import { ArrTypeId, concreteChunk } from "@tsplus/stdlib/collections/Chunk/definition"

/**
 * Takes all elements so long as the predicate returns true.
 *
 * @tsplus static Chunk.Aspects takeWhile
 * @tsplus pipeable Chunk takeWhile
 */
export function takeWhile<A>(f: Predicate<A>) {
  return (self: Chunk<A>): Chunk<A> => {
    concreteChunk(self)

    switch (self._typeId) {
      case ArrTypeId: {
        const arr = self._arrayLike()
        const len = arr.length
        let i = 0
        while (i < len && f(arr[i]!)) {
          i++
        }
        return self._take(i)
      }
      default: {
        const iterator = self._arrayLikeIterator()
        let next
        let cont = true
        let i = 0

        while (cont && (next = iterator.next()) && !next.done) {
          const array = next.value
          const len = array.length
          let j = 0
          while (cont && j < len) {
            const a = array[j]!
            if (!f(a)) {
              cont = false
            } else {
              i++
              j++
            }
          }
        }

        return self._take(i)
      }
    }
  }
}