// Copyright 2023 LiveKit, Inc.
//
// 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 utils

import (
	"sync"

	"github.com/livekit/protocol/logger"
)

type OpsQueue struct {
	logger logger.Logger
	name   string
	size   int

	lock      sync.RWMutex
	ops       chan func()
	isStarted bool
	isStopped bool
}

func NewOpsQueue(logger logger.Logger, name string, size int) *OpsQueue {
	return &OpsQueue{
		logger: logger,
		name:   name,
		size:   size,
		ops:    make(chan func(), size),
	}
}

func (oq *OpsQueue) SetLogger(logger logger.Logger) {
	oq.logger = logger
}

func (oq *OpsQueue) Start() {
	oq.lock.Lock()
	if oq.isStarted {
		oq.lock.Unlock()
		return
	}

	oq.isStarted = true
	oq.lock.Unlock()

	go oq.process()
}

func (oq *OpsQueue) Stop() {
	oq.lock.Lock()
	if oq.isStopped {
		oq.lock.Unlock()
		return
	}

	oq.isStopped = true
	close(oq.ops)
	oq.lock.Unlock()
}

func (oq *OpsQueue) IsStarted() bool {
	oq.lock.RLock()
	defer oq.lock.RUnlock()

	return oq.isStarted
}

func (oq *OpsQueue) Enqueue(op func()) {
	oq.lock.RLock()
	if oq.isStopped {
		oq.lock.RUnlock()
		return
	}

	select {
	case oq.ops <- op:
	default:
		oq.logger.Errorw("ops queue full", nil, "name", oq.name, "size", oq.size)
	}
	oq.lock.RUnlock()
}

func (oq *OpsQueue) process() {
	for op := range oq.ops {
		op()
	}
}