| 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 | if database is None: |
| 12 | self.database = {"users": []} |
| 13 | else: |
| 14 | self.database = database |
| 15 | |
| 5 | 16 | def get(self, url: str, payload: str | None = None) -> str: |
| 6 | | pass |
| 7 | | |
| 17 | """ |
| 18 | Handle GET requests to the API. |
| 19 | |
| 20 | Args: |
| 21 | url: The endpoint URL. |
| 22 | payload: Optional JSON payload. |
| 23 | |
| 24 | Returns: |
| 25 | A JSON string response. |
| 26 | """ |
| 27 | if url == "/users": |
| 28 | if payload is None: |
| 29 | # Return all users sorted by name |
| 30 | users = sorted(self.database["users"], key=lambda x: x["name"]) |
| 31 | return json.dumps({"users": users}) |
| 32 | else: |
| 33 | # Return specified users sorted by name |
| 34 | data = json.loads(payload) |
| 35 | user_names = data.get("users", []) |
| 36 | |
| 37 | # Edge Case: Handle when users list is empty |
| 38 | if not user_names: |
| 39 | return json.dumps({"users": []}) |
| 40 | |
| 41 | # Filter users by name |
| 42 | users = [user for user in self.database["users"] if user["name"] in user_names] |
| 43 | |
| 44 | # Edge Case: Handle when some requested users don't exist |
| 45 | if len(users) != len(user_names): |
| 46 | # Only return users that exist |
| 47 | pass |
| 48 | |
| 49 | # Sort by name |
| 50 | users = sorted(users, key=lambda x: x["name"]) |
| 51 | return json.dumps({"users": users}) |
| 52 | |
| 53 | # Edge Case: Handle unknown URL |
| 54 | return json.dumps({"error": "Not found"}) |
| 55 | |
| 8 | 56 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 57 | """ |
| 58 | Handle POST requests to the API. |
| 59 | |
| 60 | Args: |
| 61 | url: The endpoint URL. |
| 62 | payload: JSON payload. |
| 63 | |
| 64 | Returns: |
| 65 | A JSON string response. |
| 66 | """ |
| 67 | if payload is None: |
| 68 | # Edge Case: Handle missing payload |
| 69 | return json.dumps({"error": "Payload required"}) |
| 70 | |
| 71 | data = json.loads(payload) |
| 72 | |
| 73 | if url == "/add": |
| 74 | user_name = data.get("user") |
| 75 | |
| 76 | # Edge Case: Handle missing user name |
| 77 | if not user_name: |
| 78 | return json.dumps({"error": "User name required"}) |
| 79 | |
| 80 | # Edge Case: Handle duplicate user |
| 81 | for user in self.database["users"]: |
| 82 | if user["name"] == user_name: |
| 83 | return json.dumps({"error": "User already exists"}) |
| 84 | |
| 85 | # Create new user |
| 86 | new_user = { |
| 87 | "name": user_name, |
| 88 | "owes": {}, |
| 89 | "owed_by": {}, |
| 90 | "balance": 0.0 |
| 91 | } |
| 92 | self.database["users"].append(new_user) |
| 93 | return json.dumps(new_user) |
| 94 | |
| 95 | elif url == "/iou": |
| 96 | lender_name = data.get("lender") |
| 97 | borrower_name = data.get("borrower") |
| 98 | amount = data.get("amount") |
| 99 | |
| 100 | # Edge Case: Handle missing fields |
| 101 | if not lender_name or not borrower_name or amount is None: |
| 102 | return json.dumps({"error": "Lender, borrower, and amount required"}) |
| 103 | |
| 104 | # Edge Case: Handle invalid amount type |
| 105 | if not isinstance(amount, (int, float)): |
| 106 | return json.dumps({"error": "Amount must be a number"}) |
| 107 | |
| 108 | # Edge Case: Handle negative amount |
| 109 | if amount < 0: |
| 110 | return json.dumps({"error": "Amount must be positive"}) |
| 111 | |
| 112 | # Edge Case: Handle same lender and borrower |
| 113 | if lender_name == borrower_name: |
| 114 | return json.dumps({"error": "Lender and borrower cannot be the same"}) |
| 115 | |
| 116 | # Find lender and borrower |
| 117 | lender = None |
| 118 | borrower = None |
| 119 | for user in self.database["users"]: |
| 120 | if user["name"] == lender_name: |
| 121 | lender = user |
| 122 | if user["name"] == borrower_name: |
| 123 | borrower = user |
| 124 | |
| 125 | # Edge Case: Handle non-existent lender or borrower |
| 126 | if lender is None or borrower is None: |
| 127 | return json.dumps({"error": "Both lender and borrower must exist"}) |
| 128 | |
| 129 | # Update lender's owed_by |
| 130 | if borrower_name in lender["owed_by"]: |
| 131 | lender["owed_by"][borrower_name] += amount |
| 132 | else: |
| 133 | lender["owed_by"][borrower_name] = amount |
| 134 | |
| 135 | # Update borrower's owes |
| 136 | if lender_name in borrower["owes"]: |
| 137 | borrower["owes"][lender_name] += amount |
| 138 | else: |
| 139 | borrower["owes"][lender_name] = amount |
| 140 | |
| 141 | # Update balances |
| 142 | lender["balance"] += amount |
| 143 | borrower["balance"] -= amount |
| 144 | |
| 145 | # Return updated users sorted by name |
| 146 | users = sorted([lender, borrower], key=lambda x: x["name"]) |
| 147 | return json.dumps({"users": users}) |
| 148 | |
| 149 | # Edge Case: Handle unknown URL |
| 150 | return json.dumps({"error": "Not found"}) |
| 151 | |
| 152 | # Handled Edge Cases: Missing payload, missing user name, duplicate user, missing fields, |
| 153 | # invalid amount type, negative amount, same lender and borrower, non-existent lender or borrower, |
| 154 | # unknown URL |