"""v1.1 WP-C: the browser harness's download helpers, without a browser.

`tools/m11_webdriver.wait_for_download` is what decides that an export actually
left the browser as a file. It must never call a download finished because a
file appeared, because it is still being written, or because it is empty — each
of those would make "the export works" a claim the evidence does not support.

    python -m pytest tests/test_v11_c_browser_helpers.py -v
"""

import threading
import time
from pathlib import Path

import pytest

from tools import m11_webdriver as wd


def later(seconds, action):
    timer = threading.Timer(seconds, action)
    timer.start()
    return timer


def test_a_finished_file_is_returned(tmp_path):
    later(0.2, lambda: (tmp_path / "campaign.json").write_text('{"format": "x"}'))
    found = wd.wait_for_download(tmp_path, set(), timeout=5, poll=0.05)
    assert found == tmp_path / "campaign.json"


def test_a_file_that_was_already_there_is_not_the_download(tmp_path):
    (tmp_path / "old.json").write_text("{}")
    with pytest.raises(wd.WebDriverError):
        wd.wait_for_download(tmp_path, {"old.json"}, timeout=0.6, poll=0.05)


def test_an_empty_file_never_counts(tmp_path):
    (tmp_path / "empty.json").write_bytes(b"")
    with pytest.raises(wd.WebDriverError):
        wd.wait_for_download(tmp_path, set(), timeout=0.6, poll=0.05)


def test_nothing_counts_while_firefox_is_still_writing(tmp_path):
    """Firefox writes `<name>.part` beside the final name until it is done."""
    (tmp_path / "campaign.json").write_text('{"format": "x"}')
    (tmp_path / "campaign.json.part").write_text("")
    with pytest.raises(wd.WebDriverError):
        wd.wait_for_download(tmp_path, set(), timeout=0.6, poll=0.05)
    later(0.1, lambda: (tmp_path / "campaign.json.part").unlink())
    assert wd.wait_for_download(tmp_path, set(), timeout=5, poll=0.05).name == "campaign.json"


def test_a_file_that_is_still_growing_is_not_finished(tmp_path):
    target = tmp_path / "big.json"
    target.write_text("{")
    stop = threading.Event()

    def grow():
        for _ in range(8):
            if stop.is_set():
                return
            with target.open("a") as fh:
                fh.write("x" * 100)
            time.sleep(0.05)

    writer = threading.Thread(target=grow)
    started = time.monotonic()
    writer.start()
    found = wd.wait_for_download(tmp_path, set(), timeout=5, poll=0.05, stable_polls=3)
    writer.join()
    # Returned only once the size held still, so after the last write.
    assert found == target
    assert target.stat().st_size == 1 + 8 * 100
    assert time.monotonic() - started >= 0.4


def test_the_prefs_save_downloads_unasked_to_the_folder_given(tmp_path):
    prefs = wd.firefox_download_prefs(tmp_path)
    assert prefs["browser.download.folderList"] == 2
    assert prefs["browser.download.dir"] == str(tmp_path)
    assert prefs["browser.download.useDownloadDir"] is True
    assert prefs["browser.download.always_ask_before_handling_new_types"] is False
    assert "application/json" in prefs["browser.helperApps.neverAsk.saveToDisk"]


def test_a_download_folder_must_be_under_home():
    with pytest.raises(wd.WebDriverError):
        wd.require_under_home(Path("/tmp/wp-c-downloads"))
    inside = Path.home() / "v11-evidence" / "wp-c" / "downloads"
    assert wd.require_under_home(inside) == inside.resolve()