| 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 | # Edge Case: Handle None database by initializing empty users dict |
| 12 | if database is None: |
| 13 | self.users = {} |
| 14 | else: |
| 15 | self.users = database.get('users', {}) |
| 16 | |
| 17 | # Convert users list to dictionary for easier access |
| 18 | if isinstance(self.users, list): |
| 19 | self.users = {user['name']: user for user in self.users} |
| 20 | |
| 21 | # Ensure all users have the required fields |
| 22 | for user in self.users.values(): |
| 23 | if 'owes' not in user: |
| 24 | user['owes'] = {} |
| 25 | if 'owed_by' not in user: |
| 26 | user['owed_by'] = {} |
| 27 | if 'balance' not in user: |
| 28 | user['balance'] = 0.0 |
| 29 | |
| 30 | def _calculate_balance(self, user): |
| 31 | """ |
| 32 | Calculate the balance for a user based on what they owe and are owed. |
| 33 | |
| 34 | Args: |
| 35 | user: The user dictionary to calculate balance for. |
| 36 | |
| 37 | Returns: |
| 38 | float: The calculated balance. |
| 39 | """ |
| 40 | total_owed_by_others = sum(user['owed_by'].values()) |
| 41 | total_owed_to_others = sum(user['owes'].values()) |
| 42 | return round(total_owed_by_others - total_owed_to_others, 2) |
| 43 | |
| 44 | def _get_user(self, name): |
| 45 | """ |
| 46 | Get a user by name, creating them if they don't exist. |
| 47 | |
| 48 | Args: |
| 49 | name: The name of the user to retrieve. |
| 50 | |
| 51 | Returns: |
| 52 | dict: The user object. |
| 53 | """ |
| 54 | # Edge Case: Create user if they don't exist |
| 55 | if name not in self.users: |
| 56 | self.users[name] = { |
| 57 | 'name': name, |
| 58 | 'owes': {}, |
| 59 | 'owed_by': {}, |
| 60 | 'balance': 0.0 |
| 61 | } |
| 62 | return self.users[name] |
| 63 | |
| 5 | 64 | def get(self, url: str, payload: str | None = None) -> str: |
| 6 | | pass |
| 7 | | |
| 65 | """ |
| 66 | Handle GET requests to the API. |
| 67 | |
| 68 | Args: |
| 69 | url: The endpoint URL. |
| 70 | payload: Optional JSON payload. |
| 71 | |
| 72 | Returns: |
| 73 | str: JSON response. |
| 74 | """ |
| 75 | # Edge Case: Handle /users endpoint |
| 76 | if url == '/users': |
| 77 | # Edge Case: Handle payload with specific users |
| 78 | if payload is not None: |
| 79 | data = json.loads(payload) |
| 80 | user_names = data.get('users', []) |
| 81 | # Edge Case: Filter users by provided names |
| 82 | users_list = [self.users[name] for name in sorted(user_names) if name in self.users] |
| 83 | else: |
| 84 | # Edge Case: Return all users if no payload |
| 85 | users_list = [user for name, user in sorted(self.users.items())] |
| 86 | |
| 87 | # Edge Case: Ensure all users have updated balances |
| 88 | for user in users_list: |
| 89 | user['balance'] = self._calculate_balance(user) |
| 90 | |
| 91 | return json.dumps({'users': users_list}) |
| 92 | |
| 93 | # Edge Case: Handle unknown endpoints |
| 94 | return json.dumps({'error': 'Not found'}) |
| 95 | |
| 8 | 96 | def post(self, url: str, payload: str | None = None) -> str: |
| 9 | | pass |
| 97 | """ |
| 98 | Handle POST requests to the API. |
| 99 | |
| 100 | Args: |
| 101 | url: The endpoint URL. |
| 102 | payload: JSON payload. |
| 103 | |
| 104 | Returns: |
| 105 | str: JSON response. |
| 106 | """ |
| 107 | # Edge Case: Handle missing payload |
| 108 | if payload is None: |
| 109 | return json.dumps({'error': 'Payload required'}) |
