| 1 | import json |
| 2 | from typing import Dict, List, Optional, Any |
| 3 | |
| 1 | 4 | class RestAPI: |
| 2 | 5 | def __init__(self, database: dict | None = None): |
| 3 | | pass |
| 4 | | |
| 6 | """ |
| 7 | Initialize the REST API with an optional database. |
| 8 | |
| 9 | Args: |
| 10 | database: Optional initial database containing users data |
| 11 | """ |
| 12 | if database and 'users' in database: |
| 13 | # Edge Case: Handle initial database with users |
| 14 | self.users = {user['name']: user for user in database['users']} |
| 15 | else: |
| 16 | # Edge Case: Handle empty or None database |
| 17 | self.users = {} |
| 18 | |
| 19 | def _get_user(self, name: str) -> Dict[str, Any]: |
| 20 | """ |
| 21 | Get a user object with calculated balance. |
| 22 | |
| 23 | Args: |
| 24 | name: Name of the user |
| 25 | |
| 26 | Returns: |
| 27 | User object with name, owes, owed_by, and balance |
| 28 | """ |
| 29 | if name not in self.users: |
| 30 | # Edge Case: User not found |
| 31 | raise KeyError(f"User {name} not found") |
| 32 | |
| 33 | user = self.users[name] |
| 34 | |
| 35 | # Calculate total owed to others |
| 36 | total_owed = sum(user.get('owes', {}).values()) |
| 37 | |
| 38 | # Calculate total owed by others |
| 39 | total_owed_by = sum(user.get('owed_by', {}).values()) |
| 40 | |
| 41 | # Calculate balance |
| 42 | balance = total_owed_by - total_owed |
| 43 | |
| 44 | return { |
| 45 | 'name': user['name'], |
| 46 | 'owes': user.get('owes', {}), |
| 47 | 'owed_by': user.get('owed_by', {}), |
| 48 | 'balance': balance |
| 49 | } |
| 50 | |
| 5 | 51 | def get(self, url: str, payload: str | None = None) -> str: |
| 6 | | pass |
| 7 | | |
| 52 | """ |
| 53 | Handle GET requests to the API. |
| 54 | |
| 55 | Args: |
| 56 | url: The endpoint URL |
| 57 | payload: Optional JSON payload |
| 58 | |
| 59 | Returns: |
| 60 | JSON response string |
| 61 | """ |
| 62 | try: |
| 63 | if url == '/users': |
| 64 | if payload is None: |
| 65 | # Return all users |
| 66 | users_list = [self._get_user(name) for name in sorted(self.users.keys())] |
| 67 | return json.dumps({'users': users_list}) |
| 68 | else: |
| 69 | # Return specific users |
| 70 | data = json.loads(payload) |
| 71 | if 'users' not in data: |
| 72 | # Edge Case: Malformed payload |
| 73 | return json.dumps({'error': 'Invalid payload format'}) |
| 74 | |
| 75 | # Edge Case: Empty users list in payload |
| 76 | if not data['users']: |
| 77 | return json.dumps({'users': []}) |
| 78 | |
| 79 | users_list = [] |
| 80 | for name in sorted(data['users']): |
| 81 | if name in self.users: |
| 82 | users_list.append(self._get_user(name)) |
| 83 | # Edge Case: Requested user not found - skip silently as per examples |
| 84 | |
| 85 | return json.dumps({'users': users_list}) |
| 86 | else: |
| 87 | # Edge Case: Invalid URL |
| 88 | return json.dumps({'error': 'Invalid URL'}) |
| 89 | except json.JSONDecodeError: |
| 90 | # Edge Case: Invalid JSON payload |
| 91 | return json.dumps({'error': 'Invalid JSON payload'}) |
| 92 | except Exception as e: |
| 93 | # Edge Case: Unexpected error |
| 94 | return json.dumps({'error': str(e)}) |
| 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 | JSON response string |
| 106 | """ |
| 107 | try: |
| 108 | if payload is None: |
| 109 | # Edge Case: Missing payload |
| 110 | return json.dumps({'error': 'Payload required'}) |
| 111 | |
| 112 | data = json.loads(payload) |
| 113 | |
| 114 | if url == '/add': |
| 115 | # Add a new user |
| 116 | if 'user' not in data: |
| 117 | # Edge Case: Missing user field |
| 118 | return json.dumps({'error': 'Missing user field'}) |
| 119 | |
| 120 | name = data['user'] |
| 121 | |
| 122 | # Edge Case: User already exists |
| 123 | if name in self.users: |
| 124 | return json.dumps({'error': 'User already exists'}) |
| 125 | |
| 126 | # Create new user |
| 127 | new_user = { |
| 128 | 'name': name, |
| 129 | 'owes': {}, |
| 130 | 'owed_by': {} |
| 131 | } |
| 132 | self.users[name] = new_user |
| 133 | |
| 134 | # Return the new user object with calculated balance |
