package cluster

import (
	"context"
	"fmt"
	"ngs/cluster/clusterpb"
	"ngs/internal/log"
	"sync"
)

// cluster represents a ngs cluster, which contains a bunch of ngs nodes
// and each of them provide a group of different services. All services requests
// from client will send to gate firstly and be forwarded to appropriate node.
type cluster struct {
	// If cluster is not large enough, use slice is OK
	currentNode *Node
	rpcClient   *rpcClient

	mu      sync.RWMutex
	members []*Member
}

func newCluster(currentNode *Node) *cluster {
	return &cluster{currentNode: currentNode}
}

// Register implements the MasterServer gRPC service
func (c *cluster) Register(_ context.Context, req *clusterpb.RegisterRequest) (*clusterpb.RegisterResponse, error) {
	if req.MemberInfo == nil {
		return nil, ErrInvalidRegisterReq
	}

	resp := &clusterpb.RegisterResponse{}
	for _, m := range c.members {
		if m.memberInfo.ServiceAddr == req.MemberInfo.ServiceAddr {
			return nil, fmt.Errorf("address %s has registered", req.MemberInfo.ServiceAddr)
		}
	}

	// Notify registered node to update remote services
	newMember := &clusterpb.NewMemberRequest{MemberInfo: req.MemberInfo}
	for _, m := range c.members {
		resp.Members = append(resp.Members, m.memberInfo)
		if m.isMaster {
			continue
		}
		pool, err := c.rpcClient.getConnPool(m.memberInfo.ServiceAddr)
		if err != nil {
			return nil, err
		}
		client := clusterpb.NewMemberClient(pool.Get())
		_, err = client.NewMember(context.Background(), newMember)
		if err != nil {
			return nil, err
		}
	}

	log.Println("New peer register to cluster", req.MemberInfo.ServiceAddr)

	// Register services to current node
	c.currentNode.handler.addRemoteService(req.MemberInfo)
	c.mu.Lock()
	c.members = append(c.members, &Member{isMaster: false, memberInfo: req.MemberInfo})
	c.mu.Unlock()
	return resp, nil
}

// Unregister implements the MasterServer gRPC service
func (c *cluster) Unregister(_ context.Context, req *clusterpb.UnregisterRequest) (*clusterpb.UnregisterResponse, error) {
	if req.ServiceAddr == "" {
		return nil, ErrInvalidRegisterReq
	}

	var index = -1
	resp := &clusterpb.UnregisterResponse{}
	for i, m := range c.members {
		if m.memberInfo.ServiceAddr == req.ServiceAddr {
			index = i
			break
		}
	}
	if index < 0 {
		return nil, fmt.Errorf("address %s has  notregistered", req.ServiceAddr)
	}

	// Notify registered node to update remote services
	delMember := &clusterpb.DelMemberRequest{ServiceAddr: req.ServiceAddr}
	for _, m := range c.members {
		if m.MemberInfo().ServiceAddr == c.currentNode.ServiceAddr {
			continue
		}
		pool, err := c.rpcClient.getConnPool(m.memberInfo.ServiceAddr)
		if err != nil {
			return nil, err
		}
		client := clusterpb.NewMemberClient(pool.Get())
		_, err = client.DelMember(context.Background(), delMember)
		if err != nil {
			return nil, err
		}
	}

	log.Println("Exists peer unregister to cluster", req.ServiceAddr)

	// Register services to current node
	c.currentNode.handler.delMember(req.ServiceAddr)
	c.mu.Lock()
	if index == len(c.members)-1 {
		c.members = c.members[:index]
	} else {
		c.members = append(c.members[:index], c.members[index+1:]...)
	}
	c.mu.Unlock()
	return resp, nil
}

func (c *cluster) setRpcClient(client *rpcClient) {
	c.rpcClient = client
}

func (c *cluster) remoteAddrs() []string {
	var addrs []string
	c.mu.RLock()
	for _, m := range c.members {
		addrs = append(addrs, m.memberInfo.ServiceAddr)
	}
	c.mu.RUnlock()
	return addrs
}

func (c *cluster) initMembers(members []*clusterpb.MemberInfo) {
	c.mu.Lock()
	for _, info := range members {
		c.members = append(c.members, &Member{
			memberInfo: info,
		})
	}
	c.mu.Unlock()
}

func (c *cluster) addMember(info *clusterpb.MemberInfo) {
	c.mu.Lock()
	var found bool
	for _, member := range c.members {
		if member.memberInfo.ServiceAddr == info.ServiceAddr {
			member.memberInfo = info
			found = true
			break
		}
	}
	if !found {
		c.members = append(c.members, &Member{
			memberInfo: info,
		})
	}
	c.mu.Unlock()
}

func (c *cluster) delMember(addr string) {
	c.mu.Lock()
	var index = -1
	for i, member := range c.members {
		if member.memberInfo.ServiceAddr == addr {
			index = i
			break
		}
	}
	if index != -1 {
		c.members = append(c.members[:index], c.members[index+1:]...)
	}
	c.mu.Unlock()
}