package base

import (
	"bytes"
	"context"
	"encoding/base64"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"os/signal"
	"regexp"
	"strings"
	"sync"
	"syscall"

	"github.com/hashicorp/boundary/api"
	"github.com/hashicorp/boundary/api/authtokens"
	"github.com/hashicorp/boundary/sdk/wrapper"
	"github.com/mitchellh/cli"
	"github.com/pkg/errors"
	"github.com/posener/complete"
	"github.com/zalando/go-keyring"
)

const (
	// maxLineLength is the maximum width of any line.
	maxLineLength int = 78

	envToken          = "BOUNDARY_TOKEN"
	EnvTokenName      = "BOUNDARY_TOKEN_NAME"
	envRecoveryConfig = "BOUNDARY_RECOVERY_CONFIG"
)

// reRemoveWhitespace is a regular expression for stripping whitespace from
// a string.
var reRemoveWhitespace = regexp.MustCompile(`[\s]+`)

var DevOnlyControllerFlags = func(*Command, *FlagSet) {}

type Command struct {
	Context    context.Context
	UI         cli.Ui
	ShutdownCh chan struct{}

	flags     *FlagSets
	flagsOnce sync.Once

	flagAddr    string
	flagVerbose bool

	flagTLSCACert     string
	flagTLSCAPath     string
	flagTLSClientCert string
	flagTLSClientKey  string
	flagTLSServerName string
	flagTLSInsecure   bool

	flagFormat           string
	FlagToken            string
	FlagTokenName        string
	FlagRecoveryConfig   string
	flagOutputCurlString bool

	FlagScopeId     string
	FlagId          string
	FlagName        string
	FlagDescription string
	FlagVersion     int

	client *api.Client
}

// New returns a new instance of a base.Command type
func NewCommand(ui cli.Ui) *Command {
	ctx, cancel := context.WithCancel(context.Background())
	ret := &Command{
		UI:         ui,
		ShutdownCh: MakeShutdownCh(),
		Context:    ctx,
	}

	go func() {
		<-ret.ShutdownCh
		cancel()
	}()

	return ret
}

// MakeShutdownCh returns a channel that can be used for shutdown
// notifications for commands. This channel will send a message for every
// SIGINT or SIGTERM received.
func MakeShutdownCh() chan struct{} {
	resultCh := make(chan struct{})

	shutdownCh := make(chan os.Signal, 4)
	signal.Notify(shutdownCh, os.Interrupt, syscall.SIGTERM)
	go func() {
		<-shutdownCh
		close(resultCh)
	}()
	return resultCh
}

// Client returns the HTTP API client. The client is cached on the command to
// save performance on future calls.
func (c *Command) Client(opt ...Option) (*api.Client, error) {
	// Read the test client if present
	if c.client != nil {
		return c.client, nil
	}

	opts := getOpts(opt...)

	config, err := api.DefaultConfig()
	if err != nil {
		return nil, err
	}

	if c.flagOutputCurlString {
		config.OutputCurlString = c.flagOutputCurlString
	}

	c.client, err = api.NewClient(config)
	if err != nil {
		return nil, err
	}
	if c.flagAddr != "" {
		if err := c.client.SetAddr(c.flagAddr); err != nil {
			return nil, fmt.Errorf("error setting address on client: %w", err)
		}
	}

	// If we need custom TLS configuration, then set it
	var modifiedTLS bool
	tlsConfig := config.TLSConfig
	if c.flagTLSCACert != "" {
		tlsConfig.CACert = c.flagTLSCACert
		modifiedTLS = true
	}
	if c.flagTLSCAPath != "" {
		tlsConfig.CAPath = c.flagTLSCAPath
		modifiedTLS = true
	}
	if c.flagTLSClientCert != "" {
		tlsConfig.ClientCert = c.flagTLSClientCert
		modifiedTLS = true
	}
	if c.flagTLSClientKey != "" {
		tlsConfig.ClientKey = c.flagTLSClientKey
		modifiedTLS = true
	}
	if c.flagTLSServerName != "" {
		tlsConfig.ServerName = c.flagTLSServerName
		modifiedTLS = true
	}
	if c.flagTLSInsecure {
		tlsConfig.Insecure = c.flagTLSInsecure
		modifiedTLS = true
	}
	if modifiedTLS {
		// Setup TLS config
		if err := c.client.SetTLSConfig(tlsConfig); err != nil {
			return nil, errors.Wrap(err, "failed to setup TLS config")
		}
	}

