erc20Streaming.ts

import { type BytesLike, bytesToHex, isHexString } from '@metamask/utils';

import {
  defaultOptions,
  prepareResult,
  type EncodingOptions,
  type ResultValue,
} from '../returns';
import type { Hex } from '../types';
import { toHexString } from '../utils';

// Upper bound for timestamps (January 1, 10000 CE)
const TIMESTAMP_UPPER_BOUND_SECONDS = 253402300799;

/**
 * Terms for configuring a linear streaming allowance of ERC20 tokens.
 */
export type ERC20StreamingTerms = {
  /** The address of the ERC20 token contract. */
  tokenAddress: BytesLike;
  /** The initial amount available immediately. */
  initialAmount: bigint;
  /** The maximum total amount that can be transferred. */
  maxAmount: bigint;
  /** The rate at which allowance increases per second. */
  amountPerSecond: bigint;
  /** Unix timestamp when streaming begins. */
  startTime: number;
};

/**
 * Creates terms for the ERC20Streaming caveat, configuring a linear
 * streaming allowance of ERC20 tokens.
 *
 * @param terms - The terms for the ERC20Streaming caveat.
 * @param encodingOptions - The encoding options for the result.
 * @returns Hex-encoded terms for the caveat (160 bytes).
 * @throws Error if tokenAddress is invalid.
 * @throws Error if initialAmount is negative.
 * @throws Error if maxAmount is not positive.
 * @throws Error if maxAmount is less than initialAmount.
 * @throws Error if amountPerSecond is not positive.
 * @throws Error if startTime is not positive.
 * @throws Error if startTime exceeds upper bound.
 */
export function createERC20StreamingTerms(
  terms: ERC20StreamingTerms,
  encodingOptions?: EncodingOptions<'hex'>,
): Hex;
export function createERC20StreamingTerms(
  terms: ERC20StreamingTerms,
  encodingOptions: EncodingOptions<'bytes'>,
): Uint8Array;
/**
 * Creates terms for the ERC20Streaming caveat, configuring a linear
 * streaming allowance of ERC20 tokens.
 *
 * @param terms - The terms for the ERC20Streaming caveat.
 * @param encodingOptions - The encoding options for the result.
 * @returns The terms as a 160-byte hex string.
 * @throws Error if any of the parameters are invalid.
 */
export function createERC20StreamingTerms(
  terms: ERC20StreamingTerms,
  encodingOptions: EncodingOptions<ResultValue> = defaultOptions,
): Hex | Uint8Array {
  const { tokenAddress, initialAmount, maxAmount, amountPerSecond, startTime } =
    terms;

  if (!tokenAddress) {
    throw new Error('Invalid tokenAddress: must be a valid address');
  }

  let prefixedTokenAddressHex: string;

  if (typeof tokenAddress === 'string') {
    if (!isHexString(tokenAddress) || tokenAddress.length !== 42) {
      throw new Error('Invalid tokenAddress: must be a valid address');
    }
    prefixedTokenAddressHex = tokenAddress;
  } else {
    if (tokenAddress.length !== 20) {
      throw new Error('Invalid tokenAddress: must be a valid address');
    }
    prefixedTokenAddressHex = bytesToHex(tokenAddress);
  }

  if (initialAmount < 0n) {
    throw new Error('Invalid initialAmount: must be greater than zero');
  }

  if (maxAmount <= 0n) {
    throw new Error('Invalid maxAmount: must be a positive number');
  }

  if (maxAmount < initialAmount) {
    throw new Error('Invalid maxAmount: must be greater than initialAmount');
  }

  if (amountPerSecond <= 0n) {
    throw new Error('Invalid amountPerSecond: must be a positive number');
  }

  if (startTime <= 0) {
    throw new Error('Invalid startTime: must be a positive number');
  }

  if (startTime > TIMESTAMP_UPPER_BOUND_SECONDS) {
    throw new Error(
      'Invalid startTime: must be less than or equal to 253402300799',
    );
  }

  const initialAmountHex = toHexString({ value: initialAmount, size: 32 });
  const maxAmountHex = toHexString({ value: maxAmount, size: 32 });
  const amountPerSecondHex = toHexString({ value: amountPerSecond, size: 32 });
  const startTimeHex = toHexString({ value: startTime, size: 32 });

  const hexValue = `${prefixedTokenAddressHex}${initialAmountHex}${maxAmountHex}${amountPerSecondHex}${startTimeHex}`;

  return prepareResult(hexValue, encodingOptions);
}