orca/src/shared/clipboard-text.ts

export const CLIPBOARD_TEXT_READ_MAX_BYTES = 16 * 1024 * 1024
export const CLIPBOARD_TEXT_WRITE_MAX_BYTES = 16 * 1024 * 1024
export const CLIPBOARD_TEXT_TOO_LARGE_ERROR = 'Clipboard text is too large for this paste target.'
export const CLIPBOARD_TEXT_WRITE_TOO_LARGE_ERROR = 'Clipboard text is too large to copy safely.'
export const CLIPBOARD_TEXT_MEASURE_YIELD_CODE_UNITS = 256 * 1024

export type ReadClipboardTextOptions = {
  maxBytes?: number
}

export type WriteClipboardTextOptions = {
  maxBytes?: number
}

export type ClipboardTextByteLengthMeasurement = {
  byteLength: number
  exceededLimit: boolean
}

export function measureClipboardTextByteLength(
  text: string,
  options: { stopAfterBytes?: number } = {}
): ClipboardTextByteLengthMeasurement {
  const stopAfterBytes = options.stopAfterBytes
  let byteLength = 0
  for (let index = 0; index < text.length; index += 1) {
    const codePoint = text.codePointAt(index) ?? 0
    byteLength += getUtf8ByteLengthForCodePoint(codePoint)
    if (Number.isFinite(stopAfterBytes) && byteLength > (stopAfterBytes ?? 0)) {
      return { byteLength, exceededLimit: true }
    }
    if (codePoint > 0xffff) {
      index += 1
    }
  }
  return { byteLength, exceededLimit: false }
}

export function getClipboardTextByteLength(text: string): number {
  return measureClipboardTextByteLength(text).byteLength
}

export async function measureClipboardTextByteLengthWithYield(
  text: string,
  options: {
    stopAfterBytes?: number
    yieldAfterCodeUnits?: number
    yieldToEventLoop?: () => Promise<void>
  } = {}
): Promise<ClipboardTextByteLengthMeasurement> {
  const stopAfterBytes = options.stopAfterBytes
  const yieldAfterCodeUnits = Math.max(
    1,
    options.yieldAfterCodeUnits ?? CLIPBOARD_TEXT_MEASURE_YIELD_CODE_UNITS
  )
  const yieldToEventLoop = options.yieldToEventLoop ?? defaultClipboardTextMeasureYield
  let nextYieldAt = yieldAfterCodeUnits
  let byteLength = 0

  for (let index = 0; index < text.length; index += 1) {
    const codePoint = text.codePointAt(index) ?? 0
    byteLength += getUtf8ByteLengthForCodePoint(codePoint)
    if (Number.isFinite(stopAfterBytes) && byteLength > (stopAfterBytes ?? 0)) {
      return { byteLength, exceededLimit: true }
    }
    if (codePoint > 0xffff) {
      index += 1
    }
    if (index >= nextYieldAt) {
      await yieldToEventLoop()
      nextYieldAt = index + yieldAfterCodeUnits
    }
  }
  return { byteLength, exceededLimit: false }
}

export function isClipboardTextByteLengthOverLimit(text: string, maxBytes: number): boolean {
  return (
    text.length > maxBytes ||
    measureClipboardTextByteLength(text, { stopAfterBytes: maxBytes }).exceededLimit
  )
}

export async function isClipboardTextByteLengthOverLimitWithYield(
  text: string,
  maxBytes: number,
  options: {
    yieldAfterCodeUnits?: number
    yieldToEventLoop?: () => Promise<void>
  } = {}
): Promise<boolean> {
  if (text.length > maxBytes) {
    return true
  }
  return (
    await measureClipboardTextByteLengthWithYield(text, {
      stopAfterBytes: maxBytes,
      yieldAfterCodeUnits: options.yieldAfterCodeUnits,
      yieldToEventLoop: options.yieldToEventLoop
    })
  ).exceededLimit
}

export function getClipboardTextReadMaxBytes(
  options: ReadClipboardTextOptions | undefined,
  fallback = CLIPBOARD_TEXT_READ_MAX_BYTES
): number {
  return Number.isFinite(options?.maxBytes) && (options?.maxBytes ?? 0) > 0
    ? Math.floor(options?.maxBytes ?? fallback)
    : fallback
}

export function getClipboardTextWriteMaxBytes(
  options: WriteClipboardTextOptions | undefined,
  fallback = CLIPBOARD_TEXT_WRITE_MAX_BYTES
): number {
  return Number.isFinite(options?.maxBytes) && (options?.maxBytes ?? 0) > 0
    ? Math.floor(options?.maxBytes ?? fallback)
    : fallback
}

export function assertClipboardTextWithinLimit(
  text: string,
  options?: ReadClipboardTextOptions
): string {
  const maxBytes = getClipboardTextReadMaxBytes(options)
  if (isClipboardTextByteLengthOverLimit(text, maxBytes)) {
    throw new Error(CLIPBOARD_TEXT_TOO_LARGE_ERROR)
  }
  return text
}

export async function assertClipboardTextWithinLimitWithYield(
  text: string,
  options?: ReadClipboardTextOptions
): Promise<string> {
  const maxBytes = getClipboardTextReadMaxBytes(options)
  if (await isClipboardTextByteLengthOverLimitWithYield(text, maxBytes)) {
    throw new Error(CLIPBOARD_TEXT_TOO_LARGE_ERROR)
  }
  return text
}

export function assertClipboardTextWriteWithinLimit(
  text: string,
  options?: WriteClipboardTextOptions
): string {
  const maxBytes = getClipboardTextWriteMaxBytes(options)
  if (isClipboardTextByteLengthOverLimit(text, maxBytes)) {
    throw new Error(CLIPBOARD_TEXT_WRITE_TOO_LARGE_ERROR)
  }
  return text
}

export async function assertClipboardTextWriteWithinLimitWithYield(
  text: string,
  options?: WriteClipboardTextOptions
): Promise<string> {
  const maxBytes = getClipboardTextWriteMaxBytes(options)
  if (await isClipboardTextByteLengthOverLimitWithYield(text, maxBytes)) {
    throw new Error(CLIPBOARD_TEXT_WRITE_TOO_LARGE_ERROR)
  }
  return text
}

export function isClipboardTextTooLargeError(error: unknown): boolean {
  return error instanceof Error && error.message.includes(CLIPBOARD_TEXT_TOO_LARGE_ERROR)
}

export function isClipboardTextWriteTooLargeError(error: unknown): boolean {
  return error instanceof Error && error.message.includes(CLIPBOARD_TEXT_WRITE_TOO_LARGE_ERROR)
}

function getUtf8ByteLengthForCodePoint(codePoint: number): number {
  if (codePoint <= 0x7f) {
    return 1
  }
  if (codePoint <= 0x7ff) {
    return 2
  }
  if (codePoint <= 0xffff) {
    return 3
  }
  return 4
}

function defaultClipboardTextMeasureYield(): Promise<void> {
  return new Promise((resolve) => setTimeout(resolve, 0))
}