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

/**
 * Returns the last index of the element that satisfies the predicate.
 *
 * @tsplus static Chunk.Aspects findLastIndex
 * @tsplus pipeable Chunk findLastIndex
 */
export function findLastIndex<A>(f: Predicate<A>) {
  return (self: Chunk<A>): Maybe<number> => {
    concreteChunk(self)

    const iterator = concreteChunkId(self)._reverseArrayLikeIterator()
    let next
    let index = self.length - 1

    while ((next = iterator.next()) && !next.done) {
      const array = next.value
      const len = array.length
      let i = len - 1
      while (i >= 0) {
        const a = array[i]!
        if (f(a)) {
          return Maybe.some(index)
        }
        i--
        index--
      }
    }

    return Maybe.none
  }
}