"""The startup gate that stands in for Swarm's missing `depends_on`.

Swarm ignores `depends_on`, so the container races its own database on every
cold deploy. Under supervisord a program that fails three times goes FATAL and
stays there, so losing that race does not self-heal the way it did when Swarm
restarted a failed task — it leaves a running container with a dead
application inside it.
"""

from __future__ import annotations

import pytest

from backend.app.scripts import wait_for_deps as w


def test_it_waits_for_both_postgres_and_redis(monkeypatch):
    monkeypatch.setenv("DB_HOST", "postgres")
    monkeypatch.setenv("DB_PORT", "5432")
    monkeypatch.setenv("CELERY_BROKER_URL", "redis://redis:6379/0")

    assert w.targets() == [
        ("postgres", ("postgres", 5432)),
        ("redis", ("redis", 6379)),
    ]


def test_the_targets_come_from_the_same_env_the_app_reads(monkeypatch):
    """A gate that checks a different host than the application connects to is
    worse than no gate — it would pass while the app still cannot reach its
    database."""
    monkeypatch.setenv("DB_HOST", "10.0.0.5")
    monkeypatch.setenv("DB_PORT", "6543")
    monkeypatch.setenv("CELERY_BROKER_URL", "redis://broker.internal:6380/2")

    assert w.targets() == [
        ("postgres", ("10.0.0.5", 6543)),
        ("redis", ("broker.internal", 6380)),
    ]


def test_a_broker_url_without_a_port_falls_back_to_the_default(monkeypatch):
    monkeypatch.delenv("DB_HOST", raising=False)
    monkeypatch.setenv("CELERY_BROKER_URL", "redis://redis/0")

    assert w.targets() == [("redis", ("redis", 6379))]


def test_nothing_configured_is_not_an_error(monkeypatch):
    """`shell` and one-off runs are legitimate. Refusing to start would make
    this gate the reason a debugging container will not boot."""
    monkeypatch.delenv("DB_HOST", raising=False)
    monkeypatch.delenv("CELERY_BROKER_URL", raising=False)

    assert w.targets() == []
    assert w.main([]) == 0


def test_it_returns_as_soon_as_the_port_accepts(monkeypatch):
    attempts = {"n": 0}

    def accepts(host, port):
        attempts["n"] += 1
        return attempts["n"] >= 3

    monkeypatch.setattr(w, "_accepts", accepts)
    monkeypatch.setattr(w.time, "sleep", lambda _: None)

    assert w.wait("postgres", "h", 5432, deadline=float("inf")) is True
    assert attempts["n"] == 3


def test_it_gives_up_at_the_deadline_rather_than_hanging(monkeypatch):
    """A wait with no deadline is a bug (rule 156). A container that never
    starts and never says why is the shape this must not have."""
    monkeypatch.setattr(w, "_accepts", lambda h, p: False)
    monkeypatch.setattr(w.time, "sleep", lambda _: None)

    clock = iter([0.0, 0.0, 99.0])
    assert w.wait(
        "postgres", "h", 5432, deadline=10.0, now=lambda: next(clock),
    ) is False


def test_a_dependency_that_never_comes_up_fails_the_boot(monkeypatch):
    monkeypatch.setenv("DB_HOST", "postgres")
    monkeypatch.delenv("CELERY_BROKER_URL", raising=False)
    monkeypatch.setattr(w, "_accepts", lambda h, p: False)
    monkeypatch.setattr(w.time, "sleep", lambda _: None)

    assert w.main(["--timeout", "0"]) == 1