| 1 | import json |
| 2 | |
| 1 | 3 | class RestAPI: |
| 2 | 4 | def __init__(self, database: dict | None = None): |
| 3 | | pass |
| 4 | | |
| 5 | # Initialize the database with provided data or empty dict |
| 6 | self.database = database if database is not None else {"users": []} |
| 7 | |
| 5 | 8 | def get(self, url: str, payload: str | None = None) -> str: |
| 6 | | pass |
| 7 | | |
| 9 | # Edge Case: Handle invalid URL |
| 10 | if url != "/users": |
| 11 | return json.dumps({"error": "Invalid URL"}) |
| 12 | |
| 13 | # Edge Case: Handle invalid payload format |
| 14 | if payload is not None: |
| 15 | try: |
| 16 | payload_data = json.loads(payload) |
| 17 | except json.JSONDecodeError: |
| 18 | return json.dumps({"error": "Invalid payload format"}) |
| 19 | else: |
| 20 | payload_data = None |
| 21 | |
| 22 | # Get all users from database |
| 23 | all_users = self.database["users"] |
| 24 | |
| 25 | # Edge Case: Handle request for all users when no filter is provided |
| 26 | if payload_data is None or "users" not in payload_data: |
| 27 | # Calculate balance for each user |
| 28 | result_users = [] |
| 29 | for user in all_users: |
| 30 | owed_to_user = sum(user.get("owed_by", {}).values()) |
| 31 | owed_by_user = sum(user.get("owes", {}).values()) |
| 32 | balance = owed_to_user - owed_by_user |
| 33 | user_copy = user.copy() |
| 34 | user_copy["balance"] = balance |
| 35 | result_users.append(user_copy) |
| 36 | return json.dumps({"users": result_users}) |
| 37 | |
| 38 | # Edge Case: Handle request for specific users |
| 39 | requested_names = payload_data["users"] |
| 40 | result_users = [] |
| 41 | |
| 42 | # Find requested users |
| 43 | for user in all_users: |
| 44 | if user["name"] in requested_names: |
| 45 | owed_to_user = sum(user.get("owed_by", {}).values()) |
| 46 | owed_by_user = sum(user.get("owes", {}).values()) |
| 47 | balance = owed_to_user - owed_by_user |
| 48 | user_copy = user.copy() |
| 49 | user_copy["balance"] = balance |
| 50 | result_users.append(user_copy) |
| 51 | |
| 52 | # Sort by name |
| 53 | result_users.sort(key=lambda x: x["name"]) |
| 54 | return json.dumps({"users": result_users}) |
| 55 | |
| 8 | 56 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 57 | # Edge Case: Handle invalid payload format |
| 58 | if payload is None: |
| 59 | return json.dumps({"error": "Payload required"}) |
| 60 | |
| 61 | try: |
| 62 | payload_data = json.loads(payload) |
| 63 | except json.JSONDecodeError: |
| 64 | return json.dumps({"error": "Invalid payload format"}) |
| 65 | |
| 66 | # Handle /add endpoint |
| 67 | if url == "/add": |
| 68 | # Edge Case: Handle missing user field |
| 69 | if "user" not in payload_data: |
| 70 | return json.dumps({"error": "User field required"}) |
| 71 | |
| 72 | new_user_name = payload_data["user"] |
| 73 | |
| 74 | # Edge Case: Handle duplicate user |
| 75 | for user in self.database["users"]: |
| 76 | if user["name"] == new_user_name: |
| 77 | return json.dumps({"error": "User already exists"}) |
| 78 | |
| 79 | # Create new user |
| 80 | new_user = { |
| 81 | "name": new_user_name, |
| 82 | "owes": {}, |
| 83 | "owed_by": {}, |
| 84 | "balance": 0.0 |
| 85 | } |
| 86 | |
| 87 | self.database["users"].append(new_user) |
| 88 | return json.dumps(new_user) |
| 89 | |
| 90 | # Handle /iou endpoint |