	// Turn off retries on the CLI
	if os.Getenv(api.EnvBoundaryMaxRetries) == "" {
		c.client.SetMaxRetries(0)
	}

	tokenName := "default"
	switch {
	case c.FlagRecoveryConfig != "":
		wrapper, err := wrapper.GetWrapperFromPath(c.FlagRecoveryConfig, "recovery")
		if err != nil {
			return nil, err
		}
		if wrapper == nil {
			return nil, errors.New(`No "kms" block with purpose "recovery" found`)
		}
		if err := wrapper.Init(c.Context); err != nil {
			return nil, fmt.Errorf("Error initializing kms: %w", err)
		}
		/*
			// NOTE: ideally we should call this but at the same time we want to
			give a wrapper to the client, not a token, so it doesn't try to use
			it for two subsequent calls. This then becomes a question of
			how/when to finalize the wrapper. Probably it needs to be stored in
			the base and then at the end of the command run we finalize it if it
			exists. defer func() {if err := wrapper.Finalize(c.Context); err !=
			nil {c.UI.Error(fmt.Errorf("An error was encountered finalizing the
			kms: %w", err).Error())
			    }
			}()
		*/
		c.client.SetRecoveryKmsWrapper(wrapper)

	case c.FlagToken != "":
		c.client.SetToken(c.FlagToken)

	case c.client.Token() == "":
		if c.FlagTokenName != "" {
			tokenName = c.FlagTokenName
		}
		os.Setenv(EnvTokenName, tokenName)
		if tokenName != "none" {
			token, err := keyring.Get("HashiCorp Boundary Auth Token", tokenName)
			if err != nil {
				if err == keyring.ErrNotFound {
					c.UI.Info("No saved credential found, continuing without")
				} else {
					c.UI.Error(fmt.Sprintf("Error reading auth token from system credential store: %s", err))
				}
				token = ""
			}
			if token != "" {
				tokenBytes, err := base64.RawStdEncoding.DecodeString(token)
				switch {
				case err != nil:
					c.UI.Error(fmt.Errorf("Error base64-unmarshaling stored token from system credential store: %w", err).Error())
				case len(tokenBytes) == 0:
					c.UI.Error("Zero length token after decoding stored token from system credential store")
				default:
					var authToken authtokens.AuthToken
					if err := json.Unmarshal(tokenBytes, &authToken); err != nil {
						c.UI.Error(fmt.Sprintf("Error unmarshaling stored token information after reading from system credential store: %s", err))
					} else {
						c.client.SetToken(authToken.Token)
					}
				}
			}
		}
	}

	if opts.withNoTokenValue {
		c.client.SetToken("")
	}

	return c.client, nil
}

type FlagSetBit uint

const (
	FlagSetNone FlagSetBit = 1 << iota
	FlagSetHTTP
	FlagSetClient
	FlagSetOutputFormat
)

// FlagSet creates the flags for this command. The result is cached on the
// command to save performance on future calls.
func (c *Command) FlagSet(bit FlagSetBit) *FlagSets {
	c.flagsOnce.Do(func() {
		set := NewFlagSets(c.UI)

		if bit&FlagSetHTTP != 0 {
			f := set.NewFlagSet("Connection Options")

			f.StringVar(&StringVar{
				Name:       FlagNameAddr,
				Target:     &c.flagAddr,
				EnvVar:     api.EnvBoundaryAddr,
				Completion: complete.PredictAnything,
				Usage:      "Addr of the Boundary controller, as a complete URL (e.g. https://boundary.example.com:9200).",
			})

			f.StringVar(&StringVar{
				Name:       FlagNameCACert,
				Target:     &c.flagTLSCACert,
				EnvVar:     api.EnvBoundaryCACert,
				Completion: complete.PredictFiles("*"),
				Usage: "Path on the local disk to a single PEM-encoded CA " +
					"certificate to verify the Controller or Worker's server's SSL certificate. This " +
					"takes precedence over -ca-path.",
			})

