add auth

pkg/auth/cookie.go

@@ -0,0 +1,56 @@
+package auth
+
+import (
+	"net/http"
+	"time"
+)
+
+// CookieName is the single httpOnly cookie that carries the JWT.
+const CookieName = "spsays_auth"
+
+// CookieOptions captures the per-environment knobs for the auth cookie.
+type CookieOptions struct {
+	Domain string // empty in dev; ".prabhupadasays.org" in prod for subdomain sharing
+	Secure bool   // true in production (HTTPS-only)
+}
+
+// Set writes the JWT into a Secure, httpOnly, SameSite=Lax cookie.
+// SameSite=Lax + same-registrable-domain (prabhupadasays.org / api.prabhupadasays.org)
+// is enough for cross-subdomain auth without resorting to SameSite=None.
+func Set(w http.ResponseWriter, token string, expires time.Time, opts CookieOptions) {
+	http.SetCookie(w, &http.Cookie{
+		Name:     CookieName,
+		Value:    token,
+		Path:     "/",
+		Domain:   opts.Domain,
+		Expires:  expires,
+		MaxAge:   int(time.Until(expires).Seconds()),
+		HttpOnly: true,
+		Secure:   opts.Secure,
+		SameSite: http.SameSiteLaxMode,
+	})
+}
+
+// Clear overwrites the auth cookie with an immediately-expired one.
+func Clear(w http.ResponseWriter, opts CookieOptions) {
+	http.SetCookie(w, &http.Cookie{
+		Name:     CookieName,
+		Value:    "",
+		Path:     "/",
+		Domain:   opts.Domain,
+		Expires:  time.Unix(0, 0),
+		MaxAge:   -1,
+		HttpOnly: true,
+		Secure:   opts.Secure,
+		SameSite: http.SameSiteLaxMode,
+	})
+}
+
+// Read pulls the raw JWT out of the request cookie. Returns "" if missing.
+func Read(r *http.Request) string {
+	c, err := r.Cookie(CookieName)
+	if err != nil {
+		return ""
+	}
+	return c.Value
+}

pkg/auth/jwt.go

@@ -0,0 +1,83 @@
+// Package auth provides JWT issuance + verification for the BFF.
+//
+// Tokens carry these claims:
+//
+//	sub  user id (UUID string)
+//	tv   token_version snapshot — middleware rejects if it doesn't match the
+//	     current value on the user row. Bumping the user's token_version
+//	     invalidates every JWT ever issued to that user (used on password
+//	     change and forced logout).
+//	iat  issued-at
+//	exp  expiry
+package auth
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/golang-jwt/jwt/v5"
+)
+
+// Claims is the JWT payload we sign + verify.
+type Claims struct {
+	UserID       string `json:"sub"`
+	TokenVersion int    `json:"tv"`
+	jwt.RegisteredClaims
+}
+
+// Issuer issues and verifies tokens with a single shared HMAC secret.
+type Issuer struct {
+	secret []byte
+	ttl    time.Duration
+}
+
+// NewIssuer returns an Issuer configured with the given HMAC secret and TTL.
+// The TTL is applied to every token issued via Issue().
+func NewIssuer(secret string, ttl time.Duration) *Issuer {
+	return &Issuer{secret: []byte(secret), ttl: ttl}
+}
+
+// Issue mints a signed JWT for the given user.
+func (i *Issuer) Issue(userID string, tokenVersion int) (string, time.Time, error) {
+	exp := time.Now().Add(i.ttl)
+	claims := &Claims{
+		UserID:       userID,
+		TokenVersion: tokenVersion,
+		RegisteredClaims: jwt.RegisteredClaims{
+			IssuedAt:  jwt.NewNumericDate(time.Now()),
+			ExpiresAt: jwt.NewNumericDate(exp),
+		},
+	}
+	tok := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
+	signed, err := tok.SignedString(i.secret)
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("sign jwt: %w", err)
+	}
+	return signed, exp, nil
+}
+
+// ErrInvalidToken is returned by Parse for any verification failure.
+var ErrInvalidToken = errors.New("invalid or expired token")
+
+// Parse validates the token's signature + expiry and returns the claims.
+// Callers must additionally compare claims.TokenVersion against the user's
+// current token_version (the JWT alone can't tell us whether the user has
+// since bumped their version).
+func (i *Issuer) Parse(raw string) (*Claims, error) {
+	claims := &Claims{}
+	tok, err := jwt.ParseWithClaims(raw, claims, func(t *jwt.Token) (any, error) {
+		if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
+			return nil, fmt.Errorf("unexpected signing method: %v", t.Header["alg"])
+		}
+		return i.secret, nil
+	})
+	if err != nil || !tok.Valid {
+		return nil, ErrInvalidToken
+	}
+	return claims, nil
+}
+
+// TTL returns the configured token lifetime. Handlers use it to set cookie
+// Max-Age so the cookie and the JWT expire in lockstep.
+func (i *Issuer) TTL() time.Duration { return i.ttl }

