Improve main error handling

main.go

@@ -1,14 +1,16 @@
 package main
 
 import (
+	"fmt"
 	"os"
 	"os/signal"
 	"syscall"
 
 	"gemini-grc/common"
+	"gemini-grc/common/blackList"
 	"gemini-grc/config"
 	"gemini-grc/db"
-	"gemini-grc/gemini"
+	"gemini-grc/errors"
 	"gemini-grc/logging"
 	"github.com/jmoiron/sqlx"
 	"github.com/rs/zerolog"
@@ -20,42 +22,61 @@ func main() {
 	zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
 	zerolog.SetGlobalLevel(config.CONFIG.LogLevel)
 	zlog.Logger = zlog.Output(zerolog.ConsoleWriter{Out: os.Stderr, TimeFormat: "[2006-01-02 15:04:05]"})
-	if err := runApp(); err != nil {
-		logging.LogError("Application error: %w", err)
+	err := runApp()
+	if err != nil {
+		var asErr *errors.Error
+		if errors.As(err, &asErr) {
+			logging.LogError("Unexpected error: %v", err)
+			_, _ = fmt.Fprintf(os.Stderr, "Unexpected error: %v", err)
+		} else {
+			logging.LogError("Unexpected error: %v", err)
+		}
 		os.Exit(1)
 	}
 }
 
-func runApp() error {
-	logging.LogInfo("Starting up. Press Ctrl+C to exit")
+func runApp() (err error) {
+	logging.LogInfo("gemcrawl %s starting up. Press Ctrl+C to exit", common.VERSION)
 	signals := make(chan os.Signal, 1)
 	signal.Notify(signals, syscall.SIGINT, syscall.SIGTERM)
 
-	_db := db.ConnectToDB()
+	_db, err := db.ConnectToDB()
+	if err != nil {
+		return err
+	}
 
 	defer func(db *sqlx.DB) {
-		err := db.Close()
-		if err != nil {
-			// TODO properly log & hangle error
-			panic(err)
-		}
+		_ = db.Close()
 	}(_db)
 
-	gemini.LoadBlacklist()
+	err = blackList.LoadBlacklist()
+	if err != nil {
+		return err
+	}
 
 	common.StatusChan = make(chan common.WorkerStatus, config.CONFIG.NumOfWorkers)
+	common.ErrorsChan = make(chan error, config.CONFIG.NumOfWorkers)
 
 	// If there's an argument, visit this
 	// URL only and don't spawn other workers
 	if len(os.Args) > 1 {
 		url := os.Args[1]
-		gemini.CrawlOneURL(_db, &url)
-		return nil
-	} else {
-		go gemini.SpawnWorkers(config.CONFIG.NumOfWorkers, _db)
+		err = common.CrawlOneURL(_db, &url)
+		return err
 	}
 
-	<-signals
-	logging.LogWarn("Received SIGINT or SIGTERM signal, exiting")
-	return nil
+	go common.SpawnWorkers(config.CONFIG.NumOfWorkers, _db)
+
+	for {
+		select {
+		case <-signals:
+			logging.LogWarn("Received SIGINT or SIGTERM signal, exiting")
+			return nil
+		case err := <-common.ErrorsChan:
+			if errors.IsFatal(err) {
+				return err
+			}
+			logging.LogError("%s", fmt.Sprintf("%v", err))
+		}
+	}
 }