// Copyright 2015 The etcd 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 cmd

import (
	"context"
	"crypto/rand"
	"fmt"
	"os"
	"strings"

	"github.com/bgentry/speakeasy"
	"google.golang.org/grpc/grpclog"

	clientv3 "go.etcd.io/etcd/client/v3"
	"go.etcd.io/etcd/pkg/v3/report"
)

var (
	// dialTotal counts the number of mustCreateConn calls so that endpoint
	// connections can be handed out in round-robin order
	dialTotal int

	// leaderEps is a cache for holding endpoints of a leader node
	leaderEps []string

	// cache the username and password for multiple connections
	globalUserName string
	globalPassword string
)

func mustFindLeaderEndpoints(c *clientv3.Client) {
	resp, lerr := c.MemberList(context.TODO())
	if lerr != nil {
		fmt.Fprintf(os.Stderr, "failed to get a member list: %s\n", lerr)
		os.Exit(1)
	}

	leaderID := uint64(0)
	for _, ep := range c.Endpoints() {
		if sresp, serr := c.Status(context.TODO(), ep); serr == nil {
			leaderID = sresp.Leader
			break
		}
	}

	for _, m := range resp.Members {
		if m.ID == leaderID {
			leaderEps = m.ClientURLs
			return
		}
	}

	fmt.Fprint(os.Stderr, "failed to find a leader endpoint\n")
	os.Exit(1)
}

func getUsernamePassword(usernameFlag string) (string, string, error) {
	if globalUserName != "" && globalPassword != "" {
		return globalUserName, globalPassword, nil
	}
	colon := strings.Index(usernameFlag, ":")
	if colon == -1 {
		// Prompt for the password.
		password, err := speakeasy.Ask("Password: ")
		if err != nil {
			return "", "", err
		}
		globalUserName = usernameFlag
		globalPassword = password
	} else {
		globalUserName = usernameFlag[:colon]
		globalPassword = usernameFlag[colon+1:]
	}
	return globalUserName, globalPassword, nil
}

func mustCreateConn() *clientv3.Client {
	connEndpoints := leaderEps
	if len(connEndpoints) == 0 {
		connEndpoints = []string{endpoints[dialTotal%len(endpoints)]}
		dialTotal++
	}
	cfg := clientv3.Config{
		AutoSyncInterval: autoSyncInterval,
		Endpoints:        connEndpoints,
		DialTimeout:      dialTimeout,
	}
	if !tls.Empty() || tls.TrustedCAFile != "" {
		cfgtls, err := tls.ClientConfig()
		if err != nil {
			fmt.Fprintf(os.Stderr, "bad tls config: %v\n", err)
			os.Exit(1)
		}
		cfg.TLS = cfgtls
	}

	if len(user) != 0 {
		username, password, err := getUsernamePassword(user)
		if err != nil {
			fmt.Fprintf(os.Stderr, "bad user information: %s %v\n", user, err)
			os.Exit(1)
		}
		cfg.Username = username
		cfg.Password = password
	}

	client, err := clientv3.New(cfg)
	if targetLeader && len(leaderEps) == 0 {
		mustFindLeaderEndpoints(client)
		client.Close()
		return mustCreateConn()
	}

	grpclog.SetLoggerV2(grpclog.NewLoggerV2(os.Stderr, os.Stderr, os.Stderr))

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

	return client
}

func mustCreateClients(totalClients, totalConns uint) []*clientv3.Client {
	conns := make([]*clientv3.Client, totalConns)
	for i := range conns {
		conns[i] = mustCreateConn()
	}

	clients := make([]*clientv3.Client, totalClients)
	for i := range clients {
		clients[i] = conns[i%int(totalConns)]
	}
	return clients
}

func mustRandBytes(n int) []byte {
	rb := make([]byte, n)
	_, err := rand.Read(rb)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to generate value: %v\n", err)
		os.Exit(1)
	}
	return rb
}

func newReport() report.Report {
	p := "%4.4f"
	if precise {
		p = "%g"
	}
	if sample {
		return report.NewReportSample(p)
	}
	return report.NewReport(p)
}

func newWeightedReport() report.Report {
	p := "%4.4f"
	if precise {
		p = "%g"
	}
	if sample {
		return report.NewReportSample(p)
	}
	return report.NewWeightedReport(report.NewReport(p), p)
}
