package services

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"log/slog"
	"math"
	"math/rand/v2"
	"platform/pkg/env"
	"platform/pkg/u"
	"platform/web/auth"
	"platform/web/core"
	channel2 "platform/web/domains/channel"
	proxy2 "platform/web/domains/proxy"
	g "platform/web/globals"
	"platform/web/globals/orm"
	m "platform/web/models"
	q "platform/web/queries"
	"strconv"
	"strings"
	"time"

	"github.com/gofiber/fiber/v2/middleware/requestid"
	"github.com/redis/go-redis/v9"
	"gorm.io/gorm"
)

var Channel = &channelService{}

type channelService struct {
}

type ResourceInfo struct {
	Id         int32
	UserId     int32
	Active     bool
	Type       int32
	Live       int32
	DailyLimit int32
	DailyUsed  int32
	DailyLast  orm.LocalDateTime
	Quota      int32
	Used       int32
	Expire     orm.LocalDateTime
}

// region RemoveChannel

func (s *channelService) RemoveChannels(ctx context.Context, authCtx *auth.Context, id ...int32) error {
	var now = time.Now()
	var rid = ctx.Value(requestid.ConfigDefault.ContextKey).(string)

	err := q.Q.Transaction(func(tx *q.Query) error {

		// 查找通道
		channels, err := tx.Channel.Where(
			q.Channel.ID.In(id...),
		).Find()
		if err != nil {
			return err
		}

		// 检查权限，如果为用户操作的话，则只能删除自己的通道
		for _, channel := range channels {
			if authCtx.Payload.Type == auth.PayloadUser && authCtx.Payload.Id != channel.UserID {
				return core.ErrForbidden()
			}
		}

		// 查找代理
		proxySet := make(map[int32]struct{})
		proxyIds := make([]int32, 0)
		for _, channel := range channels {
			if _, ok := proxySet[channel.ProxyID]; !ok {
				proxyIds = append(proxyIds, channel.ProxyID)
				proxySet[channel.ProxyID] = struct{}{}
			}
		}
		proxies, err := tx.Proxy.Where(
			q.Proxy.ID.In(proxyIds...),
		).Find()
		if err != nil {
			return err
		}

		// 删除指定的通道
		result, err := tx.Channel.Debug().
			Where(q.Channel.ID.In(id...)).
			Update(q.Channel.DeletedAt, now)
		if err != nil {
			return err
		}
		if result.RowsAffected != int64(len(channels)) {
			return ChannelServiceErr("删除通道失败")
		}

		// 禁用代理端口并下线用过的节点
		if env.DebugExternalChange {
			var step = time.Now()

			// 组织数据
			var configMap = make(map[int32][]g.PortConfigsReq, len(proxies))
			var proxyMap = make(map[int32]*m.Proxy, len(proxies))
			for _, proxy := range proxies {
				configMap[proxy.ID] = make([]g.PortConfigsReq, 0)
				proxyMap[proxy.ID] = proxy
			}
			var portMap = make(map[uint64]struct{})
			for _, channel := range channels {
				var config = g.PortConfigsReq{
					Port: int(channel.ProxyPort),
					Edge: &[]string{},
					AutoEdgeConfig: &g.AutoEdgeConfig{
						Count: u.P(0),
					},
					Status: false,
				}
				configMap[channel.ProxyID] = append(configMap[channel.ProxyID], config)

				key := uint64(channel.ProxyID)<<32 | uint64(channel.ProxyPort)
				portMap[key] = struct{}{}
			}

			slog.Debug("组织数据", "rid", rid, "step", time.Since(step))

			// 更新配置
			for proxyId, configs := range configMap {
				if len(configs) == 0 {
					continue
				}
				proxy, ok := proxyMap[proxyId]
				if !ok {
					return ChannelServiceErr("代理不存在")
				}

				var secret = strings.Split(proxy.Secret, ":")
				gateway := g.NewGateway(
					proxy.Host,
					secret[0],
					secret[1],
				)

