| 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 URL. |
| 23 | payload: Optional JSON payload. |
| 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 with specific users |
| 34 | if payload is not None and payload.strip(): |
| 35 | data = json.loads(payload) |
| 36 | if "users" in data: |
| 37 | # Filter users and sort by name |
| 38 | user_names = set(data["users"]) |
| 39 | users = [user for user in self.database["users"] if user["name"] in user_names] |
| 40 | users.sort(key=lambda x: x["name"]) |
| 41 | return json.dumps({"users": users}) |
| 42 | # Edge Case: Handle request for all users |
| 43 | # Sort all users by name |
| 44 | users = sorted(self.database["users"], key=lambda x: x["name"]) |
| 45 | return json.dumps({"users": users}) |
| 46 | # Edge Case: Handle unknown URL |
| 47 | else: |
| 48 | raise ValueError(f"Unknown GET endpoint: {url}") |
| 49 | |
| 50 | # Handled Edge Cases: /users endpoint, payload with specific users, request for all users, unknown URL |
| 51 | |
| 8 | 52 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 53 | """ |
| 54 | Handle POST requests to the API. |
| 55 | |
| 56 | Args: |
| 57 | url: The endpoint URL. |
| 58 | payload: JSON payload. |
| 59 | |
| 60 | Returns: |
| 61 | JSON string response. |
| 62 | |
| 63 | Raises: |
| 64 | ValueError: If URL is not recognized or if payload is missing/invalid. |
| 65 | """ |
| 66 | # Edge Case: Handle missing payload |
| 67 | if payload is None: |
| 68 | raise ValueError("Payload is required for POST requests") |
| 69 | |
| 70 | data = json.loads(payload) |
| 71 | |
| 72 | # Edge Case: Handle /add endpoint |
| 73 | if url == "/add": |
| 74 | # Edge Case: Handle missing user field |
| 75 | if "user" not in data: |
| 76 | raise ValueError("Missing 'user' field in payload") |
| 77 | |
| 78 | user_name = data["user"] |
| 79 | |
| 80 | # Edge Case: Handle duplicate user - return existing user |
| 81 | for user in self.database["users"]: |
| 82 | if user["name"] == user_name: |
| 83 | return json.dumps(user) |
| 84 | |
| 85 | # Create new user |
| 86 | new_user = { |
| 87 | "name": user_name, |
| 88 | "owes": {}, |
| 89 | "owed_by": {}, |
| 90 | "balance": 0.0 |
| 91 | } |
| 92 | |
| 93 | self.database["users"].append(new_user) |
| 94 | return json.dumps(new_user) |
| 95 | |
| 96 | # Edge Case: Handle /iou endpoint |
| 97 | elif url == "/iou": |
| 98 | # Edge Case: Handle missing required fields |
| 99 | required_fields = ["lender", "borrower", "amount"] |
| 100 | for field in required_fields: |
| 101 | if field not in data: |
| 102 | raise ValueError(f"Missing '{field}' field in payload") |
| 103 | |
| 104 | lender_name = data["lender"] |
| 105 | borrower_name = data["borrower"] |
| 106 | amount = data["amount"] |
| 107 | |
| 108 | # Edge Case: Handle negative amount by reversing roles |
| 109 | if amount < 0: |
| 110 | lender_name, borrower_name = borrower_name, lender_name |
| 111 | amount = -amount |
| 112 | |
| 113 | # Edge Case: Handle same lender and borrower |
| 114 | if lender_name == borrower_name: |
| 115 | raise ValueError("Lender and borrower cannot be the same person") |
| 116 | |
| 117 | # Find or create lender and borrower |
| 118 | lender = None |
| 119 | borrower = None |
| 120 | |
| 121 | for user in self.database["users"]: |
| 122 | if user["name"] == lender_name: |
| 123 | lender = user |
| 124 | elif user["name"] == borrower_name: |
| 125 | borrower = user |
| 126 | |
| 127 | # Edge Case: Create non-existent lender or borrower |
| 128 | if lender is None: |
| 129 | lender = { |
| 130 | "name": lender_name, |
| 131 | "owes": {}, |
| 132 | "owed_by": {}, |
| 133 | "balance": 0.0 |
| 134 | } |
| 135 | self.database["users"].append(lender) |
| 136 | if borrower is None: |
| 137 | borrower = { |
| 138 | "name": borrower_name, |
| 139 | "owes": {}, |
| 140 | "owed_by": {}, |
| 141 | "balance": 0.0 |
| 142 | } |
| 143 | self.database["users"].append(borrower) |
| 144 | |
| 145 | # Update owes and owed_by relationships |
| 146 | # Lender is owed money by borrower |
| 147 | if borrower_name in lender["owed_by"]: |
| 148 | lender["owed_by"][borrower_name] += amount |
| 149 | else: |
| 150 | lender["owed_by"][borrower_name] = amount |
| 151 | |
| 152 | # Borrower owes money to lender |
| 153 | if lender_name in borrower["owes"]: |
| 154 | borrower["owes"][lender_name] += amount |
| 155 | else: |
| 156 | borrower["owes"][lender_name] = amount |
| 157 | |
| 158 | # Recalculate balances |
| 159 | lender_total_owed = sum(lender["owed_by"].values()) |
| 160 | lender_total_owes = sum(lender["owes"].values()) |
| 161 | lender["balance"] = lender_total_owed - lender_total_owes |
| 162 | |
| 163 | borrower_total_owed = sum(borrower["owed_by"].values()) |
| 164 | borrower_total_owes = sum(borrower["owes"].values()) |
| 165 | borrower["balance"] = borrower_total_owed - borrower_total_owes |
| 166 | |
| 167 | # Return updated users sorted by name |
| 168 | users = sorted([lender, borrower], key=lambda x: x["name"]) |
| 169 | return json.dumps({"users": users}) |
| 170 | |
| 171 | # Edge Case: Handle unknown URL |
| 172 | else: |
| 173 | raise ValueError(f"Unknown POST endpoint: {url}") |
| 174 | |
| 175 | # Handled Edge Cases: missing payload, /add endpoint, missing user field, duplicate user, /iou endpoint, |
| 176 | # missing required fields, negative amount, same lender and borrower, non-existent lender or borrower, |
| 177 | # unknown URL |
| 178 | |
| 179 | # Handled Edge Cases: None database, /users endpoint, payload with specific users, request for all users, |
| 180 | # unknown GET URL, missing POST payload, /add endpoint, missing user field, duplicate user, /iou endpoint, |
| 181 | # missing required fields, negative amount, same lender and borrower, non-existent lender or borrower, |
| 182 | # unknown POST URL |