        "message": message
124    }

1fastapi
2uvicorn
3httpx