import { map } from 'lodash'

export type List<T> = {
  items: T[]
  page: number
  next: number
  limit: number
  total: number
}

export type ListConfig = {
  limit?: number
  sort?: string // field key
  direction?: 'asc' | 'desc'
  page?: number // starts from 1
  search?: {
    keywords: string
    fields: string[]
  }
}

export const paginate = <T>(items: T[], config: ListConfig, total: number): List<T> => {
  const { limit, page } = config
  const skip = limit * (page - 1)
  const finalItems = items.slice(skip, skip + limit)
  const hasNext = page * limit < total
  const next = hasNext ? page + 1 : null

  return {
    items: finalItems,
    page,
    next,
    limit,
    total,
  }
}

const defaultListConfig: ListConfig = {
  limit: 10,
  sort: 'id',
  direction: 'desc',
  page: 1,
}

export const queryItems = <
  T extends {
    id?: string
    createdAt?: string
  }
>(
  itemsDict: {
    [id: string]: T
  },
  listConfig: ListConfig,
  total: number,
) => {
  const config = {
    ...defaultListConfig,
    ...listConfig,
  }
  return paginate(
    map(itemsDict).sort(
      (a, b) => new Date(b.createdAt).valueOf() - new Date(a.createdAt).valueOf(),
    ),
    config,
    total,
  )
}