bencode.go

package bencode

import (
	"fmt"
	"io"
	"reflect"
)

func Encode(w io.Writer, x interface{}) {
	v := reflect.ValueOf(x)
	switch v.Kind() {
	case reflect.String:
		fmt.Fprintf(w, "%d:%s", v.Len(), x)
	case reflect.Int:
		fmt.Fprintf(w, "i%de", x)
	case reflect.Slice:
		fmt.Fprint(w, "l")
		for i := 0; i < v.Len(); i++ {
			Encode(w, v.Index(i).Interface())
		}
		fmt.Fprint(w, "e")
	case reflect.Map:
		// TODO: ensure map keys are strings
		// TODO: sort map by keys
		fmt.Fprint(w, "d")
		for _, e := range v.MapKeys() {
			Encode(w, e.Interface())
			Encode(w, v.MapIndex(e).Interface())
		}
		fmt.Fprint(w, "e")
	default:
		// TODO: error
		fmt.Fprint(w, "#")
	}
}