import { getArrayCombinations } from './get-array-combinations.js'
/**
 * Generates an ordered list of group names associated with the provided
 * modifiers and selectors. The groups are generated by combining all possible
 * combinations of modifiers with each selector at the end. Selectors are
 * prioritized over the quantity of modifiers. For example, `protected abstract
 * override get fields();` should prioritize the `'get-method'` group over the
 * `'protected-abstract-override-method'` group.
 *
 * @param props - The properties including selectors, modifiers, and cache.
 * @param props.selectors - The list of selectors.
 * @param props.modifiers - The list of modifiers.
 * @param props.cache - Cache to store computed groups.
 * @returns An array of generated group names.
 */
function generatePredefinedGroups({ selectors, modifiers, cache }) {
  let modifiersAndSelectorsKey = `${modifiers.join('&')}/${selectors.join('&')}`
  let cachedValue = cache.get(modifiersAndSelectorsKey)
  if (cachedValue) {
    return cachedValue
  }
  let allModifiersCombinations = []
  for (let i = modifiers.length; i > 0; i--) {
    allModifiersCombinations.push(...getArrayCombinations(modifiers, i))
  }
  let allModifiersCombinationPermutations = allModifiersCombinations.flatMap(
    result => getPermutations(result),
  )
  let returnValue = []
  for (let selector of selectors) {
    returnValue.push(
      ...allModifiersCombinationPermutations.map(
        modifiersCombinationPermutation =>
          [...modifiersCombinationPermutation, selector].join('-'),
      ),
      selector,
    )
  }
  cache.set(modifiersAndSelectorsKey, returnValue)
  return returnValue
}
/**
 * Generates all permutations of an array. This allows variations like
 * `'abstract-override-protected-get-method'`,
 * `'override-protected-abstract-get-method'`,
 * `'protected-abstract-override-get-method'`, etc., to be entered by the user
 * and always match the same group. Note that this can theoretically cause
 * performance issues if too many modifiers are entered at once (e.g., 8
 * modifiers result in 40,320 permutations, 9 in 362,880).
 *
 * @param elements - The array of elements to permute.
 * @returns An array containing all permutations of the input elements.
 */
function getPermutations(elements) {
  let result = []
  function backtrack(first) {
    if (first === elements.length) {
      result.push([...elements])
      return
    }
    for (let i = first; i < elements.length; i++) {
      ;[elements[first], elements[i]] = [elements[i], elements[first]]
      backtrack(first + 1)
      ;[elements[first], elements[i]] = [elements[i], elements[first]]
    }
  }
  backtrack(0)
  return result
}
export { generatePredefinedGroups }