Reformat timestamps in factorio log

Author: trigrab

src/factorio/gamelog.go

@@ -1,12 +1,17 @@
 package factorio
 
 import (
+	"errors"
+	"log"
+	"regexp"
+	"strings"
+	"time"
+
 	"github.com/hpcloud/tail"
 	"github.com/mroote/factorio-server-manager/bootstrap"
-	"log"
 )
 
-func TailLog() ([]string, error) {
+func tailLog(filename string) ([]string, error) {
 	result := []string{}
 
 	config := bootstrap.GetConfig()
@@ -21,5 +26,54 @@ func TailLog() ([]string, error) {
 		result = append(result, line.Text)
 	}
 
+	result = reformatTimestamps(result)
+
 	return result, nil
 }
+
+func getOffset(line string) (string, error) {
+	re, _ := regexp.Compile(`^\d+.\d+`)
+
+	if !re.MatchString(line) {
+		log.Printf("This line has no offset", line)
+		return "error", errors.New(line)
+	}
+
+	offset := re.FindString(line)
+
+	return offset, nil
+}
+
+func getStartTime(line string) time.Time {
+	re, _ := regexp.Compile(`\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}`)
+	date := string(re.FindString(line))
+	startTime, _ := time.Parse(time.RFC3339, strings.Replace(date, " ", "T", 1)+"Z")
+
+	return startTime
+}
+
+func replaceTimestampInLine(line string, offset string, startTime time.Time) string {
+	offset, err := getOffset(line)
+	offsetDuration, _ := time.ParseDuration(offset + "s")
+	timestamp := startTime.Add(offsetDuration)
+
+	if err == nil {
+		return timestamp.Format("2006-01-02 15:04:05") + ":" + strings.Replace(line, offset, "", 1)
+	} else {
+		return line
+	}
+}
+
+func reformatTimestamps(log []string) []string {
+	firstLine := log[0]
+	startTime := getStartTime(firstLine)
+	result := []string{}
+
+	for i := range log {
+		line := strings.TrimLeft(log[i], " \t")
+		offset, _ := getOffset(line)
+		result = append(result, replaceTimestampInLine(line, offset, startTime))
+	}
+
+	return result
+}