feat: initialer Commit des csv2excel CLI-Tools

Go-CLI-Tool zum Konvertieren von CSV-Dateien in Excel (.xlsx),
mit Mage-Build-System und Architektur-Dokumentation.

main.go

@@ -0,0 +1,127 @@
+package main
+
+import (
+	"encoding/csv"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/xuri/excelize/v2"
+	"golang.org/x/text/encoding/charmap"
+	"golang.org/x/text/transform"
+)
+
+func main() {
+	sep := flag.String("sep", "auto", "Trennzeichen: auto, ',', ';', '\\t'")
+	enc := flag.String("enc", "utf8", "Encoding: utf8, windows1252")
+	out := flag.String("o", "output.xlsx", "Ausgabedatei")
+	flag.Parse()
+
+	files := flag.Args()
+	if len(files) == 0 {
+		fmt.Fprintln(os.Stderr, "Verwendung: csv2xlsx [flags] datei1.csv datei2.csv ...")
+		os.Exit(1)
+	}
+
+	fmt.Println(sep)
+	fmt.Println(enc)
+	fmt.Println(out)
+
+	xlsx := excelize.NewFile()
+	firstSheet := true
+
+	for _, path := range files {
+
+		sheetName := strings.TrimSuffix(filepath.Base(path), filepath.Ext(path))
+		// Excelize: max 31 Zeichen, keine Sonderzeichen
+		if len(sheetName) > 31 {
+			sheetName = sheetName[:31]
+		}
+
+		f, err := os.Open(path)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Fehler beim Öffnen %s: %v\n", path, err)
+			continue
+		}
+		defer f.Close()
+
+		var reader io.Reader = f
+		if *enc == "windows1252" {
+			reader = transform.NewReader(f, charmap.Windows1252.NewDecoder())
+		}
+
+		delimiter := detectDelimiter(path, *sep)
+
+		csvReader := csv.NewReader(reader)
+		csvReader.Comma = delimiter
+		csvReader.LazyQuotes = true // tolerant bei kaputten CSV-Dateien
+
+		if firstSheet {
+			xlsx.SetSheetName("Sheet1", sheetName)
+			firstSheet = false
+		} else {
+			xlsx.NewSheet(sheetName)
+		}
+
+		row := 1
+		for {
+			record, err := csvReader.Read()
+			if err == io.EOF {
+				break
+			}
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "Warnung Zeile %d in %s: %v\n", row, path, err)
+				continue
+			}
+			for col, val := range record {
+				cell, _ := excelize.CoordinatesToCellName(col+1, row)
+				xlsx.SetCellValue(sheetName, cell, val)
+			}
+			row++
+		}
+		fmt.Printf("✓ %s → Reiter \"%s\" (%d Zeilen)\n", path, sheetName, row-1)
+	}
+
+	if err := xlsx.SaveAs(*out); err != nil {
+		fmt.Fprintf(os.Stderr, "Fehler beim Speichern: %v\n", err)
+		os.Exit(1)
+	}
+	fmt.Printf("✅ Gespeichert: %s\n", *out)
+
+}
+
+func detectDelimiter(path, hint string) rune {
+	switch hint {
+	case ";":
+		return ';'
+	case "\t":
+		return '\t'
+	case ",":
+		return ','
+	}
+	// auto-detect: erste Zeile lesen und zählen
+	f, err := os.Open(path)
+	if err != nil {
+		return ';'
+	}
+	defer f.Close()
+	buf := make([]byte, 4096)
+	n, _ := f.Read(buf)
+	line := string(buf[:n])
+	if idx := strings.Index(line, "\n"); idx > 0 {
+		line = line[:idx]
+	}
+	sc := strings.Count(line, ";")
+	cc := strings.Count(line, ",")
+	tc := strings.Count(line, "\t")
+	if tc >= sc && tc >= cc {
+		return '\t'
+	}
+	if sc >= cc {
+		return ';'
+	}
+	return ','
+}