/**
 * ERC-20 Approval Gas Sponsoring Extension Type Definitions
 *
 * ERC-20 approve()-based gas sponsoring for the t402 payment protocol.
 * For tokens WITHOUT EIP-2612 permit support, the client signs an offline
 * approve() transaction and the facilitator broadcasts it on their behalf.
 */
/**
 * Information provided by server about ERC-20 approval gas sponsoring availability.
 */
interface ERC20ApprovalGasSponsorExtensionInfo {
    /** CAIP-2 network identifiers where gas sponsoring is available */
    sponsoredNetworks: string[];
    /** Maximum token amount (in base units) the sponsor will cover per approval */
    maxAmount: string;
    /** Address of the sponsor/facilitator that will submit transactions */
    sponsorAddress: string;
    /** Optional Permit2 proxy address for advanced settlement flows */
    permit2Address?: string;
    /** Whether atomic batch execution is required (e.g., via Multicall3) */
    requiresAtomicBatch: boolean;
}
/**
 * ERC-20 approval gas sponsor extension declaration for server responses.
 */
interface ERC20ApprovalGasSponsorExtension {
    /** Extension information */
    info: ERC20ApprovalGasSponsorExtensionInfo;
    /** JSON Schema for validation */
    schema: object;
}
/**
 * Complete ERC-20 approval gas sponsor payload from client.
 */
interface ERC20ApprovalGasSponsorPayload {
    /** CAIP-2 network identifier (must be in sponsoredNetworks) */
    network: string;
    /** Client wallet address that signed the transaction */
    from: string;
    /** ERC-20 token contract address */
    asset: string;
    /** Approval amount in base units */
    amount: string;
    /** Raw signed approve() transaction (hex-encoded with 0x prefix) */
    signedApprovalTx: string;
    /** Chain ID for replay protection */
    chainId: number;
    /** Client's account nonce (if known) */
    nonce?: number;
}
/**
 * Options for declaring ERC-20 approval gas sponsor extension on server.
 */
interface DeclareERC20ApprovalGasSponsorOptions {
    /** CAIP-2 network identifiers where gas sponsoring is available */
    sponsoredNetworks: string[];
    /** Maximum token amount (in base units) the sponsor will cover per approval */
    maxAmount: string;
    /** Address of the sponsor/facilitator */
    sponsorAddress: string;
    /** Optional Permit2 proxy address */
    permit2Address?: string;
    /** Whether atomic batch execution is required (defaults to false) */
    requiresAtomicBatch?: boolean;
}
/**
 * Options for validating ERC-20 approval gas sponsor payloads.
 */
interface ValidateERC20ApprovalGasSponsorOptions {
    /** Expected chain IDs per CAIP-2 network (e.g., { "eip155:8453": 8453 }) */
    expectedChainIds?: Record<string, number>;
}
/**
 * Result of ERC-20 approval gas sponsor payload validation.
 */
interface ERC20ApprovalGasSponsorValidationResult {
    /** Whether the payload is valid */
    valid: boolean;
    /** Error message if invalid */
    error?: string;
}
/**
 * Parameters for creating an ERC-20 approval gas sponsor payload.
 */
interface CreateERC20ApprovalParams {
    /** CAIP-2 network identifier */
    network: string;
    /** Client wallet address */
    from: string;
    /** ERC-20 token contract address */
    asset: string;
    /** Approval amount in base units */
    amount: string;
    /** Raw signed approve() transaction (hex-encoded) */
    signedApprovalTx: string;
    /** Chain ID for replay protection */
    chainId: number;
    /** Client's account nonce (if known) */
    nonce?: number;
}

/**
 * ERC-20 Approval Gas Sponsoring Extension Server-Side Implementation
 *
 * Provides functions for servers to declare gas sponsoring requirements,
 * parse client headers, and validate approval payloads.
 */

/**
 * Declares an ERC-20 approval gas sponsor extension for server responses.
 *
 * @param options - Extension declaration options
 * @returns Gas sponsor extension object ready for response
 *
 * @example
 * ```typescript
 * const extension = declareERC20ApprovalGasSponsorExtension({
 *   sponsoredNetworks: ["eip155:8453", "eip155:42161"],
 *   maxAmount: "1000000000",
 *   sponsorAddress: "0xFacilitator...",
 *   requiresAtomicBatch: true,
 * });
 * ```
 */
declare function declareERC20ApprovalGasSponsorExtension(options: DeclareERC20ApprovalGasSponsorOptions): ERC20ApprovalGasSponsorExtension;
/**
 * Parses an ERC-20 approval 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 = parseERC20ApprovalGasSponsorHeader(
 *   request.headers['x-t402-erc20-approval-gas-sponsoring']
 * );
 * ```
 */
declare function parseERC20ApprovalGasSponsorHeader(header: string): ERC20ApprovalGasSponsorPayload;
/**
 * Validates an ERC-20 approval 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 = validateERC20ApprovalGasSponsorPayload(payload, extension.info);
 * if (!result.valid) {
 *   throw new Error(result.error);
 * }
 * ```
 */
declare function validateERC20ApprovalGasSponsorPayload(payload: ERC20ApprovalGasSponsorPayload, extensionInfo: ERC20ApprovalGasSponsorExtensionInfo, options?: ValidateERC20ApprovalGasSponsorOptions): ERC20ApprovalGasSponsorValidationResult;

/**
 * ERC-20 Approval Gas Sponsoring Extension Client-Side Implementation
 *
 * Provides functions for clients to construct ERC-20 approve() calldata
 * and encode gas sponsor payloads for transmission.
 */