| 135 | return json.dumps(self._get_user(name)) |
| 136 | |
| 137 | elif url == '/iou': |
| 138 | # Create a new IOU |
| 139 | required_fields = ['lender', 'borrower', 'amount'] |
| 140 | for field in required_fields: |
| 141 | if field not in data: |
| 142 | # Edge Case: Missing required field |
| 143 | return json.dumps({'error': f'Missing {field} field'}) |
| 144 | |
| 145 | lender_name = data['lender'] |
| 146 | borrower_name = data['borrower'] |
| 147 | amount = data['amount'] |
| 148 | |
| 149 | # Edge Case: Lender and borrower are the same person |
| 150 | if lender_name == borrower_name: |
| 151 | return json.dumps({'error': 'Lender and borrower cannot be the same person'}) |
| 152 | |
| 153 | # Edge Case: Negative amount |
| 154 | if amount < 0: |
| 155 | return json.dumps({'error': 'Amount cannot be negative'}) |
| 156 | |
| 157 | # Edge Case: Lender not found |
| 158 | if lender_name not in self.users: |
| 159 | return json.dumps({'error': 'Lender not found'}) |
| 160 | |
| 161 | # Edge Case: Borrower not found |
| 162 | if borrower_name not in self.users: |
| 163 | return json.dumps({'error': 'Borrower not found'}) |
| 164 | |
| 165 | # Initialize owes/owed_by if they don't exist |
| 166 | if 'owes' not in self.users[lender_name]: |
| 167 | self.users[lender_name]['owes'] = {} |
| 168 | if 'owed_by' not in self.users[lender_name]: |
| 169 | self.users[lender_name]['owed_by'] = {} |
| 170 | if 'owes' not in self.users[borrower_name]: |
| 171 | self.users[borrower_name]['owes'] = {} |
| 172 | if 'owed_by' not in self.users[borrower_name]: |
| 173 | self.users[borrower_name]['owed_by'] = {} |
| 174 | |
| 175 | # Update lender's owed_by |
| 176 | if borrower_name in self.users[lender_name]['owed_by']: |
| 177 | self.users[lender_name]['owed_by'][borrower_name] += amount |
| 178 | else: |
| 179 | self.users[lender_name]['owed_by'][borrower_name] = amount |
| 180 | |
| 181 | # Update borrower's owes |
| 182 | if lender_name in self.users[borrower_name]['owes']: |
| 183 | self.users[borrower_name]['owes'][lender_name] += amount |
| 184 | else: |
| 185 | self.users[borrower_name]['owes'][lender_name] = amount |
| 186 | |
| 187 | # Return updated user objects |
| 188 | lender = self._get_user(lender_name) |
| 189 | borrower = self._get_user(borrower_name) |
| 190 | |
| 191 | # Sort by name |
| 192 | users_list = sorted([lender, borrower], key=lambda x: x['name']) |
| 193 | |
| 194 | return json.dumps({'users': users_list}) |
| 195 | |
| 196 | else: |
| 197 | # Edge Case: Invalid URL |
| 198 | return json.dumps({'error': 'Invalid URL'}) |
| 199 | |
| 200 | except json.JSONDecodeError: |
| 201 | # Edge Case: Invalid JSON payload |
| 202 | return json.dumps({'error': 'Invalid JSON payload'}) |
| 203 | except TypeError: |
| 204 | # Edge Case: Invalid data types in payload |
| 205 | return json.dumps({'error': 'Invalid data types in payload'}) |
| 206 | except Exception as e: |
| 207 | # Edge Case: Unexpected error |
| 208 | return json.dumps({'error': str(e)}) |
| 209 | |
| 210 | # Handled Edge Cases: |
| 211 | # - Empty or None database initialization |
| 212 | # - User not found |
| 213 | # - Malformed payload |
| 214 | # - Empty users list in payload |
| 215 | # - Invalid URL |
| 216 | # - Invalid JSON payload |
| 217 | # - Unexpected error |
| 218 | # - Missing payload |
| 219 | # - Missing user field |
| 220 | # - User already exists |
| 221 | # - Missing required field |
| 222 | # - Lender and borrower are the same person |
| 223 | # - Negative amount |
| 224 | # - Lender not found |
| 225 | # - Borrower not found |
| 226 | # - Invalid data types in payload |
| 227 | |
| 228 | # Handled Edge Cases: |
| 229 | # - User not found |
| 230 | # - Missing user field |
| 231 | # - User already exists |
| 232 | # - Missing required field |
| 233 | # - Lender and borrower are the same person |
| 234 | # - Negative amount |
| 235 | # - Lender not found |
| 236 | # - Borrower not found |
| 237 | # - Invalid JSON payload |
| 238 | # - Invalid data types in payload |
| 239 | # - Unexpected error |
| 240 | # - Invalid URL |
| 241 | # - Missing payload |