package auth

import (
	"bufio"
	"context"
	"fmt"
	"os"
	"strings"

	"github.com/containers/image/v5/docker"
	"github.com/containers/image/v5/pkg/docker/config"
	"github.com/containers/image/v5/pkg/sysregistriesv2"
	"github.com/containers/image/v5/types"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
	"golang.org/x/crypto/ssh/terminal"
)

// GetDefaultAuthFile returns env value REGISTRY_AUTH_FILE as default
// --authfile path used in multiple --authfile flag definitions
// Will fail over to DOCKER_CONFIG if REGISTRY_AUTH_FILE environment is not set
func GetDefaultAuthFile() string {
	authfile := os.Getenv("REGISTRY_AUTH_FILE")
	if authfile == "" {
		if authfile, ok := os.LookupEnv("DOCKER_CONFIG"); ok {
			logrus.Infof("Using DOCKER_CONFIG environment variable for authfile path %s", authfile)
		}
	}
	return authfile
}

// CheckAuthFile validates filepath given by --authfile
// used by command has --authfile flag
func CheckAuthFile(authfile string) error {
	if authfile == "" {
		return nil
	}
	if _, err := os.Stat(authfile); err != nil {
		return errors.Wrapf(err, "error checking authfile path %s", authfile)
	}
	return nil
}

// systemContextWithOptions returns a version of sys
// updated with authFile and certDir values (if they are not "").
// NOTE: this is a shallow copy that can be used and updated, but may share
// data with the original parameter.
func systemContextWithOptions(sys *types.SystemContext, authFile, certDir string) *types.SystemContext {
	if sys != nil {
		sysCopy := *sys
		sys = &sysCopy
	} else {
		sys = &types.SystemContext{}
	}

	if authFile != "" {
		sys.AuthFilePath = authFile
	}
	if certDir != "" {
		sys.DockerCertPath = certDir
	}
	return sys
}

// Login implements a “log in” command with the provided opts and args
// reading the password from opts.Stdin or the options in opts.
func Login(ctx context.Context, systemContext *types.SystemContext, opts *LoginOptions, args []string) error {
	systemContext = systemContextWithOptions(systemContext, opts.AuthFile, opts.CertDir)

	var (
		server string
		err    error
	)
	if len(args) > 1 {
		return errors.Errorf("login accepts only one registry to login to")
	}
	if len(args) == 0 {
		if !opts.AcceptUnspecifiedRegistry {
			return errors.Errorf("please provide a registry to login to")
		}
		if server, err = defaultRegistryWhenUnspecified(systemContext); err != nil {
			return err
		}
		logrus.Debugf("registry not specified, default to the first registry %q from registries.conf", server)
	} else {
		server = getRegistryName(args[0])
	}
	authConfig, err := config.GetCredentials(systemContext, server)
	if err != nil {
		return errors.Wrapf(err, "error reading auth file")
	}
	if opts.GetLoginSet {
		if authConfig.Username == "" {
			return errors.Errorf("not logged into %s", server)
		}
		fmt.Fprintf(opts.Stdout, "%s\n", authConfig.Username)
		return nil
	}
	if authConfig.IdentityToken != "" {
		return errors.Errorf("currently logged in, auth file contains an Identity token")
	}

	password := opts.Password
	if opts.StdinPassword {
		var stdinPasswordStrBuilder strings.Builder
		if opts.Password != "" {
			return errors.Errorf("Can't specify both --password-stdin and --password")
		}
		if opts.Username == "" {
			return errors.Errorf("Must provide --username with --password-stdin")
		}
		scanner := bufio.NewScanner(opts.Stdin)
		for scanner.Scan() {
			fmt.Fprint(&stdinPasswordStrBuilder, scanner.Text())
		}
		password = stdinPasswordStrBuilder.String()
	}

	// If no username and no password is specified, try to use existing ones.
	if opts.Username == "" && password == "" && authConfig.Username != "" && authConfig.Password != "" {
		fmt.Println("Authenticating with existing credentials...")
		if err := docker.CheckAuth(ctx, systemContext, authConfig.Username, authConfig.Password, server); err == nil {
			fmt.Fprintln(opts.Stdout, "Existing credentials are valid. Already logged in to", server)
			return nil
		}
		fmt.Fprintln(opts.Stdout, "Existing credentials are invalid, please enter valid username and password")
	}

	username, password, err := getUserAndPass(opts, password, authConfig.Username)
	if err != nil {
		return errors.Wrapf(err, "error getting username and password")
	}

	if err = docker.CheckAuth(ctx, systemContext, username, password, server); err == nil {
		// Write the new credentials to the authfile
		if err := config.SetAuthentication(systemContext, server, username, password); err != nil {
			return err
		}
	}
	if err == nil {
		fmt.Fprintln(opts.Stdout, "Login Succeeded!")
		return nil
	}
	if unauthorized, ok := err.(docker.ErrUnauthorizedForCredentials); ok {
		logrus.Debugf("error logging into %q: %v", server, unauthorized)
		return errors.Errorf("error logging into %q: invalid username/password", server)
	}
	return errors.Wrapf(err, "error authenticating creds for %q", server)
}

