package swarm

import (
	"fmt"

	"golang.org/x/net/context"

	"github.com/docker/docker/api/client"
	"github.com/docker/docker/cli"
	"github.com/docker/engine-api/types/swarm"
	"github.com/spf13/cobra"
	"github.com/spf13/pflag"
)

const (
	generatedSecretEntropyBytes = 16
	generatedSecretBase         = 36
	// floor(log(2^128-1, 36)) + 1
	maxGeneratedSecretLength = 25
)

type initOptions struct {
	swarmOptions
	listenAddr      NodeAddrOption
	forceNewCluster bool
}

func newInitCommand(dockerCli *client.DockerCli) *cobra.Command {
	opts := initOptions{
		listenAddr: NewListenAddrOption(),
		swarmOptions: swarmOptions{
			autoAccept: NewAutoAcceptOption(),
		},
	}

	cmd := &cobra.Command{
		Use:   "init",
		Short: "Initialize a Swarm",
		Args:  cli.NoArgs,
		RunE: func(cmd *cobra.Command, args []string) error {
			return runInit(dockerCli, cmd.Flags(), opts)
		},
	}

	flags := cmd.Flags()
	flags.Var(&opts.listenAddr, "listen-addr", "Listen address")
	flags.BoolVar(&opts.forceNewCluster, "force-new-cluster", false, "Force create a new cluster from current state.")
	addSwarmFlags(flags, &opts.swarmOptions)
	return cmd
}

func runInit(dockerCli *client.DockerCli, flags *pflag.FlagSet, opts initOptions) error {
	client := dockerCli.Client()
	ctx := context.Background()

	// If no secret was specified, we create a random one
	if !flags.Changed("secret") {
		opts.secret = generateRandomSecret()
		fmt.Fprintf(dockerCli.Out(), "No --secret provided. Generated random secret:\n\t%s\n\n", opts.secret)
	}

	req := swarm.InitRequest{
		ListenAddr:      opts.listenAddr.String(),
		ForceNewCluster: opts.forceNewCluster,
		Spec:            opts.swarmOptions.ToSpec(),
	}

	nodeID, err := client.SwarmInit(ctx, req)
	if err != nil {
		return err
	}

	fmt.Fprintf(dockerCli.Out(), "Swarm initialized: current node (%s) is now a manager.\n\n", nodeID)

	// Fetch CAHash and Address from the API
	info, err := client.Info(ctx)
	if err != nil {
		return err
	}

	node, _, err := client.NodeInspectWithRaw(ctx, nodeID)
	if err != nil {
		return err
	}

	if node.ManagerStatus != nil && info.Swarm.CACertHash != "" {
		var secretArgs string
		if opts.secret != "" {
			secretArgs = "--secret " + opts.secret
		}
		fmt.Fprintf(dockerCli.Out(), "To add a worker to this swarm, run the following command:\n\tdocker swarm join %s \\\n\t--ca-hash %s \\\n\t%s\n", secretArgs, info.Swarm.CACertHash, node.ManagerStatus.Addr)
	}

	return nil
}