				// 查询节点配置
				step = time.Now()

				actives, err := gateway.GatewayPortActive()
				if err != nil {
					return err
				}

				slog.Debug("查询节点配置", "rid", rid, "step", time.Since(step))

				// 更新节点配置
				step = time.Now()

				err = gateway.GatewayPortConfigs(configs)
				if err != nil {
					return err
				}

				slog.Debug("更新节点配置", "rid", rid, "step", time.Since(step))

				// 下线对应节点
				step = time.Now()

				var edges []string
				for portStr, active := range actives {
					port, err := strconv.Atoi(portStr)
					if err != nil {
						return err
					}
					key := uint64(proxyId)<<32 | uint64(port)
					if _, ok := portMap[key]; ok {
						edges = append(edges, active.Edge...)
					}
				}
				if len(edges) > 0 {
					_, err := g.Cloud.CloudDisconnect(g.CloudDisconnectReq{
						Uuid: proxy.Name,
						Edge: edges,
					})
					if err != nil {
						return err
					}
				}

				slog.Debug("下线对应节点", "rid", rid, "step", time.Since(step))
			}

		}

		return nil
	})
	if err != nil {
		return err
	}

	return nil
}

// endregion

// region CreateChannel

func (s *channelService) CreateChannel(
	ctx context.Context,
	authCtx *auth.Context,
	resourceId int32,
	protocol channel2.Protocol,
	authType ChannelAuthType,
	count int,
	edgeFilter ...EdgeFilterConfig,
) (newChannels []*m.Channel, err error) {
	var now = time.Now()
	var rid = ctx.Value(requestid.ConfigDefault.ContextKey).(string)
	var filter = EdgeFilterConfig{}
	if len(edgeFilter) > 0 {
		filter = edgeFilter[0]
	}

	err = q.Q.Transaction(func(q *q.Query) (err error) {

		// 查找套餐
		resource, err := findResource(q, resourceId, authCtx, count)
		if err != nil {
			return err
		}

		// 查找网关
		proxies, err := findProxies(q)
		if err != nil {
			return err
		}

		// 查找已使用的节点
		channels, err := findChannels(q, proxies)
		if err != nil {
			return err
		}

		// 查找白名单
		var whitelist *[]string
		if authType == ChannelAuthTypeIp {
			whitelist, err = findWhitelist(q, authCtx.Payload.Id)
			if err != nil {
				return err
			}
		}

		// 分配节点
		var expire = now.Add(time.Duration(resource.Live) * time.Second)
		newChannels, err = calcChannels(proxies, channels, whitelist, count, authCtx.Payload.Id, protocol, authType, expire, filter)
		if err != nil {
			return err
		}

		// 更新套餐使用记录
		err = updateResource(rid, resource, count, now)
		if err != nil {
			return err
		}

		// 保存通道
		err = saveChannels(newChannels)
		if err != nil {
			return err
		}

		// 缓存通道数据
		err = cacheChannels(ctx, rid, newChannels, whitelist)
		if err != nil {
			return err
		}

		return nil
	}, &sql.TxOptions{Isolation: sql.LevelRepeatableRead})
	if err != nil {
		return nil, err
	}

	return newChannels, nil
}

func findResource(q *q.Query, resourceId int32, authCtx *auth.Context, count int) (*ResourceInfo, error) {
	var resource = new(ResourceInfo)
	data := q.Resource.As("data")
	pss := q.ResourcePss.As("pss")
	err := data.Scopes(orm.Alias(data)).
		Select(
			data.ID, data.UserID, data.Active,
			pss.Type, pss.Live, pss.DailyUsed, pss.DailyLimit, pss.DailyLast, pss.Quota, pss.Used, pss.Expire,
		).
		LeftJoin(q.ResourcePss.As("pss"), pss.ResourceID.EqCol(data.ID)).
		Where(
			data.ID.Eq(resourceId),
			data.UserID.Eq(authCtx.Payload.Id),
		).
		Scan(&resource)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrResourceNotExist // 防止 id 猜测
		}
		return nil, err
	}

