Appendices

struct BatchInit { bytes32 commodity; bytes32 unit; uint64 producedAt; uint64 expiresAt; bytes32 originRef; bytes32 metadataHash; string uri; }
struct Batch { address issuer; uint64 createdAt; uint8 status; bytes32 commodity; bytes32 unit; uint64 producedAt; uint64 expiresAt; bytes32 originRef; bytes32 metadataHash; string uri; }


event BatchCreated(uint256 indexed id, address indexed issuer, bytes32 indexed commodity, bytes32 unit, uint256 quantity, address to);
event BatchStatusChanged(uint256 indexed id, uint8 previousStatus, uint8 newStatus, bytes32 reason);
event BatchMetadataUpdated(uint256 indexed id, bytes32 metadataHash, string uri);
event BatchTransformed(address indexed operator, uint256[] inputIds, uint256[] inputAmounts, uint256[] outputIds, uint256[] outputAmounts, bytes32 processRef);


error ARexBatchNotFound(uint256 id);
error ARexBatchRetired(uint256 id);
error ARexInvalidBatch(bytes32 reason);
error ARexInvalidStatusTransition(uint256 id, uint8 from, uint8 to);
error ARexLengthMismatch();


function createBatch(BatchInit calldata init, uint256 quantity, address to, bytes calldata data) external returns (uint256 id);
function batchOf(uint256 id) external view returns (Batch memory);
function batchExists(uint256 id) external view returns (bool);
function totalSupply(uint256 id) external view returns (uint256);
function setBatchStatus(uint256 id, uint8 status, bytes32 reason) external;
function setBatchMetadata(uint256 id, bytes32 metadataHash, string calldata uri) external;
function transform(address from, address to, uint256[] calldata inputIds, uint256[] calldata inputAmounts, BatchInit[] calldata outputs, uint256[] calldata outputAmounts, bytes32 processRef) external returns (uint256[] memory outputIds);
function parentsOf(uint256 id) external view returns (uint256[] memory);

event ForcedTransfer(address indexed from, address indexed to, uint256 indexed tokenId, uint256 amount);
event Frozen(address indexed account, uint256 indexed tokenId, uint256 amount);
error ERC7943CannotSend(address account);
error ERC7943CannotReceive(address account);
error ERC7943CannotTransfer(address from, address to, uint256 tokenId, uint256 amount);
error ERC7943InsufficientUnfrozenBalance(address account, uint256 tokenId, uint256 amount, uint256 unfrozen);
function forcedTransfer(address from, address to, uint256 tokenId, uint256 amount) external returns (bool result);
function setFrozenTokens(address account, uint256 tokenId, uint256 amount) external returns (bool result);
function canSend(address account) external view returns (bool allowed);
function canReceive(address account) external view returns (bool allowed);
function getFrozenTokens(address account, uint256 tokenId) external view returns (uint256 amount);
function canTransfer(address from, address to, uint256 tokenId, uint256 amount) external view returns (bool allowed);

interface IARexHook is IERC165 {
    error ARexHookRejected(address hook, bytes32 code);
    function hookFlags() external view returns (uint8);
    function check(uint8 op, address operator, address from, address to, uint256 id, uint256 amount, bytes calldata data) external view returns (bytes32 code);
    function onExecuted(uint8 op, address operator, address from, address to, uint256 id, uint256 amount, bytes calldata data) external;
    function canSend(address account) external view returns (bool);
    function canReceive(address account) external view returns (bool);
}
interface IARexHookManager {
    event HookRegistered(address indexed hook, uint8 flags, uint256 position);
    event HookRemoved(address indexed hook);
    error ARexHookAlreadyRegistered(address hook);
    error ARexHookNotRegistered(address hook);
    error ARexInvalidHook(address hook);
    function getHooks() external view returns (address[] memory);
    function hookFlagsOf(address hook) external view returns (uint8);
    function registerHook(address hook) external;
    function removeHook(address hook) external;
}

struct Attestation { address issuer; bytes32 ref; uint64 issuedAt; uint64 expiresAt; bool revoked; }
event Attested(uint256 indexed id, bytes32 indexed topic, address indexed issuer, bytes32 ref, uint64 expiresAt);
event AttestationRevoked(uint256 indexed id, bytes32 indexed topic, address indexed issuer, bytes32 reason);
event TrustedIssuerUpdated(bytes32 indexed topic, address indexed issuer, bool trusted);
error ARexUntrustedIssuer(bytes32 topic, address issuer);
error ARexAttestationNotFound(uint256 id, bytes32 topic);
function attest(uint256 id, bytes32 topic, bytes32 ref, uint64 expiresAt) external;
function revokeAttestation(uint256 id, bytes32 topic, bytes32 reason) external;
function getAttestation(uint256 id, bytes32 topic) external view returns (Attestation memory);
function isAttested(uint256 id, bytes32 topic) external view returns (bool);
function isTrustedIssuer(bytes32 topic, address issuer) external view returns (bool);

contract MyHook is ARexHookBase {
    function hookFlags() public pure override returns (uint8) {
        return ARexCodes.HOOK_CHECK;
    }


    function check(uint8 op, address, address, address, uint256 id, uint256, bytes calldata)
        external
        view
        override
        returns (bytes32)
    {
        if (op != ARexCodes.OP_TRANSFER) return ARexCodes.OK;
        IARexBatch.Batch memory b = IARexBatch(msg.sender).batchOf(id);
        b; // decide from b.commodity, b.producedAt, b.expiresAt, b.status ...
        return ARexCodes.OK;
    }
}

const token = await upgrades.deployProxy(await ethers.getContractFactory("ARexToken"), [admin, baseURI], { kind: "uups" });
const attestations = await (await ethers.getContractFactory("ARexAttestations")).deploy(admin, await token.getAddress());
await token.registerHook(await (await ethers.getContractFactory("EligibilityHook")).deploy(admin));
await token.registerHook(await (await ethers.getContractFactory("ExpiryHook")).deploy(true));

{ "schemaVersion": "1.0.0", "commodity": { "scheme": "HS", "code": "100199" }, "unit": "KGM", "quantity": 250000,
  "traceabilityLotCode": "…", "production": { "producedAt": "…" }, "origin": { "country": "AR", "originRef": "…" },
  "status": { "table": { "1": "IN_STORAGE" } }, "documents": [ { "type": "warehouse_receipt", "hash": "…", "registryId": "…" } ],
  "restricted": { "uri": "…", "hash": "…", "accessPolicy": "…" } }