/*
 * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package async

import (
	_ "unsafe"
)

type Void = [0]byte

type Future[T any] func() T

type IO[T any] func(e *AsyncContext) Future[T]

type AsyncContext struct {
	*Executor
	complete func()
}

func (ctx *AsyncContext) Complete() {
	ctx.complete()
}

func Async[T any](fn func(resolve func(T))) IO[T] {
	return func(ctx *AsyncContext) Future[T] {
		var result T
		var done bool
		fn(func(t T) {
			result = t
			done = true
			ctx.Complete()
		})
		return func() T {
			if !done {
				panic("async.Async: Future accessed before completion")
			}
			return result
		}
	}
}