| 91 | elif url == "/iou": |
| 92 | # Edge Case: Handle missing required fields |
| 93 | required_fields = ["lender", "borrower", "amount"] |
| 94 | for field in required_fields: |
| 95 | if field not in payload_data: |
| 96 | return json.dumps({"error": f"{field} field required"}) |
| 97 | |
| 98 | lender_name = payload_data["lender"] |
| 99 | borrower_name = payload_data["borrower"] |
| 100 | amount = payload_data["amount"] |
| 101 | |
| 102 | # Edge Case: Handle invalid amount type |
| 103 | if not isinstance(amount, (int, float)): |
| 104 | return json.dumps({"error": "Invalid amount"}) |
| 105 | |
| 106 | # Edge Case: Handle negative amount |
| 107 | if amount < 0: |
| 108 | return json.dumps({"error": "Amount must be positive"}) |
| 109 | |
| 110 | # Edge Case: Handle lender and borrower being the same person |
| 111 | if lender_name == borrower_name: |
| 112 | return json.dumps({"error": "Lender and borrower cannot be the same"}) |
| 113 | |
| 114 | # Find lender and borrower |
| 115 | lender = None |
| 116 | borrower = None |
| 117 | |
| 118 | for user in self.database["users"]: |
| 119 | if user["name"] == lender_name: |
| 120 | lender = user |
| 121 | elif user["name"] == borrower_name: |
| 122 | borrower = user |
| 123 | |
| 124 | # Edge Case: Handle lender not found |
| 125 | if lender is None: |
| 126 | return json.dumps({"error": "Lender not found"}) |
| 127 | |
| 128 | # Edge Case: Handle borrower not found |
| 129 | if borrower is None: |
| 130 | return json.dumps({"error": "Borrower not found"}) |
| 131 | |
| 132 | # Update lender's owed_by |
| 133 | if borrower_name in lender["owed_by"]: |
| 134 | lender["owed_by"][borrower_name] += amount |
| 135 | else: |
| 136 | lender["owed_by"][borrower_name] = amount |
| 137 | |
| 138 | # Update borrower's owes |
| 139 | if lender_name in borrower["owes"]: |
| 140 | borrower["owes"][lender_name] += amount |
| 141 | else: |
| 142 | borrower["owes"][lender_name] = amount |
| 143 | |
| 144 | # Calculate balances |
| 145 | lender_owed_to = sum(lender.get("owed_by", {}).values()) |
| 146 | lender_owed_by = sum(lender.get("owes", {}).values()) |
| 147 | lender_balance = lender_owed_to - lender_owed_by |
| 148 | lender["balance"] = lender_balance |
| 149 | |
| 150 | borrower_owed_to = sum(borrower.get("owed_by", {}).values()) |
| 151 | borrower_owed_by = sum(borrower.get("owes", {}).values()) |
| 152 | borrower_balance = borrower_owed_to - borrower_owed_by |
| 153 | borrower["balance"] = borrower_balance |
| 154 | |
| 155 | # Return updated users sorted by name |
| 156 | result_users = [lender, borrower] |
| 157 | result_users.sort(key=lambda x: x["name"]) |
| 158 | |
| 159 | # Create copies without balance field for response |
| 160 | result_copies = [] |
| 161 | for user in result_users: |
| 162 | user_copy = user.copy() |
| 163 | result_copies.append(user_copy) |
| 164 | |
| 165 | return json.dumps({"users": result_copies}) |
| 166 | |
| 167 | # Edge Case: Handle invalid URL |
| 168 | else: |
| 169 | return json.dumps({"error": "Invalid URL"}) |
| 170 | |
| 171 | # Handled Edge Cases: Invalid URL, invalid payload format, missing user field, duplicate user, missing required fields, invalid amount type, negative amount, lender/borrower being the same person, lender not found, borrower not found |