Implement simple parsering

main.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"regexp"
+	"time"
+
+	logger "git.site.quack-lab.dev/dave/cylogger"
+)
+
+type DateParser interface {
+	Parse(s string) (time.Time, error)
+}
+
+type DateParser8 struct {
+	re *regexp.Regexp
+}
+
+func (dp *DateParser8) Parse(s string) (time.Time, error) {
+	matches := dp.re.FindStringSubmatch(s)
+	if len(matches) == 0 {
+		return time.Time{}, fmt.Errorf("no match")
+	}
+	return time.Parse("20060102", matches[0])
+}
+
+type DateParserISO struct {
+	re *regexp.Regexp
+}
+
+func (dp *DateParserISO) Parse(s string) (time.Time, error) {
+	matches := dp.re.FindStringSubmatch(s)
+	if len(matches) == 0 {
+		return time.Time{}, fmt.Errorf("no match")
+	}
+	return time.Parse("2006-01-02", matches[0])
+}
+
+func main() {
+	flag.Parse()
+	logger.InitFlag()
+
+	if flag.NArg() == 0 {
+		logger.Error("no files provided")
+		return
+	}
+
+	parsers := []DateParser{
+		&DateParser8{re: regexp.MustCompile(`\d{8}`)},
+		&DateParserISO{re: regexp.MustCompile(`\d{4}-\d{2}-\d{2}`)},
+	}
+
+	files := flag.Args()
+
+	for _, file := range files {
+		logger.Info("processing file: %s", file)
+		date, err := parseDate(file, parsers)
+		if err != nil {
+			logger.Error("error parsing date: %s", err)
+			continue
+		}
+		logger.Info("date: %s", date)
+	}
+}
+
+func parseDate(file string, parsers []DateParser) (time.Time, error) {
+	for _, parser := range parsers {
+		date, err := parser.Parse(file)
+		if err == nil {
+			return date, nil
+		}
+	}
+	return time.Time{}, fmt.Errorf("no date found")
+}