---
import Icon from './Icon.astro'

interface Props {
  /** a number, or a signed string such as "+9.5" that is rendered as written */
  value: number | string
  unit?: string | undefined
  class?: string
}

const { value, unit = '%', class: className } = Astro.props

const amount = Number(value)
if (Number.isNaN(amount)) {
  throw new Error(`Trending: value "${value}" is not a number`)
}

const trendingColor = amount > 0 ? 'green' : amount === 0 ? 'muted' : 'red'
const trendingIcon = amount > 0 ? 'arrow-up' : amount === 0 ? 'minus' : 'arrow-down'

const classes = [`text-${trendingColor} d-inline-flex align-items-center lh-1`, className]
---

<span class:list={classes}>
  <span class="visually-hidden">{amount > 0 ? 'Increased by' : amount < 0 ? 'Decreased by' : 'No change,'} </span>{value}{unit}
  <Icon name={trendingIcon} class="ms-0" size="sm" />
</span>