/**
 * EIP-2612 Gas Sponsoring Extension Type Definitions
 *
 * EIP-2612 permit-based gas sponsoring for the t402 payment protocol.
 * Allows facilitators to sponsor gas fees by having clients sign off-chain
 * permits instead of submitting on-chain approval transactions.
 */
/**
 * Information provided by server about gas sponsoring availability.
 */
interface Eip2612GasSponsorExtensionInfo {
    /** CAIP-2 network identifiers where gas sponsoring is available */
    sponsoredNetworks: string[];
    /** Maximum token amount (in base units) the sponsor will cover per permit */
    maxAmount: string;
    /** Default permit deadline in seconds from now */
    permitDeadline: number;
    /** Address of the sponsor/facilitator that will call permit + transferFrom */
    sponsorAddress: string;
}
/**
 * Gas sponsor extension declaration for server responses.
 */
interface Eip2612GasSponsorExtension {
    /** Extension information */
    info: Eip2612GasSponsorExtensionInfo;
    /** JSON Schema for validation */
    schema: object;
}
/**
 * Complete gas sponsor payload from client including permit signature.
 */
interface Eip2612GasSponsorPayload {
    /** CAIP-2 network identifier (must be in sponsoredNetworks) */
    network: string;
    /** Full hex-encoded EIP-2612 permit signature (65 bytes, r + s + v) */
    permitSignature: string;
    /** Token owner address (the client's wallet) */
    owner: string;
    /** Spender address (must match sponsorAddress) */
    spender: string;
    /** Token amount in base units */
    value: string;
    /** Unix timestamp for permit expiry */
    deadline: number;
    /** Recovery parameter from signature */
    v: number;
    /** Signature r component (32 bytes hex) */
    r: string;
    /** Signature s component (32 bytes hex) */
    s: string;
}
/**
 * Options for declaring gas sponsor extension on server.
 */
interface DeclareEip2612GasSponsorOptions {
    /** CAIP-2 network identifiers where gas sponsoring is available */
    sponsoredNetworks: string[];
    /** Maximum token amount (in base units) the sponsor will cover per permit */
    maxAmount: string;
    /** Default permit deadline in seconds from now (defaults to 300 = 5 minutes) */
    permitDeadline?: number;
    /** Address of the sponsor/facilitator */
    sponsorAddress: string;
}
/**
 * Options for validating gas sponsor payloads.
 */
interface ValidateEip2612GasSponsorOptions {
    /** Custom time function for testing (defaults to Date.now) */
    now?: () => number;
}
/**
 * Result of gas sponsor payload validation.
 */
interface Eip2612GasSponsorValidationResult {
    /** Whether the payload is valid */
    valid: boolean;
    /** Error message if invalid */
    error?: string;
}
/**
 * Parameters for creating an EIP-2612 permit signature.
 */
interface CreatePermitParams {
    /** EIP-712 signer interface */
    signer: PermitSigner;
    /** ERC-20 token contract address */
    tokenAddress: string;
    /** Token name (used in EIP-712 domain) */
    tokenName: string;
    /** Chain ID (numeric, e.g. 8453 for Base) */
    chainId: number;
    /** Spender address (the facilitator/sponsor) */
    spender: string;
    /** Token amount in base units */
    value: string;
    /** Unix timestamp for permit expiry */
    deadline: number;
    /** Current permit nonce for the owner (defaults to 0) */
    nonce?: number;
}
/**
 * Signer interface for EIP-2612 permit signing.
 */
interface PermitSigner {
    /** Wallet address */
    address: string;
    /**
     * Sign EIP-712 typed data and return hex-encoded signature.
     *
     * @param data - EIP-712 typed data to sign
     * @param data.domain - EIP-712 domain separator fields
     * @param data.types - EIP-712 type definitions
     * @param data.primaryType - Primary type name for signing
     * @param data.message - Message values to sign
     * @returns Hex-encoded signature
     */
    signTypedData(data: {
        domain: Record<string, unknown>;
        types: Record<string, Array<{
            name: string;
            type: string;
        }>>;
        primaryType: string;
        message: Record<string, unknown>;
    }): Promise<string>;
}

