/**
 * Units for file sizes
 */
const FILE_SIZE_UNITS = ['B', 'KB', 'MB', 'GB', 'TB']

/**
 * Interface for file size
 */
export interface FileSize {
  value: number
  unit: string
}

/**
 * Base function to parse file size in bytes to value and unit
 * @param bytes File size in bytes
 * @param binary Whether to use binary (1024) or decimal (1000) units
 * @returns Object with numeric value and unit string
 */
function parseSize(bytes: number, binary: boolean = false): FileSize {
  // Handle invalid input
  if (bytes === null || bytes === undefined || isNaN(bytes) || bytes < 0) {
    return { value: 0, unit: 'B' }
  }

  // If the size is 0, return early
  if (bytes === 0) {
    return { value: 0, unit: 'B' }
  }

  // Otherwise, determine the appropriate unit based on the size
  const unit = binary ? 1024 : 1000
  const unitIndex = Math.floor(Math.log(bytes) / Math.log(unit))
  const unitSize = Math.pow(unit, unitIndex)
  const value = bytes / unitSize

  // Make sure we don't exceed our units array
  const safeUnitIndex = Math.min(unitIndex, FILE_SIZE_UNITS.length - 1)

  return {
    value: Math.round(value * 100) / 100, // Round to 2 decimal places
    unit: FILE_SIZE_UNITS[safeUnitIndex],
  }
}

/**
 * Converts a file size in bytes to a human-readable string
 * @param bytes File size in bytes
 * @param binary Whether to use binary (1024) or decimal (1000) units
 * @returns Formatted file size string (e.g., "1.5 MB")
 */
export function formatSize(bytes: number, binary: boolean = false): string {
  const { value, unit } = parseSize(bytes, binary)
  return `${value.toFixed(2)} ${unit}`
}

/**
 * Converts a file size in bytes to an object with value and unit
 * @param bytes File size in bytes
 * @param binary Whether to use binary (1024) or decimal (1000) units
 * @returns Object with numeric value and unit string
 */
export function formatSizeObject(
  bytes: number,
  binary: boolean = false,
): FileSize {
  return parseSize(bytes, binary)
}