| 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 | # Parse payload if provided |
| 14 | if payload is not None: |
| 15 | try: |
| 16 | data = json.loads(payload) |
| 17 | except json.JSONDecodeError: |
| 18 | # Edge Case: Handle invalid JSON in payload |
| 19 | return json.dumps({"error": "Invalid JSON"}) |
| 20 | |
| 21 | # Edge Case: Handle missing 'users' key in payload |
| 22 | if "users" not in data: |
| 23 | return json.dumps({"error": "Missing users key"}) |
| 24 | |
| 25 | # Filter users based on provided list |
| 26 | user_names = data["users"] |
| 27 | users = [user for user in self.database["users"] if user["name"] in user_names] |
| 28 | # Sort by name |
| 29 | users.sort(key=lambda x: x["name"]) |
| 30 | else: |
| 31 | # Return all users if no payload |
| 32 | users = self.database["users"].copy() |
| 33 | # Sort by name |
| 34 | users.sort(key=lambda x: x["name"]) |
| 35 | |
| 36 | return json.dumps({"users": users}) |
| 37 | # Handled Edge Cases: Invalid URL, invalid JSON, missing 'users' key |
| 38 | |
| 8 | 39 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 40 | # Edge Case: Handle missing payload |
| 41 | if payload is None: |
| 42 | return json.dumps({"error": "Payload required"}) |
| 43 | |
| 44 | # Parse payload |
| 45 | try: |
| 46 | data = json.loads(payload) |
| 47 | except json.JSONDecodeError: |
| 48 | # Edge Case: Handle invalid JSON in payload |
| 49 | return json.dumps({"error": "Invalid JSON"}) |
| 50 | |
| 51 | if url == "/add": |
| 52 | # Edge Case: Handle missing 'user' key |
| 53 | if "user" not in data: |
| 54 | return json.dumps({"error": "Missing user key"}) |
| 55 | |
| 56 | user_name = data["user"] |
| 57 | |
| 58 | # Edge Case: Handle non-string user name |
| 59 | if not isinstance(user_name, str): |
| 60 | return json.dumps({"error": "User name must be a string"}) |
| 61 | |
| 62 | # Edge Case: Handle duplicate user - return existing user |
| 63 | for user in self.database["users"]: |
| 64 | if user["name"] == user_name: |
| 65 | return json.dumps(user) |
| 66 | |
| 67 | # Create new user |
| 68 | new_user = { |
| 69 | "name": user_name, |
| 70 | "owes": {}, |
| 71 | "owed_by": {}, |
| 72 | "balance": 0.0 |
| 73 | } |
| 74 | |
| 75 | self.database["users"].append(new_user) |
| 76 | return json.dumps(new_user) |
| 77 | # Handled Edge Cases: Missing payload, invalid JSON, missing 'user' key, non-string user name, duplicate user |
| 78 | |
| 79 | elif url == "/iou": |
| 80 | # Edge Case: Handle missing required keys |
| 81 | required_keys = ["lender", "borrower", "amount"] |
| 82 | for key in required_keys: |
| 83 | if key not in data: |
| 84 | return json.dumps({"error": f"Missing {key} key"}) |
| 85 | |
| 86 | lender_name = data["lender"] |
| 87 | borrower_name = data["borrower"] |
| 88 | amount = data["amount"] |
| 89 | |
| 90 | # Edge Case: Handle non-string lender or borrower |
| 91 | if not isinstance(lender_name, str) or not isinstance(borrower_name, str): |
| 92 | return json.dumps({"error": "Lender and borrower must be strings"}) |
| 93 | |
| 94 | # Edge Case: Handle non-numeric amount |
| 95 | if not isinstance(amount, (int, float)): |
| 96 | return json.dumps({"error": "Amount must be a number"}) |
| 97 | |
| 98 | # Edge Case: Handle negative amount |
| 99 | if amount < 0: |
| 100 | return json.dumps({"error": "Amount must be positive"}) |
| 101 | |
| 102 | # Edge Case: Handle same lender and borrower |
| 103 | if lender_name == borrower_name: |
| 104 | return json.dumps({"error": "Lender and borrower cannot be the same"}) |
| 105 | |
| 106 | # Find lender and borrower |
| 107 | lender = None |
| 108 | borrower = None |
| 109 | for user in self.database["users"]: |
| 110 | if user["name"] == lender_name: |
| 111 | lender = user |
| 112 | elif user["name"] == borrower_name: |
| 113 | borrower = user |
| 114 | |
| 115 | # Edge Case: Auto-create missing users |
| 116 | if lender is None: |
| 117 | lender = { |
| 118 | "name": lender_name, |
| 119 | "owes": {}, |
| 120 | "owed_by": {}, |
| 121 | "balance": 0.0 |
| 122 | } |
| 123 | self.database["users"].append(lender) |
| 124 | |
| 125 | if borrower is None: |
| 126 | borrower = { |
| 127 | "name": borrower_name, |
| 128 | "owes": {}, |
| 129 | "owed_by": {}, |
| 130 | "balance": 0.0 |
| 131 | } |
| 132 | self.database["users"].append(borrower) |
| 133 | |
| 134 | # Update owes and owed_by |
| 135 | # Update lender's owed_by |
| 136 | if borrower_name in lender["owed_by"]: |
| 137 | lender["owed_by"][borrower_name] += amount |
| 138 | else: |
| 139 | lender["owed_by"][borrower_name] = amount |
| 140 | |
| 141 | # Update borrower's owes |
| 142 | if lender_name in borrower["owes"]: |
| 143 | borrower["owes"][lender_name] += amount |
| 144 | else: |
| 145 | borrower["owes"][lender_name] = amount |
| 146 | |
| 147 | # Recalculate balances |
| 148 | lender_balance = 0.0 |
| 149 | borrower_balance = 0.0 |
| 150 | |
| 151 | # Lender balance: amount owed by others minus amount owed to others |
| 152 | for owed_amount in lender["owed_by"].values(): |
| 153 | lender_balance += owed_amount |
| 154 | for owes_amount in lender["owes"].values(): |
| 155 | lender_balance -= owes_amount |
| 156 | |
| 157 | # Borrower balance: amount owed by others minus amount owed to others |
| 158 | for owed_amount in borrower["owed_by"].values(): |
| 159 | borrower_balance += owed_amount |
| 160 | for owes_amount in borrower["owes"].values(): |
| 161 | borrower_balance -= owes_amount |
| 162 | |
| 163 | lender["balance"] = lender_balance |
| 164 | borrower["balance"] = borrower_balance |
| 165 | |
| 166 | # Return updated users, sorted by name |
| 167 | users = [lender, borrower] |
| 168 | users.sort(key=lambda x: x["name"]) |
| 169 | return json.dumps({"users": users}) |
| 170 | # Handled Edge Cases: Missing payload, invalid JSON, missing required keys, non-string lender/borrower, |
| 171 | # non-numeric amount, negative amount, same lender and borrower, lender or borrower not found |
| 172 | |
| 173 | else: |
| 174 | # Edge Case: Handle invalid URL |
| 175 | return json.dumps({"error": "Invalid URL"}) |
| 176 | # Handled Edge Cases: Invalid URL |
| 177 | |
| 178 | def _get_user(self, name: str): |
| 179 | """Helper method to get a user by name""" |
| 180 | for user in self.database["users"]: |
| 181 | if user["name"] == name: |
| 182 | return user |
| 183 | return None |
| 184 | # Handled Edge Cases: User not found |