package reactive

import "context"

func CatchError[T any](source Observable[T], handle func(error, Observable[T]) Observable[T]) Observable[T] {
	return &catchError[T]{source, handle}
}

type catchError[T any] struct {
	source Observable[T]
	handle func(error, Observable[T]) Observable[T]
}

func (c *catchError[T]) Observe(ctx context.Context) <-chan Notification[T] {
	ch := make(chan Notification[T])

	go func() {
		defer close(ch)

		for {
			select {
			case n := <-c.source.Observe(ctx):
				if n.Kind() == ErrorNotification {
					Copy(c.handle(n.Error(), c.source).Observe(ctx), ch)
				} else {
					ch <- n
				}
			case <-ctx.Done():
				return
			}
		}
	}()

	return ch
}

func OnError[T any](source Observable[T], handle func(error)) Observable[T] {
	return &onError[T]{source, handle}
}

type onError[T any] struct {
	source Observable[T]
	handle func(error)
}

func (o *onError[T]) Observe(ctx context.Context) <-chan Notification[T] {
	ch := make(chan Notification[T])

	go func() {
		defer close(ch)

		for {
			select {
			case n := <-o.source.Observe(ctx):
				if n.Kind() == ErrorNotification {
					o.handle(n.Error())
				}
				ch <- n
			case <-ctx.Done():
				return
			}
		}
	}()

	return ch
}