			f.StringVar(&StringVar{
				Name:       FlagNameCAPath,
				Target:     &c.flagTLSCAPath,
				EnvVar:     api.EnvBoundaryCAPath,
				Completion: complete.PredictDirs("*"),
				Usage: "Path on the local disk to a directory of PEM-encoded CA " +
					"certificates to verify the SSL certificate of the Controller.",
			})

			f.StringVar(&StringVar{
				Name:       FlagNameClientCert,
				Target:     &c.flagTLSClientCert,
				EnvVar:     api.EnvBoundaryClientCert,
				Completion: complete.PredictFiles("*"),
				Usage: "Path on the local disk to a single PEM-encoded CA " +
					"certificate to use for TLS authentication to the Boundary Controller. If " +
					"this flag is specified, -client-key is also required.",
			})

			f.StringVar(&StringVar{
				Name:       FlagNameClientKey,
				Target:     &c.flagTLSClientKey,
				EnvVar:     api.EnvBoundaryClientKey,
				Completion: complete.PredictFiles("*"),
				Usage: "Path on the local disk to a single PEM-encoded private key " +
					"matching the client certificate from -client-cert.",
			})

			f.StringVar(&StringVar{
				Name:       FlagTLSServerName,
				Target:     &c.flagTLSServerName,
				EnvVar:     api.EnvBoundaryTLSServerName,
				Completion: complete.PredictAnything,
				Usage: "Name to use as the SNI host when connecting to the Boundary " +
					"server via TLS.",
			})

			f.BoolVar(&BoolVar{
				Name:   FlagNameTLSInsecure,
				Target: &c.flagTLSInsecure,
				EnvVar: api.EnvBoundaryTLSInsecure,
				Usage: "Disable verification of TLS certificates. Using this option " +
					"is highly discouraged as it decreases the security of data " +
					"transmissions to and from the Boundary server.",
			})
		}

		if bit&FlagSetClient != 0 {
			f := set.NewFlagSet("Client Options")

			f.StringVar(&StringVar{
				Name:   "token-name",
				Target: &c.FlagTokenName,
				EnvVar: EnvTokenName,
				Usage:  `If specified, the given value will be used as the name when storing the token in the system credential store. This can allow switching user identities for different commands. Set to "none" to disable storing the token.`,
			})

			f.StringVar(&StringVar{
				Name:   "token",
				Target: &c.FlagToken,
				EnvVar: envToken,
				Usage:  `If specified, the given value will be used as the token for the call. Overrides the "token-name" parameter.`,
			})

			f.StringVar(&StringVar{
				Name:   "recovery-config",
				Target: &c.FlagRecoveryConfig,
				EnvVar: envRecoveryConfig,
				Usage:  `If specified, the given config file will be parsed for a "kms" block with purpose "recovery" and will use the recovery mechanism to authorize the call."`,
			})

			f.BoolVar(&BoolVar{
				Name:   "output-curl-string",
				Target: &c.flagOutputCurlString,
				Usage:  "Instead of executing the request, print an equivalent cURL command string and exit.",
			})
		}

		if bit&FlagSetOutputFormat != 0 {
			f := set.NewFlagSet("Output Options")

			/*
				f.BoolVar(&BoolVar{
					Name:       "verbose",
					Target:     &c.flagVerbose,
					Completion: complete.PredictAnything,
					Usage:      "Turns on some extra verbosity in the command output.",
				})
			*/

			if bit&FlagSetOutputFormat != 0 {
				f.StringVar(&StringVar{
					Name:       "format",
					Target:     &c.flagFormat,
					Default:    "table",
					EnvVar:     EnvBoundaryCLIFormat,
					Completion: complete.PredictSet("table", "json", "yaml"),
					Usage:      "Print the output in the given format. Valid formats are \"table\" or \"json\".",
				})
			}
		}

		c.flags = set
	})

	return c.flags
}

// FlagSets is a group of flag sets.
type FlagSets struct {
	flagSets    []*FlagSet
	mainSet     *flag.FlagSet
	hiddens     map[string]struct{}
	completions complete.Flags
}

