extract method PositiveIntParamStrict()

mikebd · Oct 9, 2023 · 989f151 · 989f151
1 parent 9ab2887
commit 989f151
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Showing 2 changed files with 34 additions and 20 deletions.
diff --git a/controller/rest/util/param.go b/controller/rest/util/param.go
@@ -0,0 +1,23 @@
+package util
+
+import (
+	"fmt"
+	"net/http"
+	"strconv"
+)
+
+// PositiveIntParamStrict returns the value of the parameter as an int (>= 0), or the default value if the parameter is not present
+func PositiveIntParamStrict(w http.ResponseWriter, r *http.Request, defaultValue int, param string) (int, error) {
+	paramValue := r.URL.Query().Get(param)
+	if paramValue == "" {
+		return defaultValue, nil
+	}
+
+	intParam, err := strconv.Atoi(paramValue)
+	if intParam < 0 || err != nil {
+		RenderTextPlain(w, nil, fmt.Errorf("invalid value for parameter '%s': '%s'", param, paramValue))
+		return 0, err
+	}
+
+	return intParam, nil
+}
diff --git a/controller/rest/v1/logs.go b/controller/rest/v1/logs.go
@@ -1,15 +1,13 @@
 package v1
 
 import (
-	"fmt"
 	"github.com/julienschmidt/httprouter"
 	"go-read-var-log/config"
 	"go-read-var-log/controller/rest/util"
 	"go-read-var-log/service"
 	"log"
 	"net/http"
 	"slices"
-	"strconv"
 	"time"
 )
 
@@ -29,24 +27,17 @@ func GetLog(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
 
 	logFilename := p.ByName("log")
 
-	maxLines := config.GetArguments().NumberOfLogLines
-	maxLinesParam := r.URL.Query().Get("n")
-	if maxLinesParam != "" {
-		intParam, err := strconv.Atoi(maxLinesParam)
-		if err == nil && intParam > 0 {
-			maxLines = intParam
-		} else {
-			util.RenderTextPlain(w, nil, fmt.Errorf("invalid value for parameter 'n': '%s'", maxLinesParam))
-			return
-		}
-	}
-
-	logEvents, err := service.GetLog(config.LogDirectory, logFilename, maxLines)
+	maxLines, _ := util.PositiveIntParamStrict(w, r, config.GetArguments().NumberOfLogLines, "n")
+	if maxLines > 0 {
+		logEvents, err := service.GetLog(config.LogDirectory, logFilename, maxLines)
 
-	// Reverse the slice - we want the most recent events first.
-	// Tests to see if this is slower than just iterating backwards when rendering
-	// showed that it was not.  This is easier to read for maintainability.
-	slices.Reverse(logEvents)
+		if err == nil {
+			// Reverse the slice - we want the most recent events first.
+			// Tests to see if this is slower than just iterating backwards when rendering
+			// showed that it was not.  This is easier to read for maintainability.
+			slices.Reverse(logEvents)
+		}
 
-	util.RenderTextPlain(w, logEvents, err)
+		util.RenderTextPlain(w, logEvents, err)
+	}
 }