/**
 * Extension key for ERC-20 approval gas sponsoring in payment requirements.
 */
declare const ERC20_APPROVAL_GAS_SPONSOR_EXTENSION_KEY = "erc20ApprovalGasSponsoring";
/**
 * HTTP header name for ERC-20 approval gas sponsor payload.
 */
declare const ERC20_APPROVAL_GAS_SPONSOR_HEADER_NAME = "X-T402-ERC20-Approval-Gas-Sponsoring";
/**
 * ERC-20 approve(address,uint256) function selector.
 */
declare const APPROVE_FUNCTION_SELECTOR = "0x095ea7b3";
/**
 * Encodes ERC-20 approve(address spender, uint256 amount) calldata.
 *
 * @param spender - The spender address to approve
 * @param amount - The approval amount in base units
 * @returns Hex-encoded calldata with 0x prefix
 *
 * @example
 * ```typescript
 * const calldata = encodeApproveCalldata("0xFacilitator...", "1000000");
 * // Returns "0x095ea7b3" + abi-encoded args
 * ```
 */
declare function encodeApproveCalldata(spender: string, amount: string): string;
/**
 * Creates an ERC-20 approval gas sponsor payload from params and extension info.
 *
 * @param _info - The server's extension info (reserved for future use)
 * @param params - The approval parameters
 * @returns Gas sponsor payload ready for header encoding
 *
 * @example
 * ```typescript
 * const payload = createERC20ApprovalGasSponsorPayload(extensionInfo, {
 *   network: "eip155:8453",
 *   from: wallet.address,
 *   asset: "0xUSDT...",
 *   amount: "1000000",
 *   signedApprovalTx: signedTx,
 *   chainId: 8453,
 * });
 * ```
 */
declare function createERC20ApprovalGasSponsorPayload(_info: ERC20ApprovalGasSponsorExtensionInfo, params: CreateERC20ApprovalParams): ERC20ApprovalGasSponsorPayload;
/**
 * Encodes an ERC-20 approval 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 = encodeERC20ApprovalGasSponsorHeader(payload);
 * fetch(url, {
 *   headers: { [ERC20_APPROVAL_GAS_SPONSOR_HEADER_NAME]: header }
 * });
 * ```
 */
declare function encodeERC20ApprovalGasSponsorHeader(payload: ERC20ApprovalGasSponsorPayload): string;

/**
 * ERC-20 Approval Gas Sponsoring Extension Facilitator-Side Implementation
 *
 * Provides functions for facilitators to extract approval data from payment
 * extensions, validate the signed approve() transaction, and prepare for
 * on-chain submission.
 */

/**
 * Extracts the ERC-20 approval 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 approval = extractERC20ApprovalGasSponsorPayload(paymentPayload.extensions);
 * if (approval) {
 *   // Validate and broadcast the approval tx, then settle
 * }
 * ```
 */
declare function extractERC20ApprovalGasSponsorPayload(extensions: Record<string, unknown> | undefined): ERC20ApprovalGasSponsorPayload | null;
/**
 * Processes and validates an ERC-20 approval payload for the facilitator.
 *
 * Combines extraction validation with approve() function selector verification.
 * Checks that the signed transaction data contains the correct approve() selector
 * and that the approval amount matches the declared amount.
 *
 * @param payload - The ERC-20 approval gas sponsor payload
 * @param extensionInfo - The server's gas sponsor extension info
 * @returns Validation result
 *
 * @example
 * ```typescript
 * const result = processERC20ApprovalPayload(payload, extensionInfo);
 * if (result.valid) {
 *   // Safe to broadcast the approval tx and settle
 * }
 * ```
 */
declare function processERC20ApprovalPayload(payload: ERC20ApprovalGasSponsorPayload, extensionInfo: ERC20ApprovalGasSponsorExtensionInfo): ERC20ApprovalGasSponsorValidationResult;
/**
 * Validates and extracts the ERC-20 approval 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 = validateAndExtractApproval(
 *   paymentPayload.extensions,
 *   extensionInfo
 * );
 * if (result.valid && result.payload) {
 *   // Broadcast approval tx, then settle
 * }
 * ```
 */
declare function validateAndExtractApproval(extensions: Record<string, unknown> | undefined, extensionInfo: ERC20ApprovalGasSponsorExtensionInfo): ERC20ApprovalGasSponsorValidationResult & {
    payload?: ERC20ApprovalGasSponsorPayload;
};
/**
 * Decodes the approve() calldata from a hex string to extract spender and amount.
 *
 * @param calldata - Hex-encoded approve() calldata (with or without 0x prefix)
 * @returns Decoded spender and amount, or null if not valid approve() calldata
 *
 * @example
 * ```typescript
 * const decoded = decodeApproveCalldata("0x095ea7b3...");
 * if (decoded) {
 *   console.log(decoded.spender, decoded.amount);
 * }
 * ```
 */
declare function decodeApproveCalldata(calldata: string): {
    spender: string;
    amount: string;
} | null;

export { APPROVE_FUNCTION_SELECTOR, type CreateERC20ApprovalParams, type DeclareERC20ApprovalGasSponsorOptions, type ERC20ApprovalGasSponsorExtension, type ERC20ApprovalGasSponsorExtensionInfo, type ERC20ApprovalGasSponsorPayload, type ERC20ApprovalGasSponsorValidationResult, ERC20_APPROVAL_GAS_SPONSOR_EXTENSION_KEY, ERC20_APPROVAL_GAS_SPONSOR_HEADER_NAME, type ValidateERC20ApprovalGasSponsorOptions, createERC20ApprovalGasSponsorPayload, declareERC20ApprovalGasSponsorExtension, decodeApproveCalldata, encodeApproveCalldata, encodeERC20ApprovalGasSponsorHeader, extractERC20ApprovalGasSponsorPayload, parseERC20ApprovalGasSponsorHeader, processERC20ApprovalPayload, validateAndExtractApproval, validateERC20ApprovalGasSponsorPayload };