package cmd

import (
	"context"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"io"
	"io/fs"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"path"
	"strings"
	"syscall"

	"github.com/miekg/dns"
	log "github.com/sirupsen/logrus"
	"github.com/spf13/cobra"

	"github.com/netbirdio/netbird/formatter/hook"
	"github.com/netbirdio/netbird/management/internals/server"
	nbconfig "github.com/netbirdio/netbird/management/internals/server/config"
	"github.com/netbirdio/netbird/util"
)

var newServer = func(config *nbconfig.Config, dnsDomain, mgmtSingleAccModeDomain string, mgmtPort int, mgmtMetricsPort int, disableMetrics, disableGeoliteUpdate, userDeleteFromIDPEnabled bool) server.Server {
	return server.NewServer(config, dnsDomain, mgmtSingleAccModeDomain, mgmtPort, mgmtMetricsPort, disableMetrics, disableGeoliteUpdate, userDeleteFromIDPEnabled)
}

func SetNewServer(fn func(config *nbconfig.Config, dnsDomain, mgmtSingleAccModeDomain string, mgmtPort int, mgmtMetricsPort int, disableMetrics, disableGeoliteUpdate, userDeleteFromIDPEnabled bool) server.Server) {
	newServer = fn
}

var (
	config *nbconfig.Config

	mgmtCmd = &cobra.Command{
		Use:   "management",
		Short: "start NetBird Management Server",
		PreRunE: func(cmd *cobra.Command, args []string) error {
			flag.Parse()

			//nolint
			ctx := context.WithValue(cmd.Context(), hook.ExecutionContextKey, hook.SystemSource)

			err := util.InitLog(logLevel, logFile)
			if err != nil {
				return fmt.Errorf("failed initializing log %v", err)
			}

			// detect whether user specified a port
			userPort := cmd.Flag("port").Changed

			config, err = loadMgmtConfig(ctx, nbconfig.MgmtConfigPath)
			if err != nil {
				return fmt.Errorf("failed reading provided config file: %s: %v", nbconfig.MgmtConfigPath, err)
			}

			if cmd.Flag(idpSignKeyRefreshEnabledFlagName).Changed {
				config.HttpConfig.IdpSignKeyRefreshEnabled = idpSignKeyRefreshEnabled
			}

			tlsEnabled := false
			if mgmtLetsencryptDomain != "" || (config.HttpConfig.CertFile != "" && config.HttpConfig.CertKey != "") {
				tlsEnabled = true
			}

			if !userPort {
				// different defaults for port when tls enabled/disabled
				if tlsEnabled {
					mgmtPort = 443
				} else {
					mgmtPort = 80
				}
			}

			_, valid := dns.IsDomainName(dnsDomain)
			if !valid || len(dnsDomain) > 192 {
				return fmt.Errorf("failed parsing the provided dns-domain. Valid status: %t, Length: %d", valid, len(dnsDomain))
			}

			return nil
		},
		RunE: func(cmd *cobra.Command, args []string) error {
			flag.Parse()

			ctx, cancel := context.WithCancel(cmd.Context())
			defer cancel()
			//nolint
			ctx = context.WithValue(ctx, hook.ExecutionContextKey, hook.SystemSource)

			err := handleRebrand(cmd)
			if err != nil {
				return fmt.Errorf("migrate files %v", err)
			}

			if _, err = os.Stat(config.Datadir); os.IsNotExist(err) {
				err = os.MkdirAll(config.Datadir, 0755)
				if err != nil {
					return fmt.Errorf("failed creating datadir: %s: %v", config.Datadir, err)
				}
			}

			if disableSingleAccMode {
				mgmtSingleAccModeDomain = ""
			}

			srv := newServer(config, dnsDomain, mgmtSingleAccModeDomain, mgmtPort, mgmtMetricsPort, disableMetrics, disableGeoliteUpdate, userDeleteFromIDPEnabled)
			go func() {
				if err := srv.Start(cmd.Context()); err != nil {
					log.Fatalf("Server error: %v", err)
				}
			}()

			stopChan := make(chan os.Signal, 1)
			signal.Notify(stopChan, os.Interrupt, syscall.SIGTERM)
			select {
			case <-stopChan:
				log.Info("Received shutdown signal, stopping server...")
				err = srv.Stop()
				if err != nil {
					log.Errorf("Failed to stop server gracefully: %v", err)
				}
			case err := <-srv.Errors():
				log.Fatalf("Server stopped unexpectedly: %v", err)
			}

			return nil
		},
	}
)

func loadMgmtConfig(ctx context.Context, mgmtConfigPath string) (*nbconfig.Config, error) {
	loadedConfig := &nbconfig.Config{}
	_, err := util.ReadJsonWithEnvSub(mgmtConfigPath, loadedConfig)
	if err != nil {
		return nil, err
	}
	if mgmtLetsencryptDomain != "" {
		loadedConfig.HttpConfig.LetsEncryptDomain = mgmtLetsencryptDomain
	}
	if mgmtDataDir != "" {
		loadedConfig.Datadir = mgmtDataDir
	}

