// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract PureVersation { 
    
    // --- 0. BRANDING ---
    string public constant name = "PureVersation Research Registry";
    string public constant symbol = "VERSATION"; 

    // --- 1. IDENTITY & REPUTATION ---
    struct Researcher {
        bool isRegistered;
        uint256 reputationScore;
        string role; // Dynamic: "Initiate", "Scout", "Linguist", "Archivist", "Oracle", or "Admin"
    }
    
    mapping(address => Researcher) public researchers;
    address public labAdmin;

    // --- 2. REGISTRY & LICENSING ---
    struct DialectEntry {
        uint256 id;
        string phrase;      
        string dialect;     
        string ipfsCid;     
        address contributor;
        string licenseType; 
        uint256 verificationCount;
        bool isVerified;
    }

    uint256 public entryCounter;
    mapping(uint256 => DialectEntry) public entries;

    // --- 3. BACKUP SYSTEM ---
    struct DataSnapshot {
        uint256 timestamp;
        string dataType;    // "Database_CSV" or "Persona_JSON"
        string ipfsCid;     
        string description; 
        address uploader;
    }

    mapping(string => DataSnapshot[]) public backups; 

    // 🟢 NEW MAPPINGS FOR SECURITY
    mapping(uint256 => mapping(address => bool)) public hasVerified;
    mapping(uint256 => mapping(address => bool)) public hasRejected;
    mapping(uint256 => uint256) public rejectionCounts;

    // --- 4. EVENTS ---
    event EntryProposed(uint256 indexed id, string phrase, address indexed proposer);
    event EntryVerified(uint256 indexed id, address indexed verifier);
    event EntryRejected(uint256 indexed id, address indexed rejector); // 🟢 NEW EVENT
    event ReputationMinted(address indexed researcher, uint256 amount);
    event RankUpgraded(address indexed researcher, string newRole); 
    event BackupCreated(string indexed dataKey, string ipfsCid, uint256 timestamp);

    constructor() {
        labAdmin = msg.sender;
        researchers[msg.sender] = Researcher(true, 100, "Admin"); 
    }

    // --- MODIFIERS ---
    modifier onlyAdmin() {
        require(msg.sender == labAdmin, "Only Lab Admin can do this");
        _;
    }

    modifier onlyRegistered() {
        require(researchers[msg.sender].isRegistered, "Must be registered researcher");
        _;
    }

    // --- CORE FUNCTIONS ---

    function registerResearcher(address _user, string memory _initialRole) public onlyAdmin {
        researchers[_user] = Researcher(true, 10, _initialRole); 
        _updateRank(_user); 
    }

    function proposeEntry(string memory _phrase, string memory _dialect, string memory _ipfsCid, string memory _license, address _contributor) public onlyRegistered {
        entryCounter++;
        entries[entryCounter] = DialectEntry(entryCounter, _phrase, _dialect, _ipfsCid, _contributor, _license, 0, false);
        emit EntryProposed(entryCounter, _phrase, _contributor);
        
        if (!researchers[_contributor].isRegistered) {
            researchers[_contributor] = Researcher(true, 0, "Initiate");
        }
    }

    function verifyEntry(uint256 _id) public onlyRegistered {
        require(entries[_id].contributor != msg.sender, "Cannot verify own entry");
        require(!entries[_id].isVerified, "Already verified");
        
        if (msg.sender == labAdmin) {
            // Admin can verify instantly
            _applyVerification(_id);
        } else {
            // Peer consensus
            require(!hasVerified[_id][msg.sender], "Already verified by you");
            hasVerified[_id][msg.sender] = true;
            entries[_id].verificationCount++;

            if (entries[_id].verificationCount >= 2) {
                _applyVerification(_id);
            }
        }
        
        // Reward the verifier
        _mintReputation(msg.sender, 10); 
    }

    // 🟢 Helper for verification
    function _applyVerification(uint256 _id) internal {
        entries[_id].isVerified = true;
        _mintReputation(entries[_id].contributor, 50); 
        emit EntryVerified(_id, msg.sender);
    }

    // 🟢 FIX 2: Admin or Peer consensus rejection
    function rejectEntry(uint256 _id) public onlyRegistered {
        require(!entries[_id].isVerified, "Cannot reject an already verified entry");
        
        if (msg.sender == labAdmin) {
            // Admin can reject instantly
            _applyRejection(_id);
        } else {
            // Peer consensus (3 out of 5 typical)
            require(!hasRejected[_id][msg.sender], "Already rejected by you");
            hasRejected[_id][msg.sender] = true;
            rejectionCounts[_id]++;
            
            if (rejectionCounts[_id] >= 3) {
                _applyRejection(_id);
            }
        }
    }

    // 🟢 Helper for rejection
    function _applyRejection(uint256 _id) internal {
        address badActor = entries[_id].contributor;
        _burnReputation(badActor, 10);
        emit EntryRejected(_id, msg.sender);
    }

    function createBackup(string memory _dataKey, string memory _dataType, string memory _ipfsCid, string memory _description) public onlyRegistered {
        DataSnapshot memory newSnap = DataSnapshot(block.timestamp, _dataType, _ipfsCid, _description, msg.sender);
        backups[_dataKey].push(newSnap);
        emit BackupCreated(_dataKey, _ipfsCid, block.timestamp);
    }

    // --- HELPER & VIEW FUNCTIONS ---
    
    function getLatestBackup(string memory _dataKey) public view returns (string memory ipfsCid, uint256 timestamp) {
        require(backups[_dataKey].length > 0, "No backups found");
        DataSnapshot memory snap = backups[_dataKey][backups[_dataKey].length - 1];
        return (snap.ipfsCid, snap.timestamp);
    } 

    function getLicenseInfo(uint256 _id) public view returns (string memory license, address contributor) {
        return (entries[_id].licenseType, entries[_id].contributor);
    }

    // --- INTERNAL REPUTATION & RANKING LOGIC ---
    
    function _mintReputation(address _user, uint256 _amount) internal {
        researchers[_user].reputationScore += _amount;
        emit ReputationMinted(_user, _amount);
        _updateRank(_user);
    }

    function _burnReputation(address _user, uint256 _amount) internal {
        if (researchers[_user].reputationScore >= _amount) {
            researchers[_user].reputationScore -= _amount;
        } else {
            researchers[_user].reputationScore = 0;
        }
        _updateRank(_user);
    }
    
    function _updateRank(address _user) internal {
        Researcher storage r = researchers[_user];
        
        if (keccak256(abi.encodePacked(r.role)) == keccak256(abi.encodePacked("Admin"))) {
            return;
        }

        uint256 score = r.reputationScore;
        string memory newRole;

        if (score >= 1500) {
            newRole = "Oracle";
        } else if (score >= 800) {
            newRole = "Archivist";
        } else if (score >= 300) {
            newRole = "Linguist";
        } else if (score >= 100) {
            newRole = "Scout";
        } else {
            newRole = "Initiate";
        }

        if (keccak256(abi.encodePacked(r.role)) != keccak256(abi.encodePacked(newRole))) {
            r.role = newRole;
            emit RankUpgraded(_user, newRole);
        }
    }
}