// Copyright (c) 2020 tickstep.
//
// 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 downloader

import (
	"net/http"
	"sync/atomic"
)

type (
	// LoadBalancerResponse 负载均衡响应状态
	LoadBalancerResponse struct {
		URL     string
	}

	// LoadBalancerResponseList 负载均衡列表
	LoadBalancerResponseList struct {
		lbr    []*LoadBalancerResponse
		cursor int32
	}

	LoadBalancerCompareFunc func(info map[string]string, subResp *http.Response) bool
)

// NewLoadBalancerResponseList 初始化负载均衡列表
func NewLoadBalancerResponseList(lbr []*LoadBalancerResponse) *LoadBalancerResponseList {
	return &LoadBalancerResponseList{
		lbr: lbr,
	}
}

// SequentialGet 顺序获取
func (lbrl *LoadBalancerResponseList) SequentialGet() *LoadBalancerResponse {
	if len(lbrl.lbr) == 0 {
		return nil
	}

	if int(lbrl.cursor) >= len(lbrl.lbr) {
		lbrl.cursor = 0
	}

	lbr := lbrl.lbr[int(lbrl.cursor)]
	atomic.AddInt32(&lbrl.cursor, 1)
	return lbr
}

// RandomGet 随机获取
func (lbrl *LoadBalancerResponseList) RandomGet() *LoadBalancerResponse {
	return lbrl.lbr[RandomNumber(0, len(lbrl.lbr))]
}

// AddLoadBalanceServer 增加负载均衡服务器
func (der *Downloader) AddLoadBalanceServer(urls ...string) {
	der.loadBalansers = append(der.loadBalansers, urls...)
}

// DefaultLoadBalancerCompareFunc 检测负载均衡的服务器是否一致
func DefaultLoadBalancerCompareFunc(info map[string]string, subResp *http.Response) bool {
	if info == nil || subResp == nil {
		return false
	}

	for headerKey, value := range info {
		if value != subResp.Header.Get(headerKey) {
			return false
		}
	}

	return true
}