import {
  buildCsvDownloadItem,
  buildPngDownloadItem,
  type DownloadItem,
} from '../actions/download'
import type { HistogramWidgetData } from './types'

/**
 * Download menu items for histograms. Always includes a CSV item with
 * `bin_low, bin_high, series_1_count, series_2_count, …` columns (one row
 * per bin). When `getCaptureEl` is supplied, prepends a PNG item that
 * rasterises the captured element via `html2canvas`.
 */
export function createHistogramDownloadConfig(args: {
  filename: string
  getData: () => HistogramWidgetData
  getTicks: () => readonly number[]
  seriesNames?: readonly string[]
  getCaptureEl?: () => HTMLElement | null
  pngPixelRatio?: number
  pngBackgroundColor?: string | null
}): DownloadItem[] {
  const items: DownloadItem[] = []
  if (args.getCaptureEl) {
    items.push(
      buildPngDownloadItem({
        filename: args.filename,
        getCaptureEl: args.getCaptureEl,
        pixelRatio: args.pngPixelRatio,
        backgroundColor: args.pngBackgroundColor,
      }),
    )
  }
  items.push(
    buildCsvDownloadItem({
      filename: args.filename,
      getRows: () => {
        const data = args.getData()
        const ticks = args.getTicks()
        const seriesCount = data.length
        const header: unknown[] = ['bin_low', 'bin_high']
        for (let i = 0; i < seriesCount; i++) {
          header.push(args.seriesNames?.[i] ?? `series_${i + 1}`)
        }
        const rows: unknown[][] = [header]
        for (let bin = 0; bin < Math.max(0, ticks.length - 1); bin++) {
          const row: unknown[] = [ticks[bin], ticks[bin + 1]]
          for (let s = 0; s < seriesCount; s++) row.push(data[s]?.[bin] ?? 0)
          rows.push(row)
        }
        return rows
      },
    }),
  )
  return items
}