// getRegistryName scrubs and parses the input to get the server name
func getRegistryName(server string) string {
	// removes 'http://' or 'https://' from the front of the
	// server/registry string if either is there.  This will be mostly used
	// for user input from 'Buildah login' and 'Buildah logout'.
	server = strings.TrimPrefix(strings.TrimPrefix(server, "https://"), "http://")
	// gets the registry from the input. If the input is of the form
	// quay.io/myuser/myimage, it will parse it and just return quay.io
	split := strings.Split(server, "/")
	return split[0]
}

// getUserAndPass gets the username and password from STDIN if not given
// using the -u and -p flags.  If the username prompt is left empty, the
// displayed userFromAuthFile will be used instead.
func getUserAndPass(opts *LoginOptions, password, userFromAuthFile string) (user, pass string, err error) {
	reader := bufio.NewReader(opts.Stdin)
	username := opts.Username
	if username == "" {
		if userFromAuthFile != "" {
			fmt.Fprintf(opts.Stdout, "Username (%s): ", userFromAuthFile)
		} else {
			fmt.Fprint(opts.Stdout, "Username: ")
		}
		username, err = reader.ReadString('\n')
		if err != nil {
			return "", "", errors.Wrapf(err, "error reading username")
		}
		// If the user just hit enter, use the displayed user from the
		// the authentication file.  This allows to do a lazy
		// `$ buildah login -p $NEW_PASSWORD` without specifying the
		// user.
		if strings.TrimSpace(username) == "" {
			username = userFromAuthFile
		}
	}
	if password == "" {
		fmt.Fprint(opts.Stdout, "Password: ")
		pass, err := terminal.ReadPassword(0)
		if err != nil {
			return "", "", errors.Wrapf(err, "error reading password")
		}
		password = string(pass)
		fmt.Fprintln(opts.Stdout)
	}
	return strings.TrimSpace(username), password, err
}

// Logout implements a “log out” command with the provided opts and args
func Logout(systemContext *types.SystemContext, opts *LogoutOptions, args []string) error {
	if err := CheckAuthFile(opts.AuthFile); err != nil {
		return err
	}
	systemContext = systemContextWithOptions(systemContext, opts.AuthFile, "")

	var (
		server string
		err    error
	)
	if len(args) > 1 {
		return errors.Errorf("logout accepts only one registry to logout from")
	}
	if len(args) == 0 && !opts.All {
		if !opts.AcceptUnspecifiedRegistry {
			return errors.Errorf("please provide a registry to logout from")
		}
		if server, err = defaultRegistryWhenUnspecified(systemContext); err != nil {
			return err
		}
		logrus.Debugf("registry not specified, default to the first registry %q from registries.conf", server)
	}
	if len(args) != 0 {
		if opts.All {
			return errors.Errorf("--all takes no arguments")
		}
		server = getRegistryName(args[0])
	}

	if opts.All {
		if err := config.RemoveAllAuthentication(systemContext); err != nil {
			return err
		}
		fmt.Fprintln(opts.Stdout, "Removed login credentials for all registries")
		return nil
	}

	err = config.RemoveAuthentication(systemContext, server)
	switch errors.Cause(err) {
	case nil:
		fmt.Fprintf(opts.Stdout, "Removed login credentials for %s\n", server)
		return nil
	case config.ErrNotLoggedIn:
		authConfig, err := config.GetCredentials(systemContext, server)
		if err != nil {
			return errors.Wrapf(err, "error reading auth file")
		}
		authInvalid := docker.CheckAuth(context.Background(), systemContext, authConfig.Username, authConfig.Password, server)
		if authConfig.Username != "" && authConfig.Password != "" && authInvalid == nil {
			fmt.Printf("Not logged into %s with current tool. Existing credentials were established via docker login. Please use docker logout instead.\n", server)
			return nil
		}
		return errors.Errorf("Not logged into %s\n", server)
	default:
		return errors.Wrapf(err, "error logging out of %q", server)
	}
}

// defaultRegistryWhenUnspecified returns first registry from search list of registry.conf
// used by login/logout when registry argument is not specified
func defaultRegistryWhenUnspecified(systemContext *types.SystemContext) (string, error) {
	registriesFromFile, err := sysregistriesv2.UnqualifiedSearchRegistries(systemContext)
	if err != nil {
		return "", errors.Wrapf(err, "error getting registry from registry.conf, please specify a registry")
	}
	if len(registriesFromFile) == 0 {
		return "", errors.Errorf("no registries found in registries.conf, a registry must be provided")
	}
	return registriesFromFile[0], nil
}