| 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 | # Handle GET requests to /users endpoint |
| 10 | if url == '/users': |
| 11 | # Edge Case: Handle when payload is None - return all users |
| 12 | if payload is None: |
| 13 | # Return all users sorted by name |
| 14 | users = sorted(self.database["users"], key=lambda x: x["name"]) |
| 15 | return json.dumps({"users": users}) |
| 16 | |
| 17 | # Edge Case: Handle when payload is provided but not valid JSON |
| 18 | try: |
| 19 | payload_data = json.loads(payload) |
| 20 | except json.JSONDecodeError: |
| 21 | return json.dumps({"error": "Invalid payload"}) |
| 22 | |
| 23 | # Edge Case: Handle when 'users' key is missing in payload |
| 24 | if "users" not in payload_data: |
| 25 | return json.dumps({"error": "Missing users field"}) |
| 26 | |
| 27 | # Filter users based on the requested names |
| 28 | requested_names = payload_data["users"] |
| 29 | filtered_users = [user for user in self.database["users"] if user["name"] in requested_names] |
| 30 | # Sort by name as required |
| 31 | filtered_users.sort(key=lambda x: x["name"]) |
| 32 | return json.dumps({"users": filtered_users}) |
| 33 | |
| 34 | # Edge Case: Handle unknown endpoints |
| 35 | return json.dumps({"error": "Not found"}) |
| 36 | |
| 8 | 37 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 38 | # Handle POST requests to /add and /iou endpoints |
| 39 | |
| 40 | # Edge Case: Handle when payload is None |
| 41 | if payload is None: |
| 42 | return json.dumps({"error": "Payload required"}) |
| 43 | |
| 44 | # Edge Case: Handle when payload is not valid JSON |
| 45 | try: |
| 46 | payload_data = json.loads(payload) |
| 47 | except json.JSONDecodeError: |
| 48 | return json.dumps({"error": "Invalid payload"}) |
| 49 | |
| 50 | if url == '/add': |
| 51 | # Edge Case: Handle when 'user' key is missing in payload |
| 52 | if "user" not in payload_data: |
| 53 | return json.dumps({"error": "Missing user field"}) |
| 54 | |
| 55 | new_user_name = payload_data["user"] |
| 56 | |
| 57 | # Edge Case: Handle when user already exists |
| 58 | for user in self.database["users"]: |
| 59 | if user["name"] == new_user_name: |
| 60 | return json.dumps({"error": "User already exists"}) |
| 61 | |
| 62 | # Create new user with default values |
| 63 | new_user = { |
| 64 | "name": new_user_name, |
| 65 | "owes": {}, |
| 66 | "owed_by": {}, |
| 67 | "balance": 0.0 |
| 68 | } |
| 69 | |
| 70 | self.database["users"].append(new_user) |
| 71 | return json.dumps(new_user) |
| 72 | |
| 73 | elif url == '/iou': |
| 74 | # Edge Case: Handle missing required fields in payload |
| 75 | required_fields = ["lender", "borrower", "amount"] |
| 76 | for field in required_fields: |
| 77 | if field not in payload_data: |
| 78 | return json.dumps({"error": f"Missing {field} field"}) |
| 79 | |
| 80 | lender_name = payload_data["lender"] |
| 81 | borrower_name = payload_data["borrower"] |
| 82 | amount = payload_data["amount"] |
| 83 | |
| 84 | # Edge Case: Handle when amount is not a positive number |
| 85 | if not isinstance(amount, (int, float)) or amount <= 0: |
| 86 | return json.dumps({"error": "Amount must be positive"}) |
| 87 | |
| 88 | # Edge Case: Handle when lender and borrower are the same person |
| 89 | if lender_name == borrower_name: |
| 90 | return json.dumps({"error": "Cannot create IOU between same user"}) |
| 91 | |
| 92 | # Find lender and borrower in database |
| 93 | lender = None |
| 94 | borrower = None |
| 95 | |
| 96 | for user in self.database["users"]: |
| 97 | if user["name"] == lender_name: |
| 98 | lender = user |
| 99 | elif user["name"] == borrower_name: |
| 100 | borrower = user |
| 101 | |
| 102 | # Edge Case: Handle when lender or borrower doesn't exist |
| 103 | if lender is None or borrower is None: |
| 104 | return json.dumps({"error": "User not found"}) |
| 105 | |
| 106 | # Update owes and owed_by relationships |
| 107 | # Update lender's owed_by |
| 108 | if borrower_name in lender["owed_by"]: |
| 109 | lender["owed_by"][borrower_name] += amount |
| 110 | else: |
| 111 | lender["owed_by"][borrower_name] = amount |
| 112 | |
| 113 | # Update borrower's owes |
| 114 | if lender_name in borrower["owes"]: |
| 115 | borrower["owes"][lender_name] += amount |
| 116 | else: |
| 117 | borrower["owes"][lender_name] = amount |
| 118 | |
| 119 | # Recalculate balances for both users |
| 120 | lender_total_owed = sum(lender["owed_by"].values()) |
| 121 | lender_total_owes = sum(lender["owes"].values()) |
| 122 | lender["balance"] = lender_total_owed - lender_total_owes |
| 123 | |
| 124 | borrower_total_owed = sum(borrower["owed_by"].values()) |
| 125 | borrower_total_owes = sum(borrower["owes"].values()) |
| 126 | borrower["balance"] = borrower_total_owed - borrower_total_owes |
| 127 | |
| 128 | # Return updated user objects sorted by name |
| 129 | updated_users = sorted([lender, borrower], key=lambda x: x["name"]) |
| 130 | return json.dumps({"users": updated_users}) |
| 131 | |
| 132 | # Edge Case: Handle unknown endpoints |
| 133 | return json.dumps({"error": "Not found"}) |
| 134 | |
| 135 | # Handled Edge Cases: |
| 136 | # - GET /users with None payload (return all users) |
| 137 | # - GET /users with invalid JSON payload |
| 138 | # - GET /users with missing 'users' field |
| 139 | # - Unknown GET endpoints |
| 140 | # - POST with None payload |
| 141 | # - POST with invalid JSON payload |
| 142 | # - POST /add with missing 'user' field |
| 143 | # - POST /add with existing user |
| 144 | # - POST /iou with missing required fields |
| 145 | # - POST /iou with non-positive amount |
| 146 | # - POST /iou with same lender and borrower |
| 147 | # - POST /iou with non-existent users |
| 148 | # - Unknown POST endpoints |