added the rate limiter - Whoa There, Tiger!

config/config.go

@@ -15,6 +15,7 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
+	"math"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -35,6 +36,9 @@ const AMSTERDAM_COPYRIGHT = "2025-2026"
 // CONFIGFILE_NAME is the name of the standard configuration file.
 const CONFIGFILE_NAME = "amsterdam.yaml"
 
+// epsilon is used in testing if a float value is 0.
+const epsilon = 1e-9
+
 // AmCLI is the command-line interface arguments structure.
 type AmCLI struct {
 	ConfigFile       string `arg:"-C,--config,env:AMSTERDAM_CONFIG" help:"Location of the configuration file."`
@@ -90,6 +94,11 @@ type AmConfig struct {
 		WelcomeTitle          string `yaml:"welcomeTitle"`
 		WelcomeMessage        string `yaml:"welcomeMessage"`
 		TopPostsTitle         string `yaml:"topPostsTitle"`
+		RateLimit             struct {
+			Rate          float64 `yaml:"rate"`
+			Burst         int     `yaml:"burst"`
+			ExpireMinutes int     `yaml:"expireMinutes"`
+		} `yaml:"rateLimit"`
 	} `yaml:"site"`
 	Database struct {
 		Driver string `yaml:"driver"`
@@ -278,6 +287,14 @@ func overlayStructValue(dest, loaded, defaults reflect.Value) {
 			} else {
 				fldDest.Set(fldLoaded)
 			}
+		} else if fldDest.CanFloat() {
+			// float field handling
+			n := fldLoaded.Float()
+			if math.Abs(n) <= epsilon {
+				fldDest.Set(fldDefaults)
+			} else {
+				fldDest.Set(fldLoaded)
+			}
 		} else {
 			// if we see this message, this function needs more work
 			log.Errorf("*** unable to deal with field %s of type %s", structField.Name, typ.Name())