Implemented proper logging and added more log messages

README.md

@@ -31,11 +31,12 @@ Example:
 ```json
 {
   "api_fetch_interval": 600,
+  "datafile": "data",
   "enabled_api_endpoints": [
     "bay",
     "bund"
   ],
-  "datafile": "data",
+  "loglevel": 2,
   "recipients": [
     {
       "address": "guenther@example.org",
@@ -59,6 +60,8 @@ Example:
 }
 ```
 
+To show debug messages, set the `loglevel` to `3`.
+
 ## Filters
 
 You define filters for notices to be sent per recipient. Multiple filters can be set per recipient and multiple criteria can be used per filter. The configuration field for those filters is `include`. See [Configuration](#configuration) for an example.

datastore.go

@@ -5,7 +5,6 @@ package main
 import (
 	"encoding/json"
 	"errors"
-	"fmt"
 	"io/fs"
 	"os"
 	"time"
@@ -15,6 +14,7 @@ type Config struct {
 	ApiFetchInterval int `json:"api_fetch_interval"` // in seconds
 	EnabledApiEndpoints []string `json:"enabled_api_endpoints"`
 	PersistentDataFilePath string `json:"datafile"`
+	LogLevel int `json:"loglevel"`
 	Recipients []Recipient `json:"recipients"`
 	SmtpConfiguration SmtpSettings `json:"smtp"`
 	Template MailTemplateConfig `json:"template"`
@@ -26,6 +26,7 @@ func NewConfig() Config {
 		ApiFetchInterval: 60 * 10, // every 10 minutes,
 		EnabledApiEndpoints: []string{"bay", "bund"},
 		PersistentDataFilePath: "data",
+		LogLevel: 2,
 		Recipients: []Recipient{},
 		SmtpConfiguration: SmtpSettings{
 			From: "from@example.org",
@@ -43,21 +44,21 @@ func NewConfig() Config {
 
 func checkConfig(config Config) {
 	if len(config.Recipients) < 1 {
-		fmt.Println("ERROR\tConfiguration is incomplete.")
+		logger.error("Configuration is incomplete")
 		panic(errors.New("no recipients are configured"))
 	}
 	for _, r := range config.Recipients {
 		if !mailAddressIsValid(r.Address) {
-			fmt.Println("ERROR\tConfiguration includes invalid data.")
+			logger.error("Configuration includes invalid data")
 			panic(errors.New("'" + r.Address + "' is not a valid e-mail address"))
 		}
 		if len(r.Filters) < 1 {
-			fmt.Println("ERROR\tConfiguration is incomplete.")
+			logger.error("Configuration is incomplete")
 			panic(errors.New("recipient " + r.Address + " has no filter defined - at least {'any': true/false} should be configured"))
 		}
 	}
 	if !mailAddressIsValid(config.SmtpConfiguration.From) {
-		fmt.Println("ERROR\tConfiguration includes invalid data.")
+		logger.error("Configuration includes invalid data")
 		panic(errors.New("'" + config.SmtpConfiguration.From + "' is not a valid e-mail address"))
 	}
 }

