| 1 | import json |
| 2 | |
| 1 | 3 | class RestAPI: |
| 2 | 4 | def __init__(self, database: dict | None = None): |
| 3 | | pass |
| 4 | | |
| 5 | """ |
| 6 | Initialize the REST API with an optional database. |
| 7 | |
| 8 | Args: |
| 9 | database: A dictionary containing initial user data. |
| 10 | """ |
| 11 | self.database = database if database is not None else {"users": []} |
| 12 | |
| 5 | 13 | def get(self, url: str, payload: str | None = None) -> str: |
| 6 | | pass |
| 14 | """ |
| 15 | Handle GET requests to the API. |
| 16 | |
| 17 | Args: |
| 18 | url: The endpoint URL. |
| 19 | payload: Optional JSON payload. |
| 20 | |
| 21 | Returns: |
| 22 | A JSON string response. |
| 23 | """ |
| 24 | if url == "/users": |
| 25 | if payload is None: |
| 26 | # Return all users |
| 27 | return json.dumps({"users": sorted(self.database["users"], key=lambda x: x["name"])}) |
| 28 | else: |
| 29 | # Return specific users |
| 30 | data = json.loads(payload) |
| 31 | user_names = data.get("users", []) |
| 32 | |
| 33 | # Edge Case: Empty users list in payload |
| 34 | if not user_names: |
| 35 | return json.dumps({"users": []}) |
| 36 | |
| 37 | # Filter users by name |
| 38 | users = [user for user in self.database["users"] if user["name"] in user_names] |
| 39 | |
| 40 | # Edge Case: Some requested users don't exist |
| 41 | # Non-existent users are simply not included in the response |
| 42 | |
| 43 | return json.dumps({"users": sorted(users, key=lambda x: x["name"])}) |
| 44 | |
| 45 | # Edge Case: Invalid URL |
| 46 | return json.dumps({"error": "Invalid URL"}) |
| 47 | # Handled Edge Cases: Empty users list in payload, Some requested users don't exist, Invalid URL |
| 7 | 48 | |
| 8 | 49 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 50 | """ |
| 51 | Handle POST requests to the API. |
| 52 | |
| 53 | Args: |
| 54 | url: The endpoint URL. |
| 55 | payload: JSON payload. |
| 56 | |
| 57 | Returns: |
| 58 | A JSON string response. |
| 59 | """ |
| 60 | if payload is None: |
| 61 | # Edge Case: Missing payload |
| 62 | return json.dumps({"error": "Payload required"}) |
| 63 | |
| 64 | data = json.loads(payload) |
| 65 | |
| 66 | if url == "/add": |
| 67 | user_name = data.get("user") |
| 68 | |
| 69 | # Edge Case: Missing user name |
| 70 | if user_name is None: |
| 71 | return json.dumps({"error": "User name required"}) |
| 72 | |
| 73 | # Edge Case: User already exists |
| 74 | if any(user["name"] == user_name for user in self.database["users"]): |
| 75 | return json.dumps({"error": "User already exists"}) |
| 76 | |
| 77 | # Create new user |
| 78 | new_user = { |
| 79 | "name": user_name, |
| 80 | "owes": {}, |
| 81 | "owed_by": {}, |
| 82 | "balance": 0.0 |
| 83 | } |
| 84 | self.database["users"].append(new_user) |
| 85 | |
| 86 | return json.dumps(new_user) |
| 87 | |
| 88 | elif url == "/iou": |
| 89 | lender_name = data.get("lender") |
| 90 | borrower_name = data.get("borrower") |
| 91 | amount = data.get("amount") |
| 92 | |
| 93 | # Edge Case: Missing required fields |
| 94 | if lender_name is None or borrower_name is None or amount is None: |
| 95 | return json.dumps({"error": "Lender, borrower, and amount are required"}) |
| 96 | |
| 97 | # Edge Case: Lender and borrower are the same person |
| 98 | if lender_name == borrower_name: |
| 99 | return json.dumps({"error": "Lender and borrower cannot be the same person"}) |
| 100 | |
| 101 | # Edge Case: Negative amount |
| 102 | if amount < 0: |
| 103 | return json.dumps({"error": "Amount must be positive"}) |
| 104 | |
| 105 | # Find users |
| 106 | lender = next((user for user in self.database["users"] if user["name"] == lender_name), None) |
| 107 | borrower = next((user for user in self.database["users"] if user["name"] == borrower_name), None) |
| 108 | |
| 109 | # Edge Case: Lender or borrower doesn't exist |
| 110 | if lender is None or borrower is None: |
| 111 | return json.dumps({"error": "Lender or borrower does not exist"}) |
| 112 | |
| 113 | # Update owes and owed_by |
| 114 | # Update lender's owed_by |
| 115 | if borrower_name in lender["owed_by"]: |
| 116 | lender["owed_by"][borrower_name] += amount |
| 117 | else: |
| 118 | lender["owed_by"][borrower_name] = amount |
| 119 | |
| 120 | # Update borrower's owes |
| 121 | if lender_name in borrower["owes"]: |
| 122 | borrower["owes"][lender_name] += amount |
| 123 | else: |
| 124 | borrower["owes"][lender_name] = amount |
| 125 | |
| 126 | # Recalculate balances |
| 127 | lender_balance = sum(lender["owed_by"].values()) - sum(lender["owes"].values()) |
| 128 | borrower_balance = sum(borrower["owed_by"].values()) - sum(borrower["owes"].values()) |
| 129 | |
| 130 | lender["balance"] = lender_balance |
| 131 | borrower["balance"] = borrower_balance |
| 132 | |
| 133 | # Return updated users |
| 134 | users = sorted([lender, borrower], key=lambda x: x["name"]) |
| 135 | return json.dumps({"users": users}) |
| 136 | |
| 137 | # Edge Case: Invalid URL |
| 138 | return json.dumps({"error": "Invalid URL"}) |
| 139 | # Handled Edge Cases: Missing payload, Missing user name, User already exists, Missing required fields, |
| 140 | # Lender and borrower are the same person, Negative amount, Lender or borrower doesn't exist, Invalid URL |