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/**
 * Validates an input address and classifies it as a wallet, token account, or invalid.
 *
 * @param inputAddress - The address to validate
 * @param rpc - Optional RPC client (defaults to mainnet)
 * @returns Classification result:
 *   - IS_WALLET: Valid wallet address
 *   - IS_TOKEN_ACCOUNT: Valid token account
 *   - REJECT: Invalid address for transfers
 */
export async function validateAddress(
  inputAddress: Address,
  rpc: Rpc<GetAccountInfoApi> = defaultRpc
): Promise<ValidationResult> {
  const account = await fetchJsonParsedAccount(rpc, inputAddress);
  // Log the account data for demo
  console.log("\nAccount:", account);

  // Account doesn't exist onchain
  if (!account.exists) {
    // Off-curve = PDA that doesn't exist as an account
    // Reject conservatively to avoid sending to an address that may be inaccessible.
    if (isOffCurveAddress(inputAddress)) {
      return { type: "REJECT", reason: "PDA doesn't exist as an account" };
    }
    // On-curve = valid keypair address, treat as unfunded wallet
    return { type: "IS_WALLET" };
  }

  // Account exists, check program owner
  const owner = account.programAddress;

  // System Program = wallet
  if (owner === SYSTEM_PROGRAM) {
    return { type: "IS_WALLET" };
  }

  // Token Program or Token-2022, check if token account
  if (owner === TOKEN_PROGRAM || owner === TOKEN_2022_PROGRAM) {
    const accountType = (
      account.data as { parsedAccountMeta?: { type?: string } }
    ).parsedAccountMeta?.type;

    if (accountType === "account") {
      return { type: "IS_TOKEN_ACCOUNT" };
    }
    // Reject if not a token account (mint account)
    return {
      type: "REJECT",
      reason: "Not a token account"
    };
  }

  // Unknown program owner
  return { type: "REJECT", reason: "Unknown program owner" };
}

/**
 * Native SOL is only safe to send to a wallet. Any other account locks it.
 */
function canReceiveNativeSol(result: ValidationResult): boolean {
  return result.type === "IS_WALLET";
}

/**
 * SPL tokens can go to a wallet (via its ATA) or directly to a token account.
 */
function canReceiveSplToken(result: ValidationResult): boolean {
  return result.type === "IS_WALLET" || result.type === "IS_TOKEN_ACCOUNT";
}

// =============================================================================
// Examples
// =============================================================================