import { downloadToCSV, downloadToPNG, type DownloadItem } from '../actions'
import type { ConfigProps } from '../loader/types'
import type {
  CategoryWidgetConfig,
  CategoryWidgetData,
  CategorySeriesConfig,
} from './types'

interface CategoryDownloadConfigProps extends ConfigProps {
  series?: CategorySeriesConfig[]
}

/**
 * Creates download configuration for category widgets, supporting PNG (screenshot) and CSV (data) exports. CSV output groups values by category across multiple series.
 *
 * @param props - Configuration with `refUI` reference and optional `series` for CSV column headers.
 * @returns Array of download items for use with the Download action.
 */
export function categoryDownloadConfig({
  refUI,
  series,
}: CategoryDownloadConfigProps): DownloadItem<CategoryWidgetData>[] {
  return [
    {
      ...downloadToPNG,
      modifier: () => downloadToPNG.modifier(refUI),
    },
    {
      ...downloadToCSV,
      modifier: async (data) => {
        if (!data?.length || data[0]?.length === 0) {
          return downloadToCSV.modifier([])
        }

        // data is CategoryDataItem[][] where data[seriesIndex] contains items for that series
        const seriesCount = data.length
        const grouped = new Map<string, number[]>()
        const nameOrder: string[] = []

        // Iterate over each series (outer array)
        for (let seriesIndex = 0; seriesIndex < seriesCount; seriesIndex++) {
          const seriesData = data[seriesIndex]!
          for (const item of seriesData) {
            let values = grouped.get(item.name)
            if (!values) {
              values = new Array<number>(seriesCount).fill(0)
              grouped.set(item.name, values)
              nameOrder.push(item.name)
            }
            values[seriesIndex] = item.value
          }
        }

        // Build rows
        const rows = nameOrder.map((name) => [name, ...grouped.get(name)!])

        const isMulti = seriesCount > 1
        const headers = isMulti
          ? [
              'Category',
              ...(series?.map((s: CategorySeriesConfig) => s.name) ??
                Array.from(
                  { length: seriesCount },
                  (_, i) => `Series ${i + 1}`,
                )),
            ]
          : ['Category', 'Value']

        return downloadToCSV.modifier([headers, ...rows])
      },
    },
  ]
}

/**
 * Returns the default configuration for category list widgets, including empty series and a default `maxItems` of 10.
 *
 * @returns Default category widget config.
 */
export function categoryConfig(): CategoryWidgetConfig {
  return {
    series: [],
    maxItems: 10,
    max: undefined,
  }
}