//# region get all combinations
// 使用迭代生成组合
function combine(arr, min, max) {
  const result = []
  const n = arr.length

  // 生成长度在[min, max]范围内的所有组合
  for (let r = min; r <= Math.min(max, n); r++) {
    const indices = Array(r)
      .fill(0)
      .map((_, i) => i) // 初始化索引
    result.push(indices.map((i) => arr[i])) // 保存初始组合

    while (true) {
      let i = r - 1

      // 从后往前找第一个未到达上界的索引
      while (i >= 0 && indices[i] === i + n - r) {
        i--
      }

      // 没有更多组合时退出
      if (i < 0) break

      indices[i]++

      // 更新接下来的所有索引
      for (let j = i + 1; j < r; j++) {
        indices[j] = indices[j - 1] + 1
      }

      result.push(indices.map((j) => arr[j]))
    }
  }

  return result
}

// 生成符合"0"限制的组合
function combineWithZero(arr, min, max) {
  let combineResult;
  if (arr.includes(0)) {
    // 如果包含 0，0不参与组合
    combineResult = [].concat(
      combine(
        arr.filter((x) => x !== 0),
        min,
        max
      )
    );
  } else {
    // 如果不包含 0，直接生成组合
    combineResult = [].concat(combine(arr, min, max));
  }
  return combineResult;
}

export function* combineFiltersWithConstraintsGenerator(selectedFilters) {
  const { salaryList, experienceList, degreeList, scaleList, industryList } =
    selectedFilters;

  // 生成符合限制条件的组合
  const salaryComb = combineWithZero(salaryList, 0, 1) // Salary: 0-1 个
  const experienceComb = combineWithZero(experienceList, 0, experienceList.length) // Experience: 0 个或更多
  const degreeComb = combineWithZero(degreeList, 0, degreeList.length) // Degree: 0 个或更多
  const scaleComb = combineWithZero(scaleList, 0, scaleList.length) // Scale: 0 个或更多
  const industryComb = combineWithZero(industryList, 0, 3) // Industry: 0-3 个

  // 通过迭代生成所有组合
  for (const salary of salaryComb) {
    for (const experience of experienceComb) {
      for (const degree of degreeComb) {
        for (const scale of scaleComb) {
          for (const industry of industryComb) {
            yield {
              salaryList: salary,
              experienceList: experience,
              degreeList: degree,
              scaleList: scale,
              industryList: industry
            }
          }
        }
      }
    }
  }
}
//#endregion

//#region get count of combinations

// 计算符合限制条件的组合数量
export function calculateTotalCombinations(selectedFilters) {
  const {
    salaryList = [],
    experienceList = [],
    degreeList = [],
    scaleList = [],
    industryList = []
  } = selectedFilters

  // 生成符合限制条件的组合
  const salaryComb = combineWithZero(salaryList, 0, 1) // Salary: 0-1 个
  const experienceComb = combineWithZero(experienceList, 0, experienceList.length) // Experience: 0 个或更多
  const degreeComb = combineWithZero(degreeList, 0, degreeList.length) // Degree: 0 个或更多
  const scaleComb = combineWithZero(scaleList, 0, scaleList.length) // Scale: 0 个或更多
  const industryComb = combineWithZero(industryList, 0, 3) // Industry: 0-3 个

  return [salaryComb, experienceComb, degreeComb, scaleComb, industryComb].reduce((accu, cur) => {
    return accu * cur.length
  }, 1)
}
//#endregion