// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

/// @notice Records provenance, never asserts that the observation is factually true.
contract RealityRegistry {
    uint256 public constant registryVersion = 1;
    uint256 public totalProofs;
    mapping(uint256 => uint256) public proofsByDay;
    mapping(address => uint256) public lastContribution;
    struct RealityProof { bytes32 contentHash; address contributor; uint256 generation; uint256 timestamp; uint8 proofType; }
    mapping(address => mapping(bytes32 => RealityProof)) public proofs;
    mapping(address => uint256) public proofCount;
    mapping(address => uint256) public checkpointCount;
    mapping(address => mapping(uint256 => bytes32)) public checkpoints;
    event RealitySubmitted(bytes32 indexed contentHash, address indexed contributor, uint256 generation, uint8 proofType, uint256 timestamp);
    event GenerationCheckpoint(address indexed contributor, uint256 indexed generation, bytes32 stateHash);

    function submitRealityProof(bytes32 contentHash, uint256 generation, uint8 proofType) external {
        require(contentHash != bytes32(0), 'EMPTY_HASH');
        require(proofType <= 4, 'INVALID_TYPE');
        require(proofs[msg.sender][contentHash].timestamp == 0, 'DUPLICATE_PROOF');
        proofs[msg.sender][contentHash] = RealityProof(contentHash, msg.sender, generation, block.timestamp, proofType);
        proofCount[msg.sender]++;
        totalProofs++;
        proofsByDay[block.timestamp / 1 days]++;
        lastContribution[msg.sender] = generation;
        emit RealitySubmitted(contentHash, msg.sender, generation, proofType, block.timestamp);
    }
    /// @notice A checkpoint is an operator's attestation, not a privileged global state.
    function checkpointGeneration(uint256 generation, bytes32 stateHash) external {
        require(stateHash != bytes32(0), 'EMPTY_HASH');
        require(checkpoints[msg.sender][generation] == bytes32(0), 'ALREADY_CHECKPOINTED');
        checkpoints[msg.sender][generation] = stateHash;
        checkpointCount[msg.sender]++;
        emit GenerationCheckpoint(msg.sender, generation, stateHash);
    }
}