/**
 * Copied over from uint8array-extras to sort out ESM build issues. Should be replaced with imports from that module eventually
 */

const objectToString = Object.prototype.toString
const uint8ArrayStringified = '[object Uint8Array]'

function isUint8Array(value: unknown): value is Uint8Array {
  if (!value) {
    return false
  }

  if (value.constructor === Uint8Array) {
    return true
  }

  return objectToString.call(value) === uint8ArrayStringified
}

function assertUint8Array(value: unknown): asserts value is Uint8Array {
  if (!isUint8Array(value)) {
    throw new TypeError(`Expected \`Uint8Array\`, got \`${typeof value}\``)
  }
}

export function concatUint8Arrays(arrays: Uint8Array[], totalLength?: number) {
  if (arrays.length === 0) {
    return new Uint8Array(0)
  }

  totalLength ??= arrays.reduce((accumulator, currentValue) => accumulator + currentValue.length, 0)

  const returnValue = new Uint8Array(totalLength)

  let offset = 0
  for (const array of arrays) {
    assertUint8Array(array)
    returnValue.set(array, offset)
    offset += array.length
  }

  return returnValue
}