// Copyright (C) 2019 Storj Labs, Inc.
// See LICENSE for copying information.

package process

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"log"
	"os"
	"os/signal"
	"path/filepath"
	"strings"
	"sync"
	"syscall"
	"time"

	"github.com/spf13/cobra"
	"github.com/spf13/pflag"
	"github.com/spf13/viper"
	"github.com/zeebo/errs"
	"github.com/zeebo/structs"
	"go.uber.org/zap"
	monkit "gopkg.in/spacemonkeygo/monkit.v2"
	"gopkg.in/spacemonkeygo/monkit.v2/collect"
	"gopkg.in/spacemonkeygo/monkit.v2/present"

	"storj.io/storj/pkg/cfgstruct"
	"storj.io/storj/private/version"
)

// DefaultCfgFilename is the default filename used for storing a configuration.
const DefaultCfgFilename = "config.yaml"

var (
	mon = monkit.Package()

	commandMtx sync.Mutex
	contexts   = map[*cobra.Command]context.Context{}
	cancels    = map[*cobra.Command]context.CancelFunc{}
	configs    = map[*cobra.Command][]interface{}{}
	vipers     = map[*cobra.Command]*viper.Viper{}
)

// Bind sets flags on a command that match the configuration struct
// 'config'. It ensures that the config has all of the values loaded into it
// when the command runs.
func Bind(cmd *cobra.Command, config interface{}, opts ...cfgstruct.BindOpt) {
	commandMtx.Lock()
	defer commandMtx.Unlock()

	cfgstruct.Bind(cmd.Flags(), config, opts...)
	configs[cmd] = append(configs[cmd], config)
}

// Exec runs a Cobra command. If a "config" flag is defined it will be parsed
// and loaded using viper.
func Exec(cmd *cobra.Command) {
	cmd.AddCommand(&cobra.Command{
		Use:         "version",
		Short:       "output the version's build information, if any",
		RunE:        cmdVersion,
		Annotations: map[string]string{"type": "setup"}})

	exe, err := os.Executable()
	if err == nil {
		cmd.Use = exe
	}

	pflag.CommandLine.AddGoFlagSet(flag.CommandLine)
	cleanup(cmd)
	err = cmd.Execute()
	if err != nil {
		os.Exit(1)
	}
}

// Ctx returns the appropriate context.Context for ExecuteWithConfig commands
func Ctx(cmd *cobra.Command) (context.Context, context.CancelFunc) {
	commandMtx.Lock()
	defer commandMtx.Unlock()

	ctx := contexts[cmd]
	if ctx == nil {
		ctx = context.Background()
		contexts[cmd] = ctx
	}

	cancel := cancels[cmd]
	if cancel == nil {
		ctx, cancel = context.WithCancel(ctx)
		contexts[cmd] = ctx
		cancels[cmd] = cancel

		c := make(chan os.Signal, 1)
		signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
		go func() {
			sig := <-c
			log.Printf("Got a signal from the OS: %q", sig)
			signal.Stop(c)
			cancel()
		}()
	}

	return ctx, cancel
}

// Viper returns the appropriate *viper.Viper for the command, creating if necessary.
func Viper(cmd *cobra.Command) (*viper.Viper, error) {
	commandMtx.Lock()
	defer commandMtx.Unlock()

	if vip := vipers[cmd]; vip != nil {
		return vip, nil
	}

	vip := viper.New()
	if err := vip.BindPFlags(cmd.Flags()); err != nil {
		return nil, err
	}
	vip.SetEnvPrefix("storj")
	vip.SetEnvKeyReplacer(strings.NewReplacer(".", "_", "-", "_"))
	vip.AutomaticEnv()

	cfgFlag := cmd.Flags().Lookup("config-dir")
	if cfgFlag != nil && cfgFlag.Value.String() != "" {
		path := filepath.Join(os.ExpandEnv(cfgFlag.Value.String()), DefaultCfgFilename)
		if cmd.Annotations["type"] != "setup" || fileExists(path) {
			vip.SetConfigFile(path)
			if err := vip.ReadInConfig(); err != nil {
				return nil, err
			}
		}
	}

	vipers[cmd] = vip
	return vip, nil
}

var traceOut = flag.String("debug.trace-out", "", "If set, a path to write a process trace SVG to")

func cleanup(cmd *cobra.Command) {
	for _, ccmd := range cmd.Commands() {
		cleanup(ccmd)
	}
	if cmd.Run != nil {
		panic("Please use cobra's RunE instead of Run")
	}
	internalRun := cmd.RunE
	if internalRun == nil {
		return
	}

	cmd.RunE = func(cmd *cobra.Command, args []string) (err error) {
		ctx := context.Background()
		defer mon.TaskNamed("root")(&ctx)(&err)

		vip, err := Viper(cmd)
		if err != nil {
			return err
		}

		commandMtx.Lock()
		configValues := configs[cmd]
		commandMtx.Unlock()

		var (
			brokenKeys  = map[string]struct{}{}
			missingKeys = map[string]struct{}{}
			usedKeys    = map[string]struct{}{}
			allKeys     = map[string]struct{}{}
			allSettings = vip.AllSettings()
		)

