package ranges

import (
	"surdeus.su/core/gods/iters"
	cnts "golang.org/x/exp/constraints"
)


type Range[V cnts.Ordered] struct {
	start, step, end V
}

// Returns the new Range strucucture with corresponding start, step and end.
// If the values can never reach the end then the function will return nil.
func New[V cnts.Ordered](start, step, end V) *Range[V] {
	return &Range[V]{
		start, step, end,
	}
}

func (r *Range[V]) Chan() iters.PairChan[int, V] {

	less := func(a, b V) bool {
		return a < b
	}
	more := func(a, b V) bool {
		return a > b
	}
	
	var compare func(a, b V) bool
	start, step, end := r.start, r.step, r.end
	if start < end {
		compare = less
	} else {
		compare = more
	}

	c := make(iters.PairChan[int, V])
	go func(){
		
		
		j := 0
		for i := start ; compare(i, end) ; i += step {
			c <- iters.Pair[int, V]{
				K:j,
				V:i,
			}
			j++
		}
		
		close(c)
	}()
	
	return c
}