| 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 | 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 sorted by name |
| 33 | users = [self._create_user_object(user) for user in self.database["users"]] |
| 34 | users.sort(key=lambda x: x["name"]) |
| 35 | return json.dumps({"users": users}) |
| 36 | else: |
| 37 | # Return specified users sorted by name |
| 38 | data = json.loads(payload) |
| 39 | user_names = data.get("users", []) |
| 40 | |
| 41 | # Edge Case: Empty user list in payload |
| 42 | if not user_names: |
| 43 | return json.dumps({"users": []}) |
| 44 | |
| 45 | # Edge Case: Non-existent users in payload |
| 46 | users = [] |
| 47 | for name in user_names: |
| 48 | user = self._find_user(name) |
| 49 | if user is not None: |
| 50 | users.append(self._create_user_object(user)) |
| 51 | |
| 52 | users.sort(key=lambda x: x["name"]) |
| 53 | return json.dumps({"users": users}) |
| 54 | else: |
| 55 | # Edge Case: Invalid URL |
| 56 | raise ValueError(f"Invalid URL: {url}") |
| 57 | |
| 58 | # Handled Edge Cases: Empty user list in payload, Non-existent users in payload, Invalid URL |
| 59 | |
| 8 | 60 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 61 | """ |
| 62 | Handle POST requests to the API. |
| 63 | |
| 64 | Args: |
| 65 | url: The endpoint URL. |
| 66 | payload: JSON payload. |
| 67 | |
| 68 | Returns: |
| 69 | A JSON string response. |
| 70 | |
| 71 | Raises: |
| 72 | ValueError: If the URL is not recognized or if there are issues with the payload. |
| 73 | """ |
| 74 | if url == "/add": |
| 75 | if payload is None: |
| 76 | # Edge Case: Missing payload |
| 77 | raise ValueError("Payload is required for /add endpoint") |
| 78 | |
| 79 | data = json.loads(payload) |
| 80 | user_name = data.get("user") |
| 81 | |
| 82 | # Edge Case: Missing user name in payload |
| 83 | if user_name is None: |
| 84 | raise ValueError("User name is required in payload") |
| 85 | |
| 86 | # Edge Case: User already exists |
| 87 | if self._find_user(user_name) is not None: |
| 88 | raise ValueError(f"User {user_name} already exists") |
| 89 | |
| 90 | new_user = { |
| 91 | "name": user_name, |
| 92 | "owes": {}, |
| 93 | "owed_by": {}, |
| 94 | "balance": 0.0 |
| 95 | } |
| 96 | |
| 97 | self.database["users"].append(new_user) |
| 98 | return json.dumps(self._create_user_object(new_user)) |
| 99 | |
| 100 | elif url == "/iou": |
| 101 | if payload is None: |
| 102 | # Edge Case: Missing payload |
| 103 | raise ValueError("Payload is required for /iou endpoint") |
| 104 | |
| 105 | data = json.loads(payload) |
| 106 | lender_name = data.get("lender") |
| 107 | borrower_name = data.get("borrower") |
| 108 | amount = data.get("amount") |
| 109 | |
| 110 | # Edge Case: Missing required fields in payload |
| 111 | if lender_name is None or borrower_name is None or amount is None: |
| 112 | raise ValueError("Lender, borrower, and amount are required in payload") |
| 113 | |
| 114 | # Edge Case: Lender and borrower are the same person |
| 115 | if lender_name == borrower_name: |
| 116 | raise ValueError("Lender and borrower cannot be the same person") |
| 117 | |
| 118 | lender = self._find_user(lender_name) |
| 119 | borrower = self._find_user(borrower_name) |
| 120 | |
| 121 | # Edge Case: Lender or borrower does not exist |
| 122 | if lender is None or borrower is None: |
| 123 | raise ValueError("Both lender and borrower must exist") |
| 124 | |
| 125 | # Edge Case: Negative amount |
| 126 | if amount < 0: |
| 127 | raise ValueError("Amount must be non-negative") |
| 128 | |
| 129 | # Update lender's owed_by |
| 130 | if borrower_name in lender["owed_by"]: |
| 131 | lender["owed_by"][borrower_name] += amount |
| 132 | else: |
| 133 | lender["owed_by"][borrower_name] = amount |
| 134 | |
| 135 | # Update borrower's owes |
| 136 | if lender_name in borrower["owes"]: |
| 137 | borrower["owes"][lender_name] += amount |
| 138 | else: |
| 139 | borrower["owes"][lender_name] = amount |
| 140 | |
| 141 | # Update balances |
| 142 | lender["balance"] += amount |
| 143 | borrower["balance"] -= amount |
| 144 | |
| 145 | # Create response with updated user objects |
| 146 | updated_users = [ |
| 147 | self._create_user_object(lender), |
| 148 | self._create_user_object(borrower) |
| 149 | ] |
| 150 | updated_users.sort(key=lambda x: x["name"]) |
| 151 | |
| 152 | return json.dumps({"users": updated_users}) |
| 153 | |
| 154 | else: |
| 155 | # Edge Case: Invalid URL |
| 156 | raise ValueError(f"Invalid URL: {url}") |
| 157 | |
| 158 | # Handled Edge Cases: Missing payload, Missing user name in payload, User already exists, |
| 159 | # Missing required fields in payload, Lender and borrower are the same person, |
| 160 | # Lender or borrower does not exist, Negative amount, Invalid URL |
| 161 | |
| 162 | def _find_user(self, name: str): |
| 163 | """ |
| 164 | Find a user by name in the database. |
| 165 | |
| 166 | Args: |
| 167 | name: The name of the user to find. |
| 168 | |
| 169 | Returns: |
| 170 | The user dictionary if found, otherwise None. |
| 171 | """ |
| 172 | for user in self.database["users"]: |
| 173 | if user["name"] == name: |
| 174 | return user |
| 175 | return None |
| 176 | |
| 177 | def _create_user_object(self, user): |
| 178 | """ |
| 179 | Create a user object for API responses. |
| 180 | |
| 181 | Args: |
| 182 | user: The user dictionary from the database. |
| 183 | |
| 184 | Returns: |
| 185 | A dictionary representing the user object for API responses. |
| 186 | """ |
| 187 | # Calculate balance from owes and owed_by |
| 188 | total_owed = sum(user["owes"].values()) |
| 189 | total_owed_by = sum(user["owed_by"].values()) |
| 190 | balance = total_owed_by - total_owed |
| 191 | |
| 192 | return { |
| 193 | "name": user["name"], |
| 194 | "owes": user["owes"], |
| 195 | "owed_by": user["owed_by"], |
| 196 | "balance": balance |
| 197 | } |
| 198 | |
| 199 | # Handled Edge Cases: None in this helper function |