| 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 a database. |
| 7 | |
| 8 | Args: |
| 9 | database: A dictionary containing user data or None to initialize with an empty database. |
| 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 | A 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 |
| 33 | result = {"users": []} |
| 34 | for user in self.database["users"]: |
| 35 | user_copy = user.copy() |
| 36 | user_copy["balance"] = round(user_copy["balance"], 2) |
| 37 | result["users"].append(user_copy) |
| 38 | return json.dumps(result) |
| 39 | else: |
| 40 | # Return specific users |
| 41 | data = json.loads(payload) |
| 42 | user_names = data.get("users") |
| 43 | |
| 44 | # Edge Case: Empty user list in payload or no users specified |
| 45 | if user_names is None or not user_names: |
| 46 | # Return all users when no specific users requested |
| 47 | result = {"users": []} |
| 48 | for user in self.database["users"]: |
| 49 | user_copy = user.copy() |
| 50 | user_copy["balance"] = round(user_copy["balance"], 2) |
| 51 | result["users"].append(user_copy) |
| 52 | # Sort by name |
| 53 | result["users"].sort(key=lambda x: x["name"]) |
| 54 | return json.dumps(result) |
| 55 | |
| 56 | result_users = [] |
| 57 | for user in self.database["users"]: |
| 58 | if user["name"] in user_names: |
| 59 | user_copy = user.copy() |
| 60 | user_copy["balance"] = round(user_copy["balance"], 2) |
| 61 | result_users.append(user_copy) |
| 62 | |
| 63 | # Sort by name |
| 64 | result_users.sort(key=lambda x: x["name"]) |
| 65 | return json.dumps({"users": result_users}) |
| 66 | else: |
| 67 | # Edge Case: Invalid URL |
| 68 | raise ValueError(f"Invalid URL: {url}") |
| 69 | |
| 70 | # Handled Edge Cases: Empty user list in payload, Invalid URL |
| 71 | |
| 8 | 72 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 73 | """ |
| 74 | Handle POST requests to the API. |
| 75 | |
| 76 | Args: |
| 77 | url: The endpoint URL. |
| 78 | payload: JSON payload. |
| 79 | |
| 80 | Returns: |
| 81 | A JSON string response. |
| 82 | |
| 83 | Raises: |
| 84 | ValueError: If the URL is not recognized or if there are issues with the payload. |
| 85 | """ |
| 86 | if url == "/add": |
| 87 | if payload is None: |
| 88 | # Edge Case: Missing payload |
| 89 | raise ValueError("Payload required for /add endpoint") |
| 90 | |
| 91 | data = json.loads(payload) |
| 92 | user_name = data.get("user") |
| 93 | |
| 94 | # Edge Case: Missing user name in payload |
| 95 | if user_name is None: |
| 96 | raise ValueError("User name required in payload") |
| 97 | |
| 98 | # Check if user already exists |
| 99 | for user in self.database["users"]: |
| 100 | if user["name"] == user_name: |
| 101 | # Edge Case: User already exists - return existing user |
| 102 | result_user = user.copy() |
| 103 | result_user["balance"] = round(result_user["balance"], 2) |
| 104 | return json.dumps(result_user) |
| 105 | |
| 106 | # Create new user |
| 107 | new_user = { |
| 108 | "name": user_name, |
| 109 | "owes": {}, |
| 110 | "owed_by": {}, |
| 111 | "balance": 0.0 |
| 112 | } |
| 113 | self.database["users"].append(new_user) |
| 114 | |
| 115 | # Return the new user with rounded balance |
| 116 | result_user = new_user.copy() |
| 117 | result_user["balance"] = round(result_user["balance"], 2) |
| 118 | return json.dumps(result_user) |
| 119 | |
| 120 | elif url == "/iou": |
| 121 | if payload is None: |
| 122 | # Edge Case: Missing payload |
| 123 | raise ValueError("Payload required for /iou endpoint") |
| 124 | |
| 125 | data = json.loads(payload) |
| 126 | lender_name = data.get("lender") |
| 127 | borrower_name = data.get("borrower") |
| 128 | amount = data.get("amount") |
| 129 | |
| 130 | # Edge Case: Missing required fields in payload |
| 131 | if lender_name is None or borrower_name is None or amount is None: |
| 132 | raise ValueError("Lender, borrower, and amount are required in payload") |
| 133 | |
| 134 | # Edge Case: Lender and borrower are the same person |