/**
 * EIP-2612 Gas Sponsoring Extension Server-Side Implementation
 *
 * Provides functions for servers to declare gas sponsoring requirements,
 * parse client headers, and validate permit payloads.
 */

/**
 * Declares an EIP-2612 gas sponsor extension for server responses.
 *
 * @param options - Extension declaration options
 * @returns Gas sponsor extension object ready for response
 *
 * @example
 * ```typescript
 * const extension = declareEip2612GasSponsorExtension({
 *   sponsoredNetworks: ["eip155:8453", "eip155:42161"],
 *   maxAmount: "1000000000",
 *   sponsorAddress: "0xFacilitator...",
 * });
 * ```
 */
declare function declareEip2612GasSponsorExtension(options: DeclareEip2612GasSponsorOptions): Eip2612GasSponsorExtension;
/**
 * Parses an EIP-2612 gas sponsor header from client request.
 *
 * The header format is base64-encoded JSON.
 *
 * @param header - Base64-encoded gas sponsor header value
 * @returns Parsed gas sponsor payload
 * @throws Error if header is invalid
 *
 * @example
 * ```typescript
 * const payload = parseEip2612GasSponsorHeader(
 *   request.headers['x-t402-eip2612-gas-sponsoring']
 * );
 * ```
 */
declare function parseEip2612GasSponsorHeader(header: string): Eip2612GasSponsorPayload;
/**
 * Validates an EIP-2612 gas sponsor payload against server extension info.
 *
 * @param payload - The gas sponsor payload from the client
 * @param extensionInfo - The server's gas sponsor extension info
 * @param options - Validation options
 * @returns Validation result
 *
 * @example
 * ```typescript
 * const result = validateEip2612GasSponsorPayload(payload, extension.info);
 * if (!result.valid) {
 *   throw new Error(result.error);
 * }
 * ```
 */
declare function validateEip2612GasSponsorPayload(payload: Eip2612GasSponsorPayload, extensionInfo: Eip2612GasSponsorExtensionInfo, options?: ValidateEip2612GasSponsorOptions): Eip2612GasSponsorValidationResult;

/**
 * EIP-2612 Gas Sponsoring Extension Client-Side Implementation
 *
 * Provides functions for clients to create EIP-2612 permit signatures
 * and encode gas sponsor payloads for transmission.
 */

/**
 * Extension key for EIP-2612 gas sponsoring in payment requirements.
 */
declare const EIP2612_GAS_SPONSOR_EXTENSION_KEY = "eip2612GasSponsoring";
/**
 * HTTP header name for EIP-2612 gas sponsor payload.
 */
declare const EIP2612_GAS_SPONSOR_HEADER_NAME = "X-T402-EIP2612-Gas-Sponsoring";
/**
 * Creates an EIP-2612 permit signature using EIP-712 typed data signing.
 *
 * @param params - Permit signing parameters
 * @returns Permit data including the signature components
 *
 * @example
 * ```typescript
 * const permit = await createPermitSignature({
 *   signer: wallet,
 *   tokenAddress: "0xUSDT...",
 *   tokenName: "Tether USD",
 *   chainId: 8453,
 *   spender: facilitatorAddress,
 *   value: "1000000",
 *   deadline: Math.floor(Date.now() / 1000) + 300,
 * });
 * ```
 */
declare function createPermitSignature(params: CreatePermitParams): Promise<{
    owner: string;
    spender: string;
    value: string;
    deadline: number;
    v: number;
    r: string;
    s: string;
    permitSignature: string;
}>;
/**
 * Creates a gas sponsor payload from permit data and network.
 *
 * @param permit - Permit signature data from createPermitSignature
 * @param permit.owner - Token owner address
 * @param permit.spender - Approved spender address
 * @param permit.value - Token amount in base units
 * @param permit.deadline - Unix timestamp for permit expiry
 * @param permit.v - Recovery parameter from signature
 * @param permit.r - Signature r component (32 bytes hex)
 * @param permit.s - Signature s component (32 bytes hex)
 * @param permit.permitSignature - Full hex-encoded permit signature
 * @param network - CAIP-2 network identifier (e.g., "eip155:8453")
 * @returns Gas sponsor payload ready for header encoding
 *
 * @example
 * ```typescript
 * const payload = createEip2612GasSponsorPayload(permit, "eip155:8453");
 * ```
 */
declare function createEip2612GasSponsorPayload(permit: {
    owner: string;
    spender: string;
    value: string;
    deadline: number;
    v: number;
    r: string;
    s: string;
    permitSignature: string;
}, network: string): Eip2612GasSponsorPayload;
/**
 * Encodes a gas sponsor payload for transmission in HTTP header.
 *
 * @param payload - The gas sponsor payload to encode
 * @returns Base64-encoded JSON string
 *
 * @example
 * ```typescript
 * const header = encodeEip2612GasSponsorHeader(payload);
 * fetch(url, {
 *   headers: { [EIP2612_GAS_SPONSOR_HEADER_NAME]: header }
 * });
 * ```
 */
declare function encodeEip2612GasSponsorHeader(payload: Eip2612GasSponsorPayload): string;