logging.go

@@ -0,0 +1,48 @@
+// Copyright (c) 2023 Julian Müller (ChaoticByte)
+
+package main
+
+import (
+	"log"
+	"os"
+)
+
+type Logger struct {
+	LogLevel int
+	ErrorLogger *log.Logger		// 0
+	WarningLogger *log.Logger	// 1
+	InfoLogger *log.Logger		// 2
+	DebugLogger *log.Logger		// 3
+}
+
+func (l *Logger) error(msg any) {
+	l.ErrorLogger.Println(msg)
+}
+
+func (l *Logger) warn(msg any) {
+	if l.LogLevel >= 1 {
+		l.WarningLogger.Println(msg)
+	}
+}
+
+func (l *Logger) info(msg any) {
+	if l.LogLevel >= 2 {
+		l.InfoLogger.Println(msg)
+	}
+}
+
+func (l *Logger) debug(msg any) {
+	if l.LogLevel >= 3 {
+		l.DebugLogger.Println(msg)
+	}
+}
+
+func NewLogger(loglevel int) Logger {
+	l := Logger{}
+	l.LogLevel = loglevel
+	l.ErrorLogger 	= log.New(os.Stderr, "ERROR ", log.Ldate|log.Ltime|log.Lmicroseconds|log.Lshortfile)
+	l.WarningLogger = log.New(os.Stderr, "WARN  ", log.Ldate|log.Ltime|log.Lmicroseconds|log.Lshortfile)
+	l.InfoLogger 	= log.New(os.Stderr, "INFO  ", log.Ldate|log.Ltime|log.Lmicroseconds)
+	l.DebugLogger 	= log.New(os.Stderr, "DEBUG ", log.Ldate|log.Ltime|log.Lmicroseconds)
+	return l
+}

mail.go

@@ -64,11 +64,13 @@ func (r Recipient) filterAndSendNotices(notices []WidNotice, template MailTempla
 		}
 	}
 	slices.Reverse(filteredNotices)
+	logger.debug(fmt.Sprintf("Including %v of %v notices for recipient %v", len(filteredNotices), len(notices), r.Address))
+	logger.debug("Templating and sending mails for recipient " + r.Address + " ...")
 	for _, n := range filteredNotices {
 		mailContent, err := template.generate(n)
 		if err != nil {
-			fmt.Println("ERROR\tCould not create mail from template.")
+			logger.error("Could not create mail from template")
-			fmt.Println(err)
+			logger.error(err)
 		}
 		// serialize & send mail
 		data := mailContent.serializeValidMail(smtpConfig.From, r.Address)
@@ -82,8 +84,8 @@ func (r Recipient) filterAndSendNotices(notices []WidNotice, template MailTempla
 		if err != nil {
 			return err
 		}
-		// fmt.Printf("%v", strings.ReplaceAll(string(data), "\r", "\\r"))
 	}
+	logger.debug("Sent all mails for recipient " + r.Address)
 	return nil
 }
 

main.go

@@ -9,6 +9,8 @@ import (
 	"time"
 )
 
