1 files changed, 92 insertions, 0 deletions
diff --git a/bencode/encode.go b/bencode/encode.go
new file mode 100644
index 0000000..4890359
--- /dev/null
+++ b/bencode/encode.go
@@ -0,0 +1,92 @@
+package bencode
+
+import (
+	"errors"
+	"fmt"
+	"sort"
+)
+
+// Encode encodes a string, int, dict or list value to a bencoded string.
+func Encode(data interface{}) ([]byte, error) {
+	return encodeItem(data)
+}
+
+// EncodeString encodes a string value.
+func EncodeString(data string) ([]byte, error) {
+	length := fmt.Sprintf("%d:", len(data))
+	out := make([]byte, 0, len(length)+len(data)+1)
+	out = append(out, []byte(length)...)
+	return append(out, []byte(data)...), nil
+}
+
+// EncodeInt encodes a int value.
+func EncodeInt(data int64) ([]byte, error) {
+	ib := fmt.Sprintf("i%de", data)
+	return []byte(ib), nil
+}
+
+// EncodeDict encodes a dict value.
+func EncodeDict(data map[string]interface{}) ([]byte, error) {
+	out := make([]byte, 0, 2)
+	out = append(out, 'd')
+
+	// Sort keys
+	list := make(sort.StringSlice, len(data))
+	i := 0
+	for key := range data {
+		list[i] = key
+		i++
+	}
+	list.Sort()
+
+	for _, key := range list {
+		keyb, err := EncodeString(key)
+		if err != nil {
+			return nil, err
+		}
+		value, err := encodeItem(data[key])
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, keyb...)
+		out = append(out, value...)
+	}
+	return append(out, 'e'), nil
+}
+
+// EncodeList encodes a list value.
+func EncodeList(data []interface{}) ([]byte, error) {
+	out := make([]byte, 0, 2)
+	out = append(out, 'l')
+
+	for _, item := range data {
+		b, err := encodeItem(item)
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, b...)
+	}
+	return append(out, 'e'), nil
+}
+
+// EncodeItem encodes an item of dict or list.
+func encodeItem(data interface{}) ([]byte, error) {
+	switch v := data.(type) {
+	case string:
+		return EncodeString(v)
+	case int:
+		return EncodeInt(int64(v))
+	case int16:
+		return EncodeInt(int64(v))
+	case int32:
+		return EncodeInt(int64(v))
+	case int64:
+		return EncodeInt(int64(v))
+	case []interface{}:
+		return EncodeList(v)
+	case map[string]interface{}:
+		return EncodeDict(v)
+	default:
+		return nil, errors.New("bencode: invalid type to encode")
+	}
+}