/**
 * @module utils/merchant-validator
 * @description Standard Synapse merchant middleware for x402 settlement.
 *
 * Reads `X-Payment-*` headers from incoming HTTP requests, validates
 * the escrow on-chain, auto-generates the correct `AccountMeta[]`,
 * and throws explicit errors (e.g. {@link MissingEscrowAtaError})
 * instead of letting the program return a generic crash.
 *
 * Designed for agents like Syra/Invoica that receive x402 payments.
 *
 * @category Utils
 * @since v0.6.4
 */
import { type PublicKey, type Connection, type AccountMeta } from "@solana/web3.js";
import { BN } from "@coral-xyz/anchor";
import type { EscrowValidationResult } from "./escrow-validation";
import type { EscrowAccountV2Data } from "../types";
/**
 * @interface ParsedX402Headers
 * @description Parsed and typed x402 payment headers from incoming HTTP request.
 * @category Utils
 * @since v0.6.4
 */
export interface ParsedX402Headers {
    /** x402 protocol identifier — must be "SAP-x402". */
    readonly protocol: string;
    /** Escrow PDA address. */
    readonly escrowPda: PublicKey;
    /** Agent PDA address. */
    readonly agentPda: PublicKey;
    /** Depositor wallet address. */
    readonly depositorWallet: PublicKey;
    /** Max calls allowed. */
    readonly maxCalls: BN;
    /** Price per call. */
    readonly pricePerCall: BN;
    /** SAP program ID. */
    readonly programId: PublicKey;
    /** Network identifier. */
    readonly network: string;
}
/**
 * @interface MerchantValidationResult
 * @description Complete validation result for merchant-side x402 processing.
 * @category Utils
 * @since v0.6.4
 */
export interface MerchantValidationResult {
    /** Whether the escrow is valid and ready for settlement. */
    readonly valid: boolean;
    /** Parsed x402 headers. */
    readonly headers: ParsedX402Headers;
    /** Full escrow validation result. */
    readonly escrowValidation: EscrowValidationResult;
    /** Pre-built AccountMeta[] for settlement TX (empty for SOL escrows). */
    readonly accountMetas: AccountMeta[];
    /** All validation errors. */
    readonly errors: string[];
}
/**
 * @name parseX402Headers
 * @description Parse and validate x402 headers from an HTTP request.
 *
 * @param headers - HTTP headers object (case-insensitive key lookup).
 * @returns Parsed x402 headers.
 * @throws {SapValidationError} If required headers are missing or malformed.
 *
 * @category Utils
 * @since v0.6.4
 */
export declare function parseX402Headers(headers: Record<string, string | string[] | undefined>): ParsedX402Headers;
/**
 * @name SapMerchantValidator
 * @description Standard Synapse merchant middleware for x402 payment validation.
 *
 * Reads `X-Payment-*` headers, validates escrow state on-chain, generates
 * correct `AccountMeta[]` for SPL token escrows, and throws explicit errors
 * (e.g. {@link MissingEscrowAtaError}) when ATA accounts are missing.
 *
 * @category Utils
 * @since v0.6.4
 *
 * @example
 * ```ts
 * const validator = new SapMerchantValidator(connection, fetchEscrow);
 *
 * // Express.js integration
 * app.post("/api/v1/chat", async (req, res) => {
 *   try {
 *     const validation = await validator.validateRequest(req.headers, {
 *       callsToSettle: 1,
 *     });
 *
 *     if (!validation.valid) {
 *       return res.status(402).json({ errors: validation.errors });
 *     }
 *
 *     // Process request...
 *
 *     // Settle payment using pre-built account metas
 *     await client.escrow.settle(
 *       validation.headers.depositorWallet,
 *       1,
 *       serviceHash,
 *       validation.accountMetas,
 *     );
 *
 *     res.json({ result: "..." });
 *   } catch (err) {
 *     if (err instanceof MissingEscrowAtaError) {
 *       return res.status(402).json({
 *         error: err.message,
 *         side: err.side,
 *         ata: err.ataAddress,
 *       });
 *     }
 *     throw err;
 *   }
 * });
 * ```
 */
export declare class SapMerchantValidator {
    private readonly connection;
    private readonly fetchEscrow;
    /**
     * @param connection  - Solana RPC connection.
     * @param fetchEscrow - Callback to fetch escrow account data by PDA.
     *   Typically `(pda) => client.escrow.fetchByPda(pda).catch(() => null)`.
     */
    constructor(connection: Connection, fetchEscrow: (escrowPda: PublicKey) => Promise<EscrowAccountV2Data | null>);
    /**
     * @name validateRequest
     * @description Full validation pipeline for an incoming x402 request.
     *
     * Steps:
     * 1. Parse `X-Payment-*` headers
     * 2. Fetch escrow on-chain
     * 3. Validate escrow state (balance, expiry, max calls)
     * 4. If SPL escrow: validate ATAs exist and mint matches
     * 5. Build `AccountMeta[]` for settlement TX
     *
     * @param headers - HTTP headers from the incoming request.
     * @param opts
     * @param opts.callsToSettle     - Number of calls to validate affordability for (default: 1).
     * @param opts.throwOnMissingAta - Throw {@link MissingEscrowAtaError} instead of returning errors (default: true).
     *
     * @returns A complete {@link MerchantValidationResult}.
     *
     * @throws {SapValidationError} If headers are missing or malformed.
     * @throws {MissingEscrowAtaError} If SPL ATAs are missing and `throwOnMissingAta` is true.
     *
     * @category Utils
     * @since v0.6.4
     */
    validateRequest(headers: Record<string, string | string[] | undefined>, opts?: {
        callsToSettle?: number;
        throwOnMissingAta?: boolean;
    }): Promise<MerchantValidationResult>;
    /**
     * @name validateEscrow
     * @description Validate escrow from pre-parsed headers (convenience method).
     * Call this when you've already parsed the headers yourself.
     *
     * @param headers - Pre-parsed x402 headers.
     * @param opts
     * @returns The escrow validation result with pre-built account metas.
     *
     * @category Utils
     * @since v0.6.4
     */
    validateEscrow(headers: ParsedX402Headers, opts?: {
        callsToSettle?: number;
    }): Promise<EscrowValidationResult>;
}
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