//
// Copyright © 2022 Hardcore Engineering Inc.
//
// Licensed under the Eclipse Public License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License. You may
// obtain a copy of the License at https://www.eclipse.org/legal/epl-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//
// See the License for the specific language governing permissions and
// limitations under the License.
//

import core, { ApplyOperations, SortingOrder, Status, TxOperations, generateId } from '@hcengineering/core'
import { LexoRank, LexoDecimal, LexoNumeralSystem36 } from 'lexorank'
import LexoRankBucket from 'lexorank/lib/lexoRank/lexoRankBucket'

/**
 * @public
 */
export const genRanks = (count: number): Generator<string, void, unknown> =>
  (function * () {
    const sys = new LexoNumeralSystem36()
    const base = 36
    const max = base ** 6
    const gap = LexoDecimal.parse(Math.trunc(max / (count + 2)).toString(base), sys)
    let cur = LexoDecimal.parse('0', sys)

    for (let i = 0; i < count; i++) {
      cur = cur.add(gap)
      yield new LexoRank(LexoRankBucket.BUCKET_0, cur).toString()
    }
  })()

/**
 * @public
 */
export const calcRank = (prev?: { rank: string }, next?: { rank: string }): string => {
  const a = prev?.rank !== undefined ? LexoRank.parse(prev.rank) : LexoRank.min()
  const b = next?.rank !== undefined ? LexoRank.parse(next.rank) : LexoRank.max()
  if (a.equals(b)) {
    return a.genNext().toString()
  }
  return a.between(b).toString()
}

/**
 * Generates statuses for provided space.
 *
 * @public
 */
export async function createStatuses (
  client: TxOperations | ApplyOperations,
  spaceId: Status['space'],
  statusClass: Status['_class'],
  categoryOfAttribute: Status['ofAttribute'],
  defaultStatusId: Status['_id']
): Promise<void> {
  const categories = await client.findAll(
    core.class.StatusCategory,
    { ofAttribute: categoryOfAttribute },
    { sort: { order: SortingOrder.Ascending } }
  )
  const ranks = [...genRanks(categories.length)]

  for (const [i, category] of categories.entries()) {
    const statusId = i === 0 ? defaultStatusId : generateId<Status>()
    const rank = ranks[i]

    await client.createDoc(
      statusClass,
      spaceId,
      {
        ofAttribute: categoryOfAttribute,
        name: category.defaultStatusName,
        category: category._id,
        rank
      },
      statusId
    )
  }
}