Add ability to debug to file

Author: mjarkk

README.md

@@ -199,7 +199,7 @@ Ok Response
 {"type":"pong"}
 ```
 
-## How to develop
+## How to develop / Debug
 
 ```sh
 # After a change update the binary in your path using:
@@ -212,12 +212,21 @@ go run .
 
 Debug data send by scraper to this program
 ```sh
+# Logs the IO to scraper_client_input.log
 export LOG_SCRAPER_CLIENT_INPUT=true
+
+# Logs the debug messages to scraper_client.log
+export ENABLE_SCRAPER_CLIENT_LOG=true
+
 # Now run your scraper
 go run .
 
 # Now all messages written to this program are also written to scraper_client_input.log
-# You can follow the input by tailing the file:
+# You can follow the input by tailing the file in a new terminal:
+tail -f scraper_client_input.log
+
+# All debug messages are now visible in scraper_client.log
+# You can follow the input by tailing the file in a new terminal:
 tail -f scraper_client_input.log
 
 # After collecting the input data you can also use rtcv_scraper_client to replay sending the data
@@ -230,6 +239,7 @@ rtcv_scraper_client \
     -replaySkipCommands has_cached_reference,set_cached_reference,ping,get_users_secret
 ```
 
+
 ## How to ship?
 
 Currently we don't have pre build binaries so you'll need to compile the binary yourself

logger.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+)
+
+const logfileName = "scraper_client.log"
+
+func openLogFile() (*os.File, error) {
+	return os.OpenFile(logfileName, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+}
+
+var truthyStringValues = map[string]bool{
+	"1":    true,
+	"t":    true,
+	"true": true,
+}
+
+var logFileEnabled = truthyStringValues[strings.ToLower(os.Getenv("ENABLE_SCRAPER_CLIENT_LOG"))]
+
+// DebugToLogfile appends a new debug line to the logfile
+func DebugToLogfile(a ...interface{}) {
+	if !logFileEnabled {
+		return
+	}
+
+	f, err := openLogFile()
+	if err != nil {
+		if !errors.Is(err, os.ErrNotExist) {
+			return
+		}
+		_, err = os.Create(logfileName)
+		if err != nil {
+			return
+		}
+		f, err = openLogFile()
+		if err != nil {
+			return
+		}
+	}
+
+	f.WriteString(fmt.Sprintln(a...))
+	f.Close()
+}

main.go

@@ -89,11 +89,7 @@ func main() {
 
 	api := NewAPI()
 
-	logInput := map[string]bool{
-		"1":    true,
-		"t":    true,
-		"true": true,
-	}[strings.ToLower(os.Getenv("LOG_SCRAPER_CLIENT_INPUT"))]
+	logInput := truthyStringValues[strings.ToLower(os.Getenv("LOG_SCRAPER_CLIENT_INPUT"))]
 
 	var logInputFile *os.File
 	var err error
@@ -226,6 +222,8 @@ func LoopAction(api *API, inputJSON string) (msgType MessageType, msgContent int
 			return returnErr(err)
 		}
 
+		DebugToLogfile(referenceNrs)
+
 		now := time.Now()
 		for _, nr := range referenceNrs {
 			api.Cache[nr] = now
@@ -335,7 +333,10 @@ func LoopAction(api *API, inputJSON string) (msgType MessageType, msgContent int
 			return MessageTypeOk, nil
 		}
 
-		return MessageTypeOk, api.CacheEntryExists(referenceNr)
+		hasCachedReference := api.CacheEntryExists(referenceNr)
+		DebugToLogfile("has_cached_reference", referenceNr, ">", hasCachedReference)
+
+		return MessageTypeOk, hasCachedReference
 	case "ping":
 		return MessageTypePong, nil
 	default: