codecrafters submit [skip ci]

2 files changed, 105 insertions, 31 deletions

diff --git a/cmd/mybittorrent/file.go b/cmd/mybittorrent/file.go
new file mode 100644
index 0000000..2302976
--- /dev/null
+++ b/cmd/mybittorrent/file.go
@@ -0,0 +1,85 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+)
+
+type File struct {
+	Announce string   `bencode:"announce"`
+	Info     FileInfo `bencode:"info"`
+}
+
+type FileInfo struct {
+	Length      int    `bencode:"length"`
+	Name        string `bencode:"name"`
+	PieceLength int    `bencode:"piece length"`
+	Pieces      string `bencode:"pieces"`
+}
+
+func NewFile() *File {
+	return &File{}
+}
+
+func (f *File) ReadFrom(r io.ReadCloser) error {
+	buf := new(bytes.Buffer)
+
+	_, err := buf.ReadFrom(r)
+	if err != nil {
+		return err
+	}
+
+	defer func(r io.ReadCloser) {
+		err := r.Close()
+		if err != nil {
+			fmt.Printf("failed to close: %v+\n", err)
+		}
+	}(r)
+
+	if err != nil {
+		return err
+	}
+
+	decoded, err := NewDecoder(buf.String()).Decode()
+	if err != nil {
+		return err
+	}
+
+	content, ok := decoded.(map[string]any)
+	if !ok {
+		return fmt.Errorf("invalid contents")
+	}
+
+	f.Announce, ok = content["announce"].(string)
+	if !ok {
+		return fmt.Errorf("invalid announce field")
+	}
+
+	info, ok := content["info"].(map[string]any)
+	if !ok {
+		return fmt.Errorf("invalid info field")
+	}
+
+	f.Info.Length, ok = info["length"].(int)
+	if !ok {
+		return fmt.Errorf("invalid info.length field")
+	}
+
+	f.Info.Name, ok = info["name"].(string)
+	if !ok {
+		return fmt.Errorf("invalid info.name field")
+	}
+
+	f.Info.PieceLength, ok = info["piece length"].(int)
+	if !ok {
+		return fmt.Errorf("invalid info.piece length field")
+	}
+
+	f.Info.Pieces, ok = info["pieces"].(string)
+	if !ok {
+		return fmt.Errorf("invalid info.pieces field")
+	}
+
+	return nil
+}
diff --git a/cmd/mybittorrent/main.go b/cmd/mybittorrent/main.go
index e3e902a..7905e01 100644
--- a/cmd/mybittorrent/main.go
+++ b/cmd/mybittorrent/main.go
@@ -4,42 +4,14 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
-	"strconv"
-	"strings"
-	"unicode"
 	// bencode "github.com/jackpal/bencode-go" // Available if you need it!
 )
 
-func decodeBencode(bencodedString string) (interface{}, error) {
-	if unicode.IsDigit(rune(bencodedString[0])) {
-		var firstColonIndex int
-
-		for i := 0; i < len(bencodedString); i++ {
-			if bencodedString[i] == ':' {
-				firstColonIndex = i
-				break
-			}
-		}
-
-		lengthStr := bencodedString[:firstColonIndex]
-
-		length, err := strconv.Atoi(lengthStr)
-		if err != nil {
-			return "", err
-		}
-
-		return bencodedString[firstColonIndex+1 : firstColonIndex+1+length], nil
-	} else if rune(bencodedString[0]) == 'i' {
-		return strconv.Atoi(bencodedString[1:strings.IndexByte(bencodedString, 'e')])
-	} else {
-		return "", fmt.Errorf("only strings are supported at the moment")
-	}
-}
-
 func main() {
 	command := os.Args[1]
 
-	if command == "decode" {
+	switch command {
+	case "decode":
 		bencodedValue := os.Args[2]
 
 		decoded, err := NewDecoder(bencodedValue).Decode()
@@ -50,7 +22,24 @@ func main() {
 
 		jsonOutput, _ := json.Marshal(decoded)
 		fmt.Println(string(jsonOutput))
-	} else {
+
+	case "info":
+		f, err := os.Open(os.Args[2])
+		if err != nil {
+			fmt.Println("Failed to open file: " + os.Args[2])
+		}
+
+		tf := NewFile()
+
+		err = tf.ReadFrom(f)
+		if err != nil {
+			fmt.Println("Failed to parse file: " + os.Args[2])
+			panic(err)
+		}
+
+		fmt.Printf("Tracker URL: %s\nLength: %d", tf.Announce, tf.Info.Length)
+
+	default:
 		fmt.Println("Unknown command: " + command)
 		os.Exit(1)
 	}