| 110 | |
| 111 | data = json.loads(payload) |
| 112 | |
| 113 | # Edge Case: Handle /add endpoint for creating users |
| 114 | if url == '/add': |
| 115 | user_name = data.get('user') |
| 116 | # Edge Case: Handle missing user name |
| 117 | if not user_name: |
| 118 | return json.dumps({'error': 'User name required'}) |
| 119 | |
| 120 | # Edge Case: Handle duplicate user |
| 121 | if user_name in self.users: |
| 122 | return json.dumps({'error': 'User already exists'}) |
| 123 | |
| 124 | new_user = { |
| 125 | 'name': user_name, |
| 126 | 'owes': {}, |
| 127 | 'owed_by': {}, |
| 128 | 'balance': 0.0 |
| 129 | } |
| 130 | self.users[user_name] = new_user |
| 131 | return json.dumps(new_user) |
| 132 | |
| 133 | # Edge Case: Handle /iou endpoint for creating IOUs |
| 134 | elif url == '/iou': |
| 135 | lender_name = data.get('lender') |
| 136 | borrower_name = data.get('borrower') |
| 137 | amount = data.get('amount') |
| 138 | |
| 139 | # Edge Case: Handle missing required fields |
| 140 | if not lender_name or not borrower_name or amount is None: |
| 141 | return json.dumps({'error': 'Lender, borrower, and amount required'}) |
| 142 | |
| 143 | # Edge Case: Handle invalid amount type |
| 144 | if not isinstance(amount, (int, float)): |
| 145 | return json.dumps({'error': 'Amount must be a number'}) |
| 146 | |
| 147 | # Edge Case: Handle negative amount |
| 148 | if amount < 0: |
| 149 | return json.dumps({'error': 'Amount must be positive'}) |
| 150 | |
| 151 | # Edge Case: Handle lender and borrower being the same person |
| 152 | if lender_name == borrower_name: |
| 153 | return json.dumps({'error': 'Lender and borrower cannot be the same person'}) |
| 154 | |
| 155 | # Get or create users |
| 156 | lender = self._get_user(lender_name) |
| 157 | borrower = self._get_user(borrower_name) |
| 158 | |
| 159 | # Update lender's owed_by |
| 160 | if borrower_name in lender['owed_by']: |
| 161 | lender['owed_by'][borrower_name] += amount |
| 162 | else: |
| 163 | lender['owed_by'][borrower_name] = amount |
| 164 | |
| 165 | # Update borrower's owes |
| 166 | if lender_name in borrower['owes']: |
| 167 | borrower['owes'][lender_name] += amount |
| 168 | else: |
| 169 | borrower['owes'][lender_name] = amount |
| 170 | |
| 171 | # Remove entries if amount becomes 0 |
| 172 | if lender['owed_by'][borrower_name] == 0: |
| 173 | del lender['owed_by'][borrower_name] |
| 174 | |
| 175 | if borrower['owes'][lender_name] == 0: |
| 176 | del borrower['owes'][lender_name] |
| 177 | |
| 178 | # Update balances |
| 179 | lender['balance'] = self._calculate_balance(lender) |
| 180 | borrower['balance'] = self._calculate_balance(borrower) |
| 181 | |
| 182 | # Return updated users sorted by name |
| 183 | users_list = sorted([lender, borrower], key=lambda u: u['name']) |
| 184 | return json.dumps({'users': users_list}) |
| 185 | |
| 186 | # Edge Case: Handle unknown endpoints |
| 187 | return json.dumps({'error': 'Not found'}) |
| 188 | |
| 189 | # Handled Edge Cases: None database, missing payload, /users endpoint, payload with specific users, |
| 190 | # all users if no payload, unknown endpoints, missing user name, duplicate user, /iou endpoint, |
| 191 | # missing required fields, invalid amount type, negative amount, lender/borrower being same person, |
| 192 | # creating users if they don't exist, removing zero amount entries |