package algorithm

import (
	"gitee.com/jianhaolin/gostl/utils/comparator"
	"gitee.com/jianhaolin/gostl/utils/iterator"
)

// Count returns the number of elements that their value is equal to value in range [first, last)
func Count[T any](first, last iterator.ConstIterator[T], value T, cmp comparator.Comparator[T]) int {
	var count int
	for iter := first.Clone(); !iter.Equal(last); iter.Next() {
		if cmp(iter.Value(), value) == 0 {
			count++
		}
	}
	return count
}

// CountIf returns the number of elements are satisfied the function f in range [first, last)
func CountIf[T any](first, last iterator.ConstIterator[T], f func(iterator.ConstIterator[T]) bool) int {
	var count int
	for iter := first.Clone(); !iter.Equal(last); iter.Next() {
		if f(iter) {
			count++
		}
	}
	return count
}

// Find finds the first element that its value is equal to value in range [first, last), and returns its iterator, or last if not found
func Find[T any](first, last iterator.ConstIterator[T], value T, cmp comparator.Comparator[T]) iterator.ConstIterator[T] {
	for iter := first.Clone(); !iter.Equal(last); iter.Next() {
		if cmp(iter.Value(), value) == 0 {
			return iter
		}
	}
	return last
}

// FindIf finds the first element that is satisfied the function f, and returns its iterator, or last if not found
func FindIf[T any](first, last iterator.ConstIterator[T], f func(iterator.ConstIterator[T]) bool) iterator.ConstIterator[T] {
	for iter := first.Clone(); !iter.Equal(last); iter.Next() {
		if f(iter) {
			return iter
		}
	}
	return last
}

// MaxElement returns an Iterator to the largest element in the range [first, last). If several elements in the range are equivalent to the largest element, returns the iterator to the first such element. Returns last if the range is empty.
func MaxElement[T any](first, last iterator.ConstIterator[T], cmp comparator.Comparator[T]) iterator.ConstIterator[T] {
	if first.Equal(last) {
		return last
	}
	largest := first
	for iter := first.Clone(); !iter.Equal(last); iter.Next() {
		if cmp(iter.Value(), largest.Value()) > 0 {
			largest = iter.Clone()
		}
	}
	return largest
}

// MinElement returns an Iterator to the smallest element value in the range [first, last). If several elements in the range are equivalent to the smallest element value, returns the iterator to the first such element. Returns last if the range is empty.
func MinElement[T any](first, last iterator.ConstIterator[T], cmp comparator.Comparator[T]) iterator.ConstIterator[T] {
	if first.Equal(last) {
		return last
	}
	smallest := first
	for iter := first.Clone(); !iter.Equal(last); iter.Next() {
		if cmp(iter.Value(), smallest.Value()) < 0 {
			smallest = iter.Clone()
		}
	}
	return smallest
}