| 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 | self.database = database if database is not None else {"users": []} |
| 12 | # Ensure all users have the required fields |
| 13 | for user in self.database["users"]: |
| 14 | if "owes" not in user: |
| 15 | user["owes"] = {} |
| 16 | if "owed_by" not in user: |
| 17 | user["owed_by"] = {} |
| 18 | if "balance" not in user: |
| 19 | user["balance"] = 0.0 |
| 20 | |
| 5 | 21 | def get(self, url: str, payload: str | None = None) -> str: |
| 6 | | pass |
| 7 | | |
| 22 | """ |
| 23 | Handle GET requests to the API. |
| 24 | |
| 25 | Args: |
| 26 | url: The endpoint URL. |
| 27 | payload: Optional JSON payload. |
| 28 | |
| 29 | Returns: |
| 30 | JSON string response. |
| 31 | """ |
| 32 | if url == "/users": |
| 33 | if payload is None: |
| 34 | # Return all users sorted by name |
| 35 | users = sorted(self.database["users"], key=lambda x: x["name"]) |
| 36 | return json.dumps({"users": users}) |
| 37 | else: |
| 38 | # Return specific users |
| 39 | data = json.loads(payload) |
| 40 | user_names = data.get("users", []) |
| 41 | |
| 42 | # Edge Case: Empty user list in payload |
| 43 | if not user_names: |
| 44 | return json.dumps({"users": []}) |
| 45 | |
| 46 | # Filter users by name |
| 47 | result_users = [user for user in self.database["users"] if user["name"] in user_names] |
| 48 | # Sort by name |
| 49 | result_users = sorted(result_users, key=lambda x: x["name"]) |
| 50 | |
| 51 | # Edge Case: Some requested users don't exist |
| 52 | if len(result_users) != len(user_names): |
| 53 | # Only return users that exist |
| 54 | pass # We'll return what we have |
| 55 | |
| 56 | return json.dumps({"users": result_users}) |
| 57 | |
| 58 | # Edge Case: Invalid URL |
| 59 | return json.dumps({"error": "Invalid URL"}) |
| 60 | |
| 8 | 61 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 62 | """ |
| 63 | Handle POST requests to the API. |
| 64 | |
| 65 | Args: |
| 66 | url: The endpoint URL. |
| 67 | payload: JSON payload. |
| 68 | |
| 69 | Returns: |
| 70 | JSON string response. |
| 71 | """ |
| 72 | if payload is None: |
| 73 | # Edge Case: Missing payload |
| 74 | return json.dumps({"error": "Payload required"}) |
| 75 | |
| 76 | data = json.loads(payload) |
| 77 | |
| 78 | if url == "/add": |
| 79 | user_name = data.get("user") |
| 80 | |
| 81 | # Edge Case: Missing user name |
| 82 | if not user_name: |
| 83 | return json.dumps({"error": "User name required"}) |
| 84 | |
| 85 | # Edge Case: User already exists |
| 86 | for user in self.database["users"]: |
| 87 | if user["name"] == user_name: |
| 88 | return json.dumps({"error": "User already exists"}) |
| 89 | |
| 90 | # Create new user |
| 91 | new_user = { |
| 92 | "name": user_name, |
| 93 | "owes": {}, |
| 94 | "owed_by": {}, |
| 95 | "balance": 0.0 |
| 96 | } |
| 97 | self.database["users"].append(new_user) |
| 98 | return json.dumps(new_user) |
| 99 | |
| 100 | elif url == "/iou": |
| 101 | lender_name = data.get("lender") |
| 102 | borrower_name = data.get("borrower") |
| 103 | amount = data.get("amount") |
| 104 | |
| 105 | # Edge Case: Missing required fields |
| 106 | if not lender_name or not borrower_name or amount is None: |
| 107 | return json.dumps({"error": "Lender, borrower, and amount required"}) |
| 108 | |
| 109 | # Edge Case: Lender and borrower are the same |
| 110 | if lender_name == borrower_name: |
| 111 | return json.dumps({"error": "Lender and borrower cannot be the same"}) |
| 112 | |
| 113 | # Edge Case: Negative amount |
| 114 | if amount < 0: |
| 115 | return json.dumps({"error": "Amount must be positive"}) |
| 116 | |
| 117 | # Find lender and borrower |
| 118 | lender = None |
| 119 | borrower = None |
| 120 | for user in self.database["users"]: |
| 121 | if user["name"] == lender_name: |
| 122 | lender = user |
| 123 | if user["name"] == borrower_name: |
| 124 | borrower = user |
| 125 | |
| 126 | # Edge Case: Lender or borrower doesn't exist |
| 127 | if not lender or not borrower: |
| 128 | return json.dumps({"error": "Lender or borrower does not exist"}) |
| 129 | |
| 130 | # Update IOUs |
| 131 | # Update lender's owed_by |
| 132 | if borrower_name in lender["owed_by"]: |
| 133 | lender["owed_by"][borrower_name] += amount |
| 134 | else: |
| 135 | lender["owed_by"][borrower_name] = amount |
| 136 | |
| 137 | # Update borrower's owes |
| 138 | if lender_name in borrower["owes"]: |
| 139 | borrower["owes"][lender_name] += amount |
| 140 | else: |
| 141 | borrower["owes"][lender_name] = amount |
| 142 | |
| 143 | # Recalculate balances |
| 144 | lender_total_owed = sum(lender["owed_by"].values()) |
| 145 | lender_total_owes = sum(lender["owes"].values()) |
| 146 | lender["balance"] = lender_total_owed - lender_total_owes |
| 147 | |
| 148 | borrower_total_owed = sum(borrower["owed_by"].values()) |
| 149 | borrower_total_owes = sum(borrower["owes"].values()) |
| 150 | borrower["balance"] = borrower_total_owed - borrower_total_owes |
| 151 | |
| 152 | # Return updated users sorted by name |
| 153 | result_users = sorted([lender, borrower], key=lambda x: x["name"]) |
| 154 | return json.dumps({"users": result_users}) |
| 155 | |
| 156 | # Edge Case: Invalid URL |
| 157 | return json.dumps({"error": "Invalid URL"}) |
| 158 | |
| 159 | # Handled Edge Cases: Invalid URL, Missing payload, Missing user name, User already exists, Missing required fields, |
| 160 | # Lender and borrower are the same, Negative amount, Lender or borrower doesn't exist, Empty user list in payload, |
| 161 | # Some requested users don't exist |