package consul

import (
	"fmt"
	"net"

	"github.com/hashicorp/consul/consul/agent"
	"github.com/hashicorp/consul/consul/structs"
	"github.com/hashicorp/raft"
)

// Operator endpoint is used to perform low-level operator tasks for Consul.
type Operator struct {
	srv *Server
}

// RaftGetConfiguration is used to retrieve the current Raft configuration.
func (op *Operator) RaftGetConfiguration(args *structs.DCSpecificRequest, reply *structs.RaftConfigurationResponse) error {
	if done, err := op.srv.forward("Operator.RaftGetConfiguration", args, args, reply); done {
		return err
	}

	// This action requires operator read access.
	acl, err := op.srv.resolveToken(args.Token)
	if err != nil {
		return err
	}
	if acl != nil && !acl.OperatorRead() {
		return permissionDeniedErr
	}

	// We can't fetch the leader and the configuration atomically with
	// the current Raft API.
	future := op.srv.raft.GetConfiguration()
	if err := future.Error(); err != nil {
		return err
	}
	reply.Configuration = future.Configuration()
	leader := op.srv.raft.Leader()

	// Index the configuration so we can easily look up IDs by address.
	idMap := make(map[raft.ServerAddress]raft.ServerID)
	for _, s := range reply.Configuration.Servers {
		idMap[s.Address] = s.ID
	}

	// Fill out the node map and leader.
	reply.NodeMap = make(map[raft.ServerID]string)
	members := op.srv.serfLAN.Members()
	for _, member := range members {
		valid, parts := agent.IsConsulServer(member)
		if !valid {
			continue
		}

		// TODO (slackpad) We need to add a Raft API to get the leader by
		// ID so we don't have to do this mapping.
		addr := (&net.TCPAddr{IP: member.Addr, Port: parts.Port}).String()
		if id, ok := idMap[raft.ServerAddress(addr)]; ok {
			reply.NodeMap[id] = member.Name
			if leader == raft.ServerAddress(addr) {
				reply.Leader = id
			}
		}
	}
	return nil
}

// RaftRemovePeerByAddress is used to kick a stale peer (one that it in the Raft
// quorum but no longer known to Serf or the catalog) by address in the form of
// "IP:port". The reply argument is not used, but it required to fulfill the RPC
// interface.
func (op *Operator) RaftRemovePeerByAddress(args *structs.RaftPeerByAddressRequest, reply *struct{}) error {
	if done, err := op.srv.forward("Operator.RaftRemovePeerByAddress", args, args, reply); done {
		return err
	}

	// This is a super dangerous operation that requires operator write
	// access.
	acl, err := op.srv.resolveToken(args.Token)
	if err != nil {
		return err
	}
	if acl != nil && !acl.OperatorWrite() {
		return permissionDeniedErr
	}

	// Since this is an operation designed for humans to use, we will return
	// an error if the supplied address isn't among the peers since it's
	// likely they screwed up.
	{
		future := op.srv.raft.GetConfiguration()
		if err := future.Error(); err != nil {
			return err
		}
		for _, s := range future.Configuration().Servers {
			if s.Address == args.Address {
				goto REMOVE
			}
		}
		return fmt.Errorf("address %q was not found in the Raft configuration",
			args.Address)
	}

REMOVE:
	// The Raft library itself will prevent various forms of foot-shooting,
	// like making a configuration with no voters. Some consideration was
	// given here to adding more checks, but it was decided to make this as
	// low-level and direct as possible. We've got ACL coverage to lock this
	// down, and if you are an operator, it's assumed you know what you are
	// doing if you are calling this. If you remove a peer that's known to
	// Serf, for example, it will come back when the leader does a reconcile
	// pass.
	future := op.srv.raft.RemovePeer(args.Address)
	if err := future.Error(); err != nil {
		return err
	}

	return nil
}