/**
 * EIP-2612 Gas Sponsoring Extension Facilitator-Side Implementation
 *
 * Provides functions for facilitators to extract permit data from payment
 * extensions, validate permits, and prepare on-chain submission.
 */

/**
 * Extracts the EIP-2612 gas sponsor payload from payment extensions.
 *
 * @param extensions - The extensions map from a PaymentPayload
 * @returns The gas sponsor payload if present, or null
 *
 * @example
 * ```typescript
 * const permit = extractEip2612GasSponsorPayload(paymentPayload.extensions);
 * if (permit) {
 *   // Submit permit tx then settle via Permit2
 * }
 * ```
 */
declare function extractEip2612GasSponsorPayload(extensions: Record<string, unknown> | undefined): Eip2612GasSponsorPayload | null;
/**
 * Validates and extracts the EIP-2612 gas sponsor payload in one step.
 *
 * This is a convenience function for facilitators that combines extraction
 * and validation against the server's extension info.
 *
 * @param extensions - The extensions map from a PaymentPayload
 * @param extensionInfo - The server's gas sponsor extension info
 * @returns Validation result with the extracted payload if valid
 *
 * @example
 * ```typescript
 * const result = validateAndExtractPermit(
 *   paymentPayload.extensions,
 *   extensionInfo
 * );
 * if (result.valid && result.payload) {
 *   // Submit permit() on token contract, then settle via Permit2
 * }
 * ```
 */
declare function validateAndExtractPermit(extensions: Record<string, unknown> | undefined, extensionInfo: Eip2612GasSponsorExtensionInfo): Eip2612GasSponsorValidationResult & {
    payload?: Eip2612GasSponsorPayload;
};
/**
 * Builds the EIP-2612 permit function call data for on-chain submission.
 *
 * Returns the ABI-encoded parameters needed to call `permit(owner, spender, value, deadline, v, r, s)`
 * on the token contract.
 *
 * @param payload - The validated gas sponsor payload
 * @returns Object with the permit call parameters
 *
 * @example
 * ```typescript
 * const permitCall = buildPermitCallData(payload);
 * // Use permitCall with your preferred web3 library to submit the tx
 * ```
 */
declare function buildPermitCallData(payload: Eip2612GasSponsorPayload): {
    owner: string;
    spender: string;
    value: string;
    deadline: number;
    v: number;
    r: string;
    s: string;
};

export { type CreatePermitParams, type DeclareEip2612GasSponsorOptions, EIP2612_GAS_SPONSOR_EXTENSION_KEY, EIP2612_GAS_SPONSOR_HEADER_NAME, type Eip2612GasSponsorExtension, type Eip2612GasSponsorExtensionInfo, type Eip2612GasSponsorPayload, type Eip2612GasSponsorValidationResult, type PermitSigner, type ValidateEip2612GasSponsorOptions, buildPermitCallData, createEip2612GasSponsorPayload, createPermitSignature, declareEip2612GasSponsorExtension, encodeEip2612GasSponsorHeader, extractEip2612GasSponsorPayload, parseEip2612GasSponsorHeader, validateAndExtractPermit, validateEip2612GasSponsorPayload };