"""
A group always opens on a tab that exists.

The landing tab comes from a preference and is chosen at mount; which
applications the group runs comes from the node, several awaits later. When the
two disagree — Chat disabled here while 'chat' is the default, or a preferred
app this group does not offer — the page used to render no panel at all, with
no tab shown active and nothing on screen to explain it.

A string comparison against a list that arrives later is not something reading
`group-page.js` makes obvious, so this renders the real `GroupPage` against a
stub node and reads the tab bar back.
"""
import json
import shutil
import subprocess
from pathlib import Path

import pytest

HARNESS = Path(__file__).parent / "harness" / "group_tab_probe.py"
STATIC = Path(__file__).resolve().parents[1] / "src" / "meshbay_hub" / "static"

pytestmark = pytest.mark.skipif(
    shutil.which("google-chrome") is None or not (STATIC / "group-page.js").exists(),
    reason="Chrome or the SPA sources are not available")


@pytest.fixture(scope="module")
def cases():
    run = subprocess.run(["python3", str(HARNESS)], capture_output=True, timeout=180)
    assert run.returncode == 0, run.stderr.decode()[-2000:]
    return {c["name"]: c for c in json.loads(run.stdout.decode())}


# Asserted by position, not by label: the harness renders in whatever language
# the browser resolves to.

def test_every_case_lands_somewhere(cases):
    """The bug, stated once: a tab bar with nothing selected and nothing under
    it."""
    for name, case in cases.items():
        assert case["active"] >= 0, f"{name}: no tab is active"
        assert case["panelDrawn"], f"{name}: a tab is active but no panel was drawn"


def test_the_default_is_the_first_app(cases):
    """Nothing changes for a group running everything."""
    case = cases["every app, default chat"]
    assert case["active"] == 0


def test_a_disabled_default_falls_back(cases):
    """'chat' is the default for everyone, and a group may not run it."""
    case = cases["chat disabled"]
    assert case["active"] == 0, "should have fallen back to the group's first app"
    assert len(case["tabs"]) == 3, "Files, Videos and Settings, with no Chat tab"


def test_a_preference_for_an_absent_app_falls_back(cases):
    """The preference is global; the app list is per group."""
    assert cases["preferred app absent"]["active"] == 0


def test_a_preference_that_names_nothing_falls_back(cases):
    """A stale or hand-edited preference must not strand anyone either."""
    assert cases["preference names nothing real"]["active"] == 0


def test_a_preference_that_arrives_after_the_group_opened_applies(cases):
    """The reported bug: Videos chosen in Settings, and a group opened directly
    (a reload, a link) still landed on Chat.

    app.js fetches the preferences after sign-in; GroupPage chose its tab at
    mount and never looked again.
    """
    case = cases["preference arrives after the group opened"]
    assert case["active"] == 2, (
        f"the preference arrived and was ignored: landed on tab {case['active']}")


def test_a_late_preference_does_not_undo_a_tab_the_reader_chose(cases):
    """Arriving late must not yank someone off a tab they just clicked."""
    case = cases["tab chosen before the preference arrives"]
    assert case["active"] == 1, (
        f"the reader clicked Files and was moved to tab {case['active']}")


def test_a_preference_the_group_offers_is_kept(cases):
    """The fallback must not become 'always the first app'."""
    case = cases["preferred app present"]
    assert case["active"] == 2, (
        "Videos was enabled and preferred; the reader should have landed on it, "
        f"not on tab {case['active']}")