Reputation Registry

1// SPDX-License-Identifier: MIT
2pragma solidity ^0.8.20;
3 
4contract ReputationRegistry {
5    address public owner;
6    mapping(address => uint256) public scoreOf;
7    mapping(address => bool) public isAttester;
8 
9    event ScoreChanged(address indexed subject, uint256 newScore, address indexed attester);
10    event AttesterSet(address indexed attester, bool allowed);
11    event OwnerChanged(address indexed newOwner);
12 
13    constructor(address initialOwner_) {
14        require(initialOwner_ != address(0), "ZERO_OWNER");
15        owner = initialOwner_;
16        isAttester[initialOwner_] = true;
17        emit AttesterSet(initialOwner_, true);
18    }
19 
20    modifier onlyOwner() {
21        require(msg.sender == owner, "NOT_OWNER");
22        _;
23    }
24 
25    modifier onlyAttester() {
26        require(isAttester[msg.sender], "NOT_ATTESTER");
27        _;
28    }
29 
30    function setAttester(address attester, bool allowed) external onlyOwner {
31        require(attester != address(0), "ZERO_ATTESTER");
32        isAttester[attester] = allowed;
33        emit AttesterSet(attester, allowed);
34    }
35 
36    function award(address subject, uint256 points) external onlyAttester {
37        require(subject != address(0), "ZERO_SUBJECT");
38        require(points > 0, "ZERO_POINTS");
39        uint256 next = scoreOf[subject] + points;
40        scoreOf[subject] = next;
41        emit ScoreChanged(subject, next, msg.sender);
42    }
43 
44    function slash(address subject, uint256 points) external onlyAttester {
45        uint256 current = scoreOf[subject];
46        uint256 next = points >= current ? 0 : current - points;
47        scoreOf[subject] = next;
48        emit ScoreChanged(subject, next, msg.sender);
49    }
50 
51    function transferOwnership(address newOwner) external onlyOwner {
52        require(newOwner != address(0), "ZERO_OWNER");
53        owner = newOwner;
54        emit OwnerChanged(newOwner);
55    }
56}
57