import type { BackendContext } from '@jaspers-ai/sdk'
import { buildXlsx } from './xlsx'
import { cleanFilename, defaultFilename, rowArrays, sheetNames } from './sheets'

export interface TableInput {
  title: string
  columns: string[]
  rows: unknown[]
}

function base64(bytes: Uint8Array): string {
  let s = ''
  for (let i = 0; i < bytes.length; i += 0x8000) s += String.fromCharCode(...bytes.subarray(i, i + 0x8000))
  return btoa(s)
}

/** Builds the workbook, writes it under exports/, opens it, and answers path, sheets, and row counts. */
export async function writeWorkbook(ctx: BackendContext, tables: TableInput[], filename?: string) {
  if (tables.length === 0) throw new Error('No tables to export.')
  const names = sheetNames(tables.map((t) => t.title))
  const sheets = tables.map((t, i) => ({ name: names[i]!, columns: t.columns, rows: rowArrays(t.columns, t.rows) }))
  const file = filename ? cleanFilename(filename) : defaultFilename(tables[0]!.title, new Date())
  const path = `exports/${file}`
  await ctx.files.write(path, base64(buildXlsx(sheets)), { encoding: 'base64' })
  let opened = true
  try {
    await ctx.files.open(path)
  } catch {
    opened = false
  }
  return {
    path,
    location: `~/Jaspers/excel-export/${path}`,
    opened,
    sheets: sheets.map((s) => s.name),
    rows: sheets.map((s) => ({ sheet: s.name, title: tables[sheets.indexOf(s)]!.title, rows: s.rows.length, columns: s.columns.length })),
  }
}