	if certKey != "" && certFile != "" {
		loadedConfig.HttpConfig.CertFile = certFile
		loadedConfig.HttpConfig.CertKey = certKey
	}

	oidcEndpoint := loadedConfig.HttpConfig.OIDCConfigEndpoint
	if oidcEndpoint != "" {
		// if OIDCConfigEndpoint is specified, we can load DeviceAuthEndpoint and TokenEndpoint automatically
		log.WithContext(ctx).Infof("loading OIDC configuration from the provided IDP configuration endpoint %s", oidcEndpoint)
		oidcConfig, err := fetchOIDCConfig(ctx, oidcEndpoint)
		if err != nil {
			return nil, err
		}
		log.WithContext(ctx).Infof("loaded OIDC configuration from the provided IDP configuration endpoint: %s", oidcEndpoint)

		log.WithContext(ctx).Infof("overriding HttpConfig.AuthIssuer with a new value %s, previously configured value: %s",
			oidcConfig.Issuer, loadedConfig.HttpConfig.AuthIssuer)
		loadedConfig.HttpConfig.AuthIssuer = oidcConfig.Issuer

		log.WithContext(ctx).Infof("overriding HttpConfig.AuthKeysLocation (JWT certs) with a new value %s, previously configured value: %s",
			oidcConfig.JwksURI, loadedConfig.HttpConfig.AuthKeysLocation)
		loadedConfig.HttpConfig.AuthKeysLocation = oidcConfig.JwksURI

		if !(loadedConfig.DeviceAuthorizationFlow == nil || strings.ToLower(loadedConfig.DeviceAuthorizationFlow.Provider) == string(nbconfig.NONE)) {
			log.WithContext(ctx).Infof("overriding DeviceAuthorizationFlow.TokenEndpoint with a new value: %s, previously configured value: %s",
				oidcConfig.TokenEndpoint, loadedConfig.DeviceAuthorizationFlow.ProviderConfig.TokenEndpoint)
			loadedConfig.DeviceAuthorizationFlow.ProviderConfig.TokenEndpoint = oidcConfig.TokenEndpoint
			log.WithContext(ctx).Infof("overriding DeviceAuthorizationFlow.DeviceAuthEndpoint with a new value: %s, previously configured value: %s",
				oidcConfig.DeviceAuthEndpoint, loadedConfig.DeviceAuthorizationFlow.ProviderConfig.DeviceAuthEndpoint)
			loadedConfig.DeviceAuthorizationFlow.ProviderConfig.DeviceAuthEndpoint = oidcConfig.DeviceAuthEndpoint

			u, err := url.Parse(oidcEndpoint)
			if err != nil {
				return nil, err
			}
			log.WithContext(ctx).Infof("overriding DeviceAuthorizationFlow.ProviderConfig.Domain with a new value: %s, previously configured value: %s",
				u.Host, loadedConfig.DeviceAuthorizationFlow.ProviderConfig.Domain)
			loadedConfig.DeviceAuthorizationFlow.ProviderConfig.Domain = u.Host

			if loadedConfig.DeviceAuthorizationFlow.ProviderConfig.Scope == "" {
				loadedConfig.DeviceAuthorizationFlow.ProviderConfig.Scope = nbconfig.DefaultDeviceAuthFlowScope
			}
		}

		if loadedConfig.PKCEAuthorizationFlow != nil {
			log.WithContext(ctx).Infof("overriding PKCEAuthorizationFlow.TokenEndpoint with a new value: %s, previously configured value: %s",
				oidcConfig.TokenEndpoint, loadedConfig.PKCEAuthorizationFlow.ProviderConfig.TokenEndpoint)
			loadedConfig.PKCEAuthorizationFlow.ProviderConfig.TokenEndpoint = oidcConfig.TokenEndpoint
			log.WithContext(ctx).Infof("overriding PKCEAuthorizationFlow.AuthorizationEndpoint with a new value: %s, previously configured value: %s",
				oidcConfig.AuthorizationEndpoint, loadedConfig.PKCEAuthorizationFlow.ProviderConfig.AuthorizationEndpoint)
			loadedConfig.PKCEAuthorizationFlow.ProviderConfig.AuthorizationEndpoint = oidcConfig.AuthorizationEndpoint
		}
	}

	if loadedConfig.Relay != nil {
		log.Infof("Relay addresses: %v", loadedConfig.Relay.Addresses)
	}

	return loadedConfig, err
}

// OIDCConfigResponse used for parsing OIDC config response
type OIDCConfigResponse struct {
	Issuer                string `json:"issuer"`
	TokenEndpoint         string `json:"token_endpoint"`
	DeviceAuthEndpoint    string `json:"device_authorization_endpoint"`
	JwksURI               string `json:"jwks_uri"`
	AuthorizationEndpoint string `json:"authorization_endpoint"`
}

