Function createAltTextForTrendLineChart

app/utils/charts.ts:487–566

({
  dataset,
  config,
}: AltCopyArgs<TrendLineDataset, TrendLineConfig>)

// Used for TrendsChart.vue
export function createAltTextForTrendLineChart({
  dataset,
  config,
}: AltCopyArgs<TrendLineDataset, TrendLineConfig>): string {
  if (!dataset) return ''

  const analysis = dataset.lines.map(({ name, series }) => ({
    name,
    ...computeLineChartAnalysis(series),
    dates: config.formattedDates,
    hasEstimation: config.hasEstimation,
  }))

  const granularityKeyByGranularity: Record<string, string> = {
    daily: 'package.trends.granularity_daily',
    weekly: 'package.trends.granularity_weekly',
    monthly: 'package.trends.granularity_monthly',
    yearly: 'package.trends.granularity_yearly',
  }

  const granularityKey =
    granularityKeyByGranularity[config.granularity] ?? 'package.trends.granularity_weekly'

  const granularity = String(config.$t(granularityKey)).toLocaleLowerCase()

  const packages_analysis = analysis
    .map((pkg, i) => {
      const trendText = (() => {
        switch (pkg.interpretation.trend) {
          case 'none':
            return config.$t('package.trends.copy_alt.trend_none')
          case 'weak':
            return config.$t('package.trends.copy_alt.trend_weak')
          case 'strong':
            return config.$t('package.trends.copy_alt.trend_strong')
          case 'undefined':
          default:
            return config.$t('package.trends.copy_alt.trend_undefined')
        }
      })()

      return config.$t('package.trends.copy_alt.analysis', {
        package_name: pkg.name,
        start_value: config.formattedDatasetValues[i]?.[0] ?? 0,
        end_value: config.formattedDatasetValues[i]?.at(-1) ?? 0,
        trend: trendText,
        downloads_slope: config.numberFormatter(pkg.slope),
      })
    })
    .join(', ')

  const isSinglePackage = analysis.length === 1

  const estimation_notice = config.hasEstimation
    ? ` ${
        isSinglePackage
          ? config.$t('package.trends.copy_alt.estimation')
          : config.$t('package.trends.copy_alt.estimations')