package main

import (
	"fmt"
	"os"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/nspcc-dev/neofs-s3-gw/internal/version"
	"github.com/nspcc-dev/neofs-sdk-go/pkg/pool"
	"github.com/spf13/pflag"
	"github.com/spf13/viper"
	"go.uber.org/zap"
)

const (
	minimumTTLInMinutes = 5

	defaultTTL = minimumTTLInMinutes * time.Minute

	defaultRebalanceTimer  = 15 * time.Second
	defaultRequestTimeout  = 15 * time.Second
	defaultConnectTimeout  = 30 * time.Second
	defaultShutdownTimeout = 15 * time.Second

	defaultMaxClientsCount    = 100
	defaultMaxClientsDeadline = time.Second * 30
)

const ( // Settings.
	// Logger.
	cfgLoggerLevel              = "logger.level"
	cfgLoggerFormat             = "logger.format"
	cfgLoggerTraceLevel         = "logger.trace_level"
	cfgLoggerNoCaller           = "logger.no_caller"
	cfgLoggerNoDisclaimer       = "logger.no_disclaimer"
	cfgLoggerSamplingInitial    = "logger.sampling.initial"
	cfgLoggerSamplingThereafter = "logger.sampling.thereafter"

	// Wallet.
	cfgWallet           = "wallet"
	cfgAddress          = "address"
	cfgWalletPassphrase = "wallet.passphrase"

	// HTTPS/TLS.
	cfgTLSKeyFile  = "tls.key_file"
	cfgTLSCertFile = "tls.cert_file"

	// Timeouts.
	cfgConnectionTTL  = "con_ttl"
	cfgConnectTimeout = "connect_timeout"
	cfgRequestTimeout = "request_timeout"
	cfgRebalanceTimer = "rebalance_timer"

	// MaxClients.
	cfgMaxClientsCount    = "max_clients_count"
	cfgMaxClientsDeadline = "max_clients_deadline"

	// gRPC.
	cfgGRPCVerbose = "verbose"

	// Metrics / Profiler / Web.
	cfgEnableMetrics  = "metrics"
	cfgEnableProfiler = "pprof"
	cfgListenAddress  = "listen_address"
	cfgListenDomains  = "listen_domains"

	// Peers.
	cfgPeers = "peers"

	// Application.
	cfgApplicationName      = "app.name"
	cfgApplicationVersion   = "app.version"
	cfgApplicationBuildTime = "app.build_time"

	// Command line args.
	cmdHelp    = "help"
	cmdVersion = "version"
	cmdConfig  = "config"

	// applicationName is gateway name.
	applicationName = "neofs-s3-gw"

	// envPrefix is environment variables prefix used for configuration.
	envPrefix = "S3_GW"
)

var ignore = map[string]struct{}{
	cfgApplicationName:      {},
	cfgApplicationVersion:   {},
	cfgApplicationBuildTime: {},

	cfgPeers: {},

	cmdHelp:    {},
	cmdVersion: {},
}

func fetchPeers(l *zap.Logger, v *viper.Viper) *pool.Builder {
	pb := new(pool.Builder)

	for i := 0; ; i++ {
		key := cfgPeers + "." + strconv.Itoa(i) + "."
		address := v.GetString(key + "address")
		weight := v.GetFloat64(key + "weight")

		if address == "" {
			l.Warn("skip, empty address")
			break
		}
		if weight <= 0 { // unspecified or wrong
			weight = 1
		}
		pb.AddNode(address, weight)

		l.Info("added connection peer",
			zap.String("address", address),
			zap.Float64("weight", weight))
	}

	return pb
}

func fetchDomains(v *viper.Viper) []string {
	cnt := v.GetInt(cfgListenDomains + ".count")
	res := make([]string, 0, cnt)
	for i := 0; ; i++ {
		domain := v.GetString(cfgListenDomains + "." + strconv.Itoa(i))
		if domain == "" {
			break
		}

		res = append(res, domain)
	}

	return res
}

func newSettings() *viper.Viper {
	v := viper.New()

	v.AutomaticEnv()
	v.SetEnvPrefix(envPrefix)
	v.SetConfigType("yaml")
	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
	v.AllowEmptyEnv(true)

