| 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. |
| 10 | """ |
| 11 | # Edge Case: Handle None database by initializing empty structure |
| 12 | if database is None: |
| 13 | self.database = {"users": []} |
| 14 | else: |
| 15 | self.database = database |
| 16 | |
| 5 | 17 | def get(self, url: str, payload: str | None = None) -> str: |
| 6 | | pass |
| 7 | | |
| 18 | """ |
| 19 | Handle GET requests to the API. |
| 20 | |
| 21 | Args: |
| 22 | url: The endpoint being accessed. |
| 23 | payload: Optional JSON payload with request parameters. |
| 24 | |
| 25 | Returns: |
| 26 | JSON string response. |
| 27 | |
| 28 | Raises: |
| 29 | ValueError: If URL is not recognized. |
| 30 | """ |
| 31 | # Edge Case: Handle /users endpoint |
| 32 | if url == "/users": |
| 33 | # Edge Case: Handle payload filtering |
| 34 | if payload is not None: |
| 35 | data = json.loads(payload) |
| 36 | if "users" in data: |
| 37 | # Filter users by provided list |
| 38 | filtered_users = [user for user in self.database["users"] if user["name"] in data["users"]] |
| 39 | # Sort by name |
| 40 | filtered_users.sort(key=lambda x: x["name"]) |
| 41 | return json.dumps({"users": filtered_users}) |
| 42 | # Return all users sorted by name |
| 43 | sorted_users = sorted(self.database["users"], key=lambda x: x["name"]) |
| 44 | return json.dumps({"users": sorted_users}) |
| 45 | # Edge Case: Handle unknown URLs |
| 46 | else: |
| 47 | raise ValueError(f"Unknown URL: {url}") |
| 48 | # Handled Edge Cases: /users endpoint, payload filtering, unknown URLs |
| 49 | |
| 8 | 50 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 51 | """ |
| 52 | Handle POST requests to the API. |
| 53 | |
| 54 | Args: |
| 55 | url: The endpoint being accessed. |
| 56 | payload: JSON payload with request data. |
| 57 | |
| 58 | Returns: |
| 59 | JSON string response. |
| 60 | |
| 61 | Raises: |
| 62 | ValueError: If URL is not recognized or if data is invalid. |
| 63 | """ |
| 64 | # Edge Case: Handle None payload |
| 65 | if payload is None: |
| 66 | raise ValueError("Payload is required") |
| 67 | |
| 68 | data = json.loads(payload) |
| 69 | |
| 70 | # Edge Case: Handle /add endpoint |
| 71 | if url == "/add": |
| 72 | # Edge Case: Check if user field exists |
| 73 | if "user" not in data: |
| 74 | raise ValueError("User field is required") |
| 75 | |
| 76 | user_name = data["user"] |
| 77 | |
| 78 | # Edge Case: Check if user already exists |
| 79 | for user in self.database["users"]: |
| 80 | if user["name"] == user_name: |
| 81 | raise ValueError(f"User {user_name} already exists") |
| 82 | |
| 83 | # Create new user |
| 84 | new_user = { |
| 85 | "name": user_name, |
| 86 | "owes": {}, |
| 87 | "owed_by": {}, |
| 88 | "balance": 0.0 |
| 89 | } |
| 90 | |
| 91 | self.database["users"].append(new_user) |
| 92 | return json.dumps(new_user) |
| 93 | |
| 94 | # Edge Case: Handle /iou endpoint |
| 95 | elif url == "/iou": |
| 96 | # Edge Case: Validate required fields |
| 97 | required_fields = ["lender", "borrower", "amount"] |
| 98 | for field in required_fields: |
| 99 | if field not in data: |
| 100 | raise ValueError(f"Missing required field: {field}") |
| 101 | |
| 102 | lender_name = data["lender"] |
| 103 | borrower_name = data["borrower"] |
| 104 | amount = data["amount"] |
| 105 | |
| 106 | # Edge Case: Validate amount is positive |
