package nomad

import (
	"fmt"
	"net"

	log "github.com/hashicorp/go-hclog"

	"github.com/hashicorp/consul/agent/consul/autopilot"
	"github.com/hashicorp/nomad/nomad/structs"
	"github.com/hashicorp/raft"
	"github.com/hashicorp/serf/serf"
)

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

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

	// Check management permissions
	if aclObj, err := op.srv.ResolveToken(args.AuthToken); err != nil {
		return err
	} else if aclObj != nil && !aclObj.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// 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
	}

	// Index the Nomad information about the servers.
	serverMap := make(map[raft.ServerAddress]serf.Member)
	for _, member := range op.srv.serf.Members() {
		valid, parts := isNomadServer(member)
		if !valid {
			continue
		}

		addr := (&net.TCPAddr{IP: member.Addr, Port: parts.Port}).String()
		serverMap[raft.ServerAddress(addr)] = member
	}

	// Fill out the reply.
	leader := op.srv.raft.Leader()
	reply.Index = future.Index()
	for _, server := range future.Configuration().Servers {
		node := "(unknown)"
		raftProtocolVersion := "unknown"
		if member, ok := serverMap[server.Address]; ok {
			node = member.Name
			if raftVsn, ok := member.Tags["raft_vsn"]; ok {
				raftProtocolVersion = raftVsn
			}
		}

		entry := &structs.RaftServer{
			ID:           server.ID,
			Node:         node,
			Address:      server.Address,
			Leader:       server.Address == leader,
			Voter:        server.Suffrage == raft.Voter,
			RaftProtocol: raftProtocolVersion,
		}
		reply.Servers = append(reply.Servers, entry)
	}
	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
	}

	// Check management permissions
	if aclObj, err := op.srv.ResolveToken(args.AuthToken); err != nil {
		return err
	} else if aclObj != nil && !aclObj.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// 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 {
		op.logger.Warn("failed to remove Raft peer", "peer", args.Address, "error", err)
		return err
	}

	op.logger.Warn("removed Raft peer", "peer", args.Address)
	return nil
}

// RaftRemovePeerByID is used to kick a stale peer (one that is 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 is required to fulfill the RPC
// interface.
func (op *Operator) RaftRemovePeerByID(args *structs.RaftPeerByIDRequest, reply *struct{}) error {
	if done, err := op.srv.forward("Operator.RaftRemovePeerByID", args, args, reply); done {
		return err
	}

	// Check management permissions
	if aclObj, err := op.srv.ResolveToken(args.AuthToken); err != nil {
		return err
	} else if aclObj != nil && !aclObj.IsManagement() {
		return structs.ErrPermissionDenied
	}

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

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.
	minRaftProtocol, err := op.srv.autopilot.MinRaftProtocol()
	if err != nil {
		return err
	}

	var future raft.Future
	if minRaftProtocol >= 2 {
		future = op.srv.raft.RemoveServer(args.ID, 0, 0)
	} else {
		future = op.srv.raft.RemovePeer(address)
	}
	if err := future.Error(); err != nil {
		op.logger.Warn("failed to remove Raft peer", "peer_id", args.ID, "error", err)
		return err
	}

	op.logger.Warn("removed Raft peer", "peer_id", args.ID)
	return nil
}

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

	// This action requires operator read access.
	rule, err := op.srv.ResolveToken(args.AuthToken)
	if err != nil {
		return err
	}
	if rule != nil && !rule.AllowOperatorRead() {
		return structs.ErrPermissionDenied
	}

	state := op.srv.fsm.State()
	_, config, err := state.AutopilotConfig()
	if err != nil {
		return err
	}
	if config == nil {
		return fmt.Errorf("autopilot config not initialized yet")
	}

	*reply = *config

	return nil
}

// AutopilotSetConfiguration is used to set the current Autopilot configuration.
func (op *Operator) AutopilotSetConfiguration(args *structs.AutopilotSetConfigRequest, reply *bool) error {
	if done, err := op.srv.forward("Operator.AutopilotSetConfiguration", args, args, reply); done {
		return err
	}

	// This action requires operator write access.
	rule, err := op.srv.ResolveToken(args.AuthToken)
	if err != nil {
		return err
	}
	if rule != nil && !rule.AllowOperatorWrite() {
		return structs.ErrPermissionDenied
	}

	// Apply the update
	resp, _, err := op.srv.raftApply(structs.AutopilotRequestType, args)
	if err != nil {
		op.logger.Error("failed applying AutoPilot configuration", "error", err)
		return err
	}
	if respErr, ok := resp.(error); ok {
		return respErr
	}

	// Check if the return type is a bool.
	if respBool, ok := resp.(bool); ok {
		*reply = respBool
	}
	return nil
}

// ServerHealth is used to get the current health of the servers.
func (op *Operator) ServerHealth(args *structs.GenericRequest, reply *autopilot.OperatorHealthReply) error {
	// This must be sent to the leader, so we fix the args since we are
	// re-using a structure where we don't support all the options.
	args.AllowStale = false
	if done, err := op.srv.forward("Operator.ServerHealth", args, args, reply); done {
		return err
	}

	// This action requires operator read access.
	rule, err := op.srv.ResolveToken(args.AuthToken)
	if err != nil {
		return err
	}
	if rule != nil && !rule.AllowOperatorRead() {
		return structs.ErrPermissionDenied
	}

	// Exit early if the min Raft version is too low
	minRaftProtocol, err := op.srv.autopilot.MinRaftProtocol()
	if err != nil {
		return fmt.Errorf("error getting server raft protocol versions: %s", err)
	}
	if minRaftProtocol < 3 {
		return fmt.Errorf("all servers must have raft_protocol set to 3 or higher to use this endpoint")
	}

	*reply = op.srv.autopilot.GetClusterHealth()

	return nil
}