cli/actions/auth.go

package actions

import (
	"bufio"
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"syscall"
	"time"

	"git.t-juice.club/microfilm/auth"
	"github.com/golang-jwt/jwt/v5"
	"github.com/jedib0t/go-pretty/v6/table"
	"github.com/urfave/cli/v2"
	"golang.org/x/term"
)

func Login(cCtx *cli.Context) error {
	username, password, err := getCreds()
	if err != nil {
		return err
	}

	ctx, cancel := context.WithTimeout(cCtx.Context, 15*time.Second)
	defer cancel()

	body := jsonToReader(&auth.TokenRequest{
		Password: password,
	})

	url := fmt.Sprintf("http://localhost:8085/auth/%s/token", username)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, body)
	if err != nil {
		return err
	}

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		if resp.StatusCode == http.StatusUnauthorized {
			return fmt.Errorf("Invalid username/password.")
		}

		var errData auth.ErrorResponse
		decoder := json.NewDecoder(resp.Body)
		if err := decoder.Decode(&errData); err != nil {
			return fmt.Errorf("unable to decode error: %w", err)
		}

		return fmt.Errorf("error %d when authenticating: %s", errData.Status, errData.Message)
	}

	var responseData auth.TokenResponse

	decoder := json.NewDecoder(resp.Body)
	if err := decoder.Decode(&responseData); err != nil {
		return err
	}

	if err := SaveToken(responseData.Token); err != nil {
		return err
	}

	if cCtx.Bool("claims") {
		claims, err := ClaimsFromToken(responseData.Token)
		if err != nil {
			return err
		}
		printClaims(claims)

	}

	return nil
}

func getCreds() (string, string, error) {
	reader := bufio.NewReader(os.Stdin)

	fmt.Print("Enter Username: ")
	username, err := reader.ReadString('\n')
	if err != nil {
		return "", "", err
	}

	fmt.Print("Enter Password: ")
	bytePassword, err := term.ReadPassword(int(syscall.Stdin))
	if err != nil {
		return "", "", err
	}

	password := string(bytePassword)
	fmt.Printf("\n")
	return strings.TrimSpace(username), strings.TrimSpace(password), nil
}

func jsonToReader(data any) io.Reader {
	var buf bytes.Buffer
	encoder := json.NewEncoder(&buf)
	if err := encoder.Encode(data); err != nil {
		panic(err)
	}

	return &buf
}

func SaveToken(token string) error {
	configBaseDir, err := os.UserCacheDir()
	if err != nil {
		return err
	}
	configDir := filepath.Join(configBaseDir, "microfilm")
	if err := os.MkdirAll(configDir, os.ModePerm); err != nil {
		return err
	}

	configFilePath := filepath.Join(configDir, "token.json")

	f, err := os.Create(configFilePath)
	if err != nil {
		return err
	}
	defer f.Close()

	encoder := json.NewEncoder(f)
	if err := encoder.Encode(token); err != nil {
		return err
	}

	return nil
}

func LoadToken() (string, error) {
	configBaseDir, err := os.UserCacheDir()
	if err != nil {
		return "", err
	}
	configFilePath := filepath.Join(configBaseDir, "microfilm", "token.json")

	f, err := os.Open(configFilePath)
	if err != nil {
		return "", err
	}
	defer f.Close()

	var token string
	decoder := json.NewDecoder(f)
	if err := decoder.Decode(&token); err != nil {
		return "", err
	}

	return token, nil
}

func ClaimsFromToken(tokenString string) (*auth.MicrofilmClaims, error) {
	parser := jwt.NewParser()
	token, _, err := parser.ParseUnverified(tokenString, &auth.MicrofilmClaims{})
	if err != nil {
		return nil, err
	}

	claims := token.Claims.(*auth.MicrofilmClaims)
	return claims, nil
}

func claimsToMap(claims *auth.MicrofilmClaims) map[string]string {
	m := make(map[string]string)

	m["role"] = claims.Role
	m["sub"] = claims.Subject
	m["aud"] = strings.Join(claims.Audience, ",")
	m["jti"] = claims.ID
	m["iat"] = claims.IssuedAt.String()
	m["nbf"] = claims.NotBefore.String()
	m["exp"] = claims.ExpiresAt.String()
	m["iss"] = claims.Issuer

	return m
}

func printClaims(claims *auth.MicrofilmClaims) {
	tw := table.NewWriter()

	tw.AppendHeader(table.Row{"Field", "Value"})
	for k, v := range claimsToMap(claims) {
		tw.AppendRow(table.Row{k, v})
	}

	fmt.Println(tw.Render())
}