import type { CSSProperties } from 'react'

export type UserAvatarStyle = Pick<CSSProperties, 'backgroundColor' | 'color'>

function hashString(value: string): number {
  let hash = 0
  for (let i = 0; i < value.length; i++) {
    hash = (hash * 31 + value.charCodeAt(i)) >>> 0
  }
  return hash
}

export function getUserAvatarStyle(name: string): UserAvatarStyle {
  const hash = hashString(name)
  const hue = hash % 360
  const saturation = 54 + (hash % 8)
  const lightness = 52 + ((hash >> 4) % 8)

  return {
    backgroundColor: `hsl(${hue} ${saturation}% ${lightness}% / 0.82)`,
    color: 'white',
  }
}

export function getUserAvatarFallback(name: string): string {
  return name.trim().charAt(0).toUpperCase() || '?'
}
