| 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 | if url == '/users': |
| 28 | if payload is None: |
| 29 | # Return all users sorted by name |
| 30 | users = sorted(self.database['users'], key=lambda x: x['name']) |
| 31 | return json.dumps({'users': users}) |
| 32 | else: |
| 33 | # Return specific users |
| 34 | data = json.loads(payload) |
| 35 | user_names = data.get('users', []) |
| 36 | |
| 37 | # Edge Case: Handle when users list is empty |
| 38 | if not user_names: |
| 39 | return json.dumps({'users': []}) |
| 40 | |
| 41 | # Filter users by name |
| 42 | result_users = [user for user in self.database['users'] if user['name'] in user_names] |
| 43 | # Sort by name |
| 44 | result_users.sort(key=lambda x: x['name']) |
| 45 | return json.dumps({'users': result_users}) |
| 46 | |
| 47 | # Edge Case: Handle unknown URLs |
| 48 | return json.dumps({'error': 'Not found'}) |
| 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 URL. |
| 56 | payload: JSON payload. |
| 57 | |
| 58 | Returns: |
| 59 | A JSON string response. |
| 60 | """ |
| 61 | if payload is None: |
| 62 | # Edge Case: Handle missing payload |
| 63 | return json.dumps({'error': 'Payload required'}) |
| 64 | |
| 65 | data = json.loads(payload) |
| 66 | |
| 67 | if url == '/add': |
| 68 | user_name = data.get('user') |
| 69 | |
| 70 | # Edge Case: Handle missing user name |
| 71 | if not user_name: |
| 72 | return json.dumps({'error': 'User name required'}) |
| 73 | |
| 74 | # Edge Case: Handle duplicate user |
| 75 | for user in self.database['users']: |
| 76 | if user['name'] == user_name: |
| 77 | return json.dumps({'error': 'User already exists'}) |
| 78 | |
| 79 | # Create new user |
| 80 | new_user = { |
| 81 | 'name': user_name, |
| 82 | 'owes': {}, |
| 83 | 'owed_by': {}, |
| 84 | 'balance': 0.0 |
| 85 | } |
| 86 | self.database['users'].append(new_user) |
| 87 | return json.dumps(new_user) |
| 88 | |
| 89 | elif url == '/iou': |
| 90 | lender_name = data.get('lender') |
| 91 | borrower_name = data.get('borrower') |
| 92 | amount = data.get('amount') |
| 93 | |
| 94 | # Edge Case: Handle missing fields |
| 95 | if not lender_name or not borrower_name or amount is None: |
| 96 | return json.dumps({'error': 'Lender, borrower, and amount are required'}) |
| 97 | |
| 98 | # Edge Case: Handle non-numeric amount |
| 99 | try: |
| 100 | amount = float(amount) |
| 101 | except (ValueError, TypeError): |
| 102 | return json.dumps({'error': 'Amount must be a number'}) |
| 103 | |
| 104 | # Edge Case: Handle negative amount |
| 105 | if amount < 0: |
| 106 | return json.dumps({'error': 'Amount must be positive'}) |
| 107 | |
| 108 | # Edge Case: Handle same lender and borrower |
| 109 | if lender_name == borrower_name: |
| 110 | return json.dumps({'error': 'Lender and borrower cannot be the same'}) |
| 111 | |
| 112 | # Find users |
| 113 | lender = None |
| 114 | borrower = None |
| 115 | for user in self.database['users']: |
| 116 | if user['name'] == lender_name: |
| 117 | lender = user |
| 118 | elif user['name'] == borrower_name: |
| 119 | borrower = user |
| 120 | |
| 121 | # Edge Case: Handle unknown users |
| 122 | if lender is None or borrower is None: |
| 123 | return json.dumps({'error': 'Both lender and borrower must exist'}) |
| 124 | |
| 125 | # Update IOUs |
| 126 | # Update lender's owed_by |
| 127 | if borrower_name in lender['owed_by']: |
| 128 | lender['owed_by'][borrower_name] += amount |
| 129 | else: |
| 130 | lender['owed_by'][borrower_name] = amount |
| 131 | |
| 132 | # Update borrower's owes |
| 133 | if lender_name in borrower['owes']: |
| 134 | borrower['owes'][lender_name] += amount |
| 135 | else: |
| 136 | borrower['owes'][lender_name] = amount |
| 137 | |
| 138 | # Recalculate balances |
| 139 | lender_total_owed = sum(lender['owed_by'].values()) |
| 140 | lender_total_owes = sum(lender['owes'].values()) |
| 141 | lender['balance'] = lender_total_owed - lender_total_owes |
| 142 | |
| 143 | borrower_total_owed = sum(borrower['owed_by'].values()) |
| 144 | borrower_total_owes = sum(borrower['owes'].values()) |
| 145 | borrower['balance'] = borrower_total_owed - borrower_total_owes |
| 146 | |
| 147 | # Return updated users sorted by name |
| 148 | result_users = sorted([lender, borrower], key=lambda x: x['name']) |
| 149 | return json.dumps({'users': result_users}) |
| 150 | |
| 151 | # Edge Case: Handle unknown URLs |
| 152 | return json.dumps({'error': 'Not found'}) |
| 153 | |
| 154 | # Handled Edge Cases: Missing payload, missing user name, duplicate user, missing fields, |
| 155 | # non-numeric amount, negative amount, same lender and borrower, unknown users, unknown URLs |