	// 检查套餐状态
	if !resource.Active {
		return nil, ErrResourceInvalid
	}

	// 检查每日限额
	today := time.Now().Format("2006-01-02") == time.Time(resource.DailyLast).Format("2006-01-02")
	dailyRemain := int(math.Max(float64(resource.DailyLimit-resource.DailyUsed), 0))
	if today && dailyRemain < count {
		return nil, ErrResourceDailyLimit
	}

	// 检查时间或配额
	if resource.Type == 1 { // 包时
		if time.Time(resource.Expire).Before(time.Now()) {
			return nil, ErrResourceExpired
		}
	} else { // 包量
		remain := int(math.Max(float64(resource.Quota-resource.Used), 0))
		if remain < count {
			return nil, ErrResourceExhausted
		}
	}

	return resource, nil
}

func findProxies(q *q.Query) (proxies []*m.Proxy, err error) {
	proxies, err = q.Proxy.
		Where(q.Proxy.Type.Eq(int32(proxy2.TypeThirdParty))).
		Find()
	if err != nil {
		return nil, err
	}

	return proxies, nil
}

func findChannels(q *q.Query, proxies []*m.Proxy) (channels []*m.Channel, err error) {
	var proxyIds = make([]int32, len(proxies))
	for i, proxy := range proxies {
		proxyIds[i] = proxy.ID
	}
	channels, err = q.Channel.
		Select(
			q.Channel.ProxyID,
			q.Channel.ProxyPort).
		Where(
			q.Channel.ProxyID.In(proxyIds...),
			q.Channel.Expiration.Gt(orm.LocalDateTime(time.Now()))).
		Group(
			q.Channel.ProxyPort,
			q.Channel.ProxyID).
		Find()
	if err != nil {
		return nil, err
	}

	return channels, nil
}

func findWhitelist(q *q.Query, userId int32) (*[]string, error) {
	var whitelist []string
	err := q.Whitelist.
		Where(q.Whitelist.UserID.Eq(userId)).
		Select(q.Whitelist.Host).
		Scan(&whitelist)
	if err != nil {
		return nil, err
	}
	if len(whitelist) == 0 {
		return nil, ChannelServiceErr("用户没有白名单")
	}

	return &whitelist, nil
}

func calcChannels(
	proxies []*m.Proxy,
	allChannels []*m.Channel,
	whitelist *[]string,
	count int,
	userId int32,
	protocol channel2.Protocol,
	authType ChannelAuthType,
	expiration time.Time,
	filter EdgeFilterConfig,
) ([]*m.Channel, error) {
	var step = time.Now()

	// 查询已配置的节点
	remoteConfigs, err := g.Cloud.CloudAutoQuery()
	if err != nil {
		return nil, err
	}

	// 统计已用节点量与端口查找表
	var proxyUses = make(map[int32]int, len(allChannels))
	var portsMap = make(map[uint64]struct{})
	for _, channel := range allChannels {
		proxyUses[channel.ProxyID]++
		key := uint64(channel.ProxyID)<<32 | uint64(channel.ProxyPort)
		portsMap[key] = struct{}{}
	}

	// 计算分配额度
	var total = len(allChannels) + count
	var avg = int(math.Ceil(float64(total) / float64(len(proxies))))

	// 分配节点
	var newChannels []*m.Channel
	for _, proxy := range proxies {

		// 分配前后的节点量
		var prev = proxyUses[proxy.ID]
		var next = int(math.Max(float64(prev), float64(int(math.Min(float64(avg), float64(total))))))
		total -= next