// NewFlagSets creates a new flag sets.
func NewFlagSets(ui cli.Ui) *FlagSets {
	mainSet := flag.NewFlagSet("", flag.ContinueOnError)

	// Errors and usage are controlled by the CLI.
	mainSet.Usage = func() {}
	mainSet.SetOutput(ioutil.Discard)

	return &FlagSets{
		flagSets:    make([]*FlagSet, 0, 6),
		mainSet:     mainSet,
		hiddens:     make(map[string]struct{}),
		completions: complete.Flags{},
	}
}

// NewFlagSet creates a new flag set from the given flag sets.
func (f *FlagSets) NewFlagSet(name string) *FlagSet {
	flagSet := NewFlagSet(name)
	flagSet.mainSet = f.mainSet
	flagSet.completions = f.completions
	f.flagSets = append(f.flagSets, flagSet)
	return flagSet
}

// Completions returns the completions for this flag set.
func (f *FlagSets) Completions() complete.Flags {
	if f == nil {
		return nil
	}
	return f.completions
}

// Parse parses the given flags, returning any errors.
func (f *FlagSets) Parse(args []string) error {
	return f.mainSet.Parse(args)
}

// Parsed reports whether the command-line flags have been parsed.
func (f *FlagSets) Parsed() bool {
	return f.mainSet.Parsed()
}

// Args returns the remaining args after parsing.
func (f *FlagSets) Args() []string {
	return f.mainSet.Args()
}

// Visit visits the flags in lexicographical order, calling fn for each. It
// visits only those flags that have been set.
func (f *FlagSets) Visit(fn func(*flag.Flag)) {
	f.mainSet.Visit(fn)
}

// Help builds custom help for this command, grouping by flag set.
func (fs *FlagSets) Help() string {
	var out bytes.Buffer

	for _, set := range fs.flagSets {
		printFlagTitle(&out, set.name+":")
		set.VisitAll(func(f *flag.Flag) {
			// Skip any hidden flags
			if v, ok := f.Value.(FlagVisibility); ok && v.Hidden() {
				return
			}
			printFlagDetail(&out, f)
		})
	}

	return strings.TrimRight(out.String(), "\n")
}

// FlagSet is a grouped wrapper around a real flag set and a grouped flag set.
type FlagSet struct {
	name        string
	flagSet     *flag.FlagSet
	mainSet     *flag.FlagSet
	completions complete.Flags
}

// NewFlagSet creates a new flag set.
func NewFlagSet(name string) *FlagSet {
	return &FlagSet{
		name:    name,
		flagSet: flag.NewFlagSet(name, flag.ContinueOnError),
	}
}

// Name returns the name of this flag set.
func (f *FlagSet) Name() string {
	return f.name
}

func (f *FlagSet) Visit(fn func(*flag.Flag)) {
	f.flagSet.Visit(fn)
}

func (f *FlagSet) VisitAll(fn func(*flag.Flag)) {
	f.flagSet.VisitAll(fn)
}

// printFlagTitle prints a consistently-formatted title to the given writer.
func printFlagTitle(w io.Writer, s string) {
	fmt.Fprintf(w, "%s\n\n", s)
}

// printFlagDetail prints a single flag to the given writer.
func printFlagDetail(w io.Writer, f *flag.Flag) {
	// Check if the flag is hidden - do not print any flag detail or help output
	// if it is hidden.
	if h, ok := f.Value.(FlagVisibility); ok && h.Hidden() {
		return
	}

	// Check for a detailed example
	example := ""
	if t, ok := f.Value.(FlagExample); ok {
		example = t.Example()
	}

	if example != "" {
		fmt.Fprintf(w, "  -%s=<%s>\n", f.Name, example)
	} else {
		fmt.Fprintf(w, "  -%s\n", f.Name)
	}

	usage := reRemoveWhitespace.ReplaceAllString(f.Usage, " ")
	indented := WrapAtLengthWithPadding(usage, 6)
	fmt.Fprintf(w, "%s\n\n", indented)
}
