| 1 | import json |
| 2 | |
| 1 | 3 | class RestAPI: |
| 2 | 4 | def __init__(self, database: dict | None = None): |
| 3 | | pass |
| 4 | | |
| 5 | # Edge Case: Handle None database by initializing empty structure |
| 6 | if database is None: |
| 7 | self.database = {"users": []} |
| 8 | else: |
| 9 | self.database = database |
| 10 | |
| 5 | 11 | def get(self, url: str, payload: str | None = None) -> str: |
| 6 | | pass |
| 7 | | |
| 12 | # Edge Case: Handle invalid URL |
| 13 | if url != "/users": |
| 14 | return json.dumps({"error": "Invalid URL"}) |
| 15 | |
| 16 | # Edge Case: Handle empty payload |
| 17 | if payload is None: |
| 18 | return json.dumps({"users": sorted(self.database["users"], key=lambda x: x["name"])}) |
| 19 | |
| 20 | # Edge Case: Handle invalid JSON payload |
| 21 | try: |
| 22 | data = json.loads(payload) |
| 23 | except json.JSONDecodeError: |
| 24 | return json.dumps({"error": "Invalid JSON payload"}) |
| 25 | |
| 26 | # Edge Case: Handle missing 'users' key in payload |
| 27 | if "users" not in data: |
| 28 | return json.dumps({"error": "Missing 'users' key in payload"}) |
| 29 | |
| 30 | # Edge Case: Handle non-list 'users' value |
| 31 | if not isinstance(data["users"], list): |
| 32 | return json.dumps({"error": "'users' must be a list"}) |
| 33 | |
| 34 | # Filter users based on the requested names |
| 35 | requested_names = data["users"] |
| 36 | filtered_users = [user for user in self.database["users"] if user["name"] in requested_names] |
| 37 | |
| 38 | # Edge Case: Handle non-existent users (they are simply not included in the response) |
| 39 | return json.dumps({"users": sorted(filtered_users, key=lambda x: x["name"])}) |
| 40 | |
| 8 | 41 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 42 | # Edge Case: Handle invalid URL |
| 43 | if url not in ["/add", "/iou"]: |
| 44 | return json.dumps({"error": "Invalid URL"}) |
| 45 | |
| 46 | # Edge Case: Handle empty payload |
| 47 | if payload is None: |
| 48 | return json.dumps({"error": "Payload required"}) |
| 49 | |
| 50 | # Edge Case: Handle invalid JSON payload |
| 51 | try: |
| 52 | data = json.loads(payload) |
| 53 | except json.JSONDecodeError: |
| 54 | return json.dumps({"error": "Invalid JSON payload"}) |
| 55 | |
| 56 | if url == "/add": |
| 57 | # Edge Case: Handle missing 'user' key |
| 58 | if "user" not in data: |
| 59 | return json.dumps({"error": "Missing 'user' key"}) |
| 60 | |
| 61 | # Edge Case: Handle non-string user name |
| 62 | if not isinstance(data["user"], str): |
| 63 | return json.dumps({"error": "User name must be a string"}) |
| 64 | |
| 65 | # Edge Case: Handle duplicate user |
| 66 | for user in self.database["users"]: |
| 67 | if user["name"] == data["user"]: |
| 68 | return json.dumps({"error": "User already exists"}) |
| 69 | |
| 70 | # Create new user |
| 71 | new_user = { |
| 72 | "name": data["user"], |
| 73 | "owes": {}, |
| 74 | "owed_by": {}, |
| 75 | "balance": 0.0 |
| 76 | } |
| 77 | self.database["users"].append(new_user) |
| 78 | return json.dumps(new_user) |
| 79 | |
| 80 | elif url == "/iou": |
| 81 | # Edge Case: Handle missing required keys |
| 82 | required_keys = ["lender", "borrower", "amount"] |
| 83 | for key in required_keys: |
| 84 | if key not in data: |
| 85 | return json.dumps({"error": f"Missing '{key}' key"}) |
| 86 | |
| 87 | # Edge Case: Handle non-string lender/borrower |
| 88 | if not isinstance(data["lender"], str) or not isinstance(data["borrower"], str): |
| 89 | return json.dumps({"error": "Lender and borrower must be strings"}) |
| 90 | |
| 91 | # Edge Case: Handle non-numeric amount |
| 92 | if not isinstance(data["amount"], (int, float)): |
| 93 | return json.dumps({"error": "Amount must be a number"}) |
| 94 | |
| 95 | # Edge Case: Handle negative amount |
| 96 | if data["amount"] < 0: |
| 97 | return json.dumps({"error": "Amount must be positive"}) |
| 98 | |
| 99 | # Edge Case: Handle lender equals borrower |
| 100 | if data["lender"] == data["borrower"]: |
| 101 | return json.dumps({"error": "Lender and borrower cannot be the same"}) |
| 102 | |
| 103 | # Find lender and borrower |
| 104 | lender = None |
| 105 | borrower = None |
| 106 | for user in self.database["users"]: |
| 107 | if user["name"] == data["lender"]: |
| 108 | lender = user |
| 109 | elif user["name"] == data["borrower"]: |
| 110 | borrower = user |
| 111 | |
| 112 | # Edge Case: Handle non-existent lender or borrower |
| 113 | if lender is None or borrower is None: |
| 114 | return json.dumps({"error": "Lender or borrower does not exist"}) |
| 115 | |
| 116 | # Update owes and owed_by relationships |
| 117 | # Update lender's owed_by |
| 118 | if data["borrower"] in lender["owed_by"]: |
| 119 | lender["owed_by"][data["borrower"]] += data["amount"] |
| 120 | else: |
| 121 | lender["owed_by"][data["borrower"]] = data["amount"] |
| 122 | |
| 123 | # Update borrower's owes |
| 124 | if data["lender"] in borrower["owes"]: |
| 125 | borrower["owes"][data["lender"]] += data["amount"] |
| 126 | else: |
| 127 | borrower["owes"][data["lender"]] = data["amount"] |
| 128 | |
| 129 | # Update balances |
| 130 | lender["balance"] += data["amount"] |
| 131 | borrower["balance"] -= data["amount"] |
| 132 | |
| 133 | # Return updated users |
| 134 | updated_users = [lender, borrower] |
| 135 | return json.dumps({"users": sorted(updated_users, key=lambda x: x["name"])}) |
| 136 | |
| 137 | # Handled Edge Cases: None database, invalid URL, empty payload, invalid JSON, missing keys, non-list values, non-existent users, duplicate user, non-string names, negative amounts, lender equals borrower, non-numeric amounts |