flatrender/services/render/internal/middleware/auth.go

package middleware

import (
	"fmt"
	"net/http"
	"strconv"
	"strings"

	"github.com/flatrender/render-svc/internal/models"
	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v5"
	"github.com/google/uuid"
)

const (
	CtxUserID     = "user_id"
	CtxTenantID   = "tenant_id"
	CtxIsAdmin    = "is_admin"
	CtxRole       = "role"
	CtxMaxRenders = "max_renders"
)

func JWTAuth(secret string) gin.HandlerFunc {
	return func(c *gin.Context) {
		hdr := c.GetHeader("Authorization")
		if !strings.HasPrefix(hdr, "Bearer ") {
			c.AbortWithStatusJSON(http.StatusUnauthorized, models.APIError{Code: "unauthorized", Message: "missing bearer token"})
			return
		}
		tokenStr := hdr[7:]
		token, err := jwt.Parse(tokenStr, func(t *jwt.Token) (interface{}, error) {
			if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
				return nil, jwt.ErrSignatureInvalid
			}
			return []byte(secret), nil
		})
		if err != nil || !token.Valid {
			c.AbortWithStatusJSON(http.StatusUnauthorized, models.APIError{Code: "unauthorized", Message: "invalid token"})
			return
		}
		claims, ok := token.Claims.(jwt.MapClaims)
		if !ok {
			c.AbortWithStatusJSON(http.StatusUnauthorized, models.APIError{Code: "unauthorized", Message: "bad claims"})
			return
		}
		userID, _ := uuid.Parse(fmt.Sprintf("%v", claims["sub"]))
		tenantID, _ := uuid.Parse(fmt.Sprintf("%v", claims["tenant_id"]))
		// is_admin may arrive as a JSON bool or as the string "true" (identity emits a
		// string). Accept both so [RequireAdmin] works regardless of token encoding.
		isAdmin := false
		switch v := claims["is_admin"].(type) {
		case bool:
			isAdmin = v
		case string:
			isAdmin = v == "true"
		}
		role, _ := claims["role"].(string)

		// max_renders: concurrent-render ceiling. Identity emits it as a string;
		// also accept a JSON number. Default 1 when absent/unparseable.
		maxRenders := 1
		switch v := claims["max_renders"].(type) {
		case string:
			if n, err := strconv.Atoi(v); err == nil && n > 0 {
				maxRenders = n
			}
		case float64:
			if v >= 1 {
				maxRenders = int(v)
			}
		}

		c.Set(CtxUserID, userID)
		c.Set(CtxTenantID, tenantID)
		c.Set(CtxIsAdmin, isAdmin)
		c.Set(CtxRole, role)
		c.Set(CtxMaxRenders, maxRenders)
		c.Next()
	}
}

func RequireAdmin() gin.HandlerFunc {
	return func(c *gin.Context) {
		isAdmin, _ := c.Get(CtxIsAdmin)
		b, _ := isAdmin.(bool)
		if !b {
			c.AbortWithStatusJSON(http.StatusForbidden, models.APIError{Code: "forbidden", Message: "admin required"})
			return
		}
		c.Next()
	}
}

// RequireServiceRole allows callers presenting a token with role="Service"
func RequireServiceRole() gin.HandlerFunc {
	return func(c *gin.Context) {
		role, _ := c.Get(CtxRole)
		isAdmin, _ := c.Get(CtxIsAdmin)
		b, _ := isAdmin.(bool)
		if role != "Service" && !b {
			c.AbortWithStatusJSON(http.StatusForbidden, models.APIError{Code: "forbidden", Message: "service role required"})
			return
		}
		c.Next()
	}
}

// NodeHMAC verifies the X-Node-Signature header for node-agent calls
func NodeHMAC(nodeSecret string) gin.HandlerFunc {
	return func(c *gin.Context) {
		sig := c.GetHeader("X-Node-Signature")
		if sig == "" || sig != nodeSecret {
			c.AbortWithStatusJSON(http.StatusUnauthorized, models.APIError{Code: "unauthorized", Message: "invalid node signature"})
			return
		}
		c.Next()
	}
}

func GetUserID(c *gin.Context) uuid.UUID {
	v, _ := c.Get(CtxUserID)
	id, _ := v.(uuid.UUID)
	return id
}

func GetTenantID(c *gin.Context) uuid.UUID {
	v, _ := c.Get(CtxTenantID)
	id, _ := v.(uuid.UUID)
	return id
}

// GetMaxRenders returns the user's concurrent-render ceiling (default 1).
func GetMaxRenders(c *gin.Context) int {
	v, ok := c.Get(CtxMaxRenders)
	if !ok {
		return 1
	}
	n, _ := v.(int)
	if n < 1 {
		return 1
	}
	return n
}