/**
 * Tencent is pleased to support the open source community by making polaris-go available.
 *
 * Copyright (C) 2019 THL A29 Limited, a Tencent company. All rights reserved.
 *
 * Licensed under the BSD 3-Clause License (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * https://opensource.org/licenses/BSD-3-Clause
 *
 * 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 http

import (
	"net/http"
	"net/url"
	"time"

	"gitee.com/meng_mengs_boys/polaris-go/pkg/config"
	"gitee.com/meng_mengs_boys/polaris-go/pkg/log"
	"gitee.com/meng_mengs_boys/polaris-go/pkg/model"
	"gitee.com/meng_mengs_boys/polaris-go/pkg/plugin"
	"gitee.com/meng_mengs_boys/polaris-go/pkg/plugin/common"
	"gitee.com/meng_mengs_boys/polaris-go/pkg/plugin/healthcheck"
	"gitee.com/meng_mengs_boys/polaris-go/plugin/healthcheck/utils"
)

// Detector TCP协议的实例健康探测器
type Detector struct {
	*plugin.PluginBase
	cfg     *Config
	timeout time.Duration
}

// Type 插件类型
func (g *Detector) Type() common.Type {
	return common.TypeHealthCheck
}

// Name 插件名，一个类型下插件名唯一
func (g *Detector) Name() string {
	return "http"
}

// Init 初始化插件
func (g *Detector) Init(ctx *plugin.InitContext) (err error) {
	g.PluginBase = plugin.NewPluginBase(ctx)
	cfgValue := ctx.Config.GetConsumer().GetHealthCheck().GetPluginConfig(g.Name())
	if cfgValue != nil {
		g.cfg = cfgValue.(*Config)
	}
	g.timeout = ctx.Config.GetConsumer().GetHealthCheck().GetTimeout()
	return nil
}

// Destroy 销毁插件，可用于释放资源
func (g *Detector) Destroy() error {
	return nil
}

// DetectInstance 探测服务实例健康
func (g *Detector) DetectInstance(ins model.Instance) (result healthcheck.DetectResult, err error) {
	start := time.Now()
	// 得到Http address
	address := utils.GetAddressByInstance(ins)
	success := g.doHttpDetect(address)
	result = &healthcheck.DetectResultImp{
		Success:        success,
		DetectTime:     start,
		DetectInstance: ins,
	}
	return result, nil
}

// IsEnable .
func (g *Detector) IsEnable(cfg config.Configuration) bool {
	return cfg.GetGlobal().GetSystem().GetMode() != model.ModeWithAgent
}

// doHttpDetect 执行一次健康探测逻辑
func (g *Detector) doHttpDetect(address string) bool {
	c := &http.Client{
		Timeout: g.timeout,
	}
	request := &http.Request{
		Method: http.MethodGet,
		URL: &url.URL{
			Scheme: "http",
			Host:   address,
			Path:   g.cfg.Path,
		},
	}
	header := http.Header{}
	if len(g.cfg.Host) > 0 {
		header.Add("Host", g.cfg.Host)
	}
	if len(g.cfg.RequestHeadersToAdd) > 0 {
		for _, requestHeader := range g.cfg.RequestHeadersToAdd {
			header.Add(requestHeader.Key, requestHeader.Value)
		}
	}
	if len(header) > 0 {
		request.Header = header
	}
	resp, err := c.Do(request)
	if err != nil {
		log.GetDetectLogger().Errorf("[HealthCheck][http] fail to check %s, err is %v", address, err)
		return false
	}
	defer resp.Body.Close()
	code := resp.StatusCode
	for _, statusCodeRange := range g.cfg.ExpectedStatuses {
		if code >= statusCodeRange.Start && code < statusCodeRange.End {
			return true
		}
	}
	return false
}

// init 注册插件信息
func init() {
	plugin.RegisterConfigurablePlugin(&Detector{}, &Config{})
}