		// 网关配置的节点量
		var count = 0
		remoteConfig, ok := remoteConfigs[proxy.Name]
		if ok {
			for _, config := range remoteConfig {
				if config.Isp == filter.Isp && config.City == filter.City && config.Province == filter.Prov {
					count = config.Count
					break
				}
			}
		}

		if env.DebugExternalChange && next > count {
			var step = time.Now()

			var multiple float64 = 2 // 扩张倍数
			var newConfig = g.AutoConfig{
				Province: filter.Prov,
				City:     filter.City,
				Isp:      filter.Isp,
				Count:    int(math.Ceil(float64(next) * multiple)),
			}

			var newConfigs []g.AutoConfig
			if count == 0 {
				newConfigs = append(newConfigs, newConfig)
			} else {
				newConfigs = make([]g.AutoConfig, len(remoteConfig))
				for i, config := range remoteConfig {
					if config.Isp == filter.Isp && config.City == filter.City && config.Province == filter.Prov {
						count = config.Count
						break
					}
					newConfigs[i] = config
				}
			}

			err := g.Cloud.CloudConnect(g.CloudConnectReq{
				Uuid:       proxy.Name,
				Edge:       nil,
				AutoConfig: newConfigs,
			})
			if err != nil {
				return nil, err
			}

			slog.Debug("提交节点配置",
				slog.Duration("step", time.Since(step)),
				slog.String("proxy", proxy.Name),
				slog.Int("used", prev),
				slog.Int("count", next),
			)
		}

		// 节点增量
		var acc = next - prev
		if acc <= 0 {
			continue
		}

		// 筛选可用端口
		var portConfigs = make([]g.PortConfigsReq, 0, acc)
		for port := 10000; port < 20000 && len(portConfigs) < acc; port++ {
			// 跳过存在的端口
			key := uint64(proxy.ID)<<32 | uint64(port)
			_, ok := portsMap[key]
			if ok {
				continue
			}

			// 配置新端口
			var portConf = g.PortConfigsReq{
				Port:   port,
				Edge:   nil,
				Status: true,
				AutoEdgeConfig: &g.AutoEdgeConfig{
					Province:   filter.Prov,
					City:       filter.City,
					Isp:        filter.Isp,
					Count:      u.P(1),
					PacketLoss: 30,
				},
			}
			var newChannel = &m.Channel{
				UserID:     userId,
				ProxyID:    proxy.ID,
				ProxyHost:  proxy.Host,
				ProxyPort:  int32(port),
				Protocol:   int32(protocol),
				Expiration: orm.LocalDateTime(expiration),
			}

			switch authType {

			case ChannelAuthTypeIp:
				portConf.Whitelist = whitelist
				portConf.Userpass = u.P("")
				newChannel.AuthIP = true

			case ChannelAuthTypePass:
				username, password := genPassPair()
				portConf.Whitelist = &[]string{}
				portConf.Userpass = u.P(fmt.Sprintf("%s:%s", username, password))
				newChannel.AuthPass = true
				newChannel.Username = username
				newChannel.Password = password

			default:
				return nil, ChannelServiceErr("不支持的通道认证方式")
			}

			portConfigs = append(portConfigs, portConf)
			newChannels = append(newChannels, newChannel)
		}
		if len(portConfigs) < acc {
			return nil, ChannelServiceErr("网关端口数量到达上限，无法分配")
		}

		// 提交端口配置并更新节点列表
		if env.DebugExternalChange {
			var step = time.Now()

			var secret = strings.Split(proxy.Secret, ":")
			gateway := g.NewGateway(
				proxy.Host,
				secret[0],
				secret[1],
			)
			err = gateway.GatewayPortConfigs(portConfigs)
			if err != nil {
				return nil, err
			}

