| 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: Optional initial database dictionary containing 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 | JSON string response. |
| 26 | |
| 27 | Raises: |
| 28 | ValueError: If the URL is not recognized. |
| 29 | """ |
| 30 | if url == "/users": |
| 31 | if payload is None: |
| 32 | # Return all users sorted by name |
| 33 | users = sorted(self.database["users"], key=lambda u: u["name"]) |
| 34 | return json.dumps({"users": users}) |
| 35 | else: |
| 36 | # Return only specified users |
| 37 | data = json.loads(payload) |
| 38 | user_names = data.get("users", []) |
| 39 | |
| 40 | # Edge Case: Empty user list in payload |
| 41 | if not user_names: |
| 42 | return json.dumps({"users": []}) |
| 43 | |
| 44 | # Filter users by name |
| 45 | filtered_users = [user for user in self.database["users"] if user["name"] in user_names] |
| 46 | |
| 47 | # Edge Case: Non-existent users in payload |
| 48 | # Only existing users are returned, non-existent ones are ignored |
| 49 | |
| 50 | # Sort by name |
| 51 | filtered_users.sort(key=lambda u: u["name"]) |
| 52 | return json.dumps({"users": filtered_users}) |
| 53 | else: |
| 54 | # Edge Case: Invalid URL |
| 55 | raise ValueError(f"Invalid URL: {url}") |
| 56 | |
| 8 | 57 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 58 | """ |
| 59 | Handle POST requests to the API. |
| 60 | |
| 61 | Args: |
| 62 | url: The endpoint URL. |
| 63 | payload: JSON payload. |
| 64 | |
| 65 | Returns: |
| 66 | JSON string response. |
| 67 | |
| 68 | Raises: |
| 69 | ValueError: If the URL is not recognized or if there are validation errors. |
| 70 | """ |
| 71 | if url == "/add": |
| 72 | if payload is None: |
| 73 | # Edge Case: Missing payload |
| 74 | raise ValueError("Payload required for /add endpoint") |
| 75 | |
| 76 | data = json.loads(payload) |
| 77 | user_name = data.get("user") |
| 78 | |
| 79 | # Edge Case: Missing user field in payload |
| 80 | if user_name is None: |
| 81 | raise ValueError("'user' field is required in payload") |
| 82 | |
| 83 | # Edge Case: User already exists |
| 84 | for user in self.database["users"]: |
| 85 | if user["name"] == user_name: |
| 86 | raise ValueError(f"User {user_name} already exists") |
| 87 | |
| 88 | # Create new user |
| 89 | new_user = { |
| 90 | "name": user_name, |
| 91 | "owes": {}, |
| 92 | "owed_by": {}, |
| 93 | "balance": 0.0 |
| 94 | } |
| 95 | self.database["users"].append(new_user) |
| 96 | return json.dumps(new_user) |
| 97 | |
| 98 | elif url == "/iou": |
| 99 | if payload is None: |
| 100 | # Edge Case: Missing payload |
| 101 | raise ValueError("Payload required for /iou endpoint") |
| 102 | |
| 103 | data = json.loads(payload) |
| 104 | lender_name = data.get("lender") |
| 105 | borrower_name = data.get("borrower") |
| 106 | amount = data.get("amount") |
| 107 | |
| 108 | # Edge Case: Missing required fields |
| 109 | if lender_name is None or borrower_name is None or amount is None: |
| 110 | raise ValueError("'lender', 'borrower', and 'amount' fields are required in payload") |
| 111 | |
| 112 | # Edge Case: Lender and borrower are the same person |
| 113 | if lender_name == borrower_name: |
| 114 | raise ValueError("Lender and borrower cannot be the same person") |
| 115 | |
| 116 | # Edge Case: Negative amount |
| 117 | if amount < 0: |
| 118 | raise ValueError("Amount must be non-negative") |
| 119 | |
| 120 | # Find lender and borrower |
| 121 | lender = None |
| 122 | borrower = None |
| 123 | for user in self.database["users"]: |
| 124 | if user["name"] == lender_name: |
| 125 | lender = user |
| 126 | elif user["name"] == borrower_name: |
| 127 | borrower = user |
| 128 | |
| 129 | # Edge Case: Lender or borrower does not exist |
| 130 | if lender is None or borrower is None: |
| 131 | raise ValueError("Both lender and borrower must exist") |
| 132 | |
| 133 | # Update lender's owed_by |
| 134 | if borrower_name in lender["owed_by"]: |
| 135 | lender["owed_by"][borrower_name] += amount |
| 136 | else: |
| 137 | lender["owed_by"][borrower_name] = amount |
| 138 | |
| 139 | # Update borrower's owes |
| 140 | if lender_name in borrower["owes"]: |
| 141 | borrower["owes"][lender_name] += amount |
| 142 | else: |
| 143 | borrower["owes"][lender_name] = amount |
| 144 | |
| 145 | # Update balances |
| 146 | lender_total_owed = sum(lender["owed_by"].values()) |
| 147 | lender_total_owes = sum(lender["owes"].values()) |
| 148 | lender["balance"] = lender_total_owed - lender_total_owes |
| 149 | |
| 150 | borrower_total_owed = sum(borrower["owed_by"].values()) |
| 151 | borrower_total_owes = sum(borrower["owes"].values()) |
| 152 | borrower["balance"] = borrower_total_owed - borrower_total_owes |
| 153 | |
| 154 | # Return updated users sorted by name |
| 155 | updated_users = sorted([lender, borrower], key=lambda u: u["name"]) |
| 156 | return json.dumps({"users": updated_users}) |
| 157 | |
| 158 | else: |
| 159 | # Edge Case: Invalid URL |
| 160 | raise ValueError(f"Invalid URL: {url}") |
| 161 | |
| 162 | # Handled Edge Cases: Invalid URL |
| 163 | # Handled Edge Cases: Empty user list in payload, Non-existent users in payload, Invalid URL |
| 164 | # Handled Edge Cases: Missing payload, Missing user field in payload, User already exists, Missing payload, |
| 165 | # Missing required fields, Lender and borrower are the same person, Negative amount, Lender or borrower does not exist, Invalid URL |