package services

import (
	"fmt"
	"platform/pkg/env"
	"platform/pkg/u"
	"platform/web/core"
	g "platform/web/globals"
	m "platform/web/models"
	q "platform/web/queries"
	"strings"

	"gorm.io/gen"
)

type channelGostProvider struct{}

func (s *channelGostProvider) prepareCreate(ctx *channelCreateContext) (*channelCreateResult, error) {
	edges, err := s.selectEdge(ctx.Filter, ctx.Area, ctx.Count)
	if err != nil {
		return nil, err
	}

	client, err := proxyGost(ctx.Proxy)
	if err != nil {
		return nil, err
	}

	admissions := make([]*g.GostAdmissionConfig, 0, ctx.Count)
	authers := make([]*g.GostAutherConfig, 0, ctx.Count)
	services := make([]*g.GostServiceConfig, len(ctx.Ports))
	channels := make([]*m.Channel, len(ctx.Ports))

	for i, portRef := range ctx.Ports {
		edge := edges[i]
		port := portRef.Port()
		serviceName := gostServiceName(ctx.BatchNo, port)
		channel := newBaseChannel(ctx, port)
		channel.EdgeID = u.P(edge.ID)
		channel.EdgeRef = u.P(serviceName)
		channel.IP = u.P(edge.IP)

		service := &g.GostServiceConfig{
			Name: serviceName,
			Addr: fmt.Sprintf(":%d", port),
			Handler: g.GostHandlerConfig{
				Type:  "auto",
				Chain: edge.Mac,
			},
			Listener: g.GostListenerConfig{
				Type: "tcp",
			},
			Recorders: []g.GostRecorderConfig{
				{Name: "record-file", Record: "recorder.service.handler"},
			},
		}

		if ctx.AuthWhitelist {
			service.Admission = gostAdmissionName(ctx.BatchNo, port)
			admissions = append(admissions, &g.GostAdmissionConfig{
				Name:      service.Admission,
				Whitelist: true,
				Matchers:  ctx.Whitelists,
			})
		}
		if username, password, ok := applyChannelAuth(ctx, channel); ok {
			service.Handler.Auther = gostAutherName(ctx.BatchNo, port)
			authers = append(authers, &g.GostAutherConfig{
				Name: service.Handler.Auther,
				Auths: []g.GostAuthConfig{{
					Username: username,
					Password: password,
				}},
			})
		}

		services[i] = service
		channels[i] = channel
	}

	return &channelCreateResult{
		Channels: channels,
		applyRemote: func() error {
			for _, admission := range admissions {
				if err := client.CreateAdmission(admission); err != nil {
					return core.NewServErr(fmt.Sprintf("创建 GOST admission 失败: %s", admission.Name), err)
				}
			}
			for _, auther := range authers {
				if err := client.CreateAuther(auther); err != nil {
					return core.NewServErr(fmt.Sprintf("创建 GOST auther 失败: %s", auther.Name), err)
				}
			}
			for _, service := range services {
				if err := client.CreateService(service); err != nil {
					return core.NewServErr(fmt.Sprintf("创建 GOST service 失败: %s", service.Name), err)
				}
			}
			return nil
		},
	}, nil
}

func (s *channelGostProvider) removeRemote(batchNo string, batch *usedChanBatch) error {
	proxy, err := q.Proxy.Where(q.Proxy.ID.Eq(batch.ProxyID)).Take()
	if err != nil {
		return core.NewServErr("获取代理数据失败", err)
	}

	client, err := proxyGost(proxy)
	if err != nil {
		return core.NewServErr("创建 GOST 客户端失败", err)
	}
	var deleteErrs []error
	for _, ch := range batch.Chans {
		port := ch.Port()
		serviceName := gostServiceName(batchNo, port)
		deleteErrs = append(deleteErrs, deleteGostResource("service", serviceName, func() error {
			return client.DeleteService(serviceName)
		}))

		autherName := gostAutherName(batchNo, port)
		deleteErrs = append(deleteErrs, deleteGostResource("auther", autherName, func() error {
			return client.DeleteAuther(autherName)
		}))

		admissionName := gostAdmissionName(batchNo, port)
		deleteErrs = append(deleteErrs, deleteGostResource("admission", admissionName, func() error {
			return client.DeleteAdmission(admissionName)
		}))
	}
	return u.CombineErrors(deleteErrs)
}

func (s *channelGostProvider) selectProxy(count int) (*m.Proxy, error) {
	return selectProxyByType(m.ProxyTypeGost, count)
}

func (s *channelGostProvider) selectEdge(filter *EdgeFilter, area *m.Area, count int) ([]*m.Edge, error) {
	if filter == nil {
		filter = &EdgeFilter{}
	}

	conds := []gen.Condition{
		q.Edge.Type.Eq(int(m.EdgeTypeGostChain)),
		q.Edge.Status.Eq(int(m.EdgeStatusNormal)),
	}
	if isp := u.X(filter.Isp.String()); isp != nil {
		conds = append(conds, q.Edge.ISP.Eq(int(*filter.Isp)))
	}

	query := q.Edge.Where(conds...)
	if area != nil {
		switch area.Level {
		case m.AreaLevelProvince:
			edgeArea := q.Area.As("EdgeArea")
			query = query.
				Join(edgeArea, edgeArea.ID.EqCol(q.Edge.AreaID)).
				Where(edgeArea.ParentID.Eq(area.ID))
		case m.AreaLevelCity:
			query = query.Where(q.Edge.AreaID.Eq(area.ID))
		default:
			return nil, core.NewBizErr("地区层级不支持")
		}
	}

	edges, err := query.
		Order(q.Edge.ID).
		Limit(count).
		Find()
	if err != nil {
		return nil, core.NewBizErr("查询可用节点失败", err)
	}
	return expandGostEdges(edges, count)
}

func expandGostEdges(edges []*m.Edge, count int) ([]*m.Edge, error) {
	if len(edges) == 0 {
		return nil, core.NewBizErr("地区可用节点数量不足")
	}

	result := make([]*m.Edge, count)
	for i := range count {
		result[i] = edges[i%len(edges)]
	}
	return result, nil
}

func proxyGost(proxy *m.Proxy) (g.GostClient, error) {
	secret := strings.Split(u.Z(proxy.Secret), ":")
	if len(secret) != 2 {
		return nil, core.NewServErr(fmt.Sprintf("代理 %s 密钥格式错误", proxy.IP.String()), nil)
	}

	host := u.Else(proxy.Host, proxy.IP.String())
	return g.NewGost(host, env.GostApiPort, env.GostApiPathPrefix, secret[0], secret[1]), nil
}

func deleteGostResource(kind string, name string, deleteFn func() error) error {
	if err := deleteFn(); err != nil && !g.IsGostNotFound(err) {
		return core.NewServErr(fmt.Sprintf("删除 GOST %s 配置失败: %s", kind, name), err)
	}
	return nil
}

func gostServiceName(batchNo string, port uint16) string {
	return fmt.Sprintf("gost-svc-%s-%d", batchNo, port)
}

func gostAutherName(batchNo string, port uint16) string {
	return fmt.Sprintf("gost-auther-%s-%d", batchNo, port)
}

func gostAdmissionName(batchNo string, port uint16) string {
	return fmt.Sprintf("gost-adm-%s-%d", batchNo, port)
}