import { describe, it, expect, beforeEach, vi } from 'vitest'
import { createHistogramDownloadConfig } from './download'
import type { HistogramWidgetData } from './types'

const data: HistogramWidgetData = [
  [1, 2, 3],
  [4, 5, 6],
]
const ticks = [0, 10, 20, 30]

let csvText = ''

beforeEach(() => {
  csvText = ''
  vi.spyOn(URL, 'createObjectURL').mockReturnValue('blob:mock')
  vi.spyOn(URL, 'revokeObjectURL').mockImplementation(() => undefined)
  const RealBlob = global.Blob
  vi.stubGlobal(
    'Blob',
    class extends RealBlob {
      constructor(parts: BlobPart[], opts?: BlobPropertyBag) {
        csvText = typeof parts[0] === 'string' ? parts[0] : ''
        super(parts, opts)
      }
    },
  )
})

describe('createHistogramDownloadConfig', () => {
  it('CSV-only by default', () => {
    const items = createHistogramDownloadConfig({
      filename: 'h',
      getData: () => data,
      getTicks: () => ticks,
    })
    expect(items.map((i) => i.id)).toEqual(['csv'])
  })

  it('prepends PNG when getCaptureEl is provided', () => {
    const items = createHistogramDownloadConfig({
      filename: 'h',
      getData: () => data,
      getTicks: () => ticks,
      getCaptureEl: () => document.createElement('div'),
    })
    expect(items.map((i) => i.id)).toEqual(['png', 'csv'])
  })

  it('CSV resolve serialises bins × series with default series names', async () => {
    const items = createHistogramDownloadConfig({
      filename: 'h',
      getData: () => data,
      getTicks: () => ticks,
    })
    const handle = await items.find((i) => i.id === 'csv')!.resolve()
    expect(handle.filename).toBe('h.csv')
    expect(csvText).toBe(
      'bin_low,bin_high,series_1,series_2\n0,10,1,4\n10,20,2,5\n20,30,3,6',
    )
  })

  it('CSV honours supplied seriesNames', async () => {
    const items = createHistogramDownloadConfig({
      filename: 'h',
      getData: () => data,
      getTicks: () => ticks,
      seriesNames: ['lo', 'hi'],
    })
    await items.find((i) => i.id === 'csv')!.resolve()
    expect(csvText.startsWith('bin_low,bin_high,lo,hi')).toBe(true)
  })

  it('CSV emits header-only when ticks has < 2 entries', async () => {
    const items = createHistogramDownloadConfig({
      filename: 'h',
      getData: () => data,
      getTicks: () => [0],
    })
    await items.find((i) => i.id === 'csv')!.resolve()
    expect(csvText).toBe('bin_low,bin_high,series_1,series_2')
  })

  it('CSV fills missing series values with 0', async () => {
    const sparse: HistogramWidgetData = [[1, 2, 3], []]
    const items = createHistogramDownloadConfig({
      filename: 'h',
      getData: () => sparse,
      getTicks: () => ticks,
    })
    await items.find((i) => i.id === 'csv')!.resolve()
    expect(csvText).toContain('0,10,1,0')
    expect(csvText).toContain('10,20,2,0')
  })
})