1 files changed, 103 insertions, 0 deletions
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..d20f574
--- /dev/null
+++ b/main.go
@@ -0,0 +1,103 @@
+package main
+
+import (
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"mime"
+	"mime/multipart"
+	"net/mail"
+	"os"
+	"strings"
+)
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintf(flag.CommandLine.Output(), "Usage: mimeslicer <command> [options]\n\n")
+		fmt.Fprintf(flag.CommandLine.Output(), "Commands:\n")
+		os.Exit(0)
+	}
+
+	if len(os.Args) < 2 {
+		fmt.Println("Error: Command missing.")
+		flag.Usage()
+	}
+
+	inspectCmd := flag.NewFlagSet("inspect", flag.ExitOnError)
+	inspectCmdInputFile := inspectCmd.String("i", "", "input file")
+
+	switch os.Args[1] {
+	case "inspect":
+		inspectCmd.Parse(os.Args[2:])
+
+		if err := inspect(*inspectCmdInputFile); err != nil {
+			fmt.Printf("Error: %s", err.Error())
+			os.Exit(1)
+		}
+	case "-h", "--help", "help":
+		flag.Usage()
+	default:
+		fmt.Printf("Error: unknown command %q\n\n", os.Args[1])
+		flag.Usage()
+	}
+}
+
+func inspect(file string) error {
+	fd, err := os.Open(file)
+	if err != nil {
+		return err
+	}
+	defer fd.Close()
+
+	msg, err := mail.ReadMessage(fd)
+	if err != nil {
+		return err
+	}
+
+	for k, v := range msg.Header {
+		for _, val := range v {
+			fmt.Printf("%s: %s\n", k, val)
+		}
+	}
+
+	contentType := msg.Header.Get("Content-Type")
+	mediaType, params, err := mime.ParseMediaType(contentType)
+	if err != nil {
+		return errors.Join(err, errors.New("failed to parse mediate type from  contentType"))
+	}
+
+	if !strings.HasPrefix(mediaType, "multipart/") {
+		return errors.New("expected multipler/ TOOD")
+	}
+
+	boundary, ok := params["boundary"]
+	if !ok {
+		return errors.New("Error: no boundary in Content-Type header for multipart media type")
+	}
+
+	mr := multipart.NewReader(msg.Body, boundary)
+
+	partIndex := 0
+	fmt.Printf("\nMIME body parts\n\n")
+
+	for {
+		part, err := mr.NextPart()
+		if err == io.EOF {
+			break
+		}
+
+		fmt.Printf("[%d]\n", partIndex)
+
+		fmt.Printf("Headers:\n")
+		for k, v := range part.Header {
+			for _, val := range v {
+				fmt.Printf("  %s: %s\n", k, val)
+			}
+		}
+
+		partIndex++
+	}
+
+	return nil
+}