package app

import (
	"context"
	"sync/atomic"
)

const (
	Idle int32 = iota
	Initialized
	Starting
	Running
	Stopping
	Stopped
)

var (
	// 当前状态
	status int32

	// 应用上下文
	ctx  context.Context
	exit context.CancelFunc

	start func() // 应用启动钩子
	stop  func() // 应用停止钩子
	free  func() // 内存释放钩子
)

func initLifecycle() {
	ctx, exit = context.WithCancel(context.Background())

	start = func() {
		// nothing
	}

	stop = func() {
		if exit != nil {
			exit()
		}
	}

	free = func() {
		ctx = nil
		start = nil
		stop = nil
		exit = nil
	}
}

// setStatus 设置应用状态
func setStatus(newStatus int32) {
	atomic.StoreInt32(&status, newStatus)
}

// Status 返回当前状态
func Status() int32 {
	return atomic.LoadInt32(&status)
}

func OnStart(fn func()) {
	oldStart := start
	start = func() {
		oldStart()
		fn()
	}
}

func OnStop(fn func()) {
	oldStop := stop
	stop = func() {
		fn()
		oldStop()
	}
}

func OnFree(fn func()) {
	oldFree := free
	free = func() {
		fn()
		oldFree()
	}
}