Add admin config page and runtime-tunable upload/rate-limit settings

internal/file/handlers.go

@@ -1,6 +1,7 @@
 package file
 
 import (
+	"ResendIt/internal/config"
 	"ResendIt/internal/util"
 	"fmt"
 	"net/http"
@@ -12,11 +13,19 @@ import (
 )
 
 type Handler struct {
-	service *Service
+	service       *Service
+	configService ConfigService
 }
 
-func NewHandler(s *Service) *Handler {
-	return &Handler{service: s}
+// ConfigService is the small interface we need from the config package.
+// Keeping it as an interface avoids import cycles and keeps file.Handler easy to test.
+type ConfigService interface {
+	GetIntDefault(key string, def int) int
+	GetInt64Default(key string, def int64) int64
+}
+
+func NewHandler(s *Service, cfg ConfigService) *Handler {
+	return &Handler{service: s, configService: cfg}
 }
 
 func (h *Handler) Upload(c *gin.Context) {
@@ -32,6 +41,12 @@ func (h *Handler) Upload(c *gin.Context) {
 		return
 	}
 
+	maxSize := h.configService.GetInt64Default(config.KeyUploadMaxFileSizeBytes, config.DefaultUploadMaxFileSizeBytes)
+	if file.Size > maxSize {
+		c.JSON(http.StatusRequestEntityTooLarge, gin.H{"error": "file too large"})
+		return
+	}
+
 	f, err := file.Open()
 	if err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "cannot open file"})
@@ -46,6 +61,10 @@ func (h *Handler) Upload(c *gin.Context) {
 	if err != nil || hours <= 0 {
 		hours = 24 // default
 	}
+	maxHours := h.configService.GetIntDefault(config.KeyUploadMaxHours, config.DefaultUploadMaxHours)
+	if hours > maxHours {
+		hours = maxHours
+	}
 
 	duration := time.Duration(hours) * time.Hour