food-ai/backend/internal/infra/middleware/auth.go

package middleware

import (
	"context"
	"net/http"
	"strings"
)

const (
	userIDKey   contextKey = "user_id"
	userPlanKey contextKey = "user_plan"
)

// TokenClaims represents the result of validating an access token.
type TokenClaims struct {
	UserID string
	Plan   string
}

// AccessTokenValidator validates JWT access tokens.
type AccessTokenValidator interface {
	ValidateAccessToken(tokenStr string) (*TokenClaims, error)
}

func Auth(validator AccessTokenValidator) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			header := r.Header.Get("Authorization")
			if !strings.HasPrefix(header, "Bearer ") {
				http.Error(w, `{"error":"unauthorized"}`, http.StatusUnauthorized)
				return
			}

			tokenStr := strings.TrimPrefix(header, "Bearer ")
			claims, err := validator.ValidateAccessToken(tokenStr)
			if err != nil {
				http.Error(w, `{"error":"invalid token"}`, http.StatusUnauthorized)
				return
			}

			ctx := context.WithValue(r.Context(), userIDKey, claims.UserID)
			ctx = context.WithValue(ctx, userPlanKey, claims.Plan)
			next.ServeHTTP(w, r.WithContext(ctx))
		})
	}
}

func UserIDFromCtx(ctx context.Context) string {
	id, _ := ctx.Value(userIDKey).(string)
	return id
}

func UserPlanFromCtx(ctx context.Context) string {
	plan, _ := ctx.Value(userPlanKey).(string)
	return plan
}