custom callback_host for arcade login (#481)

Say you are @shubcodes and running arcade on replit or vs codespaces.
Today, `arcade login` assumes that the browser you've opened for the
auth flow's "localhost" is the same that is running the `arcade login`
command. If you are running on one of these remote code execution
environments, that won't be true.

Usage:
```
arcade login --callback-host "https://replit.com:9999/path/to/my/codespace"
```

libs/arcade-cli/arcade_cli/main.py

@@ -99,6 +99,11 @@ def login(
         "--port",
         help="The port of the Arcade Cloud host (if running locally).",
     ),
+    callback_host: str = typer.Option(
+        "localhost",
+        "--callback-host",
+        help="The host to use to complete the auth flow - this should be the same as the host that the CLI is running on. Include the port if needed.",
+    ),
     debug: bool = typer.Option(False, "--debug", "-d", help="Show debug information"),
 ) -> None:
     """
@@ -119,7 +124,7 @@ def login(
 
     try:
         # Open the browser for user login
-        login_url = compute_login_url(host, state, port)
+        login_url = compute_login_url(host, state, port, callback_host)
 
         console.print("Opening a browser to log you in...")
         if not webbrowser.open(login_url):

libs/arcade-cli/arcade_cli/utils.py

@@ -176,11 +176,22 @@ def compute_base_url(
         return f"{protocol}://{encoded_host}"
 
 
-def compute_login_url(host: str, state: str, port: int | None) -> str:
+def compute_login_url(
+    host: str, state: str, port: int | None, callback_host: str | None = None
+) -> str:
     """
     Compute the full URL for the CLI login endpoint.
     """
-    callback_uri = f"http://{LOCALHOST}:9905/callback"
+    if callback_host:
+        if not (callback_host.startswith("http://") or callback_host.startswith("https://")):
+            callback_uri = f"http://{callback_host}"
+        else:
+            callback_uri = callback_host
+        if not callback_uri.rstrip("/").endswith("/callback"):
+            callback_uri = callback_uri.rstrip("/") + "/callback"
+    else:
+        callback_uri = f"http://{LOCALHOST}:9905/callback"
+
     params = urlencode({"callback_uri": callback_uri, "state": state})
 
     port = port if port else 8000

libs/tests/cli/test_utils.py

@@ -218,9 +218,22 @@ def test_compute_base_url(inputs: dict, expected_output: str):
             "https://cloud.arcade.dev/api/v1/auth/cli_login?callback_uri=http%3A%2F%2Flocalhost%3A9905%2Fcallback&state=123",
             id="cloud host with an ignored custom port",
         ),
+        pytest.param(
+            {
+                "host_input": DEFAULT_CLOUD_HOST,
+                "port_input": DEFAULT_PORT,
+                "state": "123",
+                "callback_host": "other-host.com/123",
+            },
+            "https://cloud.arcade.dev/api/v1/auth/cli_login?callback_uri=http%3A%2F%2Fother-host.com%2F123%2Fcallback&state=123",
+            id="cloud host with a custom callback host",
+        ),
     ],
 )
 def test_compute_login_url(inputs: dict, expected_output: str):
-    login_url = compute_login_url(inputs["host_input"], inputs["state"], inputs["port_input"])
+    callback_host = inputs.get("callback_host")
+    login_url = compute_login_url(
+        inputs["host_input"], inputs["state"], inputs["port_input"], callback_host
+    )
 
     assert login_url == expected_output