// Copyright 2015 CoreOS, Inc.
//
// 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 command

import (
	"fmt"
	"sync"
	"time"

	"github.com/coreos/etcd/clientv3"
	"github.com/coreos/etcd/pkg/flags"
	"github.com/spf13/cobra"
)

// NewEpHealthCommand returns the cobra command for "endpoint-health".
func NewEpHealthCommand() *cobra.Command {
	cmd := &cobra.Command{
		Use:   "endpoint-health",
		Short: "endpoint-health checks the healthiness of endpoints specified in `--endpoints` flag",
		Run:   epHealthCommandFunc,
	}
	return cmd
}

// epHealthCommandFunc executes the "endpoint-health" command.
func epHealthCommandFunc(cmd *cobra.Command, args []string) {
	flags.SetPflagsFromEnv("ETCDCTL", cmd.InheritedFlags())
	endpoints, err := cmd.Flags().GetStringSlice("endpoints")
	if err != nil {
		ExitWithError(ExitError, err)
	}

	sec := secureCfgFromCmd(cmd)
	dt := dialTimeoutFromCmd(cmd)
	cfgs := []*clientv3.Config{}
	for _, ep := range endpoints {
		cfg, err := newClientCfg([]string{ep}, dt, sec)
		if err != nil {
			ExitWithError(ExitBadArgs, err)
		}
		cfgs = append(cfgs, cfg)
	}

	var wg sync.WaitGroup

	for _, cfg := range cfgs {
		wg.Add(1)
		go func(cfg *clientv3.Config) {
			defer wg.Done()
			ep := cfg.Endpoints[0]
			cli, err := clientv3.New(*cfg)
			if err != nil {
				fmt.Printf("%s is unhealthy: failed to connect: %v\n", ep, err)
				return
			}
			st := time.Now()
			// get a random key. As long as we can get the response without an error, the
			// endpoint is health.
			ctx, cancel := commandCtx(cmd)
			_, err = cli.Get(ctx, "health")
			cancel()
			if err != nil {
				fmt.Printf("%s is unhealthy: failed to commit proposal: %v\n", ep, err)
			} else {
				fmt.Printf("%s is healthy: successfully committed proposal: took = %v\n", ep, time.Since(st))
			}
		}(cfg)
	}

	wg.Wait()
}