package tasks

import (
	"context"
	"crypto/tls"
	"encoding/json"
	"github.com/TeaOSLab/EdgeAPI/internal/db/models"
	"github.com/TeaOSLab/EdgeAPI/internal/db/models/dns"
	"github.com/TeaOSLab/EdgeAPI/internal/errors"
	"github.com/TeaOSLab/EdgeCommon/pkg/serverconfigs"
	"github.com/iwind/TeaGo/lists"
	"github.com/iwind/TeaGo/logs"
	"github.com/iwind/TeaGo/types"
	"net"
	"net/http"
	"strconv"
	"strings"
	"sync"
	"time"
)

type HealthCheckExecutor struct {
	clusterId int64
}

func NewHealthCheckExecutor(clusterId int64) *HealthCheckExecutor {
	return &HealthCheckExecutor{clusterId: clusterId}
}

func (this *HealthCheckExecutor) Run() ([]*HealthCheckResult, error) {
	cluster, err := models.NewNodeClusterDAO().FindEnabledNodeCluster(nil, this.clusterId)
	if err != nil {
		return nil, err
	}
	if cluster == nil {
		return nil, errors.New("can not find cluster with id '" + strconv.FormatInt(this.clusterId, 10) + "'")
	}
	if len(cluster.HealthCheck) == 0 || cluster.HealthCheck == "null" {
		return nil, errors.New("health check config is not found")
	}

	healthCheckConfig := &serverconfigs.HealthCheckConfig{}
	err = json.Unmarshal([]byte(cluster.HealthCheck), healthCheckConfig)
	if err != nil {
		return nil, err
	}

	results := []*HealthCheckResult{}
	nodes, err := models.NewNodeDAO().FindAllEnabledNodesWithClusterId(nil, this.clusterId)
	if err != nil {
		return nil, err
	}
	for _, node := range nodes {
		if node.IsOn != 1 {
			continue
		}
		result := &HealthCheckResult{
			Node: node,
		}

		ipAddr, err := models.NewNodeIPAddressDAO().FindFirstNodeAccessIPAddress(nil, int64(node.Id))
		if err != nil {
			return nil, err
		}
		if len(ipAddr) == 0 {
			result.Error = "no ip address can be used"
		} else {
			result.NodeAddr = ipAddr
		}

		results = append(results, result)
	}

	// 并行检查
	preparedResults := []*HealthCheckResult{}
	for _, result := range results {
		if len(result.NodeAddr) > 0 {
			preparedResults = append(preparedResults, result)
		}
	}

	if len(preparedResults) == 0 {
		return results, nil
	}

	countResults := len(preparedResults)
	queue := make(chan *HealthCheckResult, countResults)
	for _, result := range preparedResults {
		queue <- result
	}

	countTries := types.Int(healthCheckConfig.CountTries)
	if countTries > 10 { // 限定最多尝试10次 TODO 应该在管理界面提示用户
		countTries = 10
	}
	if countTries < 1 {
		countTries = 1
	}

	tryDelay := 1 * time.Second
	if healthCheckConfig.TryDelay != nil {
		tryDelay = healthCheckConfig.TryDelay.Duration()

		if tryDelay > 1*time.Minute { // 最多不能超过1分钟 TODO 应该在管理界面提示用户
			tryDelay = 1 * time.Minute
		}
	}

	countRoutines := 10
	wg := sync.WaitGroup{}
	wg.Add(countResults)
	for i := 0; i < countRoutines; i++ {
		go func() {
			for {
				select {
				case result := <-queue:
					for i := 1; i <= countTries; i++ {
						before := time.Now()
						err := this.checkNode(healthCheckConfig, result)
						result.CostMs = time.Since(before).Seconds() * 1000
						if err != nil {
							result.Error = err.Error()
						}
						if result.IsOk {
							break
						}
						if tryDelay > 0 {
							time.Sleep(tryDelay)
						}
					}

					// 修改节点状态
					if healthCheckConfig.AutoDown {
						isChanged, err := models.SharedNodeDAO.UpdateNodeUp(nil, int64(result.Node.Id), result.IsOk, healthCheckConfig.CountUp, healthCheckConfig.CountDown)
						if err != nil {
							logs.Println("[HEALTH_CHECK]" + err.Error())
						} else if isChanged {
							// 通知DNS更新
							err = dns.SharedDNSTaskDAO.CreateNodeTask(nil, int64(result.Node.Id), dns.DNSTaskTypeNodeChange)
							if err != nil {
								logs.Println("[HEALTH_CHECK]" + err.Error())
							}

							// 通知恢复或下线
							if result.IsOk {
								err = models.NewMessageDAO().CreateNodeMessage(nil, this.clusterId, int64(result.Node.Id), models.MessageTypeHealthCheckNodeUp, models.MessageLevelSuccess, "健康检查成功，节点\""+result.Node.Name+"\"已恢复上线", nil)
							} else {
								err = models.NewMessageDAO().CreateNodeMessage(nil, this.clusterId, int64(result.Node.Id), models.MessageTypeHealthCheckNodeDown, models.MessageLevelError, "健康检查失败，节点\""+result.Node.Name+"\"已自动下线", nil)
							}
						}
					}

					wg.Done()
				default:
					return
				}
			}
		}()
	}
	wg.Wait()

	return results, nil
}

// 检查单个节点
func (this *HealthCheckExecutor) checkNode(healthCheckConfig *serverconfigs.HealthCheckConfig, result *HealthCheckResult) error {
	url := strings.ReplaceAll(healthCheckConfig.URL, "${host}", result.NodeAddr)
	req, err := http.NewRequest(http.MethodGet, url, nil)
	if err != nil {
		return err
	}

	timeout := 5 * time.Second
	if healthCheckConfig.Timeout != nil {
		timeout = healthCheckConfig.Timeout.Duration()
	}

	client := &http.Client{
		Timeout: timeout,
		Transport: &http.Transport{
			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
				_, port, err := net.SplitHostPort(addr)
				if err != nil {
					return nil, err
				}
				return net.Dial(network, result.NodeAddr+":"+port)
			},
			MaxIdleConns:          1,
			MaxIdleConnsPerHost:   1,
			MaxConnsPerHost:       1,
			IdleConnTimeout:       2 * time.Minute,
			ExpectContinueTimeout: 1 * time.Second,
			TLSHandshakeTimeout:   0,
			TLSClientConfig: &tls.Config{
				InsecureSkipVerify: true,
			},
		},
	}
	defer func() {
		client.CloseIdleConnections()
	}()

	resp, err := client.Do(req)
	if err != nil {
		return err
	}
	_ = resp.Body.Close()

	if len(healthCheckConfig.StatusCodes) > 0 && !lists.ContainsInt(healthCheckConfig.StatusCodes, resp.StatusCode) {
		result.Error = "invalid response status code '" + strconv.Itoa(resp.StatusCode) + "'"
		return nil
	}

	result.IsOk = true

	return nil
}