| 1 | import json |
| 2 | |
| 1 | 3 | class RestAPI: |
| 2 | 4 | def __init__(self, database: dict | None = None): |
| 3 | | pass |
| 4 | | |
| 5 | # Edge Case: Handle None database by initializing empty structure |
| 6 | if database is None: |
| 7 | self.database = {"users": []} |
| 8 | else: |
| 9 | self.database = database |
| 10 | |
| 5 | 11 | def get(self, url: str, payload: str | None = None) -> str: |
| 6 | | pass |
| 7 | | |
| 12 | if url == "/users": |
| 13 | # Edge Case: Handle GET /users with no payload - return all users |
| 14 | if payload is None: |
| 15 | return json.dumps({"users": sorted(self.database["users"], key=lambda x: x["name"])}) |
| 16 | else: |
| 17 | # Edge Case: Handle GET /users with payload - return specified users |
| 18 | data = json.loads(payload) |
| 19 | user_names = data.get("users", []) |
| 20 | result_users = [user for user in self.database["users"] if user["name"] in user_names] |
| 21 | result_users.sort(key=lambda x: x["name"]) |
| 22 | return json.dumps({"users": result_users}) |
| 23 | # Edge Case: Handle unknown URL |
| 24 | return json.dumps({"error": "Not found"}) |
| 25 | |
| 8 | 26 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 27 | if payload is None: |
| 28 | # Edge Case: Handle POST with no payload |
| 29 | return json.dumps({"error": "Payload required"}) |
| 30 | |
| 31 | data = json.loads(payload) |
| 32 | |
| 33 | if url == "/add": |
| 34 | user_name = data.get("user") |
| 35 | # Edge Case: Handle missing user name in /add |
| 36 | if user_name is None: |
| 37 | return json.dumps({"error": "User name required"}) |
| 38 | |
| 39 | # Edge Case: Handle duplicate user name in /add |
| 40 | for user in self.database["users"]: |
| 41 | if user["name"] == user_name: |
| 42 | return json.dumps({"error": "User already exists"}) |
| 43 | |
| 44 | new_user = { |
| 45 | "name": user_name, |
| 46 | "owes": {}, |
| 47 | "owed_by": {}, |
| 48 | "balance": 0.0 |
| 49 | } |
| 50 | self.database["users"].append(new_user) |
| 51 | return json.dumps(new_user) |
| 52 | |
| 53 | elif url == "/iou": |
| 54 | lender_name = data.get("lender") |
| 55 | borrower_name = data.get("borrower") |
| 56 | amount = data.get("amount") |
| 57 | |
| 58 | # Edge Case: Handle missing fields in /iou |
| 59 | if lender_name is None or borrower_name is None or amount is None: |
| 60 | return json.dumps({"error": "Lender, borrower, and amount are required"}) |
| 61 | |
| 62 | # Edge Case: Handle lender and borrower being the same person |
| 63 | if lender_name == borrower_name: |
| 64 | # Find the user |
| 65 | user = None |
| 66 | for u in self.database["users"]: |
| 67 | if u["name"] == lender_name: |
| 68 | user = u |
| 69 | break |
| 70 | # Return the user in a list |
| 71 | if user: |
| 72 | return json.dumps({"users": [user]}) |
| 73 | else: |
| 74 | return json.dumps({"error": "User does not exist"}) |
| 75 | |
| 76 | # Handle negative amount by swapping lender and borrower |
| 77 | if amount < 0: |
| 78 | lender_name, borrower_name = borrower_name, lender_name |
| 79 | amount = -amount |
| 80 | |
| 81 | # Find lender and borrower |
| 82 | lender = None |
| 83 | borrower = None |
| 84 | for user in self.database["users"]: |
| 85 | if user["name"] == lender_name: |
| 86 | lender = user |
| 87 | elif user["name"] == borrower_name: |
| 88 | borrower = user |
| 89 | |
| 90 | # Edge Case: Handle lender or borrower not existing |
| 91 | if lender is None or borrower is None: |
| 92 | # Return empty users list as expected by tests |
| 93 | return json.dumps({"users": []}) |
| 94 | |
| 95 | # Handle zero amount - don't create entries |
| 96 | if amount == 0: |
| 97 | # Return updated users sorted by name |
| 98 | result_users = sorted([lender, borrower], key=lambda x: x["name"]) |
| 99 | return json.dumps({"users": result_users}) |
| 100 | |
| 101 | # Update lender's owed_by |
| 102 | if borrower_name in lender["owed_by"]: |
| 103 | lender["owed_by"][borrower_name] += amount |
| 104 | else: |
| 105 | lender["owed_by"][borrower_name] = amount |
| 106 | |
| 107 | # Update borrower's owes |
| 108 | if lender_name in borrower["owes"]: |
| 109 | borrower["owes"][lender_name] += amount |
| 110 | else: |
| 111 | borrower["owes"][lender_name] = amount |
| 112 | |
| 113 | # Remove zero entries from owes/owed_by |
| 114 | lender["owes"] = {k: v for k, v in lender["owes"].items() if v != 0} |
| 115 | lender["owed_by"] = {k: v for k, v in lender["owed_by"].items() if v != 0} |
| 116 | borrower["owes"] = {k: v for k, v in borrower["owes"].items() if v != 0} |
| 117 | borrower["owed_by"] = {k: v for k, v in borrower["owed_by"].items() if v != 0} |
| 118 | |
| 119 | # Update balances |
| 120 | lender_total_owed = sum(lender["owed_by"].values()) |
| 121 | lender_total_owes = sum(lender["owes"].values()) |
| 122 | lender["balance"] = round(lender_total_owed - lender_total_owes, 2) |
| 123 | |
| 124 | borrower_total_owed = sum(borrower["owed_by"].values()) |
| 125 | borrower_total_owes = sum(borrower["owes"].values()) |
| 126 | borrower["balance"] = round(borrower_total_owed - borrower_total_owes, 2) |
| 127 | |
| 128 | # Return updated users sorted by name |
| 129 | result_users = sorted([lender, borrower], key=lambda x: x["name"]) |
| 130 | return json.dumps({"users": result_users}) |
| 131 | |
| 132 | # Edge Case: Handle unknown URL |
| 133 | return json.dumps({"error": "Not found"}) |
| 134 | |
| 135 | # Handled Edge Cases: None database, GET /users with no payload, GET /users with payload, unknown URL in GET, |
| 136 | # POST with no payload, missing user name in /add, duplicate user name in /add, missing fields in /iou, |
| 137 | # lender and borrower being the same person, negative amount, lender or borrower not existing, unknown URL in POST |