//
// Copyright © 2020, 2021 Anticrm Platform Contributors.
//
// 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 { 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()

  return a.between(b).toString()
}