// Copyright 2019 the Kilo authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"fmt"
	"net"
	"os"
	"strings"

	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/clientcmd"

	"github.com/spf13/cobra"
	"github.com/squat/kilo/pkg/k8s"
	"github.com/squat/kilo/pkg/mesh"
	"github.com/squat/kilo/pkg/version"
)

const (
	logLevelAll   = "all"
	logLevelDebug = "debug"
	logLevelInfo  = "info"
	logLevelWarn  = "warn"
	logLevelError = "error"
	logLevelNone  = "none"
)

var (
	availableBackends = strings.Join([]string{
		k8s.Backend,
	}, ", ")
	availableGranularities = strings.Join([]string{
		string(mesh.DataCenterGranularity),
		string(mesh.NodeGranularity),
	}, ", ")
	availableLogLevels = strings.Join([]string{
		logLevelAll,
		logLevelDebug,
		logLevelInfo,
		logLevelWarn,
		logLevelError,
		logLevelNone,
	}, ", ")
	opts struct {
		backend     mesh.Backend
		granularity mesh.Granularity
		subnet      *net.IPNet
	}
	backend     string
	granularity string
	kubeconfig  string
	subnet      string
)

func runRoot(_ *cobra.Command, _ []string) error {
	_, s, err := net.ParseCIDR(subnet)
	if err != nil {
		return fmt.Errorf("failed to parse %q as CIDR: %v", subnet, err)
	}
	opts.subnet = s

	opts.granularity = mesh.Granularity(granularity)
	switch opts.granularity {
	case mesh.DataCenterGranularity:
	case mesh.NodeGranularity:
	default:
		return fmt.Errorf("mesh granularity %v unknown; posible values are: %s", granularity, availableGranularities)
	}

	switch backend {
	case k8s.Backend:
		config, err := clientcmd.BuildConfigFromFlags("", kubeconfig)
		if err != nil {
			return fmt.Errorf("failed to create Kubernetes config: %v", err)
		}
		client := kubernetes.NewForConfigOrDie(config)
		opts.backend = k8s.New(client)
	default:
		return fmt.Errorf("backend %v unknown; posible values are: %s", backend, availableBackends)
	}

	if err := opts.backend.Init(make(chan struct{})); err != nil {
		return fmt.Errorf("failed to initialize backend: %v", err)
	}
	return nil
}

func main() {
	cmd := &cobra.Command{
		Use:               "kgctl",
		Short:             "Manage a Kilo network",
		Long:              "",
		PersistentPreRunE: runRoot,
		Version:           version.Version,
	}
	cmd.PersistentFlags().StringVar(&backend, "backend", k8s.Backend, fmt.Sprintf("The backend for the mesh. Possible values: %s", availableBackends))
	cmd.PersistentFlags().StringVar(&granularity, "mesh-granularity", string(mesh.DataCenterGranularity), fmt.Sprintf("The granularity of the network mesh to create. Possible values: %s", availableGranularities))
	cmd.PersistentFlags().StringVar(&kubeconfig, "kubeconfig", "", "Path to kubeconfig.")
	cmd.PersistentFlags().StringVar(&subnet, "subnet", "10.4.0.0/16", "CIDR from which to allocate addressees to WireGuard interfaces.")

	for _, subCmd := range []*cobra.Command{
		newGraph(),
	} {
		cmd.AddCommand(subCmd)
	}

	if err := cmd.Execute(); err != nil {
		fmt.Fprintf(os.Stderr, "%v\n", err)
		os.Exit(1)
	}
}