Show WireGuard QR, full .conf and ZIP download after 3x-ui client create

Co-authored-by: Cursor <cursoragent@cursor.com>

app/services/crypto.py

@@ -43,6 +43,50 @@ def generate_keypair() -> KeyPair:
     )
 
 
+def public_key_from_private(private_key_b64: str) -> str:
+    """Derive WireGuard/X25519 public key from a base64 private key."""
+    raw = base64.b64decode(private_key_b64.strip())
+    if len(raw) != 32:
+        raise ValueError("Invalid private key length")
+    private = X25519PrivateKey.from_private_bytes(raw)
+    public_bytes = private.public_key().public_bytes(Encoding.Raw, PublicFormat.Raw)
+    return base64.b64encode(public_bytes).decode("ascii")
+
+
+def render_xui_wireguard_config(
+    *,
+    private_key: str,
+    address: str,
+    dns: str,
+    mtu: int,
+    server_public_key: str,
+    endpoint: str,
+    peer_allowed_ips: str = "0.0.0.0/0, ::/0",
+    remark: str = "",
+) -> str:
+    addr = address if "/" in address else f"{address}/32"
+    lines = [
+        "[Interface]",
+        f"PrivateKey = {private_key}",
+        f"Address = {addr}",
+        f"DNS = {dns}",
+        f"MTU = {mtu}",
+        "",
+    ]
+    if remark:
+        lines.append(f"# {remark}")
+    lines.extend(
+        [
+            "[Peer]",
+            f"PublicKey = {server_public_key}",
+            f"AllowedIPs = {peer_allowed_ips}",
+            f"Endpoint = {endpoint}",
+            "",
+        ]
+    )
+    return "\n".join(lines)
+
+
 def generate_preshared_key() -> str:
     return base64.b64encode(secrets.token_bytes(32)).decode("ascii")