feat yandex desktop downloads

internal/download/downloader_test.go

@@ -2,8 +2,10 @@ package download
 
 import (
 	"context"
+	"crypto/aes"
 	"crypto/cipher"
 	"errors"
+	"encoding/hex"
 	"io"
 	"net/http"
 	"net/http/httptest"
@@ -110,6 +112,45 @@ func TestFileDeezerEncrypted(t *testing.T) {
 	}
 }
 
+func TestFileYandexEncrypted(t *testing.T) {
+	plain := make([]byte, 8192+333)
+	for i := range plain {
+		plain[i] = byte((i * 11) % 251)
+	}
+	keyHex := "00112233445566778899aabbccddeeff"
+	key, err := hex.DecodeString(keyHex)
+	if err != nil {
+		t.Fatalf("DecodeString() error = %v", err)
+	}
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		t.Fatalf("NewCipher() error = %v", err)
+	}
+	enc := make([]byte, len(plain))
+	copy(enc, plain)
+	stream := cipher.NewCTR(block, make([]byte, aes.BlockSize))
+	stream.XORKeyStream(enc, enc)
+
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write(enc)
+	}))
+	defer ts.Close()
+
+	d := NewWithOptions(true, false, 0)
+	out := filepath.Join(t.TempDir(), "x", "a.m4a")
+	if err = d.FileYandexEncrypted(context.Background(), ts.URL, out, keyHex); err != nil {
+		t.Fatalf("FileYandexEncrypted() error = %v", err)
+	}
+
+	got, err := os.ReadFile(out)
+	if err != nil {
+		t.Fatalf("ReadFile() error = %v", err)
+	}
+	if string(got) != string(plain) {
+		t.Fatalf("decrypted file mismatch")
+	}
+}
+
 func TestDownloaderFileTruncatedResponseRemovesPartialFile(t *testing.T) {
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
 		w.Header().Set("Content-Length", "10")
@@ -160,6 +201,15 @@ func TestFileDeezerEncryptedBadStatus(t *testing.T) {
 	}
 }
 
+func TestFileYandexEncryptedBadKey(t *testing.T) {
+	d := NewWithOptions(true, false, 0)
+	out := filepath.Join(t.TempDir(), "x", "a.m4a")
+	err := d.FileYandexEncrypted(context.Background(), "https://example.com/file", out, "abcd")
+	if err == nil || !strings.Contains(err.Error(), "invalid yandex key length") {
+		t.Fatalf("expected key length error, got %v", err)
+	}
+}
+
 func TestDownloaderFileContextCancellationRemovesPartialFile(t *testing.T) {
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "application/octet-stream")