// fetchOIDCConfig fetches OIDC configuration from the IDP
func fetchOIDCConfig(ctx context.Context, oidcEndpoint string) (OIDCConfigResponse, error) {
	res, err := http.Get(oidcEndpoint)
	if err != nil {
		return OIDCConfigResponse{}, fmt.Errorf("failed fetching OIDC configuration from endpoint %s %v", oidcEndpoint, err)
	}

	defer func() {
		err := res.Body.Close()
		if err != nil {
			log.WithContext(ctx).Debugf("failed closing response body %v", err)
		}
	}()

	body, err := io.ReadAll(res.Body)
	if err != nil {
		return OIDCConfigResponse{}, fmt.Errorf("failed reading OIDC configuration response body: %v", err)
	}

	if res.StatusCode != 200 {
		return OIDCConfigResponse{}, fmt.Errorf("OIDC configuration request returned status %d with response: %s",
			res.StatusCode, string(body))
	}

	config := OIDCConfigResponse{}
	err = json.Unmarshal(body, &config)
	if err != nil {
		return OIDCConfigResponse{}, fmt.Errorf("failed unmarshaling OIDC configuration response: %v", err)
	}

	return config, nil
}

func handleRebrand(cmd *cobra.Command) error {
	var err error
	if logFile == defaultLogFile {
		if migrateToNetbird(oldDefaultLogFile, defaultLogFile) {
			cmd.Printf("will copy Log dir %s and its content to %s\n", oldDefaultLogDir, defaultLogDir)
			err = cpDir(oldDefaultLogDir, defaultLogDir)
			if err != nil {
				return err
			}
		}
	}
	if nbconfig.MgmtConfigPath == defaultMgmtConfig {
		if migrateToNetbird(oldDefaultMgmtConfig, defaultMgmtConfig) {
			cmd.Printf("will copy Config dir %s and its content to %s\n", oldDefaultMgmtConfigDir, defaultMgmtConfigDir)
			err = cpDir(oldDefaultMgmtConfigDir, defaultMgmtConfigDir)
			if err != nil {
				return err
			}
		}
	}
	if mgmtDataDir == defaultMgmtDataDir {
		if migrateToNetbird(oldDefaultMgmtDataDir, defaultMgmtDataDir) {
			cmd.Printf("will copy Config dir %s and its content to %s\n", oldDefaultMgmtDataDir, defaultMgmtDataDir)
			err = cpDir(oldDefaultMgmtDataDir, defaultMgmtDataDir)
			if err != nil {
				return err
			}
		}
	}
	return nil
}

func cpFile(src, dst string) error {
	var err error
	var srcfd *os.File
	var dstfd *os.File
	var srcinfo os.FileInfo

	if srcfd, err = os.Open(src); err != nil {
		return err
	}
	defer srcfd.Close()

	if dstfd, err = os.Create(dst); err != nil {
		return err
	}
	defer dstfd.Close()

	if _, err = io.Copy(dstfd, srcfd); err != nil {
		return err
	}
	if srcinfo, err = os.Stat(src); err != nil {
		return err
	}
	return os.Chmod(dst, srcinfo.Mode())
}

func copySymLink(source, dest string) error {
	link, err := os.Readlink(source)
	if err != nil {
		return err
	}
	return os.Symlink(link, dest)
}

func cpDir(src string, dst string) error {
	var err error
	var fds []os.DirEntry
	var srcinfo os.FileInfo

	if srcinfo, err = os.Stat(src); err != nil {
		return err
	}

	if err = os.MkdirAll(dst, srcinfo.Mode()); err != nil {
		return err
	}

	if fds, err = os.ReadDir(src); err != nil {
		return err
	}
	for _, fd := range fds {
		srcfp := path.Join(src, fd.Name())
		dstfp := path.Join(dst, fd.Name())

		fileInfo, err := os.Stat(srcfp)
		if err != nil {
			log.Fatalf("Couldn't get fileInfo; %v", err)
		}

		switch fileInfo.Mode() & os.ModeType {
		case os.ModeSymlink:
			if err = copySymLink(srcfp, dstfp); err != nil {
				log.Fatalf("Failed to copy from %s to %s; %v", srcfp, dstfp, err)
			}
		case os.ModeDir:
			if err = cpDir(srcfp, dstfp); err != nil {
				log.Fatalf("Failed to copy from %s to %s; %v", srcfp, dstfp, err)
			}
		default:
			if err = cpFile(srcfp, dstfp); err != nil {
				log.Fatalf("Failed to copy from %s to %s; %v", srcfp, dstfp, err)
			}
		}
	}
	return nil
}

func migrateToNetbird(oldPath, newPath string) bool {
	_, errOld := os.Stat(oldPath)
	_, errNew := os.Stat(newPath)

	if errors.Is(errOld, fs.ErrNotExist) || errNew == nil {
		return false
	}

	return true
}