// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

// A representation of an empty/uninitialized UID.
bytes32 constant EMPTY_UID = 0;

// A zero expiration represents an non-expiring attestation.
uint64 constant NO_EXPIRATION_TIME = 0;

error AccessDenied();
error DeadlineExpired();
error InvalidEAS();
error InvalidLength();
error InvalidSignature();
error NotFound();

/// @notice A struct representing ECDSA signature data.
struct Signature {
    uint8 v; // The recovery ID.
    bytes32 r; // The x-coordinate of the nonce R.
    bytes32 s; // The signature data.
}

/// @notice A struct representing a single attestation.
struct Attestation {
    bytes32 uid; // A unique identifier of the attestation.
    bytes32 schema; // The unique identifier of the schema.
    uint64 time; // The time when the attestation was created (Unix timestamp).
    uint64 expirationTime; // The time when the attestation expires (Unix timestamp).
    uint64 revocationTime; // The time when the attestation was revoked (Unix timestamp).
    bytes32 refUID; // The UID of the related attestation.
    address recipient; // The recipient of the attestation.
    address attester; // The attester/sender of the attestation.
    bool revocable; // Whether the attestation is revocable.
    bytes data; // Custom attestation data.
}