			slog.Debug("提交端口配置", "step", time.Since(step))
		}
	}

	slog.Debug("申请节点", "total", time.Since(step))
	return newChannels, nil
}

func updateResource(rid string, resource *ResourceInfo, count int, now time.Time) (err error) {
	toUpdate := m.ResourcePss{
		Used:      resource.Used + int32(count),
		DailyLast: orm.LocalDateTime(now),
	}
	var last = time.Time(resource.DailyLast)
	if now.Year() != last.Year() || now.Month() != last.Month() || now.Day() != last.Day() {
		toUpdate.DailyUsed = int32(count)
	} else {
		toUpdate.DailyUsed = resource.DailyUsed + int32(count)
	}
	_, err = q.ResourcePss.
		Where(q.ResourcePss.ResourceID.Eq(resource.Id)).
		Select(
			q.ResourcePss.Used,
			q.ResourcePss.DailyUsed,
			q.ResourcePss.DailyLast,
		).
		Updates(toUpdate)
	if err != nil {
		return err
	}

	return nil
}

func saveChannels(channels []*m.Channel) (err error) {
	err = q.Channel.
		Omit(
			q.Channel.EdgeID,
			q.Channel.EdgeHost,
			q.Channel.DeletedAt,
		).
		Create(channels...)
	if err != nil {
		return err
	}

	return nil
}

func cacheChannels(ctx context.Context, rid string, channels []*m.Channel, whitelists *[]string) (err error) {
	if len(channels) == 0 {
		return nil
	}

	pipe := g.Redis.TxPipeline()

	zList := make([]redis.Z, 0, len(channels))
	for _, channel := range channels {
		expiration := time.Time(channel.Expiration)
		keys := chAuthItems(channel, whitelists)
		for _, key := range keys {
			pipe.Set(ctx, key, true, time.Since(expiration))
		}
		zList = append(zList, redis.Z{
			Score:  float64(expiration.Unix()),
			Member: channel.ID,
		})
	}
	pipe.ZAdd(ctx, "tasks:channel", zList...)

	_, err = pipe.Exec(ctx)
	if err != nil {
		return err
	}

	return nil
}

// endregion

func genPassPair() (string, string) {
	//goland:noinspection SpellCheckingInspection
	var alphabet = []rune("abcdefghjkmnpqrstuvwxyz")
	var numbers = []rune("23456789")

	var username = make([]rune, 6)
	var password = make([]rune, 6)
	for i := range 6 {
		if i < 2 {
			username[i] = alphabet[rand.N(len(alphabet))]
		} else {
			username[i] = numbers[rand.N(len(numbers))]
		}
		password[i] = numbers[rand.N(len(numbers))]
	}

	return string(username), string(password)
}

func chAuthItems(channel *m.Channel, whitelists *[]string) []string {
	var count = 1
	var ips = make([]string, 0)
	if channel.AuthIP && whitelists != nil {
		count = len(*whitelists)
		ips = *whitelists
	}

	var proxy = channel.ProxyHost + ":" + strconv.Itoa(int(channel.ProxyPort))
	var sb = strings.Builder{}
	var items = make([]string, count)
	for i := range items {
		// 权限 key 格式：<proxy_host>:<proxy_port>:<user_ip>?:<username>?:<password>?
		sb.WriteString(proxy)
		if channel.AuthIP {
			sb.WriteString(":" + ips[i])
		}
		if channel.AuthPass {
			sb.WriteString(":" + channel.Username + ":" + channel.Password)
		}
	}

	return items
}

type ChannelAuthType int

const (
	ChannelAuthTypeIp ChannelAuthType = iota + 1
	ChannelAuthTypePass
)

type ChannelServiceErr string

func (c ChannelServiceErr) Error() string {
	return string(c)
}

const (
	ErrResourceNotExist   = ChannelServiceErr("套餐不存在")
	ErrResourceInvalid    = ChannelServiceErr("套餐不可用")
	ErrResourceExhausted  = ChannelServiceErr("套餐已用完")
	ErrResourceExpired    = ChannelServiceErr("套餐已过期")
	ErrResourceDailyLimit = ChannelServiceErr("套餐每日配额已用完")
)