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import io
from unittest import mock
from urllib.error import HTTPError, URLError

import pytest

from scripts import change_detector


def _make_response(body: bytes) -> mock.MagicMock:
    """Builds a mock that mimics urlopen's context-manager response."""
    response: mock.MagicMock = mock.MagicMock()
    response.__enter__.return_value.read.return_value = body
    return response


def test_fetch_retries_transient_error_then_succeeds() -> None:
    payload: list[dict[str, str]] = [{"filename": "superset/foo.py"}]
    side_effects: list[object] = [
        HTTPError("http://api", 500, "Server Error", {}, None),  # type: ignore
        HTTPError("http://api", 502, "Bad Gateway", {}, None),  # type: ignore
        _make_response(b'[{"filename": "superset/foo.py"}]'),
    ]
    with (
        mock.patch.object(
            change_detector, "urlopen", side_effect=side_effects
        ) as urlopen_mock,
        mock.patch.object(change_detector.time, "sleep") as sleep_mock,
    ):
        result = change_detector.fetch_files_github_api("http://api")

    assert result == payload
    assert urlopen_mock.call_count == 3
    assert sleep_mock.call_count == 2


def test_fetch_retries_rate_limit_then_succeeds() -> None:
    side_effects: list[object] = [
        HTTPError("http://api", 429, "Too Many Requests", {}, None),  # type: ignore
        _make_response(b"[]"),
    ]
    with (
        mock.patch.object(
            change_detector, "urlopen", side_effect=side_effects
        ) as urlopen_mock,
        mock.patch.object(change_detector.time, "sleep") as sleep_mock,
    ):
        result = change_detector.fetch_files_github_api("http://api")

    assert result == []
    assert urlopen_mock.call_count == 2
    assert sleep_mock.call_count == 1


def test_fetch_does_not_retry_client_error() -> None:
    with (
        mock.patch.object(
            change_detector,
            "urlopen",
            side_effect=HTTPError("http://api", 404, "Not Found", {}, None),  # type: ignore
        ) as urlopen_mock,
        mock.patch.object(change_detector.time, "sleep") as sleep_mock,
    ):
        with pytest.raises(HTTPError):
            change_detector.fetch_files_github_api("http://api")

    assert urlopen_mock.call_count == 1
    assert sleep_mock.call_count == 0


def test_fetch_gives_up_after_max_retries() -> None:
    with (
        mock.patch.object(
            change_detector, "urlopen", side_effect=URLError("connection reset")
        ) as urlopen_mock,
        mock.patch.object(change_detector.time, "sleep"),
    ):
        with pytest.raises(URLError):
            change_detector.fetch_files_github_api("http://api")

    assert urlopen_mock.call_count == change_detector.MAX_RETRIES


def _http_error(
    status: int, headers: dict[str, str] | None = None, body: bytes = b""
) -> HTTPError:
    """Builds an HTTPError carrying headers and a readable body, as urllib does."""
    return HTTPError(
        "http://api",
        status,
        "Forbidden",
        headers or {},  # type: ignore[arg-type]
        io.BytesIO(body),
    )


def test_fetch_does_not_retry_a_permission_denied_403() -> None:
    """A missing token scope is deterministic; retrying only delays the failure."""
    error = _http_error(
        403,
        headers={"x-ratelimit-remaining": "4998"},
        body=b'{"message": "Resource not accessible by integration"}',
    )
    with (
        mock.patch.object(
            change_detector, "urlopen", side_effect=error
        ) as urlopen_mock,
        mock.patch.object(change_detector.time, "sleep") as sleep_mock,
    ):
        with pytest.raises(HTTPError):
            change_detector.fetch_files_github_api("http://api")

    assert urlopen_mock.call_count == 1
    sleep_mock.assert_not_called()


def test_fetch_retries_a_rate_limited_403() -> None:
    """GitHub signals rate limiting with 403 and an exhausted remaining count."""
    side_effects: list[object] = [
        _http_error(403, headers={"x-ratelimit-remaining": "0"}),
        _make_response(b'[{"filename": "superset/foo.py"}]'),
    ]
    with (
        mock.patch.object(change_detector, "urlopen", side_effect=side_effects),
        mock.patch.object(change_detector.time, "sleep"),
    ):
        result = change_detector.fetch_files_github_api("http://api")

    assert result == [{"filename": "superset/foo.py"}]


def test_fetch_reports_the_api_error_message(capsys) -> None:
    """The response body names the cause; without it a 403 is unactionable."""
    error = _http_error(
        403,
        headers={"x-ratelimit-remaining": "4998"},
        body=b'{"message": "Resource not accessible by integration"}',
    )
    with mock.patch.object(change_detector, "urlopen", side_effect=error):
        with pytest.raises(HTTPError):
            change_detector.fetch_files_github_api("http://api")

    assert "Resource not accessible by integration" in capsys.readouterr().out


def test_image_tag_compose_changes_trigger_python_tests() -> None:
    assert change_detector.detect_changes(
        ["docker-compose-image-tag.yml"],
        change_detector.PATTERNS["python"],
    )