	// flags setup:
	flags := pflag.NewFlagSet("commandline", pflag.ExitOnError)
	flags.SetOutput(os.Stdout)
	flags.SortFlags = false

	flags.Bool(cfgEnableProfiler, false, "enable pprof")
	flags.Bool(cfgEnableMetrics, false, "enable prometheus metrics")

	help := flags.BoolP(cmdHelp, "h", false, "show help")
	versionFlag := flags.BoolP(cmdVersion, "v", false, "show version")

	flags.StringP(cfgWallet, "w", "", `path to the wallet`)
	flags.String(cfgAddress, "", `address of wallet account`)
	config := flags.String(cmdConfig, "", "config path")

	flags.Bool(cfgGRPCVerbose, false, "set debug mode of gRPC connections")
	flags.Duration(cfgRequestTimeout, defaultRequestTimeout, "set gRPC request timeout")
	flags.Duration(cfgConnectTimeout, defaultConnectTimeout, "set gRPC connect timeout")
	flags.Duration(cfgRebalanceTimer, defaultRebalanceTimer, "set gRPC connection rebalance timer")

	flags.Int(cfgMaxClientsCount, defaultMaxClientsCount, "set max-clients count")
	flags.Duration(cfgMaxClientsDeadline, defaultMaxClientsDeadline, "set max-clients deadline")

	ttl := flags.DurationP(cfgConnectionTTL, "t", defaultTTL, "set gRPC connection time to live")

	flags.String(cfgListenAddress, "0.0.0.0:8080", "set address to listen")
	flags.String(cfgTLSCertFile, "", "TLS certificate file to use")
	flags.String(cfgTLSKeyFile, "", "TLS key file to use")

	peers := flags.StringArrayP(cfgPeers, "p", nil, "set NeoFS nodes")

	domains := flags.StringArrayP(cfgListenDomains, "d", nil, "set domains to be listened")

	// set prefers:
	v.Set(cfgApplicationName, applicationName)
	v.Set(cfgApplicationVersion, version.Version)

	// set defaults:

	// logger:
	v.SetDefault(cfgLoggerLevel, "debug")
	v.SetDefault(cfgLoggerFormat, "console")
	v.SetDefault(cfgLoggerTraceLevel, "panic")
	v.SetDefault(cfgLoggerNoCaller, false)
	v.SetDefault(cfgLoggerNoDisclaimer, true)
	v.SetDefault(cfgLoggerSamplingInitial, 1000)
	v.SetDefault(cfgLoggerSamplingThereafter, 1000)

	if err := v.BindPFlags(flags); err != nil {
		panic(err)
	}

	if err := flags.Parse(os.Args); err != nil {
		panic(err)
	}

	if peers != nil && len(*peers) > 0 {
		for i := range *peers {
			v.SetDefault(cfgPeers+"."+strconv.Itoa(i)+".address", (*peers)[i])
			v.SetDefault(cfgPeers+"."+strconv.Itoa(i)+".weight", 1)
		}
	}

	if domains != nil && len(*domains) > 0 {
		for i := range *domains {
			v.SetDefault(cfgListenDomains+"."+strconv.Itoa(i), (*domains)[i])
		}

		v.SetDefault(cfgListenDomains+".count", len(*domains))
	}

	switch {
	case help != nil && *help:
		fmt.Printf("NeoFS S3 gateway %s\n", version.Version)
		flags.PrintDefaults()

		fmt.Println()
		fmt.Println("Default environments:")
		fmt.Println()
		keys := v.AllKeys()
		sort.Strings(keys)

		for i := range keys {
			if _, ok := ignore[keys[i]]; ok {
				continue
			}

			k := strings.Replace(keys[i], ".", "_", -1)
			fmt.Printf("%s_%s = %v\n", envPrefix, strings.ToUpper(k), v.Get(keys[i]))
		}

		fmt.Println()
		fmt.Println("Peers preset:")
		fmt.Println()

		fmt.Printf("%s_%s_[N]_ADDRESS = string\n", envPrefix, strings.ToUpper(cfgPeers))
		fmt.Printf("%s_%s_[N]_WEIGHT = 0..1 (float)\n", envPrefix, strings.ToUpper(cfgPeers))

		os.Exit(0)
	case versionFlag != nil && *versionFlag:
		fmt.Printf("NeoFS S3 gateway %s\n", version.Version)
		os.Exit(0)
	case ttl != nil && ttl.Minutes() < minimumTTLInMinutes:
		fmt.Printf("connection ttl should not be less than %s", defaultTTL)
	}

	if v.IsSet(cmdConfig) {
		if cfgFile, err := os.Open(*config); err != nil {
			panic(err)
		} else if err := v.ReadConfig(cfgFile); err != nil {
			panic(err)
		}
	}

	return v
}