└── Mapping


/Mapping:
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 1 | // SPDX-License-Identifier: MIT
 2 | pragma solidity ^0.8.17;
 3 | 
 4 | /**
 5 |  * @title FavoriteRecords
 6 |  * @dev Contract to manage a list of approved music records and allow users to add them to their favorites
 7 |  */
 8 | contract FavoriteRecords {
 9 |     // Mapping to store whether a record is approved
10 |     mapping(string => bool) private approvedRecords;
11 |     // Array to store the index of approved records
12 |     string[] private approvedRecordsIndex;
13 | 
14 |     // Mapping to store user's favorite records
15 |     mapping(address => mapping(string => bool)) public userFavorites;
16 |     // Mapping to store the index of user's favorite records
17 |     mapping(address => string[]) private userFavoritesIndex;
18 | 
19 |     // Custom error to handle unapproved records
20 |     error NotApproved(string albumName);
21 | 
22 |     /**
23 |      * @dev Constructor that initializes the approved records list
24 |      */
25 |     constructor() {
26 |         // Predefined list of approved records
27 |         approvedRecordsIndex = [
28 |             "Thriller", 
29 |             "Back in Black", 
30 |             "The Bodyguard", 
31 |             "The Dark Side of the Moon", 
32 |             "Their Greatest Hits (1971-1975)", 
33 |             "Hotel California", 
34 |             "Come On Over", 
35 |             "Rumours", 
36 |             "Saturday Night Fever"
37 |         ];
38 |         // Initialize the approved records mapping
39 |         for (uint i = 0; i < approvedRecordsIndex.length; i++) {
40 |             approvedRecords[approvedRecordsIndex[i]] = true;
41 |         }
42 |     }
43 | 
44 |     /**
45 |      * @dev Returns the list of approved records
46 |      * @return An array of approved record names
47 |      */
48 |     function getApprovedRecords() public view returns (string[] memory) {
49 |         return approvedRecordsIndex;
50 |     }
51 | 
52 |     /**
53 |      * @dev Adds an approved record to the user's favorites
54 |      * @param _albumName The name of the album to be added
55 |      */
56 |     function addRecord(string memory _albumName) public {
57 |         // Check if the record is approved
58 |         if (!approvedRecords[_albumName]) {
59 |             revert NotApproved({albumName: _albumName});
60 |         }
61 |         // Check if the record is not already in the user's favorites
62 |         if (!userFavorites[msg.sender][_albumName]) {
63 |             // Add the record to the user's favorites
64 |             userFavorites[msg.sender][_albumName] = true;
65 |             // Add the record to the user's favorites index
66 |             userFavoritesIndex[msg.sender].push(_albumName);
67 |         }
68 |     }
69 | 
70 |     /**
71 |      * @dev Returns the list of a user's favorite records
72 |      * @param _address The address of the user
73 |      * @return An array of user's favorite record names
74 |      */
75 |     function getUserFavorites(address _address) public view returns (string[] memory) {
76 |         return userFavoritesIndex[_address];
77 |     }
78 | 
79 |     /**
80 |      * @dev Resets the caller's list of favorite records
81 |      */
82 |     function resetUserFavorites() public {
83 |         // Iterate through the user's favorite records
84 |         for (uint i = 0; i < userFavoritesIndex[msg.sender].length; i++) {
85 |             // Delete each record from the user's favorites mapping
86 |             delete userFavorites[msg.sender][userFavoritesIndex[msg.sender][i]];
87 |         }
88 |         // Delete the user's favorites index
89 |         delete userFavoritesIndex[msg.sender];
90 |     }
91 | }
92 | 


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