pkg/mailer/mailer.go

@@ -0,0 +1,103 @@
+// Package mailer is a thin SMTP wrapper used by the auth flows.
+//
+// The stdlib `net/smtp` is sufficient for our needs (password reset +
+// email verification — low volume, plain-MIME). We keep one interface
+// (Mailer) so handlers can be tested with an in-memory implementation
+// and so we can swap to a transactional provider later (Resend, SES)
+// without touching the call sites.
+package mailer
+
+import (
+	"fmt"
+	"net/smtp"
+	"strings"
+
+	"go.uber.org/zap"
+)
+
+// Mailer is the small surface auth services depend on.
+type Mailer interface {
+	Send(to, subject, htmlBody string) error
+}
+
+// Config carries the per-environment SMTP knobs.
+type Config struct {
+	Host     string
+	Port     int
+	Username string
+	Password string
+	From     string // "Name <addr@host>" or just "addr@host"
+}
+
+// Configured returns true if enough SMTP creds are present to send mail.
+// Used by the auth service to decide whether to send-or-log.
+func (c Config) Configured() bool { return c.Host != "" && c.From != "" }
+
+// SMTP is the production Mailer. Connects per call (low volume → fine).
+type SMTP struct {
+	cfg    Config
+	logger *zap.Logger
+}
+
+// New returns an SMTP mailer if creds are present, otherwise a NoopLogger
+// that logs the message body to zap (useful in dev — the password-reset
+// link shows up in your server logs).
+func New(cfg Config, logger *zap.Logger) Mailer {
+	if !cfg.Configured() {
+		logger.Warn("SMTP not configured — mailer will log messages instead of sending")
+		return &NoopLogger{logger: logger}
+	}
+	return &SMTP{cfg: cfg, logger: logger}
+}
+
+// Send delivers a single HTML email. Plain-text alternative is omitted —
+// the templates are short and modern clients render HTML fine.
+func (m *SMTP) Send(to, subject, htmlBody string) error {
+	addr := fmt.Sprintf("%s:%d", m.cfg.Host, m.cfg.Port)
+	auth := smtp.PlainAuth("", m.cfg.Username, m.cfg.Password, m.cfg.Host)
+
+	var msg strings.Builder
+	msg.WriteString("From: ")
+	msg.WriteString(m.cfg.From)
+	msg.WriteString("\r\n")
+	msg.WriteString("To: ")
+	msg.WriteString(to)
+	msg.WriteString("\r\n")
+	msg.WriteString("Subject: ")
+	msg.WriteString(subject)
+	msg.WriteString("\r\n")
+	msg.WriteString("MIME-Version: 1.0\r\n")
+	msg.WriteString("Content-Type: text/html; charset=UTF-8\r\n\r\n")
+	msg.WriteString(htmlBody)
+
+	// Most relays on port 587 want STARTTLS + AUTH. Port 465 = implicit TLS,
+	// not handled here — add only if needed.
+	if err := smtp.SendMail(addr, auth, fromAddr(m.cfg.From), []string{to}, []byte(msg.String())); err != nil {
+		return fmt.Errorf("smtp send: %w", err)
+	}
+	return nil
+}
+
+// fromAddr extracts the bare address from a "Name <addr>" string. SendMail's
+// `from` argument is the envelope-from, which must be the bare address.
+func fromAddr(s string) string {
+	if i := strings.LastIndex(s, "<"); i >= 0 {
+		if j := strings.LastIndex(s, ">"); j > i {
+			return s[i+1 : j]
+		}
+	}
+	return s
+}
+
+// NoopLogger satisfies Mailer by writing the message into the application
+// logger. Use it in development so you can copy reset links from the console.
+type NoopLogger struct{ logger *zap.Logger }
+
+func (n *NoopLogger) Send(to, subject, htmlBody string) error {
+	n.logger.Info("📧 mailer (not sent — SMTP unconfigured)",
+		zap.String("to", to),
+		zap.String("subject", subject),
+		zap.String("body", htmlBody))
+	return nil
+}
+