| 107 | if amount <= 0: |
| 108 | raise ValueError("Amount must be positive") |
| 109 | |
| 110 | # Edge Case: Validate lender and borrower are different |
| 111 | if lender_name == borrower_name: |
| 112 | raise ValueError("Lender and borrower must be different") |
| 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: Validate both users exist |
| 125 | if lender is None: |
| 126 | raise ValueError(f"User {lender_name} does not exist") |
| 127 | if borrower is None: |
| 128 | raise ValueError(f"User {borrower_name} does not exist") |
| 129 | |
| 130 | # Update IOUs |
| 131 | # If lender is owed by borrower, adjust that amount |
| 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 | # If borrower owes lender, adjust that amount |
| 138 | if lender_name in borrower["owes"]: |
| 139 | borrower["owes"][lender_name] += amount |
| 140 | else: |
| 141 | borrower["owes"][lender_name] = amount |
| 142 | |
| 143 | # If borrower is owed by lender, we need to net the amounts |
| 144 | if borrower_name in lender["owes"]: |
| 145 | # Edge Case: Handle netting of debts |
| 146 | lender_owes_borrower = lender["owes"][borrower_name] |
| 147 | lender_owed_by_borrower = lender["owed_by"][borrower_name] |
| 148 | |
| 149 | if lender_owes_borrower > lender_owed_by_borrower: |
| 150 | # Net down the owes amount |
| 151 | lender["owes"][borrower_name] = lender_owes_borrower - lender_owed_by_borrower |
| 152 | # Remove the owed_by entry |
| 153 | del lender["owed_by"][borrower_name] |
| 154 | # Update borrower's records |
| 155 | del borrower["owes"][lender_name] |
| 156 | borrower["owed_by"][lender_name] = lender_owes_borrower - lender_owed_by_borrower |
| 157 | elif lender_owes_borrower < lender_owed_by_borrower: |
| 158 | # Net down the owed_by amount |
| 159 | lender["owed_by"][borrower_name] = lender_owed_by_borrower - lender_owes_borrower |
| 160 | # Remove the owes entry |
| 161 | del lender["owes"][borrower_name] |
| 162 | # Update borrower's records |
| 163 | del borrower["owed_by"][lender_name] |
| 164 | borrower["owes"][lender_name] = lender_owed_by_borrower - lender_owes_borrower |
| 165 | else: # Equal amounts |
| 166 | # Remove both entries |
| 167 | del lender["owes"][borrower_name] |
| 168 | del lender["owed_by"][borrower_name] |
| 169 | del borrower["owes"][lender_name] |
| 170 | del borrower["owed_by"][lender_name] |
| 171 | |
| 172 | # Recalculate balances |
| 173 | lender_total_owed = sum(lender["owed_by"].values()) |
| 174 | lender_total_owes = sum(lender["owes"].values()) |
| 175 | lender["balance"] = lender_total_owed - lender_total_owes |
| 176 | |
| 177 | borrower_total_owed = sum(borrower["owed_by"].values()) |
| 178 | borrower_total_owes = sum(borrower["owes"].values()) |
| 179 | borrower["balance"] = borrower_total_owed - borrower_total_owes |
| 180 | |
| 181 | # Return updated users sorted by name |
| 182 | updated_users = [lender, borrower] |
| 183 | updated_users.sort(key=lambda x: x["name"]) |
| 184 | return json.dumps({"users": updated_users}) |
| 185 | |
| 186 | # Edge Case: Handle unknown URLs |
| 187 | else: |
| 188 | raise ValueError(f"Unknown URL: {url}") |
| 189 | # Handled Edge Cases: None payload, /add endpoint, /iou endpoint, missing fields, |
| 190 | # negative amounts, same lender/borrower, non-existent users, |
| 191 | # netting of debts, unknown URLs |