package cli

import (
	"context"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"os"

	v1 "github.com/juanfont/headscale/gen/go/headscale/v1"
	"github.com/juanfont/headscale/hscontrol"
	"github.com/juanfont/headscale/hscontrol/types"
	"github.com/juanfont/headscale/hscontrol/util"
	"github.com/rs/zerolog/log"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials"
	"google.golang.org/grpc/credentials/insecure"
	"gopkg.in/yaml.v3"
)

const (
	HeadscaleDateTimeFormat = "2006-01-02 15:04:05"
	SocketWritePermissions  = 0o666
)

func newHeadscaleServerWithConfig() (*hscontrol.Headscale, error) {
	cfg, err := types.LoadServerConfig()
	if err != nil {
		return nil, fmt.Errorf(
			"failed to load configuration while creating headscale instance: %w",
			err,
		)
	}

	app, err := hscontrol.NewHeadscale(cfg)
	if err != nil {
		return nil, err
	}

	return app, nil
}

func newHeadscaleCLIWithConfig() (context.Context, v1.HeadscaleServiceClient, *grpc.ClientConn, context.CancelFunc) {
	cfg, err := types.LoadCLIConfig()
	if err != nil {
		log.Fatal().
			Err(err).
			Caller().
			Msgf("Failed to load configuration")
		os.Exit(-1) // we get here if logging is suppressed (i.e., json output)
	}

	log.Debug().
		Dur("timeout", cfg.CLI.Timeout).
		Msgf("Setting timeout")

	ctx, cancel := context.WithTimeout(context.Background(), cfg.CLI.Timeout)

	grpcOptions := []grpc.DialOption{
		grpc.WithBlock(),
	}

	address := cfg.CLI.Address

	// If the address is not set, we assume that we are on the server hosting hscontrol.
	if address == "" {
		log.Debug().
			Str("socket", cfg.UnixSocket).
			Msgf("HEADSCALE_CLI_ADDRESS environment is not set, connecting to unix socket.")

		address = cfg.UnixSocket

		// Try to give the user better feedback if we cannot write to the headscale
		// socket.
		socket, err := os.OpenFile(cfg.UnixSocket, os.O_WRONLY, SocketWritePermissions) // nolint
		if err != nil {
			if os.IsPermission(err) {
				log.Fatal().
					Err(err).
					Str("socket", cfg.UnixSocket).
					Msgf("Unable to read/write to headscale socket, do you have the correct permissions?")
			}
		}
		socket.Close()

		grpcOptions = append(
			grpcOptions,
			grpc.WithTransportCredentials(insecure.NewCredentials()),
			grpc.WithContextDialer(util.GrpcSocketDialer),
		)
	} else {
		// If we are not connecting to a local server, require an API key for authentication
		apiKey := cfg.CLI.APIKey
		if apiKey == "" {
			log.Fatal().Caller().Msgf("HEADSCALE_CLI_API_KEY environment variable needs to be set.")
		}
		grpcOptions = append(grpcOptions,
			grpc.WithPerRPCCredentials(tokenAuth{
				token: apiKey,
			}),
		)

		if cfg.CLI.Insecure {
			tlsConfig := &tls.Config{
				// turn of gosec as we are intentionally setting
				// insecure.
				//nolint:gosec
				InsecureSkipVerify: true,
			}

			grpcOptions = append(grpcOptions,
				grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig)),
			)
		} else {
			grpcOptions = append(grpcOptions,
				grpc.WithTransportCredentials(credentials.NewClientTLSFromCert(nil, "")),
			)
		}
	}

	log.Trace().Caller().Str("address", address).Msg("Connecting via gRPC")
	conn, err := grpc.DialContext(ctx, address, grpcOptions...)
	if err != nil {
		log.Fatal().Caller().Err(err).Msgf("Could not connect: %v", err)
		os.Exit(-1) // we get here if logging is suppressed (i.e., json output)
	}

	client := v1.NewHeadscaleServiceClient(conn)

	return ctx, client, conn, cancel
}

func output(result interface{}, override string, outputFormat string) string {
	var jsonBytes []byte
	var err error
	switch outputFormat {
	case "json":
		jsonBytes, err = json.MarshalIndent(result, "", "\t")
		if err != nil {
			log.Fatal().Err(err).Msg("failed to unmarshal output")
		}
	case "json-line":
		jsonBytes, err = json.Marshal(result)
		if err != nil {
			log.Fatal().Err(err).Msg("failed to unmarshal output")
		}
	case "yaml":
		jsonBytes, err = yaml.Marshal(result)
		if err != nil {
			log.Fatal().Err(err).Msg("failed to unmarshal output")
		}
	default:
		// nolint
		return override
	}

	return string(jsonBytes)
}

// SuccessOutput prints the result to stdout and exits with status code 0.
func SuccessOutput(result interface{}, override string, outputFormat string) {
	fmt.Println(output(result, override, outputFormat))
	os.Exit(0)
}

// ErrorOutput prints an error message to stderr and exits with status code 1.
func ErrorOutput(errResult error, override string, outputFormat string) {
	type errOutput struct {
		Error string `json:"error"`
	}

	fmt.Fprintf(os.Stderr, "%s\n", output(errOutput{errResult.Error()}, override, outputFormat))
	os.Exit(1)
}

func HasMachineOutputFlag() bool {
	for _, arg := range os.Args {
		if arg == "json" || arg == "json-line" || arg == "yaml" {
			return true
		}
	}

	return false
}

type tokenAuth struct {
	token string
}

// Return value is mapped to request headers.
func (t tokenAuth) GetRequestMetadata(
	ctx context.Context,
	in ...string,
) (map[string]string, error) {
	return map[string]string{
		"authorization": "Bearer " + t.token,
	}, nil
}

func (tokenAuth) RequireTransportSecurity() bool {
	return true
}