| 135 | if lender_name == borrower_name: |
| 136 | # Find the user |
| 137 | user = None |
| 138 | for u in self.database["users"]: |
| 139 | if u["name"] == lender_name: |
| 140 | user = u |
| 141 | break |
| 142 | |
| 143 | # Return the user with unchanged balance |
| 144 | if user: |
| 145 | result_user = user.copy() |
| 146 | result_user["balance"] = round(result_user["balance"], 2) |
| 147 | return json.dumps({"users": [result_user]}) |
| 148 | else: |
| 149 | raise ValueError("User not found") |
| 150 | |
| 151 | # Edge Case: Negative amount |
| 152 | if amount < 0: |
| 153 | raise ValueError("Amount must be non-negative") |
| 154 | |
| 155 | # Find lender and borrower |
| 156 | lender = None |
| 157 | borrower = None |
| 158 | for user in self.database["users"]: |
| 159 | if user["name"] == lender_name: |
| 160 | lender = user |
| 161 | elif user["name"] == borrower_name: |
| 162 | borrower = user |
| 163 | |
| 164 | # Edge Case: Lender or borrower not found |
| 165 | if lender is None or borrower is None: |
| 166 | raise ValueError("Lender or borrower not found") |
| 167 | |
| 168 | # Update owes and owed_by for lender |
| 169 | if borrower_name in lender["owes"]: |
| 170 | lender["owes"][borrower_name] -= amount |
| 171 | # Edge Case: If the amount becomes zero or negative, remove the entry |
| 172 | if lender["owes"][borrower_name] <= 0: |
| 173 | if lender["owes"][borrower_name] < 0: |
| 174 | # Lender now owes borrower |
| 175 | amount_owed = -lender["owes"][borrower_name] |
| 176 | lender["owed_by"][borrower_name] = amount_owed |
| 177 | del lender["owes"][borrower_name] |
| 178 | else: |
| 179 | if borrower_name in lender["owed_by"]: |
| 180 | lender["owed_by"][borrower_name] += amount |
| 181 | else: |
| 182 | lender["owed_by"][borrower_name] = amount |
| 183 | |
| 184 | # Update owes and owed_by for borrower |
| 185 | if lender_name in borrower["owes"]: |
| 186 | borrower["owes"][lender_name] += amount |
| 187 | else: |
| 188 | if lender_name in borrower["owed_by"]: |
| 189 | borrower["owed_by"][lender_name] -= amount |
| 190 | # Edge Case: If the amount becomes zero or negative, remove the entry |
| 191 | if borrower["owed_by"][lender_name] <= 0: |
| 192 | if borrower["owed_by"][lender_name] < 0: |
| 193 | # Borrower now owes lender |
| 194 | amount_owed = -borrower["owed_by"][lender_name] |
| 195 | borrower["owes"][lender_name] = amount_owed |
| 196 | del borrower["owed_by"][lender_name] |
| 197 | else: |
| 198 | borrower["owes"][lender_name] = amount |
| 199 | |
| 200 | # Recalculate balances |
| 201 | lender_balance = 0.0 |
| 202 | for owed_amount in lender["owed_by"].values(): |
| 203 | lender_balance += owed_amount |
| 204 | for owes_amount in lender["owes"].values(): |
| 205 | lender_balance -= owes_amount |
| 206 | lender["balance"] = lender_balance |
| 207 | |
| 208 | borrower_balance = 0.0 |
| 209 | for owed_amount in borrower["owed_by"].values(): |
| 210 | borrower_balance += owed_amount |
| 211 | for owes_amount in borrower["owes"].values(): |
| 212 | borrower_balance -= owes_amount |
| 213 | borrower["balance"] = borrower_balance |
| 214 | |
| 215 | # Prepare response |
| 216 | result_users = [] |
| 217 | for user in [lender, borrower]: |
| 218 | user_copy = user.copy() |
| 219 | user_copy["balance"] = round(user_copy["balance"], 2) |
| 220 | result_users.append(user_copy) |
| 221 | |
| 222 | # Sort by name |
| 223 | result_users.sort(key=lambda x: x["name"]) |
| 224 | return json.dumps({"users": result_users}) |
| 225 | |
| 226 | else: |
| 227 | # Edge Case: Invalid URL |
| 228 | raise ValueError(f"Invalid URL: {url}") |
| 229 | |
| 230 | # Handled Edge Cases: Missing payload, Missing user name in payload, User already exists, |
| 231 | # Missing required fields in payload, Lender and borrower are the same person, |
| 232 | # Negative amount, Lender or borrower not found, Invalid URL, |
| 233 | # If the amount becomes zero or negative, remove the entry |