		// Hacky hack: these two keys are noprefix which breaks all scoping
		if val, ok := allSettings["api-key"]; ok {
			allSettings["legacy.client.api-key"] = val
			delete(allSettings, "api-key")
		}
		if val, ok := allSettings["satellite-addr"]; ok {
			allSettings["legacy.client.satellite-addr"] = val
			delete(allSettings, "satellite-addr")
		}

		for _, config := range configValues {
			// Decode and all of the resulting keys into our sets
			res := structs.Decode(allSettings, config)
			for key := range res.Used {
				usedKeys[key] = struct{}{}
				allKeys[key] = struct{}{}
			}
			for key := range res.Missing {
				missingKeys[key] = struct{}{}
				allKeys[key] = struct{}{}
			}
			for key := range res.Broken {
				brokenKeys[key] = struct{}{}
				allKeys[key] = struct{}{}
			}
		}

		// Propagate keys that are missing to flags, and remove any used keys
		// from the missing set.
		for key := range missingKeys {
			if f := cmd.Flags().Lookup(key); f != nil {
				val := vip.GetString(key)
				err := f.Value.Set(val)
				f.Changed = val != f.DefValue
				if err != nil {
					brokenKeys[key] = struct{}{}
				} else {
					usedKeys[key] = struct{}{}
				}
			} else if f := flag.Lookup(key); f != nil {
				err := f.Value.Set(vip.GetString(key))
				if err != nil {
					brokenKeys[key] = struct{}{}
				} else {
					usedKeys[key] = struct{}{}
				}
			}
		}
		for key := range missingKeys {
			if _, ok := usedKeys[key]; ok {
				delete(missingKeys, key)
			}
		}

		logger, err := NewLogger()
		if err != nil {
			return err
		}

		if vip.ConfigFileUsed() != "" {
			path, err := filepath.Abs(vip.ConfigFileUsed())
			if err != nil {
				path = vip.ConfigFileUsed()
				logger.Debug("unable to resolve path", zap.Error(err))
			}

			logger.Sugar().Info("Configuration loaded from: ", path)
		}

		defer func() { _ = logger.Sync() }()
		defer zap.ReplaceGlobals(logger)()
		defer zap.RedirectStdLog(logger)()

		// okay now that logging is working, inform about the broken keys
		if cmd.Annotations["type"] != "helper" {
			for key := range missingKeys {
				logger.Sugar().Infof("Invalid configuration file key: %s", key)
			}
		}
		for key := range brokenKeys {
			logger.Sugar().Infof("Invalid configuration file value for key: %s", key)
		}

		err = initDebug(logger, monkit.Default)
		if err != nil {
			withoutStack := errors.New(err.Error())
			logger.Debug("failed to start debug endpoints", zap.Error(withoutStack))
		}

		var workErr error
		work := func(ctx context.Context) {
			commandMtx.Lock()
			contexts[cmd] = ctx
			commandMtx.Unlock()
			defer func() {
				commandMtx.Lock()
				delete(contexts, cmd)
				delete(cancels, cmd)
				commandMtx.Unlock()
			}()

			workErr = internalRun(cmd, args)
		}

		if *traceOut != "" {
			fh, err := os.Create(*traceOut)
			if err != nil {
				return err
			}
			if strings.HasSuffix(*traceOut, ".json") {
				err = present.SpansToJSON(fh, collect.CollectSpans(ctx, work))
			} else {
				err = present.SpansToSVG(fh, collect.CollectSpans(ctx, work))
			}
			err = errs.Combine(err, fh.Close())
			if err != nil {
				logger.Error("failed to write svg", zap.Error(err))
			}
		} else {
			work(ctx)
		}

		err = workErr
		if err != nil {
			// This function call os.Exit(1)
			logger.Fatal("Unrecoverable error", zap.Error(err))
		}

		return nil
	}
}

func cmdVersion(cmd *cobra.Command, args []string) (err error) {
	if version.Build.Release {
		fmt.Println("Release build")
	} else {
		fmt.Println("Development build")
	}

	if !version.Build.Version.IsZero() {
		fmt.Println("Version:", version.Build.Version.String())
	}
	if !version.Build.Timestamp.IsZero() {
		fmt.Println("Build timestamp:", version.Build.Timestamp.Format(time.RFC822))
	}
	if version.Build.CommitHash != "" {
		fmt.Println("Git commit:", version.Build.CommitHash)
	}
	return err
}