+var logger Logger
+
 func main() {
 	// get cli arguments
 	args := os.Args
@@ -17,8 +19,11 @@ func main() {
 		os.Exit(1)
 	}
 	configFilePath := os.Args[1]
+	// create logger
+	logger = NewLogger(2)
 	// init
-	println("INFO\tInitializing ...")
+	logger.info("Initializing ...")
+	defer logger.info("Exiting ...")
 	config := NewDataStore(
 		configFilePath,
 		NewConfig(),
@@ -30,15 +35,17 @@ func main() {
 		NewPersistentData(config),
 		false,
 		0640)
-	// exit handler
+	logger.LogLevel = config.LogLevel
-	defer println("INFO\tExiting ...")
+	logger.debug("Checking configuration file ...")
-	// check config
 	checkConfig(config)
 	// create mail template from mail template config
+	logger.debug("Parsing mail template ...")
 	if config.Template.SubjectTemplate == "" {
+		logger.debug("Using default template for mail subject")
 		config.Template.SubjectTemplate = DEFAULT_SUBJECT_TEMPLATE
 	}
 	if config.Template.BodyTemplate == "" {
+		logger.debug("Using default template for mail body")
 		config.Template.BodyTemplate = DEFAULT_BODY_TEMPLATE
 	}
 	mailTemplate := NewTemplateFromTemplateConfig(config.Template)
@@ -54,42 +61,48 @@ func main() {
 	for _, a := range apiEndpoints {
 		for _, b := range config.EnabledApiEndpoints {
 			if a.Id == b {
+				logger.debug("Endpoint '" + b + "' is enabled")
 				enabledApiEndpoints = append(enabledApiEndpoints, a)
 			}
 		}
 	}
 	// main loop
+	logger.debug("Entering main loop ...")
 	for {
 		t1 := time.Now().UnixMilli()
 		newNotices := []WidNotice{}
 		for _, a := range enabledApiEndpoints {
-			fmt.Printf("INFO\t%v Querying endpoint '%v' for new notices ...\n", time.Now().Format(time.RFC3339Nano), a.Id)
+			logger.info("Querying endpoint '" + a.Id + "' for new notices ...")
 			n, t, err := a.getNotices(persistent.data.(PersistentData).LastPublished[a.Id])
 			if err != nil {
 				// retry
+				logger.warn("Couldn't query notices from API endpoint '" + a.Id + "'. Retrying ...")
+				logger.warn(err)
 				n, t, err = a.getNotices(persistent.data.(PersistentData).LastPublished[a.Id])
 			}
 			if err != nil {
 				// ok then...
-				fmt.Print("ERROR\t", err)
+				logger.error("Couldn't query notices from API endpoint '" + a.Id + "'")
+				logger.error(err)
 			} else {
 				newNotices = append(newNotices, n...)
 				persistent.data.(PersistentData).LastPublished[a.Id] = t
 				persistent.save()
 			}
 		}
+		logger.debug(fmt.Sprintf("Got %v new notices", len(newNotices)))
 		if len(newNotices) > 0 {
-			fmt.Printf("INFO\t%v Sending email notifications ...\n", time.Now().Format(time.RFC3339Nano))
+			logger.info("Sending email notifications ...")
 			recipientsNotified := 0
 			for _, r := range config.Recipients {
 				err := r.filterAndSendNotices(newNotices, mailTemplate, mailAuth, config.SmtpConfiguration)
 				if err != nil {
-					fmt.Printf("ERROR\t%v\n", err)
+					logger.error(err)
 				} else {
 					recipientsNotified++
 				}
 			}
-			fmt.Printf("INFO\t%v Email notifications sent to %v of %v recipients.\n", time.Now().Format(time.RFC3339Nano), recipientsNotified, len(config.Recipients))
+			logger.info(fmt.Sprintf("Email notifications sent to %v of %v recipients", recipientsNotified, len(config.Recipients)))
 		}
 		t2 := time.Now().UnixMilli()
 		dt := int(t2 - t1)

template.go

@@ -4,7 +4,6 @@ package main
 
 import (
 	"bytes"
-	"fmt"
 	"text/template"
 )
 
@@ -58,12 +57,12 @@ func (t MailTemplate) generate(notice WidNotice) (MailContent, error) {
 func NewTemplateFromTemplateConfig(tc MailTemplateConfig) MailTemplate {
 	subjectTemplate, err := template.New("subject").Parse(tc.SubjectTemplate)
 	if err != nil {
-		fmt.Println("ERROR\tCould not parse template.")
+		logger.error("Could not parse template")
 		panic(err)
 	}
 	bodyTemplate, err := template.New("body").Parse(tc.BodyTemplate)
 	if err != nil {
-		fmt.Println("ERROR\tCould not parse template.")
+		logger.error("Could not parse template")
 		panic(err)
 	}
 	return MailTemplate{

widapi.go

@@ -66,7 +66,7 @@ func (e ApiEndpoint) getNotices(since time.Time) ([]WidNotice, time.Time, error)
 			}
 			notices = parseApiResponse(decodedData, e)
 		} else {
-			fmt.Printf("ERROR\tGet \"%v\": %v\n", url, res.Status)
+			logger.error(fmt.Sprintf("Get \"%v\": %v\n", url, res.Status))
 			return nil, time.Time{}, err
 		}
 	} else {
@@ -104,7 +104,7 @@ func parseApiResponse(data map[string]interface{}, apiEndpoint ApiEndpoint) []Wi
 		}
 		published, err := time.Parse(PUBLISHED_TIME_FORMAT, d["published"].(string))
 		if err != nil {
-			fmt.Println("ERROR\t", err)
+			logger.error(err)
 		}
 		notice.Published = published
 		// optional fields