Refactoring conf and main

conf.go

@@ -4,12 +4,14 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
-	"path/filepath"
 )
 
-const CONFIG_LOG string = "/var/lib/gocustomurls/"
+type Config struct {
+	MappingFilePath string
+	MappingRules    ImportRulesMappings
+}
 
-type ConfigFile struct {
+type ImportRulesMappings struct {
 	Mappings []struct {
 		Protocol  string `json:"protocol"`
 		VanityUrl string `json:"vanity_url"`
@@ -17,6 +19,12 @@ type ConfigFile struct {
 	} `json:"mappings"`
 }
 
+type ImportRuleStruct struct {
+	VanityUrl string
+	Proto     string
+	RepoUrl   string
+}
+
 // isFile - check if fp is a valid file
 func isFile(fp string) bool {
 	info, err := os.Stat(fp)
@@ -27,26 +35,28 @@ func isFile(fp string) bool {
 }
 
 // load mapping file
-func LoadFile() (ConfigFile, error) {
-	var mapping ConfigFile
-	dirname, err := os.UserConfigDir()
-	if err != nil {
-		return mapping, err
-	}
-	configFilePath := filepath.Join(dirname, "gocustomurls/config.json")
-	ok := isFile(configFilePath)
+func (c *Config) LoadMappingFile(fp string) error {
+	var mapping ImportRulesMappings
+	mappingFilePath := fp
+	if len(c.MappingFilePath) == 0 {
+		ok := isFile(mappingFilePath)
 		if !ok {
-		return mapping, fmt.Errorf("%s/gocustomurls/config.json file is not found", dirname)
+			return fmt.Errorf("%s is not found", mappingFilePath)
 		}
-	configFile, err := os.Open(configFilePath)
+	}
+	mappingFile, err := os.Open(mappingFilePath)
 	if err != nil {
-		return mapping, err
+		return err
 	}
-	defer configFile.Close()
+	defer mappingFile.Close()
 
-	err = json.NewDecoder(configFile).Decode(&mapping)
+	err = json.NewDecoder(mappingFile).Decode(&mapping)
 	if err != nil {
-		return mapping, err
+		return err
 	}
-	return mapping, nil
+	c.MappingRules = mapping
+	if len(c.MappingFilePath) == 0 {
+		c.MappingFilePath = mappingFilePath
+	}
+	return nil
 }

main.go

@@ -1,5 +1,115 @@
 package main
 
-func main() {
+import (
+	"context"
+	"errors"
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+)
 
+var errorLog *log.Logger = log.New(os.Stderr, "", log.LstdFlags)
+
+const (
+	DEFAULT_RULES_FILE string = "/var/lib/gocustomurls/rules.json"
+	DEFAULT_LOG_FILE   string = "/var/log/gocustomurls/app.log"
+)
+
+// flagsSet returns a set of all the flags what were actually set on the
+// command line.
+func flagsSet(flags *flag.FlagSet) map[string]bool {
+	s := make(map[string]bool)
+	flags.Visit(func(f *flag.Flag) {
+		s[f.Name] = true
+	})
+	return s
+}
+
+func main() {
+	programName := os.Args[0]
+	// errorLog = log.New(os.Stderr, "", log.LstdFlags)
+
+	flags := flag.NewFlagSet(os.Args[0], flag.ExitOnError)
+	flags.Usage = func() {
+		out := flags.Output()
+		fmt.Fprintf(out, "Usage: %v [flags]\n\n", programName)
+		fmt.Fprint(out, "  This utility serves vanity urls for the go get/install command.\n")
+		fmt.Fprint(out, "  By default, the server listens on localhost:7070.\n")
+		flags.PrintDefaults()
+	}
+
+	portFlag := flags.String("port", "7070", "port to listen to")
+	rulesFileFlag := flags.String("config", DEFAULT_RULES_FILE, "contains go-import mapping")
+	logFileFlag := flags.String("logfile", DEFAULT_LOG_FILE, "default log file")
+	flags.Parse(os.Args[1:])
+
+	if len(flags.Args()) > 1 {
+		errorLog.Println("Error: too many command-line arguments")
+		flags.Usage()
+		os.Exit(1)
+	}
+
+	allSetFlags := flagsSet(flags)
+
+	var port string
+	if allSetFlags["port"] {
+		port = *portFlag
+	}
+
+	var rulesFile string
+	if allSetFlags["config"] {
+		rulesFile = *rulesFileFlag
+	}
+
+	var logFile string
+	if allSetFlags["logFile"] {
+		logFile = *logFileFlag
+	}
+
+	// load rules mapping
+	c := &Config{}
+	err := c.LoadMappingFile(rulesFile)
+	if err != nil {
+		errorLog.Println(err)
+		os.Exit(1)
+	}
+	l, err := newFileLogger(logFile)
+	if err != nil {
+		errorLog.Println(err)
+		os.Exit(1)
+	}
+
+	app := &Application{
+		Config: c,
+		Log:    l,
+	}
+	srv := app.Setup(port)
+
+	// For graceful shutdowns
+	go func() {
+		err := srv.ListenAndServe()
+		if !errors.Is(err, http.ErrServerClosed) {
+			errorLog.Printf("HTTP Server error: %+v\n", err)
+			os.Exit(1)
+		}
+		app.Log.logger.Println("Stopped serving new connections.")
+	}()
+
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
+	<-sigChan
+
+	shutdownCtx, shutdownRelease := context.WithTimeout(context.Background(), 10*time.Second)
+	defer shutdownRelease()
+
+	if err := srv.Shutdown(shutdownCtx); err != nil {
+		errorLog.Printf("HTTP shutdown error: %+v\n", err)
+		os.Exit(1)
+	}
+	app.Log.logger.Println("Graceful shutdown complete.")
 }