Crussell/backend/mw/auth.go

package mw

import (
	"context"
	"log"
	"net/http"
	"slices"
	"strings"

	"crussell/auth"
)

type contextKey string

const (
	UserIDKey   contextKey = "user_id"
	UserRoleKey contextKey = "user_role"
	JTIKey      contextKey = "jti"
)

// RequireAuth middleware - validates JWT and adds user info to context
func RequireAuth(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		authHeader := r.Header.Get("Authorization")
		if authHeader == "" || !strings.HasPrefix(authHeader, "Bearer ") {
			http.Error(w, "missing or invalid authorization header", http.StatusUnauthorized)
			return
		}

		tokenString := strings.TrimPrefix(authHeader, "Bearer ")

		userID, role, jti, err := auth.VerifyToken(tokenString, r.Context())
		if err != nil {
			http.Error(w, "invalid token", http.StatusUnauthorized)
			return
		}

		// Add user info and JTI to context
		ctx := context.WithValue(r.Context(), UserIDKey, userID)
		ctx = context.WithValue(ctx, UserRoleKey, role)
		ctx = context.WithValue(ctx, JTIKey, jti)

		next.ServeHTTP(w, r.WithContext(ctx))
	})
}

// OptionalAuth middleware - extracts user info if token present, otherwise passes through
func OptionalAuth(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		authHeader := r.Header.Get("Authorization")
		if authHeader != "" && strings.HasPrefix(authHeader, "Bearer ") {
			tokenString := strings.TrimPrefix(authHeader, "Bearer ")

			userID, role, jti, err := auth.VerifyToken(tokenString, r.Context())
			if err != nil {
				log.Printf("OptionalAuth: invalid token: %v", err)
			} else {
				ctx := context.WithValue(r.Context(), UserIDKey, userID)
				ctx = context.WithValue(ctx, UserRoleKey, role)
				ctx = context.WithValue(ctx, JTIKey, jti)
				next.ServeHTTP(w, r.WithContext(ctx))
				return
			}
		}

		next.ServeHTTP(w, r)
	})
}

// RequireRole middleware - checks if user has required role(s)
func RequireRole(allowedRoles ...string) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			role, ok := r.Context().Value(UserRoleKey).(string)
			if !ok {
				http.Error(w, "unauthorized", http.StatusUnauthorized)
				return
			}

			// Check if user has one of the allowed roles
			hasRole := slices.Contains(allowedRoles, role)

			if !hasRole {
				http.Error(w, "forbidden", http.StatusForbidden)
				return
			}

			next.ServeHTTP(w, r)
		})
	}
}

// RequireVerified middleware - only allows verified_email and admin
func RequireVerified(next http.Handler) http.Handler {
	return RequireRole("verified_email", "admin")(next)
}

// RequireAdmin middleware - only allows admin and validates the user ID is present
// in context, so handlers don't need to re-check. The user ID is always set by
// RequireAuth before this runs, but this adds a defensive safety net.
func RequireAdmin(next http.Handler) http.Handler {
	return RequireRole("admin")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		uid, ok := r.Context().Value(UserIDKey).(string)
		if !ok || uid == "" {
			http.Error(w, "Authentication required", http.StatusUnauthorized)
			return
		}
		next.ServeHTTP(w, r)
	}))
}

// Helper functions to get user info from context
func GetUserID(ctx context.Context) (string, bool) {
	userID, ok := ctx.Value(UserIDKey).(string)
	return userID, ok
}

func GetUserRole(ctx context.Context) (string, bool) {
	role, ok := ctx.Value(UserRoleKey).(string)
	return role, ok
}

func GetJTI(ctx context.Context) (string, bool) {
	jti, ok := ctx.Value(JTIKey).(string)
	return jti, ok
}